begin debugging gvisor crash

* all: clean up code with Go 1.24+ in mind

* all: more old go cleanup

* all: even remove rand_fastrand64

* runtime: revert rand changes

* runtime: re-drop rand_fastrand64

.github/workflows/build-macos.yml

@@ -40,7 +40,7 @@ jobs:
       - name: Install Go
         uses: actions/setup-go@v6
         with:
-          go-version: '1.26.2'
+          go-version: '1.26.4'
           cache: true
       - name: Restore LLVM source cache
         uses: actions/cache/restore@v5
@@ -131,7 +131,7 @@ jobs:
       - name: Install Go
         uses: actions/setup-go@v6
         with:
-          go-version: '1.26.2'
+          go-version: '1.26.4'
           cache: true
       - name: Build TinyGo (LLVM ${{ matrix.version }})
         run: go install -tags=llvm${{ matrix.version }}

.github/workflows/compat.yml

@@ -0,0 +1,72 @@
+# This CI job checks whether at least the smoke tests pass for the oldest
+# Go/LLVM version we claim to support.
+
+name: Version compatibility test
+
+on:
+  pull_request:
+  push:
+    branches:
+      - dev
+      - release
+
+concurrency:
+  group: ${{ github.workflow }}-${{ github.ref }}
+  cancel-in-progress: true
+
+jobs:
+  test-compat:
+    runs-on: ubuntu-22.04 # this must be a specific version for the apt install below
+    env:
+      # Oldest versions currently supported by TinyGo
+      LLVM: "15"
+      Go: "1.24" # when updating this, also update minorMin in builder/config.go
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v6
+        with:
+          submodules: true
+      - name: Install Go
+        uses: actions/setup-go@v6
+        with:
+          go-version: ${{ env.Go }}
+          cache: true
+      - name: Install LLVM
+        run: |
+          echo 'deb https://apt.llvm.org/jammy/ llvm-toolchain-jammy-${{ env.LLVM }} main' | sudo tee /etc/apt/sources.list.d/llvm.list
+          wget -O - https://apt.llvm.org/llvm-snapshot.gpg.key | sudo apt-key add -
+          sudo apt-get update
+          sudo apt-get install --no-install-recommends -y \
+              llvm-${{ env.LLVM }}-dev \
+              clang-${{ env.LLVM }} \
+              libclang-${{ env.LLVM }}-dev \
+              lld-${{ env.LLVM }} \
+              binaryen
+      - name: Restore LLVM source cache
+        uses: actions/cache/restore@v5
+        id: cache-llvm-source
+        with:
+          key: llvm-source-20-linux-compat
+          path: llvm-project/compiler-rt
+      - name: Download LLVM source
+        if: steps.cache-llvm-source.outputs.cache-hit != 'true'
+        run: make llvm-source
+      - name: Save LLVM source cache
+        uses: actions/cache/save@v5
+        if: steps.cache-llvm-source.outputs.cache-hit != 'true'
+        with:
+          key: ${{ steps.cache-llvm-source.outputs.cache-primary-key }}
+          path: llvm-project/compiler-rt
+      - name: Go cache
+        uses: actions/cache@v5
+        with:
+          path: |
+            ~/.cache/go-build
+            ~/go/pkg/mod
+          key: go-build-${{ env.Go }}-llvm${{ env.LLVM }}-${{ hashFiles('go.sum') }}
+      - name: Build TinyGo
+        run: go install -tags=llvm${{ env.LLVM }}
+      - run: tinygo version
+      - run: make gen-device -j4
+      - run: go test -tags=llvm${{ env.LLVM }} -short -skip=TestErrors
+      - run: make smoketest XTENSA=0

.github/workflows/linux.yml

@@ -12,6 +12,24 @@ concurrency:
   cancel-in-progress: true
 
 jobs:
+  go-mod-tidy:
+    # Check that go.sum is up to date.
+    runs-on: ubuntu-slim
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v6
+        with:
+          submodules: true
+      - name: Install Go
+        uses: actions/setup-go@v6
+        with:
+          go-version: '1.26.4'
+          cache: true
+      - name: Run go mod tidy
+        run: go mod tidy
+      - name: Check go.mod and go.sum are up to date
+        run: git diff --exit-code
+
   build-linux:
     # Build Linux binaries, ready for release.
     # This runs inside an Alpine Linux container so we can more easily create a
@@ -142,7 +160,7 @@ jobs:
       - name: Install Go
         uses: actions/setup-go@v6
         with:
-          go-version: '1.26.2'
+          go-version: '1.26.4'
           cache: true
       - name: Install wasmtime
         uses: bytecodealliance/actions/wasmtime/setup@v1
@@ -186,7 +204,7 @@ jobs:
       - name: Install Go
         uses: actions/setup-go@v6
         with:
-          go-version: '1.26.2'
+          go-version: '1.26.4'
           cache: true
       - name: Install Node.js
         uses: actions/setup-node@v6
@@ -266,6 +284,8 @@ jobs:
       - run: make smoketest
       - run: make wasmtest
       - run: make tinygo-test-baremetal
+      - name: Check Go code formatting
+        run: make fmt-check lint
   build-linux-cross:
     # Build ARM Linux binaries, ready for release.
     # This intentionally uses an older Linux image, so that we compile against
@@ -303,7 +323,7 @@ jobs:
       - name: Install Go
         uses: actions/setup-go@v6
         with:
-          go-version: '1.26.2'
+          go-version: '1.26.4'
           cache: true
       - name: Restore LLVM source cache
         uses: actions/cache/restore@v5

.github/workflows/windows.yml

@@ -17,12 +17,6 @@ jobs:
     outputs:
       version: ${{ steps.version.outputs.version }}
     steps:
-      - name: Configure pagefile
-        uses: al-cheb/configure-pagefile-action@v1.4
-        with:
-          minimum-size: 8GB
-          maximum-size: 24GB
-          disk-root: "C:"
       - uses: MinoruSekine/setup-scoop@v4
       - name: Install Dependencies
         shell: bash
@@ -40,13 +34,13 @@ jobs:
       - name: Install Go
         uses: actions/setup-go@v6
         with:
-          go-version: '1.26.2'
+          go-version: '1.26.4'
           cache: true
       - name: Restore cached LLVM source
         uses: actions/cache/restore@v5
         id: cache-llvm-source
         with:
-          key: llvm-source-20-windows-v1
+          key: llvm-source-20-windows-v3
           path: |
             llvm-project/clang/lib/Headers
             llvm-project/clang/include
@@ -71,7 +65,7 @@ jobs:
         uses: actions/cache/restore@v5
         id: cache-llvm-build
         with:
-          key: llvm-build-20-windows-v2
+          key: llvm-build-20-windows-v4
           path: llvm-build
       - name: Build LLVM
         if: steps.cache-llvm-build.outputs.cache-hit != 'true'
@@ -93,7 +87,7 @@ jobs:
       - name: Cache Go cache
         uses: actions/cache@v5
         with:
-          key: go-cache-windows-v2-${{ hashFiles('go.mod') }}
+          key: go-cache-windows-v3-${{ hashFiles('go.mod') }}
           path: |
             C:/Users/runneradmin/AppData/Local/go-build
             C:/Users/runneradmin/go/pkg/mod
@@ -124,12 +118,6 @@ jobs:
     runs-on: windows-2022
     needs: build-windows
     steps:
-      - name: Configure pagefile
-        uses: al-cheb/configure-pagefile-action@v1.4
-        with:
-          minimum-size: 8GB
-          maximum-size: 24GB
-          disk-root: "C:"
       - uses: MinoruSekine/setup-scoop@v4
       - name: Install Dependencies
         shell: bash
@@ -141,7 +129,7 @@ jobs:
       - name: Install Go
         uses: actions/setup-go@v6
         with:
-          go-version: '1.26.2'
+          go-version: '1.26.4'
           cache: true
       - name: Download TinyGo build
         uses: actions/download-artifact@v8
@@ -157,18 +145,12 @@ jobs:
     runs-on: windows-2022
     needs: build-windows
     steps:
-      - name: Configure pagefile
-        uses: al-cheb/configure-pagefile-action@v1.4
-        with:
-          minimum-size: 8GB
-          maximum-size: 24GB
-          disk-root: "C:"
       - name: Checkout
         uses: actions/checkout@v6
       - name: Install Go
         uses: actions/setup-go@v6
         with:
-          go-version: '1.26.2'
+          go-version: '1.26.4'
           cache: true
       - name: Download TinyGo build
         uses: actions/download-artifact@v8
@@ -183,12 +165,6 @@ jobs:
     runs-on: windows-2022
     needs: build-windows
     steps:
-      - name: Configure pagefile
-        uses: al-cheb/configure-pagefile-action@v1.4
-        with:
-          minimum-size: 8GB
-          maximum-size: 24GB
-          disk-root: "C:"
       - uses: MinoruSekine/setup-scoop@v4
       - name: Install Dependencies
         shell: bash
@@ -200,7 +176,7 @@ jobs:
       - name: Install Go
         uses: actions/setup-go@v6
         with:
-          go-version: '1.26.2'
+          go-version: '1.26.4'
           cache: true
       - name: Download TinyGo build
         uses: actions/download-artifact@v8

GNUmakefile

@@ -194,6 +194,12 @@ NINJA_BUILD_TARGETS = clang llvm-config llvm-ar llvm-nm lld $(addprefix lib/lib,
 ifneq ("$(wildcard $(LLVM_BUILDDIR)/bin/llvm-config*)","")
     CGO_CPPFLAGS+=$(shell $(LLVM_CONFIG_PREFIX) $(LLVM_BUILDDIR)/bin/llvm-config --cppflags) -I$(abspath $(LLVM_BUILDDIR))/tools/clang/include -I$(abspath $(CLANG_SRC))/include -I$(abspath $(LLD_SRC))/include
     CGO_CXXFLAGS=-std=c++17
+ifneq ($(uname),Windows_NT)
+    # Disable GCC DWARF compression: lld built without zlib cannot link
+    # object files with ELFCOMPRESS_ZLIB debug sections.
+    CGO_CFLAGS+=-gz=none
+    CGO_CXXFLAGS+=-gz=none
+endif
     CGO_LDFLAGS+=-L$(abspath $(LLVM_BUILDDIR)/lib) -lclang $(CLANG_LIBS) $(LLD_LIBS) $(shell $(LLVM_CONFIG_PREFIX) $(LLVM_BUILDDIR)/bin/llvm-config --ldflags --libs --system-libs $(LLVM_COMPONENTS)) -lstdc++ $(CGO_LDFLAGS_EXTRA)
 endif
 
@@ -310,7 +316,7 @@ check-nodejs-version:
 
 tinygo: ## Build the TinyGo compiler
 	@if [ ! -f "$(LLVM_BUILDDIR)/bin/llvm-config" ]; then echo "Fetch and build LLVM first by running:"; echo "  $(MAKE) llvm-source"; echo "  $(MAKE) $(LLVM_BUILDDIR)"; exit 1; fi
-	CGO_CPPFLAGS="$(CGO_CPPFLAGS)" CGO_CXXFLAGS="$(CGO_CXXFLAGS)" CGO_LDFLAGS="$(CGO_LDFLAGS)" $(GOENVFLAGS) $(GO) build -buildmode exe -o build/tinygo$(EXE) -tags "byollvm osusergo" .
+	CGO_CPPFLAGS="$(CGO_CPPFLAGS)" CGO_CFLAGS="$(CGO_CFLAGS)" CGO_CXXFLAGS="$(CGO_CXXFLAGS)" CGO_LDFLAGS="$(CGO_LDFLAGS)" $(GOENVFLAGS) $(GO) build -buildmode exe -o build/tinygo$(EXE) -tags "byollvm osusergo" .
 test: check-nodejs-version
 	CGO_CPPFLAGS="$(CGO_CPPFLAGS)" CGO_CXXFLAGS="$(CGO_CXXFLAGS)" CGO_LDFLAGS="$(CGO_LDFLAGS)" $(GO) test $(GOTESTFLAGS) -timeout=1h -buildmode exe -tags "byollvm osusergo" $(GOTESTPKGS)
 
@@ -379,22 +385,22 @@ TEST_PACKAGES_FAST = \
 # archive/zip requires os.ReadAt, which is not yet supported on windows
 # bytes requires mmap
 # compress/flate appears to hang on wasi
-# crypto/aes fails on wasi, needs panic()/recover()
+# crypto/aes needs reflect.Type.Method(), not yet implemented
 # crypto/des fails on wasi, needs panic()/recover()
 # crypto/hmac fails on wasi, it exits with a "slice out of range" panic
 # debug/plan9obj requires os.ReadAt, which is not yet supported on windows
 # encoding/xml takes a minute on linux and gives a stack overflow on wasi
-# image requires recover(), which is not yet supported on wasi
+# image fails on wasi, needs panic()/recover()
 # io/ioutil requires os.ReadDir, which is not yet supported on windows or wasi
-# mime: fail on wasi; neds panic()/recover()
+# mime: fails on wasi, needs panic()/recover()
 # mime/multipart: needs wasip1 syscall.FDFLAG_NONBLOCK
 # mime/quotedprintable requires syscall.Faccessat
 # net/mail: needs wasip1  syscall.FDFLAG_NONBLOCK
 # net/ntextproto: needs wasip1 syscall.FDFLAG_NONBLOCK
-# regexp/syntax: fails on wasip1; needs panic()/recover()
-# strconv requires recover() which is not yet supported on wasi
-# text/tabwriter requires recover(), which is not yet supported on wasi
-# text/template/parse requires recover(), which is not yet supported on wasi
+# regexp/syntax: fails on wasip1, needs panic()/recover()
+# strconv: fails on wasi, needs panic()/recover()
+# text/tabwriter: fails on wasi, needs panic()/recover()
+# text/template/parse: fails on wasi, needs panic()/recover()
 # testing/fstest requires os.ReadDir, which is not yet supported on windows or wasi
 
 # Additional standard library packages that pass tests on individual platforms
@@ -419,6 +425,7 @@ TEST_PACKAGES_LINUX := \
 	os/user \
 	regexp/syntax \
 	strconv \
+	testing/fstest \
 	text/tabwriter \
 	text/template/parse
 
@@ -429,7 +436,11 @@ TEST_PACKAGES_WINDOWS := \
 	compress/flate \
 	crypto/des \
 	crypto/hmac \
+	image \
+	mime \
+	regexp/syntax \
 	strconv \
+	text/tabwriter \
 	text/template/parse \
 	$(nil)
 
@@ -778,6 +789,8 @@ endif
 	@$(MD5SUM) test.hex
 	$(TINYGO) build -size short -o test.hex -target=pico                examples/blinky1
 	@$(MD5SUM) test.hex
+	$(TINYGO) build -size short -o test.hex -target=pico -gc=leaking    examples/blinky1
+	@$(MD5SUM) test.hex
 	$(TINYGO) build -size short -o test.hex -target=nano-33-ble         examples/blinky1
 	@$(MD5SUM) test.hex
 	$(TINYGO) build -size short -o test.hex -target=nano-rp2040         examples/blinky1
@@ -947,6 +960,11 @@ ifneq ($(XTENSA), 0)
 	@$(MD5SUM) test.bin
 	$(TINYGO) build -size short -o test.bin -target mch2022             examples/machinetest
 	@$(MD5SUM) test.bin
+	# xiao-esp32c6
+	$(TINYGO) build -size short -o test.bin -target=xiao-esp32c6      	examples/blinky1
+	@$(MD5SUM) test.bin
+	$(TINYGO) build -size short -o test.bin -target=xiao-esp32c6   		examples/blinkm
+	@$(MD5SUM) test.bin
 	# xiao-esp32s3
 	$(TINYGO) build -size short -o test.bin -target=xiao-esp32s3   		examples/blinky1
 	@$(MD5SUM) test.bin
@@ -967,6 +985,8 @@ ifneq ($(XTENSA), 0)
 	@$(MD5SUM) test.bin
 	$(TINYGO) build -size short -o test.bin -target=esp32s3-supermini   	examples/adc
 	@$(MD5SUM) test.bin
+	$(TINYGO) build -size short -o test.bin -target=esp32s3-box-3       examples/blinky1
+	@$(MD5SUM) test.bin
 endif
     # esp32c3-supermini
 	$(TINYGO) build -size short -o test.bin -target=esp32c3-supermini	    examples/blinky1
@@ -1163,8 +1183,8 @@ endif
 	@cp -rp lib/wasi-libc/libc-top-half/musl/src/unistd             build/release/tinygo/lib/wasi-libc/libc-top-half/musl/src
 	@cp -rp lib/wasi-libc/libc-top-half/sources                     build/release/tinygo/lib/wasi-libc/libc-top-half
 	@cp -rp lib/wasi-cli/wit                                        build/release/tinygo/lib/wasi-cli/wit
-	@cp -rp llvm-project/compiler-rt/lib/builtins build/release/tinygo/lib/compiler-rt-builtins
-	@cp -rp llvm-project/compiler-rt/LICENSE.TXT  build/release/tinygo/lib/compiler-rt-builtins
+	@cp -rp ${LLVM_PROJECTDIR}/compiler-rt/lib/builtins build/release/tinygo/lib/compiler-rt-builtins
+	@cp -rp ${LLVM_PROJECTDIR}/compiler-rt/LICENSE.TXT  build/release/tinygo/lib/compiler-rt-builtins
 	@cp -rp src                          build/release/tinygo/src
 	@cp -rp targets                      build/release/tinygo/targets
 

builder/build.go

@@ -1076,7 +1076,7 @@ func Build(pkgName, outpath, tmpdir string, config *compileopts.Config) (BuildRe
 		if err != nil {
 			return result, err
 		}
-	case "esp32", "esp32-img", "esp32c3", "esp32s3", "esp8266":
+	case "esp32", "esp32-img", "esp32c3", "esp32s3", "esp32c6", "esp8266":
 		// Special format for the ESP family of chips (parsed by the ROM
 		// bootloader).
 		result.Binary = filepath.Join(tmpdir, "main"+outext)
@@ -1352,6 +1352,14 @@ func determineStackSizes(mod llvm.Module, executable string) ([]string, map[stri
 	}
 	baseStackSize, baseStackSizeType, baseStackSizeFailedAt := functions["tinygo_startTask"][0].StackSize()
 
+	// Account for the bytes that tinygo_swapTask pushes onto the goroutine stack
+	// on every context switch. The static analysis correctly traces Go calls,
+	// but it cannot see into the assembly-level register push.
+	var contextSwitchOverhead uint64
+	if swapFuncs, ok := functions["tinygo_swapTask"]; ok && len(swapFuncs) == 1 {
+		contextSwitchOverhead = swapFuncs[0].FrameSize
+	}
+
 	sizes := make(map[string]functionStackSize)
 
 	// Add the reset handler function, for convenience. The reset handler runs
@@ -1400,6 +1408,12 @@ func determineStackSizes(mod llvm.Module, executable string) ([]string, map[stri
 			// overflow will occur even before the goroutine is started.
 			stackSize = baseStackSize
 		}
+		if stackSizeType == stacksize.Bounded {
+			// Add the overhead of context switching. This is needed because the
+			// context switch (tinygo_swapTask) pushes callee-saved registers
+			// onto the current stack, which is not seen by the static analysis.
+			stackSize += contextSwitchOverhead
+		}
 		sizes[name] = functionStackSize{
 			stackSize:        stackSize,
 			stackSizeType:    stackSizeType,

builder/builder_test.go

@@ -28,6 +28,7 @@ func TestClangAttributes(t *testing.T) {
 		"cortex-m4",
 		"cortex-m7",
 		"esp32c3",
+		"esp32c6",
 		"esp32s3",
 		"fe310",
 		"gameboy-advance",

builder/config.go

@@ -25,7 +25,7 @@ func NewConfig(options *compileopts.Options) (*compileopts.Config, error) {
 	}
 
 	// Version range supported by TinyGo.
-	const minorMin = 19
+	const minorMin = 24 // when updating the min version, also update .github/workflows/compat.yml
 	const minorMax = 26
 
 	// Check that we support this Go toolchain version.

builder/esp.go

@@ -100,12 +100,24 @@ func makeESPFirmwareImage(infile, outfile, format string) error {
 	chip_id := map[string]uint16{
 		"esp32":   0x0000,
 		"esp32c3": 0x0005,
+		"esp32c6": 0x000d,
 		"esp32s3": 0x0009,
 	}[chip]
 
+	// SPI flash speed/size byte (byte 3 of header):
+	//   Upper nibble = flash size, lower nibble = flash frequency.
+	//   The espflasher auto-detects and patches the flash size (upper nibble),
+	//   but the frequency (lower nibble) must be correct per chip.
+	spiSpeedSize := map[string]uint8{
+		"esp32":   0x1f, // 80MHz=0x0F, 2MB=0x10
+		"esp32c3": 0x1f, // 80MHz=0x0F, 2MB=0x10
+		"esp32c6": 0x10, // 80MHz=0x00, 2MB=0x10 (C6 uses different freq encoding)
+		"esp32s3": 0x1f, // 80MHz=0x0F, 2MB=0x10
+	}[chip]
+
 	// Image header.
 	switch chip {
-	case "esp32", "esp32c3", "esp32s3":
+	case "esp32", "esp32c3", "esp32s3", "esp32c6":
 		// Header format:
 		// https://github.com/espressif/esp-idf/blob/v4.3/components/bootloader_support/include/esp_app_format.h#L71
 		// Note: not adding a SHA256 hash as the binary is modified by
@@ -126,8 +138,8 @@ func makeESPFirmwareImage(infile, outfile, format string) error {
 		}{
 			magic:          0xE9,
 			segment_count:  byte(len(segments)),
-			spi_mode:       2,    // ESP_IMAGE_SPI_MODE_DIO
-			spi_speed_size: 0x1f, // ESP_IMAGE_SPI_SPEED_80M, ESP_IMAGE_FLASH_SIZE_2MB
+			spi_mode:       2, // ESP_IMAGE_SPI_MODE_DIO
+			spi_speed_size: spiSpeedSize,
 			entry_addr:     uint32(inf.Entry),
 			wp_pin:         0xEE, // disable WP pin
 			chip_id:        chip_id,

builder/library.go

@@ -218,7 +218,7 @@ func (l *Library) load(config *compileopts.Config, tmpdir string) (job *compileJ
 				return err
 			}
 			// Store this archive in the cache.
-			return os.Rename(f.Name(), archiveFilePath)
+			return robustRename(f.Name(), archiveFilePath)
 		},
 	}
 

builder/robustio_other.go

@@ -0,0 +1,9 @@
+//go:build !windows
+
+package builder
+
+import "os"
+
+func robustRename(oldpath, newpath string) error {
+	return os.Rename(oldpath, newpath)
+}

builder/robustio_windows.go

@@ -0,0 +1,44 @@
+package builder
+
+import (
+	"errors"
+	"math/rand"
+	"os"
+	"syscall"
+	"time"
+)
+
+const robustRenameTimeout = 2 * time.Second
+
+func robustRename(oldpath, newpath string) error {
+	var bestErr error
+	start := time.Now()
+	nextSleep := time.Millisecond
+	for {
+		err := os.Rename(oldpath, newpath)
+		if err == nil || !isEphemeralRenameError(err) {
+			return err
+		}
+		if bestErr == nil {
+			bestErr = err
+		}
+		if d := time.Since(start) + nextSleep; d >= robustRenameTimeout {
+			return bestErr
+		}
+		time.Sleep(nextSleep)
+		nextSleep += time.Duration(rand.Int63n(int64(nextSleep)))
+	}
+}
+
+func isEphemeralRenameError(err error) bool {
+	var errno syscall.Errno
+	if errors.As(err, &errno) {
+		switch errno {
+		case syscall.Errno(2), // ERROR_FILE_NOT_FOUND
+			syscall.Errno(5),  // ERROR_ACCESS_DENIED
+			syscall.Errno(32): // ERROR_SHARING_VIOLATION
+			return true
+		}
+	}
+	return false
+}

builder/sizes.go

@@ -501,8 +501,9 @@ func loadProgramSize(path string, packagePathMap map[string]string) (*programSiz
 						Align:   section.Addralign,
 						Type:    memoryStack,
 					})
-				} else {
-					// Regular .bss section.
+				} else if section.Flags&elf.SHF_WRITE != 0 {
+					// Regular .bss section. Zero-initialized RAM is always
+					// writable, so require SHF_WRITE here.
 					sections = append(sections, memorySection{
 						Address: section.Addr,
 						Size:    section.Size,
@@ -510,6 +511,11 @@ func loadProgramSize(path string, packagePathMap map[string]string) (*programSiz
 						Type:    memoryBSS,
 					})
 				}
+				// Other (non-writable) SHT_NOBITS sections are address-space
+				// placeholders that occupy no RAM, such as the ESP linker
+				// script's .irom_dummy / .rodata_dummy sections which reserve
+				// the flash-mapped XIP virtual address ranges. They must not be
+				// counted as bss/RAM usage.
 			} else if section.Type == elf.SHT_PROGBITS && section.Flags&elf.SHF_EXECINSTR != 0 {
 				// .text
 				sections = append(sections, memorySection{

builder/sizes_test.go

@@ -42,9 +42,9 @@ func TestBinarySize(t *testing.T) {
 	// This is a small number of very diverse targets that we want to test.
 	tests := []sizeTest{
 		// microcontrollers
-		{"hifive1b", "examples/echo", 3680, 280, 0, 2252},
-		{"microbit", "examples/serial", 2694, 342, 8, 2248},
-		{"wioterminal", "examples/pininterrupt", 7074, 1510, 120, 7248},
+		{"hifive1b", "examples/echo", 3699, 297, 0, 2252},
+		{"microbit", "examples/serial", 2736, 356, 8, 2248},
+		{"wioterminal", "examples/pininterrupt", 7960, 1652, 132, 7480},
 
 		// TODO: also check wasm. Right now this is difficult, because
 		// wasm binaries are run through wasm-opt and therefore the
@@ -99,7 +99,7 @@ func TestSizeFull(t *testing.T) {
 				t.Fatal("could not read program size:", err)
 			}
 			for _, pkg := range sizes.sortedPackageNames() {
-				if pkg == "(padding)" || pkg == "(unknown)" {
+				if pkg == "(padding)" || pkg == "(unknown)" || pkg == "Go types" {
 					// TODO: correctly attribute all unknown binary size.
 					continue
 				}

builder/tools.go

@@ -121,9 +121,11 @@ func parseLLDErrors(text string) error {
 				if matches != nil {
 					parsedError = true
 					line, _ := strconv.Atoi(matches[3])
-					// TODO: detect common mistakes like -gc=none?
 					msg := "linker could not find symbol " + symbolName
-					if symbolName == "runtime.alloc_noheap" {
+					switch symbolName {
+					case "runtime.alloc":
+						msg = "object allocated on the heap with -gc=none"
+					case "runtime.alloc_noheap":
 						msg = "object allocated on the heap in //go:noheap function"
 					}
 					linkErrors = append(linkErrors, scanner.Error{

cgo/cgo.go

@@ -26,10 +26,6 @@ import (
 	"golang.org/x/tools/go/ast/astutil"
 )
 
-// Function that's only defined in Go 1.22.
-var setASTFileFields = func(f *ast.File, start, end token.Pos) {
-}
-
 // cgoPackage holds all CGo-related information of a package.
 type cgoPackage struct {
 	generated       *ast.File
@@ -654,7 +650,6 @@ func (p *cgoPackage) createUnionAccessor(field *ast.Field, typeName string) {
 		X: &ast.Ident{
 			NamePos: pos,
 			Name:    "union",
-			Obj:     nil,
 		},
 		Sel: &ast.Ident{
 			NamePos: pos,
@@ -708,7 +703,6 @@ func (p *cgoPackage) createUnionAccessor(field *ast.Field, typeName string) {
 						X: &ast.Ident{
 							NamePos: pos,
 							Name:    typeName,
-							Obj:     nil,
 						},
 					},
 				},
@@ -764,7 +758,6 @@ func (p *cgoPackage) createBitfieldGetter(bitfield bitfieldInfo, typeName string
 		X: &ast.Ident{
 			NamePos: bitfield.pos,
 			Name:    "s",
-			Obj:     nil,
 		},
 		Sel: &ast.Ident{
 			NamePos: bitfield.pos,
@@ -811,11 +804,6 @@ func (p *cgoPackage) createBitfieldGetter(bitfield bitfieldInfo, typeName string
 						{
 							NamePos: bitfield.pos,
 							Name:    "s",
-							Obj: &ast.Object{
-								Kind: ast.Var,
-								Name: "s",
-								Decl: nil,
-							},
 						},
 					},
 					Type: &ast.StarExpr{
@@ -823,7 +811,6 @@ func (p *cgoPackage) createBitfieldGetter(bitfield bitfieldInfo, typeName string
 						X: &ast.Ident{
 							NamePos: bitfield.pos,
 							Name:    typeName,
-							Obj:     nil,
 						},
 					},
 				},
@@ -881,7 +868,6 @@ func (p *cgoPackage) createBitfieldSetter(bitfield bitfieldInfo, typeName string
 		X: &ast.Ident{
 			NamePos: bitfield.pos,
 			Name:    "s",
-			Obj:     nil,
 		},
 		Sel: &ast.Ident{
 			NamePos: bitfield.pos,
@@ -964,11 +950,6 @@ func (p *cgoPackage) createBitfieldSetter(bitfield bitfieldInfo, typeName string
 						{
 							NamePos: bitfield.pos,
 							Name:    "s",
-							Obj: &ast.Object{
-								Kind: ast.Var,
-								Name: "s",
-								Decl: nil,
-							},
 						},
 					},
 					Type: &ast.StarExpr{
@@ -976,7 +957,6 @@ func (p *cgoPackage) createBitfieldSetter(bitfield bitfieldInfo, typeName string
 						X: &ast.Ident{
 							NamePos: bitfield.pos,
 							Name:    typeName,
-							Obj:     nil,
 						},
 					},
 				},
@@ -997,7 +977,6 @@ func (p *cgoPackage) createBitfieldSetter(bitfield bitfieldInfo, typeName string
 							{
 								NamePos: bitfield.pos,
 								Name:    "value",
-								Obj:     nil,
 							},
 						},
 						Type: bitfield.field.Type,
@@ -1015,7 +994,6 @@ func (p *cgoPackage) createBitfieldSetter(bitfield bitfieldInfo, typeName string
 							X: &ast.Ident{
 								NamePos: bitfield.pos,
 								Name:    "s",
-								Obj:     nil,
 							},
 							Sel: &ast.Ident{
 								NamePos: bitfield.pos,

cgo/cgo_go122.go

@@ -1,17 +0,0 @@
-//go:build go1.22
-
-package cgo
-
-// Code specifically for Go 1.22.
-
-import (
-	"go/ast"
-	"go/token"
-)
-
-func init() {
-	setASTFileFields = func(f *ast.File, start, end token.Pos) {
-		f.FileStart = start
-		f.FileEnd = end
-	}
-}

cgo/libclang.go

@@ -217,10 +217,6 @@ func (f *cgoFile) createASTNode(name string, c clangCursor) (ast.Node, any) {
 	case C.CXCursor_FunctionDecl:
 		cursorType := C.tinygo_clang_getCursorType(c)
 		numArgs := int(C.tinygo_clang_Cursor_getNumArguments(c))
-		obj := &ast.Object{
-			Kind: ast.Fun,
-			Name: "_Cgo_" + name,
-		}
 		exportName := name
 		localName := name
 		var stringSignature string
@@ -258,7 +254,6 @@ func (f *cgoFile) createASTNode(name string, c clangCursor) (ast.Node, any) {
 			Name: &ast.Ident{
 				NamePos: pos,
 				Name:    "_Cgo_" + localName,
-				Obj:     obj,
 			},
 			Type: &ast.FuncType{
 				Func: pos,
@@ -295,11 +290,6 @@ func (f *cgoFile) createASTNode(name string, c clangCursor) (ast.Node, any) {
 					{
 						NamePos: pos,
 						Name:    argName,
-						Obj: &ast.Object{
-							Kind: ast.Var,
-							Name: argName,
-							Decl: decl,
-						},
 					},
 				},
 				Type: f.makeDecayingASTType(argType, pos),
@@ -315,7 +305,6 @@ func (f *cgoFile) createASTNode(name string, c clangCursor) (ast.Node, any) {
 				},
 			}
 		}
-		obj.Decl = decl
 		return decl, stringSignature
 	case C.CXCursor_StructDecl, C.CXCursor_UnionDecl:
 		typ := f.makeASTRecordType(c, pos)
@@ -325,39 +314,27 @@ func (f *cgoFile) createASTNode(name string, c clangCursor) (ast.Node, any) {
 			// Convert to a single-field struct type.
 			typeExpr = f.makeUnionField(typ)
 		}
-		obj := &ast.Object{
-			Kind: ast.Typ,
-			Name: typeName,
-		}
 		typeSpec := &ast.TypeSpec{
 			Name: &ast.Ident{
 				NamePos: typ.pos,
 				Name:    typeName,
-				Obj:     obj,
 			},
 			Type: typeExpr,
 		}
-		obj.Decl = typeSpec
 		return typeSpec, typ
 	case C.CXCursor_TypedefDecl:
 		typeName := "_Cgo_" + name
 		underlyingType := C.tinygo_clang_getTypedefDeclUnderlyingType(c)
-		obj := &ast.Object{
-			Kind: ast.Typ,
-			Name: typeName,
-		}
 		typeSpec := &ast.TypeSpec{
 			Name: &ast.Ident{
 				NamePos: pos,
 				Name:    typeName,
-				Obj:     obj,
 			},
 			Type: f.makeASTType(underlyingType, pos),
 		}
 		if underlyingType.kind != C.CXType_Enum {
 			typeSpec.Assign = pos
 		}
-		obj.Decl = typeSpec
 		return typeSpec, nil
 	case C.CXCursor_VarDecl:
 		cursorType := C.tinygo_clang_getCursorType(c)
@@ -376,19 +353,13 @@ func (f *cgoFile) createASTNode(name string, c clangCursor) (ast.Node, any) {
 				},
 			},
 		}
-		obj := &ast.Object{
-			Kind: ast.Var,
-			Name: "_Cgo_" + name,
-		}
 		valueSpec := &ast.ValueSpec{
 			Names: []*ast.Ident{{
 				NamePos: pos,
 				Name:    "_Cgo_" + name,
-				Obj:     obj,
 			}},
 			Type: typeExpr,
 		}
-		obj.Decl = valueSpec
 		gen.Specs = append(gen.Specs, valueSpec)
 		return gen, nil
 	case C.CXCursor_MacroDefinition:
@@ -405,26 +376,16 @@ func (f *cgoFile) createASTNode(name string, c clangCursor) (ast.Node, any) {
 			Lparen: token.NoPos,
 			Rparen: token.NoPos,
 		}
-		obj := &ast.Object{
-			Kind: ast.Con,
-			Name: "_Cgo_" + name,
-		}
 		valueSpec := &ast.ValueSpec{
 			Names: []*ast.Ident{{
 				NamePos: pos,
 				Name:    "_Cgo_" + name,
-				Obj:     obj,
 			}},
 			Values: []ast.Expr{expr},
 		}
-		obj.Decl = valueSpec
 		gen.Specs = append(gen.Specs, valueSpec)
 		return gen, nil
 	case C.CXCursor_EnumDecl:
-		obj := &ast.Object{
-			Kind: ast.Typ,
-			Name: "_Cgo_" + name,
-		}
 		underlying := C.tinygo_clang_getEnumDeclIntegerType(c)
 		// TODO: gc's CGo implementation uses types such as `uint32` for enums
 		// instead of types such as C.int, which are used here.
@@ -432,12 +393,10 @@ func (f *cgoFile) createASTNode(name string, c clangCursor) (ast.Node, any) {
 			Name: &ast.Ident{
 				NamePos: pos,
 				Name:    "_Cgo_" + name,
-				Obj:     obj,
 			},
 			Assign: pos,
 			Type:   f.makeASTType(underlying, pos),
 		}
-		obj.Decl = typeSpec
 		return typeSpec, nil
 	case C.CXCursor_EnumConstantDecl:
 		value := C.tinygo_clang_getEnumConstantDeclValue(c)
@@ -452,19 +411,13 @@ func (f *cgoFile) createASTNode(name string, c clangCursor) (ast.Node, any) {
 			Lparen: token.NoPos,
 			Rparen: token.NoPos,
 		}
-		obj := &ast.Object{
-			Kind: ast.Con,
-			Name: "_Cgo_" + name,
-		}
 		valueSpec := &ast.ValueSpec{
 			Names: []*ast.Ident{{
 				NamePos: pos,
 				Name:    "_Cgo_" + name,
-				Obj:     obj,
 			}},
 			Values: []ast.Expr{expr},
 		}
-		obj.Decl = valueSpec
 		gen.Specs = append(gen.Specs, valueSpec)
 		return gen, nil
 	default:
@@ -639,7 +592,8 @@ func (p *cgoPackage) getClangLocationPosition(location C.CXSourceLocation, tu C.
 			Package: f.Pos(0),
 			Name:    ast.NewIdent(p.packageName),
 		}
-		setASTFileFields(astFile, f.Pos(0), f.Pos(int(size)))
+		astFile.FileStart = f.Pos(0)
+		astFile.FileEnd = f.Pos(int(size))
 		p.cgoFiles = append(p.cgoFiles, astFile)
 	}
 	positionFile := p.tokenFiles[filename]
@@ -956,22 +910,16 @@ func (p *cgoPackage) getIntegerType(name string, cursor clangCursor) *ast.TypeSp
 	}
 
 	// Construct an *ast.TypeSpec for this type.
-	obj := &ast.Object{
-		Kind: ast.Typ,
-		Name: name,
-	}
 	spec := &ast.TypeSpec{
 		Name: &ast.Ident{
 			NamePos: pos,
 			Name:    name,
-			Obj:     obj,
 		},
 		Type: &ast.Ident{
 			NamePos: pos,
 			Name:    goName,
 		},
 	}
-	obj.Decl = spec
 	return spec
 }
 
@@ -1104,7 +1052,6 @@ func tinygo_clang_struct_visitor(c, parent C.GoCXCursor, client_data C.CXClientD
 				pos:      prevField.Names[0].NamePos,
 			})
 			prevField.Names[0].Name = bitfieldName
-			prevField.Names[0].Obj.Name = bitfieldName
 		}
 		prevBitfield := &(*bitfieldList)[len(*bitfieldList)-1]
 		prevBitfield.endBit = bitfieldOffset
@@ -1121,11 +1068,6 @@ func tinygo_clang_struct_visitor(c, parent C.GoCXCursor, client_data C.CXClientD
 		{
 			NamePos: pos,
 			Name:    name,
-			Obj: &ast.Object{
-				Kind: ast.Var,
-				Name: name,
-				Decl: field,
-			},
 		},
 	}
 	fieldList.List = append(fieldList.List, field)

compileopts/config.go

@@ -539,7 +539,7 @@ func (c *Config) Programmer() (method, openocdInterface string) {
 	case "openocd", "msd", "command", "adb":
 		// The -programmer flag only specifies the flash method.
 		return c.Options.Programmer, c.Target.OpenOCDInterface
-	case "bmp":
+	case "bmp", "probe-rs":
 		// The -programmer flag only specifies the flash method.
 		return c.Options.Programmer, ""
 	default:

compileopts/options.go

@@ -47,6 +47,7 @@ type Options struct {
 	Nobounds                bool
 	PrintSizes              string
 	PrintAllocs             *regexp.Regexp // regexp string
+	PrintAllocsCover        bool           // emit allocs in go coverage tool format
 	PrintStacks             bool
 	Tags                    []string
 	GlobalValues            map[string]map[string]string // map[pkgpath]map[varname]value

compileopts/target.go

@@ -67,6 +67,7 @@ type TargetSpec struct {
 	ADBPreCommands   []string `json:"adb-pre-commands,omitempty"`
 	ADBPushRemote    string   `json:"adb-push-remote,omitempty"`
 	ADBPostCommands  []string `json:"adb-post-commands,omitempty"`
+	ProbeRSChip      string   `json:"probe-rs-chip,omitempty"`
 	CodeModel        string   `json:"code-model,omitempty"`
 	RelocationModel  string   `json:"relocation-model,omitempty"`
 	WITPackage       string   `json:"wit-package,omitempty"`
@@ -484,6 +485,8 @@ func defaultTarget(options *Options) (*TargetSpec, error) {
 			"--no-insert-timestamp",
 			"--no-dynamicbase",
 		)
+		spec.ExtraFiles = append(spec.ExtraFiles,
+			"src/runtime/runtime_windows.c")
 	case "wasm", "wasip1", "wasip2":
 		return nil, fmt.Errorf("GOOS=%s but GOARCH is unset. Please set GOARCH to wasm", options.GOOS)
 	default:

compiler/asserts.go

@@ -241,24 +241,37 @@ func (b *builder) createRuntimeAssert(assert llvm.Value, blockPrefix, assertFunc
 		}
 	}
 
-	// Put the fault block at the end of the function and the next block at the
-	// current insert position.
-	faultBlock := b.ctx.AddBasicBlock(b.llvmFn, blockPrefix+".throw")
+	faultBlock := b.getRuntimeAssertBlock(blockPrefix, assertFunc)
 	nextBlock := b.insertBasicBlock(blockPrefix + ".next")
 	b.currentBlockInfo.exit = nextBlock // adjust outgoing block for phi nodes
 
 	// Now branch to the out-of-bounds or the regular block.
 	b.CreateCondBr(assert, faultBlock, nextBlock)
 
-	// Fail: the assert triggered so panic.
-	b.SetInsertPointAtEnd(faultBlock)
-	b.createRuntimeCall(assertFunc, nil, "")
-	b.CreateUnreachable()
-
 	// Ok: assert didn't trigger so continue normally.
 	b.SetInsertPointAtEnd(nextBlock)
 }
 
+func (b *builder) getRuntimeAssertBlock(blockPrefix, assertFunc string) llvm.BasicBlock {
+	if b.runtimeAssertBlocks == nil {
+		b.runtimeAssertBlocks = make(map[string]llvm.BasicBlock)
+	}
+	if block := b.runtimeAssertBlocks[assertFunc]; !block.IsNil() {
+		return block
+	}
+	savedBlock := b.GetInsertBlock()
+	block := b.ctx.AddBasicBlock(b.llvmFn, blockPrefix+".throw")
+	b.runtimeAssertBlocks[assertFunc] = block
+	b.SetInsertPointAtEnd(block)
+	if b.hasDeferFrame() {
+		b.createFaultCheckpoint()
+	}
+	b.createRuntimeCall(assertFunc, nil, "")
+	b.CreateUnreachable()
+	b.SetInsertPointAtEnd(savedBlock)
+	return block
+}
+
 // extendInteger extends the value to at least targetType using a zero or sign
 // extend. The resulting value is not truncated: it may still be bigger than
 // targetType.

compiler/channel.go

@@ -48,7 +48,7 @@ func (b *builder) createChanSend(instr *ssa.Send) {
 	channelOpAlloca, channelOpAllocaSize := b.createTemporaryAlloca(channelOp, "chan.op")
 
 	// Do the send.
-	b.createRuntimeCall("chanSend", []llvm.Value{ch, valueAlloca, channelOpAlloca}, "")
+	b.createRuntimeInvoke("chanSend", []llvm.Value{ch, valueAlloca, channelOpAlloca}, "")
 
 	// End the lifetime of the allocas.
 	// This also works around a bug in CoroSplit, at least in LLVM 8:
@@ -101,7 +101,7 @@ func (b *builder) createChanRecv(unop *ssa.UnOp) llvm.Value {
 
 // createChanClose closes the given channel.
 func (b *builder) createChanClose(ch llvm.Value) {
-	b.createRuntimeCall("chanClose", []llvm.Value{ch}, "")
+	b.createRuntimeInvoke("chanClose", []llvm.Value{ch}, "")
 }
 
 // createSelect emits all IR necessary for a select statements. That's a

compiler/compiler.go

@@ -92,6 +92,7 @@ type compilerContext struct {
 	pkg              *types.Package
 	packageDir       string // directory for this package
 	runtimePkg       *types.Package
+	localTypeNames   typeutil.Map // *types.Named (synthetic local from generic instantiation) -> string
 }
 
 // newCompilerContext returns a new compiler context ready for use, most
@@ -176,6 +177,9 @@ type builder struct {
 	deferBuiltinFuncs map[ssa.Value]deferBuiltin
 	runDefersBlock    []llvm.BasicBlock
 	afterDefersBlock  []llvm.BasicBlock
+
+	runtimeAssertBlocks  map[string]llvm.BasicBlock
+	interfaceAssertBlock llvm.BasicBlock
 }
 
 func newBuilder(c *compilerContext, irbuilder llvm.Builder, f *ssa.Function) *builder {
@@ -192,16 +196,6 @@ func newBuilder(c *compilerContext, irbuilder llvm.Builder, f *ssa.Function) *bu
 	}
 }
 
-// Return the runtime.alloc function variant.
-// This is normally just "alloc", but is "alloc_noheap" if the //go:noheap
-// pragma is used.
-func (b *builder) allocFunc() string {
-	if b.info.noheap {
-		return "alloc_noheap"
-	}
-	return "alloc"
-}
-
 type blockInfo struct {
 	// entry is the LLVM basic block corresponding to the start of this *ssa.Block.
 	entry llvm.BasicBlock
@@ -310,6 +304,11 @@ func CompilePackage(moduleName string, pkg *loader.Package, ssaPkg *ssa.Package,
 	// Convert AST to SSA.
 	ssaPkg.Build()
 
+	// Assign names to function-local named types before compiling the
+	// package, so that types declared in different functions (or in
+	// different instantiations of a generic function) do not collide.
+	c.scanLocalTypes(ssaPkg)
+
 	// Initialize debug information.
 	if c.Debug {
 		c.cu = c.dibuilder.CreateCompileUnit(llvm.DICompileUnit{
@@ -869,10 +868,9 @@ func (c *compilerContext) createPackage(irbuilder llvm.Builder, pkg *ssa.Package
 			}
 			// Create the function definition.
 			b := newBuilder(c, irbuilder, member)
-			if _, ok := mathToLLVMMapping[member.RelString(nil)]; ok {
+			if ok := b.defineMathOp(); ok {
 				// The body of this function (if there is one) is ignored and
 				// replaced with a LLVM intrinsic call.
-				b.defineMathOp()
 				continue
 			}
 			if ok := b.defineMathBitsIntrinsic(); ok {
@@ -1356,6 +1354,15 @@ func (b *builder) createFunctionStart(intrinsic bool) {
 // diagnostic.
 func (b *builder) createFunction() {
 	b.createFunctionStart(false)
+	// createFunctionStart returns early (leaving blockInfo unset) when it hits
+	// an error such as a redeclared symbol. Don't plow into the block loop and
+	// panic on an empty blockInfo — the error was already recorded.
+	if b.blockInfo == nil {
+		// TINYGO-DEBUG: surface the redeclaration collision.
+		fmt.Printf("TINYGO-DEBUG skipping fn (redeclared/errored): %s  pkg=%s\n",
+			b.fn.RelString(nil), b.fn.Pkg.Pkg.Path())
+		return
+	}
 
 	// Fill blocks with instructions.
 	for _, block := range b.fn.DomPreorder() {
@@ -1895,6 +1902,12 @@ func (b *builder) createBuiltin(argTypes []types.Type, argValues []llvm.Value, c
 			// not of the current function.
 			useParentFrame = 1
 		}
+		// Prevent inlining of functions that call recover(), matching the
+		// Go compiler's behavior. If this function were inlined into a
+		// deferred function, recover() would incorrectly succeed because
+		// the inlined code runs in the deferred function's context.
+		noinline := b.ctx.CreateEnumAttribute(llvm.AttributeKindID("noinline"), 0)
+		b.llvmFn.AddFunctionAttr(noinline)
 		return b.createRuntimeCall("_recover", []llvm.Value{llvm.ConstInt(b.ctx.Int1Type(), useParentFrame, false)}, ""), nil
 	case "ssa:wrapnilchk":
 		// TODO: do an actual nil check?
@@ -2183,9 +2196,8 @@ func (b *builder) createExpr(expr ssa.Value) (llvm.Value, error) {
 			}
 			sizeValue := llvm.ConstInt(b.uintptrType, size, false)
 			layoutValue := b.createObjectLayout(typ, expr.Pos())
-			buf := b.createRuntimeCall(b.allocFunc(), []llvm.Value{sizeValue, layoutValue}, expr.Comment)
 			align := b.targetData.ABITypeAlignment(typ)
-			buf.AddCallSiteAttribute(0, b.ctx.CreateEnumAttribute(llvm.AttributeKindID("align"), uint64(align)))
+			buf := b.createAlloc(sizeValue, layoutValue, align, expr.Comment)
 			return buf, nil
 		} else {
 			buf := llvmutil.CreateEntryBlockAlloca(b.Builder, typ, expr.Comment)
@@ -2415,7 +2427,7 @@ func (b *builder) createExpr(expr ssa.Value) (llvm.Value, error) {
 		}
 		sliceSize := b.CreateBinOp(llvm.Mul, elemSizeValue, sliceCapCast, "makeslice.cap")
 		layoutValue := b.createObjectLayout(llvmElemType, expr.Pos())
-		slicePtr := b.createRuntimeCall(b.allocFunc(), []llvm.Value{sliceSize, layoutValue}, "makeslice.buf")
+		slicePtr := b.createAlloc(sliceSize, layoutValue, 0, "makeslice.buf")
 		slicePtr.AddCallSiteAttribute(0, b.ctx.CreateEnumAttribute(llvm.AttributeKindID("align"), uint64(elemAlign)))
 
 		// Extend or truncate if necessary. This is safe as we've already done

compiler/defer.go

@@ -60,10 +60,6 @@ func (b *builder) deferInitFunc() {
 	b.deferExprFuncs = make(map[ssa.Value]int)
 	b.deferBuiltinFuncs = make(map[ssa.Value]deferBuiltin)
 
-	// Create defer list pointer.
-	b.deferPtr = b.CreateAlloca(b.dataPtrType, "deferPtr")
-	b.CreateStore(llvm.ConstPointerNull(b.dataPtrType), b.deferPtr)
-
 	if b.hasDeferFrame() {
 		// Set up the defer frame with the current stack pointer.
 		// This assumes that the stack pointer doesn't move outside of the
@@ -73,12 +69,22 @@ func (b *builder) deferInitFunc() {
 		// in the setjmp-like inline assembly.
 		deferFrameType := b.getLLVMRuntimeType("deferFrame")
 		b.deferFrame = b.CreateAlloca(deferFrameType, "deferframe.buf")
+		// The field index must match the DeferPtr field in runtime.deferFrame,
+		// defined in src/runtime/panic.go.
+		b.deferPtr = b.CreateInBoundsGEP(deferFrameType, b.deferFrame, []llvm.Value{
+			llvm.ConstInt(b.ctx.Int32Type(), 0, false),
+			llvm.ConstInt(b.ctx.Int32Type(), 6, false), // DeferPtr field
+		}, "deferPtr")
 		stackPointer := b.readStackPointer()
 		b.createRuntimeCall("setupDeferFrame", []llvm.Value{b.deferFrame, stackPointer}, "")
 
 		// Create the landing pad block, which is where control transfers after
 		// a panic.
 		b.landingpad = b.ctx.AddBasicBlock(b.llvmFn, "lpad")
+	} else {
+		// Create defer list pointer.
+		b.deferPtr = b.CreateAlloca(b.dataPtrType, "deferPtr")
+		b.CreateStore(llvm.ConstPointerNull(b.dataPtrType), b.deferPtr)
 	}
 }
 
@@ -237,6 +243,17 @@ func (b *builder) createInvokeCheckpoint() {
 	b.currentBlockInfo.exit = continueBB
 }
 
+// createFaultCheckpoint is like createInvokeCheckpoint but for use in fault
+// blocks (e.g., bounds check failures). Unlike createInvokeCheckpoint, it does
+// not update currentBlockInfo.exit because the fault block is a dead-end that
+// does not participate in phi node resolution.
+func (b *builder) createFaultCheckpoint() {
+	isZero := b.createCheckpoint(b.deferFrame)
+	continueBB := b.insertBasicBlock("")
+	b.CreateCondBr(isZero, continueBB, b.landingpad)
+	b.SetInsertPointAtEnd(continueBB)
+}
+
 // isInLoop checks if there is a path from the current block to itself.
 // Use Tarjan's strongly connected components algorithm to search for cycles.
 // A one-node SCC is a cycle iff there is an edge from the node to itself.
@@ -488,7 +505,7 @@ func (b *builder) createDefer(instr *ssa.Defer) {
 		size := b.targetData.TypeAllocSize(deferredCallType)
 		sizeValue := llvm.ConstInt(b.uintptrType, size, false)
 		nilPtr := llvm.ConstNull(b.dataPtrType)
-		alloca = b.createRuntimeCall(b.allocFunc(), []llvm.Value{sizeValue, nilPtr}, "defer.alloc.call")
+		alloca = b.createAlloc(sizeValue, nilPtr, 0, "defer.alloc.call")
 	}
 	if b.NeedsStackObjects {
 		b.trackPointer(alloca)

compiler/gc.go

@@ -10,6 +10,32 @@ import (
 	"tinygo.org/x/go-llvm"
 )
 
+// Heap-allocate a buffer of the given size. This will typically call
+// runtime.alloc.
+func (b *builder) createAlloc(sizeValue, layoutValue llvm.Value, align int, comment string) llvm.Value {
+	// Normally allocate using "runtime.alloc", but use "runtime.alloc_noheap"
+	// if the //go:noheap pragma is used.
+	allocFunc := "alloc"
+	if b.info.noheap {
+		allocFunc = "alloc_noheap"
+	}
+
+	// Allocs that don't allocate anything can return an architecture-specific
+	// sentinel value.
+	if !sizeValue.IsAConstantInt().IsNil() && sizeValue.ZExtValue() == 0 {
+		allocFunc = "alloc_zero"
+	}
+
+	// Make the runtime call.
+	call := b.createRuntimeCall(allocFunc, []llvm.Value{sizeValue, layoutValue}, comment)
+	if align != 0 {
+		// TODO: make sure all callsites set the correct alignment.
+		call.AddCallSiteAttribute(0, b.ctx.CreateEnumAttribute(llvm.AttributeKindID("align"), uint64(align)))
+	}
+
+	return call
+}
+
 // trackExpr inserts pointer tracking intrinsics for the GC if the expression is
 // one of the expressions that need this.
 func (b *builder) trackExpr(expr ssa.Value, value llvm.Value) {

compiler/interface.go

@@ -10,6 +10,7 @@ import (
 	"fmt"
 	"go/token"
 	"go/types"
+	"path/filepath"
 	"sort"
 	"strconv"
 	"strings"
@@ -165,7 +166,7 @@ func (c *compilerContext) getTypeCode(typ types.Type) llvm.Value {
 		}
 	}
 
-	typeCodeName, isLocal := getTypeCodeName(typ)
+	typeCodeName, isLocal := c.getTypeCodeName(typ)
 	globalName := "reflect/types.type:" + typeCodeName
 	var global llvm.Value
 	if isLocal {
@@ -580,20 +581,50 @@ var basicTypeNames = [...]string{
 // getTypeCodeName returns a name for this type that can be used in the
 // interface lowering pass to assign type codes as expected by the reflect
 // package. See getTypeCodeNum.
-func getTypeCodeName(t types.Type) (string, bool) {
+//
+// isLocal is true when the type is declared inside a function body.
+// Such types need a per-declaration (or per instantiation) suffix
+// because their printed names are not unique.
+//
+// Ordinary function-local types (TypeName.Parent() != nil) are
+// disambiguated lazily from their declaration position: every
+// declaration in the package has a distinct (file, line, column)
+// triple, and the position is taken un-//line-adjusted so it is
+// stable across builds. Such types are only nameable inside their
+// declaring package, so the name does not need to agree with anything
+// computed in another package.
+//
+// Synthetic locals (TypeName.Parent() == nil), produced by generic
+// instantiation, are pre-registered by scanLocalTypes because their
+// names must agree across packages that materialize the same instance.
+func (c *compilerContext) getTypeCodeName(t types.Type) (name string, isLocal bool) {
 	switch t := types.Unalias(t).(type) {
 	case *types.Named:
-		if t.Obj().Parent() != t.Obj().Pkg().Scope() {
-			return "named:" + t.String() + "$local", true
+		tn := t.Obj()
+		if tn.Pkg() == nil || tn.Parent() == tn.Pkg().Scope() {
+			// Package-scope or builtin: the printed name is unique.
+			return "named:" + t.String(), false
 		}
-		return "named:" + t.String(), false
+		if tn.Parent() != nil {
+			// Ordinary function-local type. Use the un-//line-adjusted
+			// declaration position as the disambiguator.
+			pos := c.program.Fset.PositionFor(tn.Pos(), false)
+			return fmt.Sprintf("named:%s$%s:%d:%d", t.String(), filepath.Base(pos.Filename), pos.Line, pos.Column), true
+		}
+		// Synthetic local from generic instantiation: must have been
+		// pre-registered by scanLocalTypes.
+		v := c.localTypeNames.At(t)
+		if v == nil {
+			panic("compiler: synthetic local type " + tn.Name() + " was not registered by scanLocalTypes")
+		}
+		return "named:" + v.(string), true
 	case *types.Array:
-		s, isLocal := getTypeCodeName(t.Elem())
+		s, isLocal := c.getTypeCodeName(t.Elem())
 		return "array:" + strconv.FormatInt(t.Len(), 10) + ":" + s, isLocal
 	case *types.Basic:
 		return "basic:" + basicTypeNames[t.Kind()], false
 	case *types.Chan:
-		s, isLocal := getTypeCodeName(t.Elem())
+		s, isLocal := c.getTypeCodeName(t.Elem())
 		var dir string
 		switch t.Dir() {
 		case types.SendOnly:
@@ -613,7 +644,7 @@ func getTypeCodeName(t types.Type) (string, bool) {
 			if !token.IsExported(name) {
 				name = t.Method(i).Pkg().Path() + "." + name
 			}
-			s, local := getTypeCodeName(t.Method(i).Type())
+			s, local := c.getTypeCodeName(t.Method(i).Type())
 			if local {
 				isLocal = true
 			}
@@ -621,17 +652,17 @@ func getTypeCodeName(t types.Type) (string, bool) {
 		}
 		return "interface:" + "{" + strings.Join(methods, ",") + "}", isLocal
 	case *types.Map:
-		keyType, keyLocal := getTypeCodeName(t.Key())
-		elemType, elemLocal := getTypeCodeName(t.Elem())
+		keyType, keyLocal := c.getTypeCodeName(t.Key())
+		elemType, elemLocal := c.getTypeCodeName(t.Elem())
 		return "map:" + "{" + keyType + "," + elemType + "}", keyLocal || elemLocal
 	case *types.Pointer:
-		s, isLocal := getTypeCodeName(t.Elem())
+		s, isLocal := c.getTypeCodeName(t.Elem())
 		return "pointer:" + s, isLocal
 	case *types.Signature:
 		isLocal := false
 		params := make([]string, t.Params().Len())
 		for i := 0; i < t.Params().Len(); i++ {
-			s, local := getTypeCodeName(t.Params().At(i).Type())
+			s, local := c.getTypeCodeName(t.Params().At(i).Type())
 			if local {
 				isLocal = true
 			}
@@ -639,7 +670,7 @@ func getTypeCodeName(t types.Type) (string, bool) {
 		}
 		results := make([]string, t.Results().Len())
 		for i := 0; i < t.Results().Len(); i++ {
-			s, local := getTypeCodeName(t.Results().At(i).Type())
+			s, local := c.getTypeCodeName(t.Results().At(i).Type())
 			if local {
 				isLocal = true
 			}
@@ -647,7 +678,7 @@ func getTypeCodeName(t types.Type) (string, bool) {
 		}
 		return "func:" + "{" + strings.Join(params, ",") + "}{" + strings.Join(results, ",") + "}", isLocal
 	case *types.Slice:
-		s, isLocal := getTypeCodeName(t.Elem())
+		s, isLocal := c.getTypeCodeName(t.Elem())
 		return "slice:" + s, isLocal
 	case *types.Struct:
 		elems := make([]string, t.NumFields())
@@ -657,7 +688,7 @@ func getTypeCodeName(t types.Type) (string, bool) {
 			if t.Field(i).Embedded() {
 				embedded = "#"
 			}
-			s, local := getTypeCodeName(t.Field(i).Type())
+			s, local := c.getTypeCodeName(t.Field(i).Type())
 			if local {
 				isLocal = true
 			}
@@ -672,6 +703,232 @@ func getTypeCodeName(t types.Type) (string, bool) {
 	}
 }
 
+// scanLocalTypes assigns names to every synthetic *types.TypeName
+// (TypeName.Parent() == nil) reachable from this package and stores
+// them in c.localTypeNames.
+//
+// Synthetic TypeNames are produced by generic instantiation: two
+// instantiations of the same generic function (e.g. F[int] and
+// F[string]) produce TypeNames with the same printed name and the
+// same source position, so each is named with the enclosing
+// instance's RelString as prefix. RelString encodes the type
+// arguments, matching Go's runtime behavior, where F[int].Inner and
+// F[string].Inner are distinct types even when Inner does not mention
+// the type parameter.
+//
+// A given instance may be materialized by several packages (the body
+// of F[int] is compiled in every package that calls F[int]); its
+// reflect/types.type:* global has LinkOnceODRLinkage and is merged by
+// name at link time. The chosen name therefore depends only on
+// intrinsic SSA properties (RelString and the raw token.Pos used as a
+// sort key), so any package compiling the same instance produces the
+// same identifier.
+//
+// Ordinary function-local TypeNames (TypeName.Parent() != nil) are
+// not handled here: they are nameable only inside their declaring
+// package, and getTypeCodeName derives a stable per-declaration name
+// for them directly from their source position.
+func (c *compilerContext) scanLocalTypes(ssaPkg *ssa.Package) {
+	// Locate every generic instance reachable from this package
+	// (including instances declared in imported packages and any
+	// function reached through an instance subtree).
+	var instances []*ssa.Function
+	seen := map[*ssa.Function]struct{}{}
+	var walk func(fn *ssa.Function, inInstance bool)
+	walk = func(fn *ssa.Function, inInstance bool) {
+		if fn == nil {
+			return
+		}
+		if _, ok := seen[fn]; ok {
+			return
+		}
+		// fn belongs to an instance subtree if it is itself an
+		// instantiation or if we reached it from one.
+		//
+		// len(TypeArgs()) is used instead of fn.Origin() because
+		// Origin() may call Build() on fn's declaring package, which
+		// would defeat per-package compilation.
+		isInstanceRoot := len(fn.TypeArgs()) > 0
+		if !isInstanceRoot && !inInstance && fn.Pkg != ssaPkg {
+			return
+		}
+		if fn.Blocks == nil && fn.AnonFuncs == nil {
+			return
+		}
+		seen[fn] = struct{}{}
+		isInInstance := inInstance || isInstanceRoot
+		if isInInstance {
+			instances = append(instances, fn)
+		}
+		for _, anon := range fn.AnonFuncs {
+			walk(anon, isInInstance)
+		}
+		var ops [10]*ssa.Value
+		for _, b := range fn.Blocks {
+			for _, instr := range b.Instrs {
+				for _, op := range instr.Operands(ops[:0]) {
+					if op == nil || *op == nil {
+						continue
+					}
+					if callee, ok := (*op).(*ssa.Function); ok {
+						walk(callee, isInInstance)
+					}
+				}
+			}
+		}
+	}
+	for _, member := range ssaPkg.Members {
+		switch m := member.(type) {
+		case *ssa.Function:
+			walk(m, false)
+		case *ssa.Type:
+			mset := c.program.MethodSets.MethodSet(m.Type())
+			for i := 0; i < mset.Len(); i++ {
+				walk(c.program.MethodValue(mset.At(i)), false)
+			}
+			pmset := c.program.MethodSets.MethodSet(types.NewPointer(m.Type()))
+			for i := 0; i < pmset.Len(); i++ {
+				walk(c.program.MethodValue(pmset.At(i)), false)
+			}
+		}
+	}
+
+	// Registration is first-writer-wins (a synthetic TypeName may be
+	// reachable from several instances), so visit instances in a
+	// deterministic order. Pos() is a defensive tiebreaker.
+	sort.Slice(instances, func(i, j int) bool {
+		ri, rj := instances[i].RelString(nil), instances[j].RelString(nil)
+		if ri != rj {
+			return ri < rj
+		}
+		return instances[i].Pos() < instances[j].Pos()
+	})
+	for _, fn := range instances {
+		c.registerSyntheticLocalTypes(fn)
+	}
+}
+
+// registerSyntheticLocalTypes walks every type reachable from fn's
+// body and records each synthetic *types.Named (TypeName.Parent() ==
+// nil) in c.localTypeNames. Each is named with fn.RelString as the
+// owning function plus a per-function counter assigned in source
+// order.
+//
+// First-writer-wins: a *types.Named already present in
+// c.localTypeNames is left alone, so a synthetic type reachable from
+// several instances keeps the name assigned by the first (in
+// scanLocalTypes' deterministic order).
+func (c *compilerContext) registerSyntheticLocalTypes(fn *ssa.Function) {
+	var found []*types.Named
+	seen := map[types.Type]struct{}{}
+	var visit func(t types.Type)
+	visit = func(t types.Type) {
+		if t == nil {
+			return
+		}
+		if _, ok := seen[t]; ok {
+			return
+		}
+		seen[t] = struct{}{}
+		switch t := t.(type) {
+		case *types.Alias:
+			visit(types.Unalias(t))
+		case *types.Named:
+			tn := t.Obj()
+			if tn.Pkg() != nil && tn.Parent() == nil {
+				if c.localTypeNames.At(t) == nil {
+					// Reserve the slot so later calls within this
+					// scanLocalTypes invocation skip it; the final
+					// name is filled in after sorting, before any
+					// getTypeCodeName lookups happen.
+					c.localTypeNames.Set(t, "")
+					found = append(found, t)
+				}
+			}
+			targs := t.TypeArgs()
+			for i := 0; i < targs.Len(); i++ {
+				visit(targs.At(i))
+			}
+			visit(t.Underlying())
+		case *types.Pointer:
+			visit(t.Elem())
+		case *types.Slice:
+			visit(t.Elem())
+		case *types.Array:
+			visit(t.Elem())
+		case *types.Chan:
+			visit(t.Elem())
+		case *types.Map:
+			visit(t.Key())
+			visit(t.Elem())
+		case *types.Struct:
+			for i := 0; i < t.NumFields(); i++ {
+				visit(t.Field(i).Type())
+			}
+		case *types.Signature:
+			if p := t.Params(); p != nil {
+				for i := 0; i < p.Len(); i++ {
+					visit(p.At(i).Type())
+				}
+			}
+			if r := t.Results(); r != nil {
+				for i := 0; i < r.Len(); i++ {
+					visit(r.At(i).Type())
+				}
+			}
+		case *types.Tuple:
+			for i := 0; i < t.Len(); i++ {
+				visit(t.At(i).Type())
+			}
+		case *types.Interface:
+			// A synthetic local type can be reachable only through a
+			// local interface's method signature, so descend into
+			// them. getTypeCodeName encodes those signatures into
+			// the interface's identifier, and the seen map breaks
+			// cycles formed by methods that mention the interface
+			// itself.
+			for i := 0; i < t.NumMethods(); i++ {
+				visit(t.Method(i).Type())
+			}
+		}
+	}
+	for _, p := range fn.Params {
+		visit(p.Type())
+	}
+	for _, fv := range fn.FreeVars {
+		visit(fv.Type())
+	}
+	for _, l := range fn.Locals {
+		visit(l.Type())
+	}
+	var ops [10]*ssa.Value
+	for _, b := range fn.Blocks {
+		for _, instr := range b.Instrs {
+			if v, ok := instr.(ssa.Value); ok {
+				visit(v.Type())
+			}
+			for _, op := range instr.Operands(ops[:0]) {
+				if op != nil && *op != nil {
+					visit((*op).Type())
+				}
+			}
+		}
+	}
+	if len(found) == 0 {
+		return
+	}
+	// Sort by raw token.Pos: this gives a total order on declarations
+	// that is stable across builds and unaffected by //line directives
+	// (which only adjust the human-facing position from Fset.Position).
+	sort.Slice(found, func(i, j int) bool {
+		return found[i].Obj().Pos() < found[j].Obj().Pos()
+	})
+	enclosing := fn.RelString(nil)
+	for i, named := range found {
+		c.localTypeNames.Set(named, fmt.Sprintf("%s.%s$%d", enclosing, named.Obj().Name(), i))
+	}
+}
+
 // getTypeMethodSet returns a reference (GEP) to a global method set. This
 // method set should be unreferenced after the interface lowering pass.
 func (c *compilerContext) getTypeMethodSet(typ types.Type) llvm.Value {
@@ -769,7 +1026,7 @@ func (b *builder) createTypeAssert(expr *ssa.TypeAssert) llvm.Value {
 			commaOk = b.createInterfaceTypeAssert(intf, actualTypeNum)
 		}
 	} else {
-		name, _ := getTypeCodeName(expr.AssertedType)
+		name, _ := b.getTypeCodeName(expr.AssertedType)
 		globalName := "reflect/types.typeid:" + name
 		assertedTypeCodeGlobal := b.mod.NamedGlobal(globalName)
 		if assertedTypeCodeGlobal.IsNil() {
@@ -796,43 +1053,68 @@ func (b *builder) createTypeAssert(expr *ssa.TypeAssert) llvm.Value {
 
 	prevBlock := b.GetInsertBlock()
 	okBlock := b.insertBasicBlock("typeassert.ok")
-	nextBlock := b.insertBasicBlock("typeassert.next")
-	b.currentBlockInfo.exit = nextBlock // adjust outgoing block for phi nodes
-	b.CreateCondBr(commaOk, okBlock, nextBlock)
-
-	// Retrieve the value from the interface if the type assert was
-	// successful.
-	b.SetInsertPointAtEnd(okBlock)
-	var valueOk llvm.Value
-	if _, ok := expr.AssertedType.Underlying().(*types.Interface); ok {
-		// Type assert on interface type. Easy: just return the same
-		// interface value.
-		valueOk = itf
-	} else {
-		// Type assert on concrete type. Extract the underlying type from
-		// the interface (but only after checking it matches).
-		valueOk = b.extractValueFromInterface(itf, assertedType)
-	}
-	b.CreateBr(nextBlock)
-
-	// Continue after the if statement.
-	b.SetInsertPointAtEnd(nextBlock)
-	phi := b.CreatePHI(assertedType, "typeassert.value")
-	phi.AddIncoming([]llvm.Value{llvm.ConstNull(assertedType), valueOk}, []llvm.BasicBlock{prevBlock, okBlock})
 
 	if expr.CommaOk {
+		nextBlock := b.insertBasicBlock("typeassert.next")
+		b.currentBlockInfo.exit = nextBlock
+		b.CreateCondBr(commaOk, okBlock, nextBlock)
+
+		// Retrieve the value from the interface if the type assert was
+		// successful.
+		b.SetInsertPointAtEnd(okBlock)
+		var valueOk llvm.Value
+		if _, ok := expr.AssertedType.Underlying().(*types.Interface); ok {
+			// Type assert on interface type. Easy: just return the same
+			// interface value.
+			valueOk = itf
+		} else {
+			// Type assert on concrete type. Extract the underlying type from
+			// the interface (but only after checking it matches).
+			valueOk = b.extractValueFromInterface(itf, assertedType)
+		}
+		b.CreateBr(nextBlock)
+
+		// Continue after the if statement.
+		b.SetInsertPointAtEnd(nextBlock)
+		phi := b.CreatePHI(assertedType, "typeassert.value")
+		phi.AddIncoming([]llvm.Value{llvm.ConstNull(assertedType), valueOk}, []llvm.BasicBlock{prevBlock, okBlock})
+
 		tuple := b.ctx.ConstStruct([]llvm.Value{llvm.Undef(assertedType), llvm.Undef(b.ctx.Int1Type())}, false) // create empty tuple
 		tuple = b.CreateInsertValue(tuple, phi, 0, "")                                                          // insert value
 		tuple = b.CreateInsertValue(tuple, commaOk, 1, "")                                                      // insert 'comma ok' boolean
 		return tuple
 	} else {
-		// This is kind of dirty as the branch above becomes mostly useless,
-		// but hopefully this gets optimized away.
-		b.createRuntimeCall("interfaceTypeAssert", []llvm.Value{commaOk}, "")
-		return phi
+		// Type assert without comma-ok. If it fails, panic.
+		faultBlock := b.getInterfaceAssertBlock()
+		b.currentBlockInfo.exit = okBlock
+		b.CreateCondBr(commaOk, okBlock, faultBlock)
+
+		// OK: extract the value from the interface.
+		b.SetInsertPointAtEnd(okBlock)
+		if _, ok := expr.AssertedType.Underlying().(*types.Interface); ok {
+			return itf
+		}
+		return b.extractValueFromInterface(itf, assertedType)
 	}
 }
 
+func (b *builder) getInterfaceAssertBlock() llvm.BasicBlock {
+	if !b.interfaceAssertBlock.IsNil() {
+		return b.interfaceAssertBlock
+	}
+	savedBlock := b.GetInsertBlock()
+	block := b.ctx.AddBasicBlock(b.llvmFn, "typeassert.throw")
+	b.interfaceAssertBlock = block
+	b.SetInsertPointAtEnd(block)
+	if b.hasDeferFrame() {
+		b.createFaultCheckpoint()
+	}
+	b.createRuntimeCall("interfaceTypeAssert", []llvm.Value{llvm.ConstInt(b.ctx.Int1Type(), 0, false)}, "")
+	b.CreateUnreachable()
+	b.SetInsertPointAtEnd(savedBlock)
+	return block
+}
+
 // getMethodsString returns a string to be used in the "tinygo-methods" string
 // attribute for interface functions.
 func (c *compilerContext) getMethodsString(itf *types.Interface) string {
@@ -857,7 +1139,7 @@ func (c *compilerContext) getMethodSetValue(methods []*types.Func) llvm.Value {
 		if !token.IsExported(name) {
 			name = method.Pkg().Path() + "." + name
 		}
-		s, _ := getTypeCodeName(method.Type())
+		s, _ := c.getTypeCodeName(method.Type())
 		globalName := "reflect/types.signature:" + name + ":" + s
 		value := c.mod.NamedGlobal(globalName)
 		if value.IsNil() {
@@ -901,7 +1183,7 @@ func (c *compilerContext) getMethodSetValue(methods []*types.Func) llvm.Value {
 // thunk is declared, not defined: it will be defined by the interface lowering
 // pass.
 func (c *compilerContext) getInvokeFunction(instr *ssa.CallCommon) llvm.Value {
-	s, _ := getTypeCodeName(instr.Value.Type().Underlying())
+	s, _ := c.getTypeCodeName(instr.Value.Type().Underlying())
 	fnName := s + "." + instr.Method.Name() + "$invoke"
 	llvmFn := c.mod.NamedFunction(fnName)
 	if llvmFn.IsNil() {
@@ -926,7 +1208,7 @@ func (c *compilerContext) getInvokeFunction(instr *ssa.CallCommon) llvm.Value {
 // by the interface lowering pass as a type-ID comparison chain, avoiding the
 // need for runtime.typeImplementsMethodSet at compile time.
 func (b *builder) createInterfaceTypeAssert(intf *types.Interface, actualType llvm.Value) llvm.Value {
-	s, _ := getTypeCodeName(intf)
+	s, _ := b.getTypeCodeName(intf)
 	fnName := s + ".$typeassert"
 	llvmFn := b.mod.NamedFunction(fnName)
 	if llvmFn.IsNil() {

compiler/intrinsics.go

@@ -7,6 +7,7 @@ import (
 	"strconv"
 	"strings"
 
+	"github.com/tinygo-org/tinygo/compiler/llvmutil"
 	"tinygo.org/x/go-llvm"
 )
 
@@ -166,12 +167,22 @@ func (b *builder) createMachineKeepAliveImpl() {
 }
 
 var mathToLLVMMapping = map[string]string{
+	"math.Acos":  "llvm.acos.f64",
+	"math.Asin":  "llvm.asin.f64",
+	"math.Atan":  "llvm.atan.f64",
+	"math.Atan2": "llvm.atan2.f64",
 	"math.Ceil":  "llvm.ceil.f64",
+	"math.Cos":   "llvm.cos.f64",
+	"math.Cosh":  "llvm.cosh.f64",
 	"math.Exp":   "llvm.exp.f64",
 	"math.Exp2":  "llvm.exp2.f64",
 	"math.Floor": "llvm.floor.f64",
 	"math.Log":   "llvm.log.f64",
+	"math.Sin":   "llvm.sin.f64",
+	"math.Sinh":  "llvm.sinh.f64",
 	"math.Sqrt":  "llvm.sqrt.f64",
+	"math.Tan":   "llvm.tan.f64",
+	"math.Tanh":  "llvm.tanh.f64",
 	"math.Trunc": "llvm.trunc.f64",
 }
 
@@ -185,18 +196,40 @@ var mathToLLVMMapping = map[string]string{
 // float32(math.Sqrt(float64(v))) to a 32-bit floating point operation, which is
 // beneficial on architectures where 64-bit floating point operations are (much)
 // more expensive than 32-bit ones.
-func (b *builder) defineMathOp() {
-	b.createFunctionStart(true)
-	llvmName := mathToLLVMMapping[b.fn.RelString(nil)]
-	if llvmName == "" {
-		panic("unreachable: unknown math operation") // sanity check
+func (b *builder) defineMathOp() bool {
+	llvmName, ok := mathToLLVMMapping[b.fn.RelString(nil)]
+	if !ok {
+		return false
 	}
+	if strings.HasSuffix(b.Triple, "-wasi") || llvmutil.Version() < 19 {
+		// We don't have a real libc for wasip2. Until that is fixed, we need to
+		// limit math intrinsics on WASI to a subset supported natively in
+		// WebAssembly.
+		// Also, since we don't know the specific libc we will target, disallow
+		// these for all WASI targets.
+		//
+		// We also need to limit ourselves to LLVM 19 and above for the extended
+		// set of math intrinsics, see:
+		// https://discourse.llvm.org/t/rfc-all-the-math-intrinsics/78294
+		switch b.fn.Name() {
+		case "Ceil", "Exp", "Exp2", "Floor", "Log", "Sqrt", "Trunc":
+		default:
+			return false
+		}
+	}
+	b.createFunctionStart(true)
 	llvmFn := b.mod.NamedFunction(llvmName)
 	if llvmFn.IsNil() {
 		// The intrinsic doesn't exist yet, so declare it.
-		// At the moment, all supported intrinsics have the form "double
-		// foo(double %x)" so we can hardcode the signature here.
-		llvmType := llvm.FunctionType(b.ctx.DoubleType(), []llvm.Type{b.ctx.DoubleType()}, false)
+		var llvmType llvm.Type
+		switch b.fn.Name() {
+		case "Atan2":
+			// double atan2(double %y, double %x)
+			llvmType = llvm.FunctionType(b.ctx.DoubleType(), []llvm.Type{b.ctx.DoubleType(), b.ctx.DoubleType()}, false)
+		default:
+			// double foo(double %x)
+			llvmType = llvm.FunctionType(b.ctx.DoubleType(), []llvm.Type{b.ctx.DoubleType()}, false)
+		}
 		llvmFn = llvm.AddFunction(b.mod, llvmName, llvmType)
 	}
 	// Create a call to the intrinsic.
@@ -206,6 +239,7 @@ func (b *builder) defineMathOp() {
 	}
 	result := b.CreateCall(llvmFn.GlobalValueType(), llvmFn, args, "")
 	b.CreateRet(result)
+	return true
 }
 
 func (b *builder) defineCryptoIntrinsic() bool {

compiler/llvm.go

@@ -129,11 +129,7 @@ func (b *builder) emitPointerPack(values []llvm.Value) llvm.Value {
 		// Packed data is bigger than a pointer, so allocate it on the heap.
 		sizeValue := llvm.ConstInt(b.uintptrType, size, false)
 		align := b.targetData.ABITypeAlignment(packedType)
-		packedAlloc := b.createRuntimeCall(b.allocFunc(), []llvm.Value{
-			sizeValue,
-			llvm.ConstNull(b.dataPtrType),
-		}, "")
-		packedAlloc.AddCallSiteAttribute(0, b.ctx.CreateEnumAttribute(llvm.AttributeKindID("align"), uint64(align)))
+		packedAlloc := b.createAlloc(sizeValue, llvm.ConstNull(b.dataPtrType), align, "")
 		if b.NeedsStackObjects {
 			b.trackPointer(packedAlloc)
 		}

compiler/map.go

@@ -133,7 +133,7 @@ func (b *builder) createMapUpdate(keyType types.Type, m, key, value llvm.Value,
 	if t, ok := keyType.(*types.Basic); ok && t.Info()&types.IsString != 0 {
 		// key is a string
 		params := []llvm.Value{m, key, valueAlloca}
-		b.createRuntimeCall("hashmapStringSet", params, "")
+		b.createRuntimeInvoke("hashmapStringSet", params, "")
 	} else {
 		// Key stored at actual type.
 		keyAlloca, keySize := b.createTemporaryAlloca(key.Type(), "hashmap.key")
@@ -143,7 +143,7 @@ func (b *builder) createMapUpdate(keyType types.Type, m, key, value llvm.Value,
 			fnName = "hashmapGenericSet"
 		}
 		params := []llvm.Value{m, keyAlloca, valueAlloca}
-		b.createRuntimeCall(fnName, params, "")
+		b.createRuntimeInvoke(fnName, params, "")
 		b.emitLifetimeEnd(keyAlloca, keySize)
 	}
 	b.emitLifetimeEnd(valueAlloca, valueSize)

compiler/symbol.go

@@ -162,7 +162,7 @@ func (c *compilerContext) getFunction(fn *ssa.Function) (llvm.Type, llvm.Value)
 		llvmFn.AddAttributeAtIndex(1, c.ctx.CreateEnumAttribute(llvm.AttributeKindID("nocapture"), 0))
 	case "machine.keepAliveNoEscape", "machine.unsafeNoEscape":
 		llvmFn.AddAttributeAtIndex(1, c.ctx.CreateEnumAttribute(llvm.AttributeKindID("nocapture"), 0))
-	case "runtime.alloc", "runtime.alloc_noheap":
+	case "runtime.alloc", "runtime.alloc_noheap", "runtime.alloc_zero":
 		// Tell the optimizer that runtime.alloc is an allocator, meaning that it
 		// returns values that are never null and never alias to an existing value.
 		for _, attrName := range []string{"noalias", "nonnull"} {

compiler/testdata/defer-cortex-m-qemu.ll

@@ -3,7 +3,7 @@ source_filename = "defer.go"
 target datalayout = "e-m:e-p:32:32-Fi8-i64:64-v128:64:128-a:0:32-n32-S64"
 target triple = "thumbv7m-unknown-unknown-eabi"
 
-%runtime.deferFrame = type { ptr, ptr, [0 x ptr], ptr, i8, %runtime._interface }
+%runtime.deferFrame = type { ptr, ptr, [0 x ptr], ptr, i8, %runtime._interface, ptr }
 %runtime._interface = type { ptr, ptr }
 
 ; Function Attrs: nounwind
@@ -18,14 +18,14 @@ declare void @main.external(ptr) #1
 define hidden void @main.deferSimple(ptr %context) unnamed_addr #0 {
 entry:
   %defer.alloca = alloca { i32, ptr }, align 4
-  %deferPtr = alloca ptr, align 4
-  store ptr null, ptr %deferPtr, align 4
   %deferframe.buf = alloca %runtime.deferFrame, align 4
+  %deferPtr = getelementptr inbounds nuw i8, ptr %deferframe.buf, i32 24
   %0 = call ptr @llvm.stacksave.p0()
   call void @runtime.setupDeferFrame(ptr nonnull %deferframe.buf, ptr %0, ptr undef) #4
+  %defer.next = load ptr, ptr %deferPtr, align 4
   store i32 0, ptr %defer.alloca, align 4
   %defer.alloca.repack15 = getelementptr inbounds nuw i8, ptr %defer.alloca, i32 4
-  store ptr null, ptr %defer.alloca.repack15, align 4
+  store ptr %defer.next, ptr %defer.alloca.repack15, align 4
   store ptr %defer.alloca, ptr %deferPtr, align 4
   %setjmp = call i32 asm "\0Amovs r0, #0\0Amov r2, pc\0Astr r2, [r1, #4]", "={r0},{r1},~{r1},~{r2},~{r3},~{r4},~{r5},~{r6},~{r7},~{r8},~{r9},~{r10},~{r11},~{r12},~{lr},~{q0},~{q1},~{q2},~{q3},~{q4},~{q5},~{q6},~{q7},~{q8},~{q9},~{q10},~{q11},~{q12},~{q13},~{q14},~{q15},~{cpsr},~{memory}"(ptr nonnull %deferframe.buf) #5
   %setjmp.result = icmp eq i32 %setjmp, 0
@@ -111,9 +111,9 @@ rundefers.end3:                                   ; preds = %rundefers.loophead6
 ; Function Attrs: nocallback nofree nosync nounwind willreturn
 declare ptr @llvm.stacksave.p0() #2
 
-declare void @runtime.setupDeferFrame(ptr dereferenceable_or_null(24), ptr, ptr) #1
+declare void @runtime.setupDeferFrame(ptr dereferenceable_or_null(28), ptr, ptr) #1
 
-declare void @runtime.destroyDeferFrame(ptr dereferenceable_or_null(24), ptr) #1
+declare void @runtime.destroyDeferFrame(ptr dereferenceable_or_null(28), ptr) #1
 
 ; Function Attrs: nounwind
 define internal void @"main.deferSimple$1"(ptr %context) unnamed_addr #0 {
@@ -135,18 +135,18 @@ define hidden void @main.deferMultiple(ptr %context) unnamed_addr #0 {
 entry:
   %defer.alloca2 = alloca { i32, ptr }, align 4
   %defer.alloca = alloca { i32, ptr }, align 4
-  %deferPtr = alloca ptr, align 4
-  store ptr null, ptr %deferPtr, align 4
   %deferframe.buf = alloca %runtime.deferFrame, align 4
+  %deferPtr = getelementptr inbounds nuw i8, ptr %deferframe.buf, i32 24
   %0 = call ptr @llvm.stacksave.p0()
   call void @runtime.setupDeferFrame(ptr nonnull %deferframe.buf, ptr %0, ptr undef) #4
+  %defer.next = load ptr, ptr %deferPtr, align 4
   store i32 0, ptr %defer.alloca, align 4
   %defer.alloca.repack22 = getelementptr inbounds nuw i8, ptr %defer.alloca, i32 4
-  store ptr null, ptr %defer.alloca.repack22, align 4
+  store ptr %defer.next, ptr %defer.alloca.repack22, align 4
   store ptr %defer.alloca, ptr %deferPtr, align 4
   store i32 1, ptr %defer.alloca2, align 4
-  %defer.alloca2.repack23 = getelementptr inbounds nuw i8, ptr %defer.alloca2, i32 4
-  store ptr %defer.alloca, ptr %defer.alloca2.repack23, align 4
+  %defer.alloca2.repack24 = getelementptr inbounds nuw i8, ptr %defer.alloca2, i32 4
+  store ptr %defer.alloca, ptr %defer.alloca2.repack24, align 4
   store ptr %defer.alloca2, ptr %deferPtr, align 4
   %setjmp = call i32 asm "\0Amovs r0, #0\0Amov r2, pc\0Astr r2, [r1, #4]", "={r0},{r1},~{r1},~{r2},~{r3},~{r4},~{r5},~{r6},~{r7},~{r8},~{r9},~{r10},~{r11},~{r12},~{lr},~{q0},~{q1},~{q2},~{q3},~{q4},~{q5},~{q6},~{q7},~{q8},~{q9},~{q10},~{q11},~{q12},~{q13},~{q14},~{q15},~{cpsr},~{memory}"(ptr nonnull %deferframe.buf) #5
   %setjmp.result = icmp eq i32 %setjmp, 0
@@ -270,9 +270,8 @@ entry:
 ; Function Attrs: nounwind
 define hidden void @main.deferInfiniteLoop(ptr %context) unnamed_addr #0 {
 entry:
-  %deferPtr = alloca ptr, align 4
-  store ptr null, ptr %deferPtr, align 4
   %deferframe.buf = alloca %runtime.deferFrame, align 4
+  %deferPtr = getelementptr inbounds nuw i8, ptr %deferframe.buf, i32 24
   %0 = call ptr @llvm.stacksave.p0()
   call void @runtime.setupDeferFrame(ptr nonnull %deferframe.buf, ptr %0, ptr undef) #4
   br label %for.body
@@ -318,9 +317,8 @@ declare noalias nonnull ptr @runtime.alloc(i32, ptr, ptr) #3
 ; Function Attrs: nounwind
 define hidden void @main.deferLoop(ptr %context) unnamed_addr #0 {
 entry:
-  %deferPtr = alloca ptr, align 4
-  store ptr null, ptr %deferPtr, align 4
   %deferframe.buf = alloca %runtime.deferFrame, align 4
+  %deferPtr = getelementptr inbounds nuw i8, ptr %deferframe.buf, i32 24
   %0 = call ptr @llvm.stacksave.p0()
   call void @runtime.setupDeferFrame(ptr nonnull %deferframe.buf, ptr %0, ptr undef) #4
   br label %for.loop
@@ -408,9 +406,8 @@ rundefers.end1:                                   ; preds = %rundefers.loophead4
 define hidden void @main.deferBetweenLoops(ptr %context) unnamed_addr #0 {
 entry:
   %defer.alloca = alloca { i32, ptr, i32 }, align 4
-  %deferPtr = alloca ptr, align 4
-  store ptr null, ptr %deferPtr, align 4
   %deferframe.buf = alloca %runtime.deferFrame, align 4
+  %deferPtr = getelementptr inbounds nuw i8, ptr %deferframe.buf, i32 24
   %0 = call ptr @llvm.stacksave.p0()
   call void @runtime.setupDeferFrame(ptr nonnull %deferframe.buf, ptr %0, ptr undef) #4
   br label %for.loop

compiler/testdata/gc.ll

@@ -75,7 +75,7 @@ entry:
 define hidden void @main.newStruct(ptr %context) unnamed_addr #1 {
 entry:
   %stackalloc = alloca i8, align 1
-  %new = call align 1 ptr @runtime.alloc(i32 0, ptr nonnull inttoptr (i32 3 to ptr), ptr undef) #3
+  %new = call align 1 ptr @runtime.alloc_zero(i32 0, ptr nonnull inttoptr (i32 3 to ptr), ptr undef) #3
   call void @runtime.trackPointer(ptr nonnull %new, ptr nonnull %stackalloc, ptr undef) #3
   store ptr %new, ptr @main.struct1, align 4
   %new1 = call align 4 dereferenceable(8) ptr @runtime.alloc(i32 8, ptr nonnull inttoptr (i32 3 to ptr), ptr undef) #3
@@ -93,6 +93,9 @@ entry:
   ret void
 }
 
+; Function Attrs: allockind("alloc,zeroed") allocsize(0)
+declare noalias nonnull ptr @runtime.alloc_zero(i32, ptr, ptr) #2
+
 ; Function Attrs: nounwind
 define hidden ptr @main.newFuncValue(ptr %context) unnamed_addr #1 {
 entry:

compiler/testdata/generics.ll

@@ -29,13 +29,13 @@ entry:
   %a = call align 4 dereferenceable(8) ptr @runtime.alloc(i32 8, ptr nonnull inttoptr (i32 3 to ptr), ptr undef) #3
   call void @runtime.trackPointer(ptr nonnull %a, ptr nonnull %stackalloc, ptr undef) #3
   store float %a.X, ptr %a, align 4
-  %a.repack9 = getelementptr inbounds nuw i8, ptr %a, i32 4
-  store float %a.Y, ptr %a.repack9, align 4
+  %a.repack5 = getelementptr inbounds nuw i8, ptr %a, i32 4
+  store float %a.Y, ptr %a.repack5, align 4
   %b = call align 4 dereferenceable(8) ptr @runtime.alloc(i32 8, ptr nonnull inttoptr (i32 3 to ptr), ptr undef) #3
   call void @runtime.trackPointer(ptr nonnull %b, ptr nonnull %stackalloc, ptr undef) #3
   store float %b.X, ptr %b, align 4
-  %b.repack11 = getelementptr inbounds nuw i8, ptr %b, i32 4
-  store float %b.Y, ptr %b.repack11, align 4
+  %b.repack7 = getelementptr inbounds nuw i8, ptr %b, i32 4
+  store float %b.Y, ptr %b.repack7, align 4
   call void @main.checkSize(i32 4, ptr undef) #3
   call void @main.checkSize(i32 8, ptr undef) #3
   %complit = call align 4 dereferenceable(8) ptr @runtime.alloc(i32 8, ptr nonnull inttoptr (i32 3 to ptr), ptr undef) #3
@@ -43,29 +43,29 @@ entry:
   br i1 false, label %deref.throw, label %deref.next
 
 deref.next:                                       ; preds = %entry
-  br i1 false, label %deref.throw1, label %deref.next2
+  br i1 false, label %deref.throw, label %deref.next1
 
-deref.next2:                                      ; preds = %deref.next
+deref.next1:                                      ; preds = %deref.next
   %0 = load float, ptr %a, align 4
   %1 = load float, ptr %b, align 4
   %2 = fadd float %0, %1
-  br i1 false, label %deref.throw3, label %deref.next4
+  br i1 false, label %deref.throw, label %deref.next2
 
-deref.next4:                                      ; preds = %deref.next2
-  br i1 false, label %deref.throw5, label %deref.next6
+deref.next2:                                      ; preds = %deref.next1
+  br i1 false, label %deref.throw, label %deref.next3
 
-deref.next6:                                      ; preds = %deref.next4
+deref.next3:                                      ; preds = %deref.next2
   %3 = getelementptr inbounds nuw i8, ptr %b, i32 4
   %4 = getelementptr inbounds nuw i8, ptr %a, i32 4
   %5 = load float, ptr %4, align 4
   %6 = load float, ptr %3, align 4
-  br i1 false, label %store.throw, label %store.next
+  br i1 false, label %deref.throw, label %store.next
 
-store.next:                                       ; preds = %deref.next6
+store.next:                                       ; preds = %deref.next3
   store float %2, ptr %complit, align 4
-  br i1 false, label %store.throw7, label %store.next8
+  br i1 false, label %deref.throw, label %store.next4
 
-store.next8:                                      ; preds = %store.next
+store.next4:                                      ; preds = %store.next
   %7 = getelementptr inbounds nuw i8, ptr %complit, i32 4
   %8 = fadd float %5, %6
   store float %8, ptr %7, align 4
@@ -74,22 +74,7 @@ store.next8:                                      ; preds = %store.next
   %10 = insertvalue %"main.Point[float32]" %9, float %8, 1
   ret %"main.Point[float32]" %10
 
-deref.throw:                                      ; preds = %entry
-  unreachable
-
-deref.throw1:                                     ; preds = %deref.next
-  unreachable
-
-deref.throw3:                                     ; preds = %deref.next2
-  unreachable
-
-deref.throw5:                                     ; preds = %deref.next4
-  unreachable
-
-store.throw:                                      ; preds = %deref.next6
-  unreachable
-
-store.throw7:                                     ; preds = %store.next
+deref.throw:                                      ; preds = %store.next, %deref.next3, %deref.next2, %deref.next1, %deref.next, %entry
   unreachable
 }
 
@@ -107,13 +92,13 @@ entry:
   %a = call align 4 dereferenceable(8) ptr @runtime.alloc(i32 8, ptr nonnull inttoptr (i32 3 to ptr), ptr undef) #3
   call void @runtime.trackPointer(ptr nonnull %a, ptr nonnull %stackalloc, ptr undef) #3
   store i32 %a.X, ptr %a, align 4
-  %a.repack9 = getelementptr inbounds nuw i8, ptr %a, i32 4
-  store i32 %a.Y, ptr %a.repack9, align 4
+  %a.repack5 = getelementptr inbounds nuw i8, ptr %a, i32 4
+  store i32 %a.Y, ptr %a.repack5, align 4
   %b = call align 4 dereferenceable(8) ptr @runtime.alloc(i32 8, ptr nonnull inttoptr (i32 3 to ptr), ptr undef) #3
   call void @runtime.trackPointer(ptr nonnull %b, ptr nonnull %stackalloc, ptr undef) #3
   store i32 %b.X, ptr %b, align 4
-  %b.repack11 = getelementptr inbounds nuw i8, ptr %b, i32 4
-  store i32 %b.Y, ptr %b.repack11, align 4
+  %b.repack7 = getelementptr inbounds nuw i8, ptr %b, i32 4
+  store i32 %b.Y, ptr %b.repack7, align 4
   call void @main.checkSize(i32 4, ptr undef) #3
   call void @main.checkSize(i32 8, ptr undef) #3
   %complit = call align 4 dereferenceable(8) ptr @runtime.alloc(i32 8, ptr nonnull inttoptr (i32 3 to ptr), ptr undef) #3
@@ -121,29 +106,29 @@ entry:
   br i1 false, label %deref.throw, label %deref.next
 
 deref.next:                                       ; preds = %entry
-  br i1 false, label %deref.throw1, label %deref.next2
+  br i1 false, label %deref.throw, label %deref.next1
 
-deref.next2:                                      ; preds = %deref.next
+deref.next1:                                      ; preds = %deref.next
   %0 = load i32, ptr %a, align 4
   %1 = load i32, ptr %b, align 4
   %2 = add i32 %0, %1
-  br i1 false, label %deref.throw3, label %deref.next4
+  br i1 false, label %deref.throw, label %deref.next2
 
-deref.next4:                                      ; preds = %deref.next2
-  br i1 false, label %deref.throw5, label %deref.next6
+deref.next2:                                      ; preds = %deref.next1
+  br i1 false, label %deref.throw, label %deref.next3
 
-deref.next6:                                      ; preds = %deref.next4
+deref.next3:                                      ; preds = %deref.next2
   %3 = getelementptr inbounds nuw i8, ptr %b, i32 4
   %4 = getelementptr inbounds nuw i8, ptr %a, i32 4
   %5 = load i32, ptr %4, align 4
   %6 = load i32, ptr %3, align 4
-  br i1 false, label %store.throw, label %store.next
+  br i1 false, label %deref.throw, label %store.next
 
-store.next:                                       ; preds = %deref.next6
+store.next:                                       ; preds = %deref.next3
   store i32 %2, ptr %complit, align 4
-  br i1 false, label %store.throw7, label %store.next8
+  br i1 false, label %deref.throw, label %store.next4
 
-store.next8:                                      ; preds = %store.next
+store.next4:                                      ; preds = %store.next
   %7 = getelementptr inbounds nuw i8, ptr %complit, i32 4
   %8 = add i32 %5, %6
   store i32 %8, ptr %7, align 4
@@ -152,22 +137,7 @@ store.next8:                                      ; preds = %store.next
   %10 = insertvalue %"main.Point[int]" %9, i32 %8, 1
   ret %"main.Point[int]" %10
 
-deref.throw:                                      ; preds = %entry
-  unreachable
-
-deref.throw1:                                     ; preds = %deref.next
-  unreachable
-
-deref.throw3:                                     ; preds = %deref.next2
-  unreachable
-
-deref.throw5:                                     ; preds = %deref.next4
-  unreachable
-
-store.throw:                                      ; preds = %deref.next6
-  unreachable
-
-store.throw7:                                     ; preds = %store.next
+deref.throw:                                      ; preds = %store.next, %deref.next3, %deref.next2, %deref.next1, %deref.next, %entry
   unreachable
 }
 

go.mod

@@ -1,6 +1,6 @@
 module github.com/tinygo-org/tinygo
 
-go 1.23.0
+go 1.24.0
 
 require (
 	github.com/aykevl/go-wasm v0.0.2-0.20250317121156-42b86c494139
@@ -18,11 +18,11 @@ require (
 	go.bug.st/serial v1.6.4
 	go.bytecodealliance.org v0.6.2
 	go.bytecodealliance.org/cm v0.2.2
-	golang.org/x/net v0.35.0
-	golang.org/x/sys v0.30.0
-	golang.org/x/tools v0.30.0
+	golang.org/x/net v0.50.0
+	golang.org/x/sys v0.41.0
+	golang.org/x/tools v0.42.0
 	gopkg.in/yaml.v2 v2.4.0
-	tinygo.org/x/espflasher v0.6.0
+	tinygo.org/x/espflasher v0.6.1
 	tinygo.org/x/go-llvm v0.0.0-20260422095634-06c6725fe5e6
 )
 
@@ -48,6 +48,6 @@ require (
 	github.com/spf13/afero v1.11.0 // indirect
 	github.com/ulikunitz/xz v0.5.12 // indirect
 	github.com/urfave/cli/v3 v3.0.0-beta1 // indirect
-	golang.org/x/mod v0.23.0 // indirect
-	golang.org/x/text v0.22.0 // indirect
+	golang.org/x/mod v0.33.0 // indirect
+	golang.org/x/text v0.34.0 // indirect
 )

go.sum

@@ -23,6 +23,8 @@ github.com/gofrs/flock v0.8.1 h1:+gYjHKf32LDeiEEFhQaotPbLuUXjY5ZqxKgXy7n59aw=
 github.com/gofrs/flock v0.8.1/go.mod h1:F1TvTiK9OcQqauNUHlbJvyl9Qa1QvF/gOUDKA14jxHU=
 github.com/golangci/misspell v0.6.0 h1:JCle2HUTNWirNlDIAUO44hUsKhOFqGPoC4LZxlaSXDs=
 github.com/golangci/misspell v0.6.0/go.mod h1:keMNyY6R9isGaSAu+4Q8NMBwMPkh15Gtc8UCVoDtAWo=
+github.com/google/go-cmp v0.6.0 h1:ofyhxvXcZhMsU5ulbFiLKl/XBFqE1GSq7atu8tAmTRI=
+github.com/google/go-cmp v0.6.0/go.mod h1:17dUlkBOakJ0+DkrSSNjCkIjxS6bF9zb3elmeNGIjoY=
 github.com/google/shlex v0.0.0-20181106134648-c34317bd91bf h1:7+FW5aGwISbqUtkfmIpZJGRgNFg2ioYPvFaUxdqpDsg=
 github.com/google/shlex v0.0.0-20181106134648-c34317bd91bf/go.mod h1:RpwtwJQFrIEPstU94h88MWPXP2ektJZ8cZ0YntAmXiE=
 github.com/hashicorp/go-version v1.7.0 h1:5tqGy27NaOTB8yJKUZELlFAS/LTKJkrmONwQKeRZfjY=
@@ -93,24 +95,24 @@ go.bytecodealliance.org v0.6.2 h1:Jy4u5DVmSkXgsnwojBhJ+AD/YsJsR3VzVnxF0xRCqTQ=
 go.bytecodealliance.org v0.6.2/go.mod h1:gqjTJm0y9NSksG4py/lSjIQ/SNuIlOQ+hCIEPQwtJgA=
 go.bytecodealliance.org/cm v0.2.2 h1:M9iHS6qs884mbQbIjtLX1OifgyPG9DuMs2iwz8G4WQA=
 go.bytecodealliance.org/cm v0.2.2/go.mod h1:JD5vtVNZv7sBoQQkvBvAAVKJPhR/bqBH7yYXTItMfZI=
-golang.org/x/mod v0.23.0 h1:Zb7khfcRGKk+kqfxFaP5tZqCnDZMjC5VtUBs87Hr6QM=
-golang.org/x/mod v0.23.0/go.mod h1:6SkKJ3Xj0I0BrPOZoBy3bdMptDDU9oJrpohJ3eWZ1fY=
-golang.org/x/net v0.35.0 h1:T5GQRQb2y08kTAByq9L4/bz8cipCdA8FbRTXewonqY8=
-golang.org/x/net v0.35.0/go.mod h1:EglIi67kWsHKlRzzVMUD93VMSWGFOMSZgxFjparz1Qk=
-golang.org/x/sync v0.11.0 h1:GGz8+XQP4FvTTrjZPzNKTMFtSXH80RAzG+5ghFPgK9w=
-golang.org/x/sync v0.11.0/go.mod h1:Czt+wKu1gCyEFDUtn0jG5QVvpJ6rzVqr5aXyt9drQfk=
+golang.org/x/mod v0.33.0 h1:tHFzIWbBifEmbwtGz65eaWyGiGZatSrT9prnU8DbVL8=
+golang.org/x/mod v0.33.0/go.mod h1:swjeQEj+6r7fODbD2cqrnje9PnziFuw4bmLbBZFrQ5w=
+golang.org/x/net v0.50.0 h1:ucWh9eiCGyDR3vtzso0WMQinm2Dnt8cFMuQa9K33J60=
+golang.org/x/net v0.50.0/go.mod h1:UgoSli3F/pBgdJBHCTc+tp3gmrU4XswgGRgtnwWTfyM=
+golang.org/x/sync v0.19.0 h1:vV+1eWNmZ5geRlYjzm2adRgW2/mcpevXNg50YZtPCE4=
+golang.org/x/sync v0.19.0/go.mod h1:9KTHXmSnoGruLpwFjVSX0lNNA75CykiMECbovNTZqGI=
 golang.org/x/sys v0.0.0-20190222072716-a9d3bda3a223/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
 golang.org/x/sys v0.0.0-20191008105621-543471e840be/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/sys v0.0.0-20191120155948-bd437916bb0e/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/sys v0.0.0-20220715151400-c0bba94af5f8/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 golang.org/x/sys v0.0.0-20220811171246-fbc7d0a398ab/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 golang.org/x/sys v0.6.0/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
-golang.org/x/sys v0.30.0 h1:QjkSwP/36a20jFYWkSue1YwXzLmsV5Gfq7Eiy72C1uc=
-golang.org/x/sys v0.30.0/go.mod h1:/VUhepiaJMQUp4+oa/7Zr1D23ma6VTLIYjOOTFZPUcA=
-golang.org/x/text v0.22.0 h1:bofq7m3/HAFvbF51jz3Q9wLg3jkvSPuiZu/pD1XwgtM=
-golang.org/x/text v0.22.0/go.mod h1:YRoo4H8PVmsu+E3Ou7cqLVH8oXWIHVoX0jqUWALQhfY=
-golang.org/x/tools v0.30.0 h1:BgcpHewrV5AUp2G9MebG4XPFI1E2W41zU1SaqVA9vJY=
-golang.org/x/tools v0.30.0/go.mod h1:c347cR/OJfw5TI+GfX7RUPNMdDRRbjvYTS0jPyvsVtY=
+golang.org/x/sys v0.41.0 h1:Ivj+2Cp/ylzLiEU89QhWblYnOE9zerudt9Ftecq2C6k=
+golang.org/x/sys v0.41.0/go.mod h1:OgkHotnGiDImocRcuBABYBEXf8A9a87e/uXjp9XT3ks=
+golang.org/x/text v0.34.0 h1:oL/Qq0Kdaqxa1KbNeMKwQq0reLCCaFtqu2eNuSeNHbk=
+golang.org/x/text v0.34.0/go.mod h1:homfLqTYRFyVYemLBFl5GgL/DWEiH5wcsQ5gSh1yziA=
+golang.org/x/tools v0.42.0 h1:uNgphsn75Tdz5Ji2q36v/nsFSfR/9BRFvqhGBaJGd5k=
+golang.org/x/tools v0.42.0/go.mod h1:Ma6lCIwGZvHK6XtgbswSoWroEkhugApmsXyrUmBhfr0=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405 h1:yhCVgyC4o1eVCa2tZl7eS0r+SDo693bJlVdllGtEeKM=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
 gopkg.in/yaml.v2 v2.4.0 h1:D8xgwECY7CYvx+Y2n4sBz93Jn9JRvxdiyyo8CTfuKaY=
@@ -118,7 +120,7 @@ gopkg.in/yaml.v2 v2.4.0/go.mod h1:RDklbk79AGWmwhnvt/jBztapEOGDOx6ZbXqjP6csGnQ=
 gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=
 gopkg.in/yaml.v3 v3.0.1 h1:fxVm/GzAzEWqLHuvctI91KS9hhNmmWOoWu0XTYJS7CA=
 gopkg.in/yaml.v3 v3.0.1/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=
-tinygo.org/x/espflasher v0.6.0 h1:CHbGMHAIWq1tB8FKd/QwBpNFw1jvHHxpmvZiF+QOYUo=
-tinygo.org/x/espflasher v0.6.0/go.mod h1:tr5u08HoE67WD5zxJesCiiVF/R1b6Akz3yXwh5zah8U=
+tinygo.org/x/espflasher v0.6.1 h1:9jfyAP9jGjxF63FQUY2Bml9TFb5fCZYxVgbgR2IjUGs=
+tinygo.org/x/espflasher v0.6.1/go.mod h1:tr5u08HoE67WD5zxJesCiiVF/R1b6Akz3yXwh5zah8U=
 tinygo.org/x/go-llvm v0.0.0-20260422095634-06c6725fe5e6 h1:QSnqFgNV2Ij0T4hM2qKv53fcDAFElxClPjVUZXzYkWU=
 tinygo.org/x/go-llvm v0.0.0-20260422095634-06c6725fe5e6/go.mod h1:GFbusT2VTA4I+l4j80b17KFK+6whv69Wtny5U+T8RR0=

interp/interp_test.go

@@ -18,7 +18,9 @@ func TestInterp(t *testing.T) {
 		"copy",
 		"interface",
 		"revert",
+		"store",
 		"alloc",
+		"slicedata",
 	} {
 		name := name // make local to this closure
 		t.Run(name, func(t *testing.T) {

interp/interpreter.go

@@ -299,7 +299,7 @@ func (r *runner) run(fn *function, params []value, parentMem *memoryView, indent
 				// means that monotonic time in the time package is counted from
 				// time.Time{}.Sub(1), which should be fine.
 				locals[inst.localIndex] = literalValue{uint64(0)}
-			case callFn.name == "runtime.alloc" || callFn.name == "runtime.alloc_noheap":
+			case callFn.name == "runtime.alloc" || callFn.name == "runtime.alloc_noheap" || callFn.name == "runtime.alloc_zero":
 				// Allocate heap memory. At compile time, this is instead done
 				// by creating a global variable.
 

interp/memory.go

@@ -299,7 +299,8 @@ func (mv *memoryView) put(index uint32, obj object) {
 }
 
 // Load the value behind the given pointer. Returns nil if the pointer points to
-// an external global.
+// an external global or if the load is out of bounds of the object (in which
+// case the caller defers the load to runtime).
 func (mv *memoryView) load(p pointerValue, size uint32) value {
 	if checks && mv.hasExternalStore(p) {
 		panic("interp: load from object with external store")
@@ -312,14 +313,23 @@ func (mv *memoryView) load(p pointerValue, size uint32) value {
 	if p.offset() == 0 && size == obj.size {
 		return obj.buffer.clone()
 	}
-	if checks && p.offset()+size > obj.size {
-		panic("interp: load out of bounds")
+	if p.offset()+size > obj.size {
+		// The load is out of bounds of the object. This can happen for valid
+		// Go programs, for example when dereferencing the pointer returned by
+		// unsafe.SliceData on a zero-capacity slice (which points to a
+		// zero-sized object). Return nil so the caller defers this load to
+		// runtime instead of crashing the compiler.
+		return nil
 	}
 	v := obj.buffer.asRawValue(mv.r)
-	loadedValue := rawValue{
-		buf: v.buf[p.offset() : p.offset()+size],
+	loadedBuf := v.buf[p.offset() : p.offset()+size]
+	if _, writable := mv.objects[p.index()]; writable {
+		// This object's buffer is owned by this view, which means a later
+		// store may mutate it in place (see store below). Copy the loaded
+		// slice so the returned value is not aliased with the live buffer.
+		loadedBuf = append([]uint64(nil), loadedBuf...)
 	}
-	return loadedValue
+	return rawValue{buf: loadedBuf}
 }
 
 // Store to the value behind the given pointer. This overwrites the value in the
@@ -330,26 +340,37 @@ func (mv *memoryView) store(v value, p pointerValue) bool {
 	if checks && mv.hasExternalLoadOrStore(p) {
 		panic("interp: store to object with external load/store")
 	}
-	obj := mv.get(p.index())
+	index := p.index()
+	var obj object
+	writable := false
+	if mv.objects != nil {
+		obj, writable = mv.objects[index]
+	}
+	if !writable {
+		obj = mv.get(index)
+	}
 	if obj.buffer == nil {
 		// External global, return false (for a failure).
 		return false
 	}
-	if checks && p.offset()+v.len(mv.r) > obj.size {
+	valueLen := v.len(mv.r)
+	if checks && p.offset()+valueLen > obj.size {
 		panic("interp: store out of bounds")
 	}
-	if p.offset() == 0 && v.len(mv.r) == obj.buffer.len(mv.r) {
-		obj.buffer = v
+	if p.offset() == 0 && valueLen == obj.buffer.len(mv.r) {
+		obj.buffer = v.clone()
 	} else {
-		obj = obj.clone()
+		if !writable {
+			obj = obj.clone()
+		}
 		buffer := obj.buffer.asRawValue(mv.r)
 		obj.buffer = buffer
 		v := v.asRawValue(mv.r)
-		for i := uint32(0); i < v.len(mv.r); i++ {
+		for i := uint32(0); i < valueLen; i++ {
 			buffer.buf[p.offset()+i] = v.buf[i]
 		}
 	}
-	mv.put(p.index(), obj)
+	mv.put(index, obj)
 	return true // success
 }
 

interp/testdata/slicedata.ll

@@ -0,0 +1,23 @@
+target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64--linux"
+
+; Reproduction of https://github.com/tinygo-org/tinygo/issues/4214.
+; Dereferencing the pointer returned by unsafe.SliceData on a zero-capacity
+; slice produces a load that is out of bounds of a zero-sized object. The
+; interp must defer this load to runtime instead of crashing the compiler.
+
+@main.zeroSized = global {} zeroinitializer
+@main.v = global i64 0
+
+define void @runtime.initAll() unnamed_addr {
+entry:
+  call void @main.init(ptr undef)
+  ret void
+}
+
+define internal void @main.init(ptr %context) unnamed_addr {
+entry:
+  %val = load i64, ptr @main.zeroSized
+  store i64 %val, ptr @main.v
+  ret void
+}

interp/testdata/slicedata.out.ll

@@ -0,0 +1,12 @@
+target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64--linux"
+
+@main.zeroSized = local_unnamed_addr global {} zeroinitializer
+@main.v = local_unnamed_addr global i64 0
+
+define void @runtime.initAll() unnamed_addr {
+entry:
+  %val = load i64, ptr @main.zeroSized, align 8
+  store i64 %val, ptr @main.v, align 8
+  ret void
+}

interp/testdata/store.ll

@@ -0,0 +1,49 @@
+target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64--linux"
+
+@overlap.buf = global [4 x i8] c"\01\02\03\04"
+@alias.src = global [4 x i8] c"\05\06\07\08"
+@alias.dst = global [2 x i8] zeroinitializer
+@reload.buf = global [4 x i8] c"\01\02\03\04"
+@reload.out = global [2 x i8] zeroinitializer
+
+define void @runtime.initAll() unnamed_addr {
+entry:
+  call void @overlap.init(ptr undef)
+  call void @alias.init(ptr undef)
+  call void @reload.init(ptr undef)
+  ret void
+}
+
+define internal void @overlap.init(ptr %context) unnamed_addr {
+entry:
+  %tail = getelementptr [4 x i8], ptr @overlap.buf, i32 0, i32 3
+  store i8 9, ptr %tail
+  %val = load i16, ptr @overlap.buf
+  %dst = getelementptr [4 x i8], ptr @overlap.buf, i32 0, i32 1
+  store i16 %val, ptr %dst
+  ret void
+}
+
+define internal void @alias.init(ptr %context) unnamed_addr {
+entry:
+  %src = getelementptr [4 x i8], ptr @alias.src, i32 0, i32 1
+  %val = load i16, ptr %src
+  store i16 %val, ptr @alias.dst
+  store i8 9, ptr @alias.dst
+  ret void
+}
+
+define internal void @reload.init(ptr %context) unnamed_addr {
+entry:
+  ; First store makes reload.buf writable in the current memory view.
+  %tail = getelementptr [4 x i8], ptr @reload.buf, i32 0, i32 3
+  store i8 9, ptr %tail
+  ; Partial load whose result may share the underlying buffer.
+  %val = load i16, ptr @reload.buf
+  ; Subsequent in-place partial store; this must not corrupt %val.
+  store i8 99, ptr @reload.buf
+  ; Write the originally-loaded value to a separate global.
+  store i16 %val, ptr @reload.out
+  ret void
+}

interp/testdata/store.out.ll

@@ -0,0 +1,13 @@
+target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64--linux"
+
+@overlap.buf = local_unnamed_addr global [4 x i8] c"\01\01\02\09"
+@alias.src = local_unnamed_addr global [4 x i8] c"\05\06\07\08"
+@alias.dst = local_unnamed_addr global [2 x i8] c"\09\07"
+@reload.buf = local_unnamed_addr global [4 x i8] c"c\02\03\09"
+@reload.out = local_unnamed_addr global [2 x i8] c"\01\02"
+
+define void @runtime.initAll() unnamed_addr {
+entry:
+  ret void
+}

loader/goroot.go

@@ -246,6 +246,7 @@ func pathsToOverride(goMinor int, needsSyscallPackage bool) map[string]bool {
 		"internal/futex/":             false,
 		"internal/fuzz/":              false,
 		"internal/itoa/":              false,
+		"internal/poll/":              false,
 		"internal/reflectlite/":       false,
 		"internal/gclayout":           false,
 		"internal/task/":              false,

loader/loader.go

@@ -27,8 +27,6 @@ import (
 	"github.com/tinygo-org/tinygo/goenv"
 )
 
-var initFileVersions = func(info *types.Info) {}
-
 // Program holds all packages and some metadata about the program as a whole.
 type Program struct {
 	config      *compileopts.Config
@@ -435,7 +433,7 @@ func (p *Package) Check() error {
 		}
 		checker.GoVersion = fmt.Sprintf("go%d.%d", major, minor)
 	}
-	initFileVersions(&p.info)
+	p.info.FileVersions = make(map[*ast.File]string)
 
 	// Do typechecking of the package.
 	packageName := p.ImportPath
@@ -485,7 +483,7 @@ func (p *Package) parseFiles() ([]*ast.File, error) {
 		if !filepath.IsAbs(file) {
 			file = filepath.Join(p.Dir, file)
 		}
-		f, err := p.parseFile(file, parser.ParseComments)
+		f, err := p.parseFile(file, parser.ParseComments|parser.SkipObjectResolution)
 		if err != nil {
 			fileErrs = append(fileErrs, err)
 			return

loader/loader_go122.go

@@ -1,17 +0,0 @@
-//go:build go1.22
-
-// types.Info.FileVersions was added in Go 1.22, so we can only initialize it
-// when built with Go 1.22.
-
-package loader
-
-import (
-	"go/ast"
-	"go/types"
-)
-
-func init() {
-	initFileVersions = func(info *types.Info) {
-		info.FileVersions = make(map[*ast.File]string)
-	}
-}

main.go

@@ -209,6 +209,8 @@ func Build(pkgName, outpath string, config *compileopts.Config) error {
 // Test runs the tests in the given package. Returns whether the test passed and
 // possibly an error if the test failed to run.
 func Test(pkgName string, stdout, stderr io.Writer, options *compileopts.Options, outpath string) (bool, error) {
+	optionsCopy := *options
+	options = &optionsCopy
 	options.TestConfig.CompileTestBinary = true
 	config, err := builder.NewConfig(options)
 	if err != nil {
@@ -395,7 +397,7 @@ func Flash(pkgName, port, outpath string, options *compileopts.Options) error {
 		fileExt = filepath.Ext(config.Target.FlashFilename)
 	case "openocd":
 		fileExt = ".hex"
-	case "bmp":
+	case "bmp", "probe-rs":
 		fileExt = ".elf"
 	case "adb":
 		fileExt = ".hex"
@@ -535,6 +537,16 @@ func Flash(pkgName, port, outpath string, options *compileopts.Options) error {
 		if err != nil {
 			return &commandError{"failed to flash", result.Binary, err}
 		}
+	case "probe-rs":
+		// TODO: this halts the target after flashing.
+		// See: https://github.com/probe-rs/probe-rs/discussions/4005
+		cmd := executeCommand(config.Options, "probe-rs", "download", "--chip="+config.Target.ProbeRSChip, "--verify", result.Binary)
+		cmd.Stdout = os.Stdout
+		cmd.Stderr = os.Stderr
+		err = cmd.Run()
+		if err != nil {
+			return &commandError{"failed to flash", result.Binary, err}
+		}
 	case "adb":
 		// Run pre-flash adb shell commands.
 		for _, preCmd := range config.Target.ADBPreCommands {
@@ -697,6 +709,21 @@ func Debug(debugger, pkgName string, ocdOutput bool, options *compileopts.Option
 			daemon.Stdout = w
 			daemon.Stderr = w
 		}
+	case "probe-rs":
+		port = ":1337"
+		gdbCommands = append(gdbCommands, "monitor halt", "load", "monitor reset halt")
+
+		daemon = executeCommand(config.Options, "probe-rs", "gdb", "--chip="+config.Target.ProbeRSChip)
+		if ocdOutput {
+			// Make it clear which output is from the daemon.
+			w := &ColorWriter{
+				Out:    colorable.NewColorableStderr(),
+				Prefix: "probe-rs: ",
+				Color:  TermColorYellow,
+			}
+			daemon.Stdout = w
+			daemon.Stderr = w
+		}
 	case "jlink":
 		port = ":2331"
 		gdbCommands = append(gdbCommands, "load", "monitor reset halt")
@@ -1753,6 +1780,7 @@ func main() {
 	printSize := flag.String("size", "", "print sizes (none, short, full, html)")
 	printStacks := flag.Bool("print-stacks", false, "print stack sizes of goroutines")
 	printAllocsString := flag.String("print-allocs", "", "regular expression of functions for which heap allocations should be printed")
+	printAllocsCoverString := flag.String("print-allocs-cover", "", "like -print-allocs, but in go coverage tool format")
 	printCommands := flag.Bool("x", false, "Print commands")
 	flagJSON := flag.Bool("json", false, "print output in JSON format")
 	parallelism := flag.Int("p", runtime.GOMAXPROCS(0), "the number of build jobs that can run in parallel")
@@ -1833,8 +1861,14 @@ func main() {
 	}
 
 	var printAllocs *regexp.Regexp
-	if *printAllocsString != "" {
-		printAllocs, err = regexp.Compile(*printAllocsString)
+	printAllocsCover := false
+	printAllocsPattern := *printAllocsString
+	if *printAllocsCoverString != "" {
+		printAllocsPattern = *printAllocsCoverString
+		printAllocsCover = true
+	}
+	if printAllocsPattern != "" {
+		printAllocs, err = regexp.Compile(printAllocsPattern)
 		if err != nil {
 			fmt.Fprintln(os.Stderr, err)
 			os.Exit(1)
@@ -1882,6 +1916,7 @@ func main() {
 		PrintSizes:              *printSize,
 		PrintStacks:             *printStacks,
 		PrintAllocs:             printAllocs,
+		PrintAllocsCover:        printAllocsCover,
 		Tags:                    []string(tags),
 		TestConfig:              testConfig,
 		GlobalValues:            globalVarValues,

main_test.go

@@ -46,15 +46,6 @@ var supportedLinuxArches = map[string]string{
 	"WASIp1":     "wasip1/wasm",
 }
 
-func init() {
-	major, _, _ := goenv.GetGorootVersion()
-	if major < 21 {
-		// Go 1.20 backwards compatibility.
-		// Should be removed once we drop support for Go 1.20.
-		delete(supportedLinuxArches, "WASIp1")
-	}
-}
-
 var sema = make(chan struct{}, runtime.NumCPU())
 
 func TestBuild(t *testing.T) {
@@ -76,6 +67,8 @@ func TestBuild(t *testing.T) {
 		"init_multi.go",
 		"interface.go",
 		"json.go",
+		"localtypes/",
+		"localtypes.go",
 		"map.go",
 		"map_bigkey.go",
 		"math.go",

monitor.go

@@ -278,7 +278,7 @@ func ListSerialPorts() ([]SerialPortInfo, error) {
 	return serialPortInfo, nil
 }
 
-var addressMatch = regexp.MustCompile(`^panic: runtime error at 0x([0-9a-f]+): `)
+var addressMatch = regexp.MustCompile(`panic: runtime error at 0x([0-9a-f]+): `)
 
 // Extract the address from the "panic: runtime error at" message.
 func extractPanicAddress(line []byte) uint64 {

src/crypto/rand/rand_arc4random.go

@@ -20,7 +20,7 @@ type reader struct {
 
 func (r *reader) Read(b []byte) (n int, err error) {
 	if len(b) != 0 {
-		libc_arc4random_buf(unsafe.Pointer(&b[0]), uint(len(b)))
+		libc_arc4random_buf(unsafe.Pointer(unsafe.SliceData(b)), uint(len(b)))
 	}
 	return len(b), nil
 }

src/crypto/rand/rand_windows.go

@@ -25,7 +25,7 @@ func (r *reader) Read(b []byte) (n int, err error) {
 	// See for example: https://github.com/golang/go/issues/33542
 	// For Windows 7 and newer, we might switch to ProcessPrng in the future
 	// (which is a documented function and might be a tiny bit faster).
-	ok := libc_RtlGenRandom(unsafe.Pointer(&b[0]), len(b))
+	ok := libc_RtlGenRandom(unsafe.Pointer(unsafe.SliceData(b)), len(b))
 	if !ok {
 		return 0, errRandom
 	}

src/device/esp/esp32c6.S

@@ -0,0 +1,66 @@
+// This is a very minimal bootloader for the ESP32-C6. It only initializes the
+// flash and then continues with the generic RISC-V initialization code, which
+// in turn will call runtime.main.
+// It is written in assembly (and not in a higher level language) to make sure
+// it is entirely loaded into IRAM and doesn't accidentally call functions
+// stored in IROM.
+//
+// The ESP32-C6 has a unified IRAM/DRAM address space at 0x40800000, and
+// separate DROM (0x42800000) / IROM (0x42000000) flash-mapped regions.
+
+.section .init
+.global call_start_cpu0
+.type call_start_cpu0,@function
+call_start_cpu0:
+    // At this point:
+    // - The ROM bootloader is finished and has jumped to here.
+    // - We're running from IRAM: both IRAM and DRAM segments have been loaded
+    //   by the ROM bootloader.
+    // - We have a usable stack (but not the one we would like to use).
+    // - No flash mappings (MMU) are set up yet.
+
+    // Reset MMU, see bootloader_reset_mmu in the ESP-IDF.
+    call Cache_Suspend_ICache
+    mv s0, a0 // autoload value
+    call Cache_Invalidate_ICache_All
+    call Cache_MMU_Init
+
+    // Set up flash mapping (both IROM and DROM).
+    // On ESP32-C6, Cache_Dbus_MMU_Set is replaced by Cache_MSPI_MMU_Set
+    // which has an extra "sensitive" parameter.
+    // C equivalent:
+    //   Cache_MSPI_MMU_Set(0, 0, 0x42000000, 0, 64, 256, 0)
+    // Maps 16MB starting at 0x42000000, covering both IROM and DROM.
+    li a0, 0              // sensitive: no flash encryption
+    li a1, 0              // ext_ram: MMU_ACCESS_FLASH
+    li a2, 0x42000000     // vaddr: start of flash-mapped region
+    li a3, 0              // paddr: physical address in the flash chip
+    li a4, 64             // psize: always 64 (kilobytes)
+    li a5, 256            // num: pages (16MB / 64K = 256, covers IROM+DROM)
+    li a6, 0              // fixed
+    call Cache_MSPI_MMU_Set
+
+    // Enable the flash cache.
+    mv a0, s0 // restore autoload value from Cache_Suspend_ICache call
+    call Cache_Resume_ICache
+
+    // Jump to generic RISC-V initialization, which initializes the stack
+    // pointer and globals register. It should not return.
+    j _start
+
+.section .text.exception_vectors
+.global _vector_table
+.type _vector_table,@function
+
+_vector_table:
+
+    .option push
+    .option norvc
+
+    .rept 32
+    j handleInterruptASM            /* interrupt handler */
+    .endr
+
+    .option pop
+
+.size _vector_table, .-_vector_table

src/device/gba/gba.go

@@ -85,6 +85,9 @@ var (
 	SIO = (*SIO_Type)(unsafe.Add(unsafe.Pointer(REG_BASE), uintptr(0x0134)))
 
 	INTERRUPT = (*INTERRUPT_Type)(unsafe.Add(unsafe.Pointer(REG_BASE), uintptr(0x0200)))
+
+	// BIOS interrupt flags
+	BIOS_IF = (*volatile.Register16)(unsafe.Pointer(uintptr(0x03007FF8)))
 )
 
 // Main memory sections
@@ -825,3 +828,60 @@ const (
 	OAMOBJ_ATT2_PB_Pos = 0xC
 	OAMOBJ_ATT2_PB_Msk = 0xF
 )
+
+// Constants for SOUND: sound control
+const (
+	SSW_INC = 0x0    // Increasing sweep rate
+	SSW_DEC = 0x0008 // Decreasing sweep rate
+	SSW_OFF = 0x0008 // Disable sweep altogether
+
+	SSQR_DUTY1_8 = 0x0    // 12.5% duty cycle (#-------)
+	SSQR_DUTY1_4 = 0x0040 // 25% duty cycle (##------)
+	SSQR_DUTY1_2 = 0x0080 // 50% duty cycle (####----)
+	SSQR_DUTY3_4 = 0x00C0 // 75% duty cycle (######--) Equivalent to 25%
+	SSQR_INC     = 0x0    // Increasing volume
+	SSQR_DEC     = 0x0800 // Decreasing volume
+
+	SFREQ_HOLD  = 0x0    // Continuous play
+	SFREQ_TIMED = 0x4000 // Timed play
+	SFREQ_RESET = 0x8000 // Reset sound
+
+	SDMG_SQR1  = 0x01
+	SDMG_SQR2  = 0x02
+	SDMG_WAVE  = 0x04
+	SDMG_NOISE = 0x08
+
+	SDMG_LSQR1  = 0x0100 // Enable channel 1 on left
+	SDMG_LSQR2  = 0x0200 // Enable channel 2 on left
+	SDMG_LWAVE  = 0x0400 // Enable channel 3 on left
+	SDMG_LNOISE = 0x0800 // Enable channel 4 on left
+	SDMG_RSQR1  = 0x1000 // Enable channel 1 on right
+	SDMG_RSQR2  = 0x2000 // Enable channel 2 on right
+	SDMG_RWAVE  = 0x4000 // Enable channel 3 on right
+	SDMG_RNOISE = 0x8000 // Enable channel 4 on right
+
+	SDS_DMG25  = 0x0    // Tone generators at 25% volume
+	SDS_DMG50  = 0x0001 // Tone generators at 50% volume
+	SDS_DMG100 = 0x0002 // Tone generators at 100% volume
+	SDS_A50    = 0x0    // Direct Sound A at 50% volume
+	SDS_A100   = 0x0004 // Direct Sound A at 100% volume
+	SDS_B50    = 0x0    // Direct Sound B at 50% volume
+	SDS_B100   = 0x0008 // Direct Sound B at 100% volume
+	SDS_AR     = 0x0100 // Enable Direct Sound A on right
+	SDS_AL     = 0x0200 // Enable Direct Sound A on left
+	SDS_ATMR0  = 0x0    // Direct Sound A to use timer 0
+	SDS_ATMR1  = 0x0400 // Direct Sound A to use timer 1
+	SDS_ARESET = 0x0800 // Reset FIFO of Direct Sound A
+	SDS_BR     = 0x1000 // Enable Direct Sound B on right
+	SDS_BL     = 0x2000 // Enable Direct Sound B on left
+	SDS_BTMR0  = 0x0    // Direct Sound B to use timer 0
+	SDS_BTMR1  = 0x4000 // Direct Sound B to use timer 1
+	SDS_BRESET = 0x8000 // Reset FIFO of Direct Sound B
+
+	SSTAT_SQR1    = 0x0001 // (R) Channel 1 status
+	SSTAT_SQR2    = 0x0002 // (R) Channel 2 status
+	SSTAT_WAVE    = 0x0004 // (R) Channel 3 status
+	SSTAT_NOISE   = 0x0008 // (R) Channel 4 status
+	SSTAT_DISABLE = 0      // Disable sound
+	SSTAT_ENABLE  = 0x0080 // Enable sound. NOTE: enable before using any other sound regs
+)

src/internal/cm/hostlayout.go

@@ -1,5 +1,3 @@
-//go:build go1.23
-
 package cm
 
 import "structs"

src/internal/cm/hostlayout_go122.go

@@ -1,11 +0,0 @@
-//go:build !go1.23
-
-package cm
-
-// HostLayout marks a struct as using host memory layout.
-// See [structs.HostLayout] in Go 1.23 or later.
-type HostLayout struct {
-	_ hostLayout // prevent accidental conversion with plain struct{}
-}
-
-type hostLayout struct{}

src/internal/poll/export_test_wasip1.go

@@ -0,0 +1,45 @@
+//go:build wasip1
+
+// Internal-test helpers exposed via go:linkname so user code can drive
+// the deadline-aware Read/Write loop without becoming a stdlib package.
+// Not part of the public API; the names are intentionally awkward to
+// signal "for tests only".
+
+package poll
+
+import (
+	"syscall"
+	"time"
+)
+
+// pollTestReadWithDeadline opens a pollable FD wrapper for sysfd, sets
+// a read deadline d into the future, calls Read once, and returns
+// (n, err). Caller is responsible for closing sysfd.
+//
+//go:linkname pollTestReadWithDeadline
+func pollTestReadWithDeadline(sysfd int, d time.Duration, p []byte) (int, error) {
+	fd := &FD{Sysfd: sysfd, IsStream: true}
+	// Best-effort init; ignore error so a caller using a not-fcntl-able FD
+	// (stdin under wazero, etc.) still gets to test the deadline path on
+	// whatever park behaviour the runtime gives.
+	_ = fd.Init("test", true)
+	if err := fd.SetReadDeadline(time.Now().Add(d)); err != nil {
+		return 0, err
+	}
+	return fd.Read(p)
+}
+
+// pollTestSetNonblock toggles O_NONBLOCK on a raw sysfd. Useful in
+// tests when the caller wants to ensure the FD is in nonblocking mode
+// before calling pollTestReadWithDeadline (Init is best-effort and may
+// silently skip).
+//
+//go:linkname pollTestSetNonblock
+func pollTestSetNonblock(sysfd int) error {
+	flags, err := syscall.Fcntl(sysfd, syscall.F_GETFL, 0)
+	if err != nil {
+		return err
+	}
+	_, err = syscall.Fcntl(sysfd, syscall.F_SETFL, flags|syscall.O_NONBLOCK)
+	return err
+}

src/internal/poll/fd_wasip1.go

@@ -0,0 +1,549 @@
+//go:build wasip1
+
+// Package poll is a minimal subset of upstream Go's internal/poll, scoped
+// to what is needed to back a wasip1 net implementation on top of
+// TinyGo's cooperative-scheduler netpoll integration.
+//
+// On wasip1 the cooperative scheduler integrates poll_oneoff with FD
+// waiters (see runtime/netpoll_wasip1.go and syscall/syscall_libc_wasip1.go).
+// This package wraps the syscall layer to:
+//
+//   - own the O_NONBLOCK policy decision (set on Init for pollable FDs),
+//     unblocking the EAGAIN→park retry loop that syscall.Read already has;
+//   - provide a Go-shaped FD type that net.* can use without reaching
+//     into syscall directly;
+//   - thread per-FD read/write deadlines through a runtime helper that
+//     lets a time.AfterFunc callback wake the parked goroutine;
+//   - dispatch socket FDs through wasi sock_recv / sock_send / sock_accept
+//     / sock_shutdown so net.Conn/net.Listener (via upstream Go's
+//     net/file_wasip1.go) work end-to-end.
+package poll
+
+import (
+	"errors"
+	"internal/task"
+	"syscall"
+	"time"
+	"unsafe"
+)
+
+// ErrFileClosing is returned when a Read or Write is started on a closed FD.
+var ErrFileClosing = errors.New("use of closed file")
+
+// ErrNetClosing is returned for network operations on a closed FD.
+var ErrNetClosing = errors.New("use of closed network connection")
+
+// ErrDeadlineExceeded is returned by Read/Write when a deadline expired.
+// Matches the error returned by os.IsTimeout-style helpers.
+var ErrDeadlineExceeded = errors.New("i/o timeout")
+
+// ErrNoDeadline is returned if SetDeadline is called on an FD whose
+// underlying type does not support deadlines.
+var ErrNoDeadline = errors.New("file type does not support deadline")
+
+// pollMode constants must mirror runtime/netpoll_wasip1.go's pollRead/
+// pollWrite values.
+const (
+	pollModeRead  uint8 = 1
+	pollModeWrite uint8 = 2
+)
+
+//go:linkname runtime_netpoll_addwait runtime.runtime_netpoll_addwait
+func runtime_netpoll_addwait(fd uint32, mode uint8) uintptr
+
+//go:linkname runtime_netpoll_done runtime.runtime_netpoll_done
+func runtime_netpoll_done(pd uintptr)
+
+//go:linkname runtime_netpoll_pdfired runtime.runtime_netpoll_pdfired
+func runtime_netpoll_pdfired(pd uintptr) bool
+
+//go:linkname runtime_netpoll_wake runtime.runtime_netpoll_wake
+func runtime_netpoll_wake(pd uintptr)
+
+//go:linkname fd_fdstat_get_type syscall.fd_fdstat_get_type
+func fd_fdstat_get_type(fd int) (syscall.Filetype, error)
+
+// wasiIovec / wasiCiovec mirror wasi-snapshot-preview1's iovec / ciovec
+// records: a buffer pointer plus a 32-bit length. Marshalled inline with
+// each fd_read / fd_write / sock_recv / sock_send call.
+type wasiIovec struct {
+	buf    *byte
+	bufLen uint32
+}
+
+// fd_read / fd_write are bound directly here rather than going through
+// wasi-libc so the deadline-aware Read/Write loop can observe EAGAIN
+// cleanly. Outside package runtime, TinyGo's wasmimport binding
+// restricts us to unsafe.Pointer for struct args and uint32 for the
+// errno result; the wasi spec uses *iovec and uint16 respectively but
+// the wire layout is identical.
+//
+//go:wasmimport wasi_snapshot_preview1 fd_read
+func wasi_fd_read(fd int32, iovs unsafe.Pointer, iovsLen uint32, nread unsafe.Pointer) uint32
+
+//go:wasmimport wasi_snapshot_preview1 fd_write
+func wasi_fd_write(fd int32, iovs unsafe.Pointer, iovsLen uint32, nwritten unsafe.Pointer) uint32
+
+// sock_recv / sock_send are the socket-data wasi syscalls used when the
+// FD's Filetype indicates a socket. We bind them here for the same
+// reason as fd_read / fd_write: the deadline-aware loop wants direct
+// access to the EAGAIN signal without libc's translation layer.
+//
+//go:wasmimport wasi_snapshot_preview1 sock_recv
+func wasi_sock_recv(fd int32, riData unsafe.Pointer, riDataLen uint32, riFlags uint32, roDatalen unsafe.Pointer, roFlags unsafe.Pointer) uint32
+
+//go:wasmimport wasi_snapshot_preview1 sock_send
+func wasi_sock_send(fd int32, siData unsafe.Pointer, siDataLen uint32, siFlags uint32, soDatalen unsafe.Pointer) uint32
+
+// SysFile carries per-FD bookkeeping that upstream Go's poll.FD uses to
+// share an underlying syscall FD between an os.File and a net.Conn (see
+// Copy below). RefCountPtr / RefCount handle the shared-ownership case;
+// Filetype caches the wasi filetype so socket-vs-file dispatch in Read /
+// Write is a single integer compare on the hot path.
+//
+// wasip1 is single-threaded, so the refcount is a plain int — no atomics
+// needed. Match upstream's field naming for source-level compatibility
+// with code that constructs FDs via struct literal (e.g. upstream's
+// net/fd_fake.go).
+type SysFile struct {
+	RefCountPtr *int32
+	RefCount    int32
+	Filetype    uint32
+}
+
+// init lazily allocates the refcount the first time it's needed (i.e.
+// the first Init or Copy on this FD). A zero SysFile starts at refcount
+// 1 — the FD's sole owner is the caller.
+func (s *SysFile) init() {
+	if s.RefCountPtr == nil {
+		s.RefCount = 1
+		s.RefCountPtr = &s.RefCount
+	}
+}
+
+// ref increments the shared refcount and returns a SysFile that points
+// at the same counter. Used by FD.Copy.
+func (s *SysFile) ref() SysFile {
+	s.init()
+	*s.RefCountPtr++
+	return SysFile{RefCountPtr: s.RefCountPtr, Filetype: s.Filetype}
+}
+
+// destroy decrements the refcount and reports whether the underlying
+// syscall FD should now be closed (i.e. this was the last owner).
+func (s *SysFile) destroy() bool {
+	if s.RefCountPtr == nil {
+		return true
+	}
+	*s.RefCountPtr--
+	return *s.RefCountPtr <= 0
+}
+
+// FD is the wasip1 file/socket descriptor wrapped with the bookkeeping
+// that net and os rely on. It owns the lifecycle of the underlying
+// syscall FD (modulo the Copy / refcount handoff between os.File and
+// net.Conn).
+//
+// The struct mirrors upstream Go's internal/poll.FD field naming
+// (Sysfd, IsStream, ZeroReadIsEOF, SysFile) so that upstream's
+// net/file_wasip1.go and net/fd_fake.go can construct one via struct
+// literal without modification.
+type FD struct {
+	Sysfd         int
+	SysFile       SysFile
+	IsStream      bool
+	ZeroReadIsEOF bool
+	closed        bool
+
+	// Per-FD deadlines, zero means "no deadline". Subsequent Read/Write
+	// calls observe whatever the current value is at call time; an
+	// in-flight call uses the deadline it captured at its start.
+	rDeadline time.Time
+	wDeadline time.Time
+}
+
+// Init readies the FD for use. When pollable is true (i.e. the FD might
+// block — sockets, pipes, FIFOs), Init sets O_NONBLOCK so that
+// Read/Write enter the EAGAIN→park retry loop instead of blocking the
+// entire wasm module.
+//
+// Init also caches the wasi filetype so the Read/Write hot path can
+// dispatch socket vs file with a single integer compare.
+//
+// The net argument is currently ignored but kept for parity with
+// upstream Go.
+func (fd *FD) Init(net string, pollable bool) error {
+	_ = net
+	fd.SysFile.init()
+	if ft, err := fd_fdstat_get_type(fd.Sysfd); err == nil {
+		fd.SysFile.Filetype = uint32(ft)
+	}
+	if !pollable {
+		return nil
+	}
+	flags, err := syscall.Fcntl(fd.Sysfd, syscall.F_GETFL, 0)
+	if err != nil {
+		return err
+	}
+	if flags&syscall.O_NONBLOCK != 0 {
+		return nil
+	}
+	if _, err := syscall.Fcntl(fd.Sysfd, syscall.F_SETFL, flags|syscall.O_NONBLOCK); err != nil {
+		return err
+	}
+	return nil
+}
+
+// Copy returns a duplicate FD that shares the underlying Sysfd through
+// the SysFile refcount. The original and the copy can independently
+// call Close — only the last one actually issues the syscall. Used by
+// upstream net/file_wasip1.go to hand a socket FD off from an os.File
+// to a net.Listener / net.Conn.
+func (fd *FD) Copy() FD {
+	return FD{
+		Sysfd:         fd.Sysfd,
+		SysFile:       fd.SysFile.ref(),
+		IsStream:      fd.IsStream,
+		ZeroReadIsEOF: fd.ZeroReadIsEOF,
+	}
+}
+
+// Close marks the FD closed. The underlying syscall FD is only released
+// when the refcount drops to zero — earlier Close calls (e.g. on the
+// os.File side after a successful net.FileConn handoff) just decrement.
+func (fd *FD) Close() error {
+	if fd.closed {
+		return ErrFileClosing
+	}
+	fd.closed = true
+	if !fd.SysFile.destroy() {
+		return nil
+	}
+	return syscall.Close(fd.Sysfd)
+}
+
+// Exist reports whether fd points to an actual FD wrapper (non-nil).
+// Callers in package os hold a *FD via a per-target alias and need to
+// nil-check without depending on the concrete type being a pointer.
+func (fd *FD) Exist() bool { return fd != nil }
+
+// CloseFunc is the hook upstream net's poll package exposes so tests
+// can intercept Close. We just point at syscall.Close.
+var CloseFunc func(int) error = syscall.Close
+
+// String is an internal string definition for methods/functions that
+// shouldn't be used outside the stdlib. Upstream net references it
+// from rawconn.go to mark methods as not-for-external-use.
+type String string
+
+// RawControl / RawRead / RawWrite back syscall.RawConn's three callback
+// methods. They invoke f with the underlying FD; the bool return of
+// RawRead / RawWrite controls retry-on-EAGAIN, which we implement by
+// parking the goroutine on the netpoll registry and retrying until f
+// returns true (the same loop upstream uses).
+func (fd *FD) RawControl(f func(uintptr)) error {
+	if fd.closed {
+		return ErrFileClosing
+	}
+	f(uintptr(fd.Sysfd))
+	return nil
+}
+
+func (fd *FD) RawRead(f func(uintptr) bool) error {
+	if fd.closed {
+		return ErrFileClosing
+	}
+	for {
+		if f(uintptr(fd.Sysfd)) {
+			return nil
+		}
+		wait(fd.Sysfd, pollModeRead)
+	}
+}
+
+func (fd *FD) RawWrite(f func(uintptr) bool) error {
+	if fd.closed {
+		return ErrFileClosing
+	}
+	for {
+		if f(uintptr(fd.Sysfd)) {
+			return nil
+		}
+		wait(fd.Sysfd, pollModeWrite)
+	}
+}
+
+// Shutdown calls wasi sock_shutdown. how is one of syscall.SHUT_RD,
+// SHUT_WR, SHUT_RDWR.
+func (fd *FD) Shutdown(how int) error {
+	return syscall.Shutdown(fd.Sysfd, how)
+}
+
+// Accept loops over wasi sock_accept, parking the goroutine on EAGAIN
+// (waiting for a new connection) through the netpoll registry. Returns
+// (newfd, sockaddr=nil, errcall, error) — sockaddr is always nil because
+// wasi sock_accept doesn't return one.
+func (fd *FD) Accept() (int, syscall.Sockaddr, string, error) {
+	deadline := fd.rDeadline
+	for {
+		if !deadline.IsZero() && !time.Now().Before(deadline) {
+			return -1, nil, "accept", ErrDeadlineExceeded
+		}
+		nfd, _, err := syscall.Accept(fd.Sysfd)
+		if err == nil {
+			return nfd, nil, "", nil
+		}
+		if err == syscall.EINTR {
+			continue
+		}
+		if err != syscall.EAGAIN {
+			return -1, nil, "accept", err
+		}
+		if deadline.IsZero() {
+			wait(fd.Sysfd, pollModeRead)
+		} else {
+			if perr := fd.parkUntil(pollModeRead, deadline); perr != nil {
+				return -1, nil, "accept", perr
+			}
+		}
+	}
+}
+
+// isSocket reports whether the cached Filetype is a stream or datagram
+// socket. False if Init was never called (Filetype stays 0 = UNKNOWN).
+func (fd *FD) isSocket() bool {
+	ft := syscall.Filetype(fd.SysFile.Filetype)
+	return ft == syscall.FILETYPE_SOCKET_STREAM || ft == syscall.FILETYPE_SOCKET_DGRAM
+}
+
+// Read reads from the FD into p. Sockets dispatch to sock_recv (which
+// honours fd.rDeadline directly); regular files/pipes go through
+// syscall.Read for the no-deadline fast path or readWithDeadline when
+// a deadline is set.
+func (fd *FD) Read(p []byte) (int, error) {
+	if fd.closed {
+		return 0, ErrFileClosing
+	}
+	if len(p) == 0 {
+		return 0, nil
+	}
+	if fd.isSocket() {
+		return fd.sockRecv(p)
+	}
+	if fd.rDeadline.IsZero() {
+		return syscall.Read(fd.Sysfd, p)
+	}
+	return fd.readWithDeadline(p)
+}
+
+// Write writes p to the FD. Sockets dispatch to sock_send. Regular
+// files / pipes go through syscall.Write or writeWithDeadline.
+func (fd *FD) Write(p []byte) (int, error) {
+	if fd.closed {
+		return 0, ErrFileClosing
+	}
+	if fd.isSocket() {
+		return fd.sockSend(p)
+	}
+	if fd.wDeadline.IsZero() {
+		return syscall.Write(fd.Sysfd, p)
+	}
+	return fd.writeWithDeadline(p)
+}
+
+// Pread reads from the FD at the given offset. Always file semantics —
+// sockets aren't seekable so this never goes through sock_recv.
+func (fd *FD) Pread(p []byte, off int64) (int, error) {
+	if fd.closed {
+		return 0, ErrFileClosing
+	}
+	return syscall.Pread(fd.Sysfd, p, off)
+}
+
+// Pwrite writes to the FD at the given offset.
+func (fd *FD) Pwrite(p []byte, off int64) (int, error) {
+	if fd.closed {
+		return 0, ErrFileClosing
+	}
+	return syscall.Pwrite(fd.Sysfd, p, off)
+}
+
+// SetDeadline sets both the read and write deadlines.
+func (fd *FD) SetDeadline(t time.Time) error {
+	fd.rDeadline = t
+	fd.wDeadline = t
+	return nil
+}
+
+// SetReadDeadline sets the deadline for future Read calls. A zero t
+// clears the deadline.
+func (fd *FD) SetReadDeadline(t time.Time) error {
+	fd.rDeadline = t
+	return nil
+}
+
+// SetWriteDeadline sets the deadline for future Write calls.
+func (fd *FD) SetWriteDeadline(t time.Time) error {
+	fd.wDeadline = t
+	return nil
+}
+
+// readWithDeadline implements the EAGAIN→park retry loop with deadline
+// cancellation for non-socket FDs. The deadline is captured at function
+// entry; later SetReadDeadline calls don't affect this in-flight Read.
+func (fd *FD) readWithDeadline(p []byte) (int, error) {
+	deadline := fd.rDeadline
+	iov := wasiIovec{buf: &p[0], bufLen: uint32(len(p))}
+	for {
+		if !time.Now().Before(deadline) {
+			return 0, ErrDeadlineExceeded
+		}
+		var n uint32
+		errno := wasi_fd_read(int32(fd.Sysfd), unsafe.Pointer(&iov), 1, unsafe.Pointer(&n))
+		switch errno {
+		case 0:
+			return int(n), nil
+		case wasiErrnoIntr:
+			continue
+		case wasiErrnoAgain:
+			if err := fd.parkUntil(pollModeRead, deadline); err != nil {
+				return 0, err
+			}
+		default:
+			return 0, syscall.Errno(errno)
+		}
+	}
+}
+
+func (fd *FD) writeWithDeadline(p []byte) (int, error) {
+	deadline := fd.wDeadline
+	var nn int
+	for {
+		if !time.Now().Before(deadline) {
+			return nn, ErrDeadlineExceeded
+		}
+		if nn == len(p) {
+			return nn, nil
+		}
+		buf := p[nn:]
+		iov := wasiIovec{buf: &buf[0], bufLen: uint32(len(buf))}
+		var n uint32
+		errno := wasi_fd_write(int32(fd.Sysfd), unsafe.Pointer(&iov), 1, unsafe.Pointer(&n))
+		switch errno {
+		case 0:
+			nn += int(n)
+		case wasiErrnoIntr:
+			// retry
+		case wasiErrnoAgain:
+			if err := fd.parkUntil(pollModeWrite, deadline); err != nil {
+				return nn, err
+			}
+		default:
+			return nn, syscall.Errno(errno)
+		}
+	}
+}
+
+// sockRecv is the socket sibling of readWithDeadline / syscall.Read.
+// Always issues sock_recv, regardless of deadline state, so callers
+// that don't want fd_read on a socket get a guaranteed sock_recv path.
+func (fd *FD) sockRecv(p []byte) (int, error) {
+	deadline := fd.rDeadline
+	iov := wasiIovec{buf: &p[0], bufLen: uint32(len(p))}
+	for {
+		if !deadline.IsZero() && !time.Now().Before(deadline) {
+			return 0, ErrDeadlineExceeded
+		}
+		var n uint32
+		var roFlags uint32
+		errno := wasi_sock_recv(int32(fd.Sysfd), unsafe.Pointer(&iov), 1, 0, unsafe.Pointer(&n), unsafe.Pointer(&roFlags))
+		switch errno {
+		case 0:
+			return int(n), nil
+		case wasiErrnoIntr:
+			continue
+		case wasiErrnoAgain:
+			if deadline.IsZero() {
+				wait(fd.Sysfd, pollModeRead)
+			} else if err := fd.parkUntil(pollModeRead, deadline); err != nil {
+				return 0, err
+			}
+		default:
+			return 0, syscall.Errno(errno)
+		}
+	}
+}
+
+func (fd *FD) sockSend(p []byte) (int, error) {
+	deadline := fd.wDeadline
+	var nn int
+	for {
+		if !deadline.IsZero() && !time.Now().Before(deadline) {
+			return nn, ErrDeadlineExceeded
+		}
+		if nn == len(p) {
+			return nn, nil
+		}
+		buf := p[nn:]
+		iov := wasiIovec{buf: &buf[0], bufLen: uint32(len(buf))}
+		var n uint32
+		errno := wasi_sock_send(int32(fd.Sysfd), unsafe.Pointer(&iov), 1, 0, unsafe.Pointer(&n))
+		switch errno {
+		case 0:
+			nn += int(n)
+		case wasiErrnoIntr:
+			// retry
+		case wasiErrnoAgain:
+			if deadline.IsZero() {
+				wait(fd.Sysfd, pollModeWrite)
+			} else if err := fd.parkUntil(pollModeWrite, deadline); err != nil {
+				return nn, err
+			}
+		default:
+			return nn, syscall.Errno(errno)
+		}
+	}
+}
+
+// wasi snapshot preview1 errno values, kept here so the read/write loops
+// can compare without dragging in the full syscall errno table for a
+// switch on three constants. These match the wasi spec exactly; see also
+// syscall_libc_wasi.go in package syscall.
+const (
+	wasiErrnoAgain uint32 = 6
+	wasiErrnoIntr  uint32 = 27
+)
+
+// wait parks the current goroutine until the FD becomes ready in the
+// given direction. No deadline; mirrors the helper of the same name in
+// package syscall (intentionally duplicated rather than linknamed
+// across the package boundary — see project memory on shim avoidance).
+func wait(fd int, mode uint8) {
+	pd := runtime_netpoll_addwait(uint32(fd), mode)
+	task.Pause()
+	runtime_netpoll_done(pd)
+}
+
+// parkUntil parks the current goroutine on (fd, mode) with a deadline.
+// Returns nil if the FD became ready or the timer fired (caller's loop
+// re-checks the deadline at top); ErrDeadlineExceeded if the deadline
+// was already in the past.
+//
+// Race handling: the deadline timer's callback and pollIO's event walk
+// can both target the same pollDesc. The pd.fired flag guards against
+// double-pushing the task to the run queue; whichever arrives second
+// is a no-op.
+func (fd *FD) parkUntil(mode uint8, deadline time.Time) error {
+	d := time.Until(deadline)
+	if d <= 0 {
+		return ErrDeadlineExceeded
+	}
+	pd := runtime_netpoll_addwait(uint32(fd.Sysfd), mode)
+	timer := time.AfterFunc(d, func() {
+		runtime_netpoll_wake(pd)
+	})
+	task.Pause()
+	timer.Stop()
+	runtime_netpoll_done(pd)
+	return nil
+}

src/internal/reflectlite/type.go

@@ -754,6 +754,98 @@ func (t *RawType) FieldAlign() int {
 	return t.Align()
 }
 
+// ConvertibleTo returns whether a value of type t can be converted to a variable of type u
+func (r *RawType) ConvertibleTo(u *RawType) bool {
+
+	// This logic is mostly copied from Value.CanConvert
+
+	switch r.Kind() {
+	case Int, Int8, Int16, Int32, Int64:
+		switch u.Kind() {
+		case Int, Int8, Int16, Int32, Int64, Uint, Uint8, Uint16, Uint32, Uint64, Uintptr:
+			return true
+		case Float32, Float64:
+			return true
+		case String:
+			return true
+		}
+
+	case Uint, Uint8, Uint16, Uint32, Uint64, Uintptr:
+		switch u.Kind() {
+		case Int, Int8, Int16, Int32, Int64, Uint, Uint8, Uint16, Uint32, Uint64, Uintptr:
+			return true
+		case Float32, Float64:
+			return true
+		case String:
+			return true
+		}
+
+	case Float32, Float64:
+		switch u.Kind() {
+		case Int, Int8, Int16, Int32, Int64:
+			return true
+		case Uint, Uint8, Uint16, Uint32, Uint64, Uintptr:
+			return true
+		case Float32, Float64:
+			return true
+		}
+
+	case Complex64, Complex128:
+		switch u.Kind() {
+		case Complex64, Complex128:
+			return true
+		}
+
+	case Slice:
+		switch u.Kind() {
+		case Array:
+			// This may fail at runtime if there isn't room
+			if r.elem() == u.elem() {
+				return true
+			}
+
+		case Pointer:
+			// This may fail at runtime if there isn't room
+			if u.elem().Kind() == Array && r.elem() == u.elem().elem() {
+				return true
+			}
+
+		case String:
+			// bytes or runes
+			if !r.elem().isNamed() && (r.elem().Kind() == Uint8 || r.elem().Kind() == Int32) {
+				return true
+			}
+
+		}
+
+	case String:
+		// bytes or runes
+		if u.Kind() == Slice && !u.elem().isNamed() && (u.elem().Kind() == Uint8 || u.elem().Kind() == Int32) {
+			return true
+		}
+
+	case Pointer:
+		if !r.isNamed() && u.Kind() == Pointer && !u.isNamed() && r.elem().underlying() == u.elem().underlying() {
+			return true
+		}
+	}
+
+	if r.underlying() == u.underlying() {
+		return true
+	}
+
+	if u.Kind() == Interface && u.NumMethod() == 0 {
+		return true
+	}
+
+	// TODO(dgryski): Unimplemented
+	// struct types
+	// channels
+
+	return false
+
+}
+
 // AssignableTo returns whether a value of type t can be assigned to a variable
 // of type u.
 func (t *RawType) AssignableTo(u Type) bool {

src/internal/reflectlite/value.go

@@ -51,6 +51,22 @@ func (v Value) isRO() bool {
 	return v.flags&(valueFlagRO) != 0
 }
 
+// These are package methods, not methods on Value, since the reflect.Value embeds a reflectlite.Value, so any
+// methods added to reflectlite.Value are visible to the user.
+
+func IsRO(v Value) bool {
+	return v.isRO()
+}
+
+func MakeRO(v Value, ro bool) Value {
+	if ro {
+		v.flags |= valueFlagRO
+	} else {
+		v.flags &^= valueFlagRO
+	}
+	return v
+}
+
 func (v Value) checkRO() {
 	if v.isRO() {
 		panic("reflect: value is not settable")
@@ -1485,13 +1501,11 @@ func convertOp(src Value, typ Type) (Value, bool) {
 			return cvtFloat(src, rtype), true
 		}
 
-		/*
-			case Complex64, Complex128:
-				switch src.Kind() {
-				case Complex64, Complex128:
-					return cvtComplex
-				}
-		*/
+	case Complex64, Complex128:
+		switch rtype := typ.(*RawType); rtype.Kind() {
+		case Complex64, Complex128:
+			return cvtComplex(src, rtype), true
+		}
 
 	case Slice:
 		switch rtype := typ.(*RawType); rtype.Kind() {
@@ -1534,6 +1548,12 @@ func convertOp(src Value, typ Type) (Value, bool) {
 				return cvtStringRunes(src, rtype), true
 			}
 		}
+
+	case Pointer:
+		rtype := typ.(*RawType)
+		if rtype.Kind() == Pointer && !src.typecode.isNamed() && !rtype.isNamed() && src.typecode.elem().underlying() == rtype.elem().underlying() {
+			return cvtDirect(src, rtype), true
+		}
 	}
 
 	// TODO(dgryski): Unimplemented:
@@ -1578,6 +1598,18 @@ func cvtFloat(v Value, t *RawType) Value {
 	return makeFloat(v.flags, v.Float(), t)
 }
 
+func cvtDirect(v Value, t *RawType) Value {
+	return Value{
+		typecode: t,
+		value:    v.value,
+		flags:    v.flags,
+	}
+}
+
+func cvtComplex(v Value, t *RawType) Value {
+	return makeComplex(v.flags, v.Complex(), t)
+}
+
 //go:linkname stringToBytes runtime.stringToBytes
 func stringToBytes(x string) []byte
 
@@ -1661,20 +1693,76 @@ func makeFloat32(flags valueFlags, f float32, t *RawType) Value {
 	return v
 }
 
-func cvtIntString(src Value, t *RawType) Value {
-	panic("cvtUintString: unimplemented")
+func makeComplex(flags valueFlags, f complex128, t *RawType) Value {
+	size := t.Size()
+
+	v := Value{
+		typecode: t,
+		flags:    flags,
+	}
+
+	ptr := unsafe.Pointer(&v.value)
+	if size > unsafe.Sizeof(uintptr(0)) {
+		ptr = alloc(size, nil)
+		v.value = ptr
+	}
+
+	switch size {
+	case 8:
+		*(*complex64)(ptr) = complex64(f)
+	case 16:
+		*(*complex128)(ptr) = f
+	}
+	return v
 }
 
-func cvtUintString(src Value, t *RawType) Value {
-	panic("cvtUintString: unimplemented")
+func cvtIntString(v Value, t *RawType) Value {
+	s := "\uFFFD"
+	if x := v.Int(); int64(rune(x)) == x {
+		s = string(rune(x))
+	}
+	return Value{
+		typecode: t,
+		value:    unsafe.Pointer(&s),
+		flags:    v.flags,
+	}
 }
 
-func cvtStringRunes(src Value, t *RawType) Value {
-	panic("cvsStringRunes: unimplemented")
+func cvtUintString(v Value, t *RawType) Value {
+	s := "\uFFFD"
+	if x := v.Uint(); uint64(rune(x)) == x {
+		s = string(rune(x))
+	}
+
+	return Value{
+		typecode: t,
+		value:    unsafe.Pointer(&s),
+		flags:    v.flags,
+	}
 }
 
-func cvtRunesString(src Value, t *RawType) Value {
-	panic("cvsRunesString: unimplemented")
+//go:linkname stringToRunes runtime.stringToRunes
+func stringToRunes(s string) []rune
+
+func cvtStringRunes(v Value, t *RawType) Value {
+	b := stringToRunes(*(*string)(v.value))
+	return Value{
+		typecode: t,
+		value:    unsafe.Pointer(&b),
+		flags:    v.flags,
+	}
+}
+
+//go:linkname stringFromRunes runtime.stringFromRunes
+func stringFromRunes(r []rune) string
+
+func cvtRunesString(v Value, t *RawType) Value {
+	s := stringFromRunes(*(*[]rune)(v.value))
+	return Value{
+		typecode: t,
+		value:    unsafe.Pointer(&s),
+		flags:    v.flags,
+	}
 }
 
 //go:linkname slicePanic runtime.slicePanic

src/internal/syscall/unix/getrandom_wasi.go

@@ -15,7 +15,7 @@ func GetRandom(p []byte, flags GetRandomFlag) (n int, err error) {
 	if len(p) == 0 {
 		return 0, nil
 	}
-	libc_arc4random_buf(unsafe.Pointer(&p[0]), uint(len(p)))
+	libc_arc4random_buf(unsafe.Pointer(unsafe.SliceData(p)), uint(len(p)))
 	return len(p), nil
 }
 

src/internal/task/task_none.go

@@ -42,3 +42,8 @@ func SystemStack() uintptr {
 	runtimePanic("scheduler is disabled")
 	return 0 // unreachable
 }
+
+func GoroutineStack() uintptr {
+	// No separate goroutine stack without a scheduler.
+	return 0
+}

src/internal/task/task_stack_cortexm.c

@@ -11,3 +11,14 @@ uintptr_t SystemStack() {
     );
     return sp;
 }
+
+uintptr_t GoroutineStack() {
+    uintptr_t sp;
+    asm volatile(
+        "mrs %0, PSP"
+        : "=r"(sp)
+        :
+        : "memory"
+    );
+    return sp;
+}

src/internal/task/task_stack_cortexm.go

@@ -70,3 +70,10 @@ func (s *state) pause() {
 //
 //export SystemStack
 func SystemStack() uintptr
+
+// GoroutineStack returns the PSP (goroutine stack pointer). When a fault
+// occurs in goroutine context, the hardware saves the exception frame to PSP;
+// reading PSP+0x18 gives the actual faulting PC.
+//
+//export GoroutineStack
+func GoroutineStack() uintptr

src/machine/board_badger2350.go

@@ -0,0 +1,113 @@
+//go:build badger2350
+
+// Chip: RP2350A (QFN-60, 30 GPIO) -> target inherits from "rp2350".
+// Pin source: https://github.com/pimoroni/badger2350/blob/main/board/pins.csv
+//
+// NOTES (verify before first flash):
+//   - POWER_EN (GPIO27) likely switches peripheral/display power.
+//     Verify polarity against the schematic; pull HIGH early if needed,
+//     otherwise the display will remain blank.
+//   - CHARGE_STAT is connected to EXT_GPIO2 (I2C IO expander) according to pins.csv,
+//     NOT the RP2350 -> intentionally not defined as a pin here.
+
+package machine
+
+// Crystal oscillator frequency.
+const xoscFreq = 12 // MHz
+
+// User buttons.
+const (
+	BUTTON_A    Pin = GPIO7
+	BUTTON_B    Pin = GPIO9
+	BUTTON_C    Pin = GPIO10
+	BUTTON_UP   Pin = GPIO11
+	BUTTON_DOWN Pin = GPIO6
+	BUTTON_HOME Pin = GPIO22
+	BUTTON_BOOT Pin = BUTTON_HOME
+
+	// System / RTC-related buttons.
+	BUTTON_RESET Pin = GPIO14
+	BUTTON_INT   Pin = GPIO15
+)
+
+// Case LEDs (4-zone mono illumination), named CL0..CL3 in the docs.
+const (
+	CL0 Pin = GPIO0
+	CL1 Pin = GPIO1
+	CL2 Pin = GPIO2
+	CL3 Pin = GPIO3
+
+	// Convention: first zone as default LED.
+	LED = CL0
+)
+
+// E-ink display (Inky), on SPI0.
+const (
+	INKY_BUSY Pin = GPIO16
+	INKY_CS   Pin = GPIO17
+	INKY_SCLK Pin = GPIO18
+	INKY_MOSI Pin = GPIO19
+	INKY_DC   Pin = GPIO20
+	INKY_RES  Pin = GPIO21
+)
+
+// SPI0 default pins == Inky bus. SDI is unused by the EPD,
+// but GPIO16 is a valid SPI0 RX line on the RP2350.
+const (
+	SPI0_SCK_PIN = GPIO18 // INKY_SCLK
+	SPI0_SDO_PIN = GPIO19 // INKY_MOSI
+	SPI0_SDI_PIN = GPIO16 // (unused by the EPD)
+)
+
+// SPI1 is not routed to any header; NoPin satisfies the machine package.
+const (
+	SPI1_SCK_PIN Pin = NoPin
+	SPI1_SDO_PIN Pin = NoPin
+	SPI1_SDI_PIN Pin = NoPin
+)
+
+// UART pins - default RP2350 UART0 mapping.
+// Note: GPIO0/GPIO1 are also CL0/CL1 (case LEDs)
+// Do not use UART0 and LEDs simultaneously.
+const (
+	UART0_TX_PIN = GPIO0
+	UART0_RX_PIN = GPIO1
+	UART_TX_PIN  = UART0_TX_PIN
+	UART_RX_PIN  = UART0_RX_PIN
+)
+
+// I2C0 (Qwiic/STEMMA QT + RTC PCF85063A).
+const (
+	I2C0_SDA_PIN = GPIO4
+	I2C0_SCL_PIN = GPIO5
+)
+
+// I2C1 is not routed to any header; NoPin satisfies the machine package.
+const (
+	I2C1_SDA_PIN Pin = NoPin
+	I2C1_SCL_PIN Pin = NoPin
+)
+
+// Power / Sensing.
+const (
+	VBUS_DETECT Pin = GPIO12
+	RTC_ALARM   Pin = GPIO13
+	VBAT_SENSE  Pin = GPIO26
+	POWER_EN    Pin = GPIO27
+	SENSE_1V1   Pin = GPIO28
+
+	BATTERY = VBAT_SENSE
+)
+
+var DefaultUART = UART0
+
+// USB identifiers
+const (
+	usb_STRING_PRODUCT      = "Badger 2350"
+	usb_STRING_MANUFACTURER = "Pimoroni"
+)
+
+var (
+	usb_VID uint16 = 0x2E8A
+	usb_PID uint16 = 0x0005
+)

src/machine/board_blinky2350.go

@@ -0,0 +1,112 @@
+//go:build blinky2350
+
+// Chip: RP2350A (QFN-60, 30 GPIO) -> target inherits from "rp2350".
+// Pin source: https://github.com/pimoroni/blinky2350/blob/main/board/pins.csv
+//
+// NOTES (verify before first flash):
+//   - POWER_EN (GPIO27) likely switches peripheral power.
+//     Verify polarity against the schematic; pull HIGH early if needed,
+//     otherwise the display will remain blank.
+//   - CHARGE_STAT is connected to EXT_GPIO2 (I2C IO expander) according to pins.csv,
+//     NOT the RP2350 -> intentionally not defined as a pin here.
+//   - The dot matrix is NOT driven via SPI (Latch/Blank/
+//     Row-Clock are not SPI signals) -> use PIO or bit-banging.
+//     SPI0 and SPI1 are therefore set to NoPin (required by the machine package).
+
+package machine
+
+// Crystal oscillator frequency.
+const xoscFreq = 12 // MHz
+
+// User buttons.
+const (
+	BUTTON_A    Pin = GPIO7
+	BUTTON_B    Pin = GPIO9
+	BUTTON_C    Pin = GPIO10
+	BUTTON_UP   Pin = GPIO11
+	BUTTON_DOWN Pin = GPIO6
+	BUTTON_HOME Pin = GPIO22
+	BUTTON_BOOT Pin = BUTTON_HOME
+
+	BUTTON_RESET Pin = GPIO14
+	BUTTON_INT   Pin = GPIO15
+)
+
+// Case LEDs (4-zone mono illumination), named CL0..CL3 in the docs.
+const (
+	CL0 Pin = GPIO0
+	CL1 Pin = GPIO1
+	CL2 Pin = GPIO2
+	CL3 Pin = GPIO3
+
+	LED = CL0
+)
+
+// LED dot matrix: column shift register + row driver.
+// NOT SPI -> drive via PIO or bit-banging.
+const (
+	DISPLAY_COL_SCLK  Pin = GPIO16
+	DISPLAY_COL_DATA  Pin = GPIO17
+	DISPLAY_COL_LATCH Pin = GPIO18
+	DISPLAY_COL_BLANK Pin = GPIO19
+	DISPLAY_ROW_DATA  Pin = GPIO20
+	DISPLAY_ROW_CLK   Pin = GPIO21
+)
+
+// I2C0 (Qwiic/STEMMA QT + RTC).
+const (
+	I2C0_SDA_PIN = GPIO4
+	I2C0_SCL_PIN = GPIO5
+)
+
+// I2C1 is not routed to any header; NoPin satisfies the machine package.
+const (
+	I2C1_SDA_PIN Pin = NoPin
+	I2C1_SCL_PIN Pin = NoPin
+)
+
+// SPI pins - the LED matrix is driven via PIO/bit-banging, not SPI.
+// NoPin satisfies the machine package requirements.
+const (
+	SPI0_SCK_PIN Pin = NoPin
+	SPI0_SDO_PIN Pin = NoPin
+	SPI0_SDI_PIN Pin = NoPin
+
+	SPI1_SCK_PIN Pin = NoPin
+	SPI1_SDO_PIN Pin = NoPin
+	SPI1_SDI_PIN Pin = NoPin
+)
+
+// UART pins - default RP2350 UART0 mapping.
+// Note: GPIO0/GPIO1 are also CL0/CL1 (case LEDs)
+// Do not use UART0 and LEDs simultaneously.
+const (
+	UART0_TX_PIN = GPIO0
+	UART0_RX_PIN = GPIO1
+	UART_TX_PIN  = UART0_TX_PIN
+	UART_RX_PIN  = UART0_RX_PIN
+)
+
+// Power / sensing.
+const (
+	VBUS_DETECT Pin = GPIO12
+	RTC_ALARM   Pin = GPIO13
+	VBAT_SENSE  Pin = GPIO26
+	POWER_EN    Pin = GPIO27
+	SENSE_1V1   Pin = GPIO28
+
+	BATTERY = VBAT_SENSE
+)
+
+var DefaultUART = UART0
+
+// USB identifiers
+const (
+	usb_STRING_PRODUCT      = "Blinky 2350"
+	usb_STRING_MANUFACTURER = "Pimoroni"
+)
+
+var (
+	usb_VID uint16 = 0x2E8A
+	usb_PID uint16 = 0x0005
+)

src/machine/board_esp32s3-box3.go

@@ -0,0 +1,144 @@
+//go:build esp32s3_box3
+
+// This file contains the pin mappings for the ESP32-S3-BOX-3 board.
+//
+// ESP32-S3-BOX-3 is an AI voice development kit with 2.4" display.
+// - https://github.com/espressif/esp-box
+//
+// Based on ESP-BOX-3 BSP from Espressif.
+
+package machine
+
+// CPUFrequency returns the current CPU frequency for ESP32-S3-BOX-3.
+// Returns 240MHz (max speed for ESP32-S3 with PSRAM)
+func CPUFrequency() uint32 {
+	return 240_000_000 // 240MHz
+}
+
+const (
+	// GPIO pins available on ESP32-S3-BOX-3
+	// Based on ESP-BOX-3 BSP pin definitions
+	IO0  = GPIO0 // Button Config
+	IO1  = GPIO1 // Button Mute / Mute Status
+	IO2  = GPIO2 // I2S MCLK
+	IO3  = GPIO3 // LCD Touch Interrupt
+	IO4  = GPIO4 // LCD DC
+	IO5  = GPIO5 // LCD CS
+	IO6  = GPIO6 // LCD DATA0 (MOSI)
+	IO7  = GPIO7 // LCD PCLK (SCK)
+	IO8  = GPIO8 // I2C SDA
+	IO9  = GPIO9 // SD Card D0
+	IO10 = GPIO10
+	IO11 = GPIO11 // SD Card CLK
+	IO12 = GPIO12 // SD Card D3
+	IO13 = GPIO13 // SD Card D1
+	IO14 = GPIO14 // SD Card CMD
+	IO15 = GPIO15 // I2S DOUT (Speaker)
+	IO16 = GPIO16 // I2S DSIN (Microphone)
+	IO17 = GPIO17 // I2S SCLK
+	IO18 = GPIO18 // I2C SCL
+	IO19 = GPIO19 // USB_NEG
+	IO20 = GPIO20 // USB_POS
+	IO21 = GPIO21
+	IO38 = GPIO38
+	IO39 = GPIO39
+	IO40 = GPIO40 // I2C Dock SCL
+	IO41 = GPIO41 // I2C Dock SDA
+	IO42 = GPIO42 // SD Card D2
+	IO43 = GPIO43 // SD Card Power
+	IO44 = GPIO44 // (Unused)
+	IO45 = GPIO45 // I2S LCLK (LRCK)
+	IO46 = GPIO46 // Power Amp Control
+	IO47 = GPIO47 // LCD Backlight
+	IO48 = GPIO48 // LCD Reset
+)
+
+// SPI pins
+const (
+	// SPI1 - used for LCD
+	SPI1_SCK_PIN  = IO7   // LCD_PCLK
+	SPI1_MOSI_PIN = IO6   // LCD_DATA0 (MOSI)
+	SPI1_MISO_PIN = NoPin // Not used for LCD
+	SPI1_CS_PIN   = IO5   // LCD_CS
+
+	// SPI2 (not used on this board)
+	SPI2_SCK_PIN  = NoPin
+	SPI2_MOSI_PIN = NoPin
+	SPI2_MISO_PIN = NoPin
+	SPI2_CS_PIN   = NoPin
+)
+
+// LCD pins (ST7789/ILI9341)
+const (
+	LCD_SCK_PIN = SPI1_SCK_PIN
+	LCD_SDO_PIN = SPI1_MOSI_PIN
+	LCD_SDI_PIN = NoPin
+	LCD_SS_PIN  = SPI1_CS_PIN
+	LCD_DC_PIN  = IO4
+	LCD_RST_PIN = IO48
+	LCD_BL_PIN  = IO47
+)
+
+// I2C pins (Internal I2C for sensors)
+const (
+	SDA0_PIN = IO8
+	SCL0_PIN = IO18
+
+	SDA_PIN = SDA0_PIN
+	SCL_PIN = SCL0_PIN
+)
+
+// Dock I2C pins (for expansion dock)
+const (
+	SDA1_PIN = IO41
+	SCL1_PIN = IO40
+)
+
+// UART pins (USB CDC - native USB on ESP32-S3)
+// Note: Native USB doesn't require GPIO pins, these are kept for compatibility
+const (
+	UART_TX_PIN = NoPin
+	UART_RX_PIN = NoPin
+)
+
+// Built-in LED
+// Using LCD backlight as LED indicator
+const LED = GPIO47
+
+// Buttons
+const (
+	BUTTON_CONFIG = GPIO0
+	BUTTON_MUTE   = GPIO1
+)
+
+// Audio pins (I2S)
+const (
+	I2S_SCLK_PIN = IO17 // Bit Clock
+	I2S_MCLK_PIN = IO2  // Master Clock
+	I2S_LRCK_PIN = IO45 // Left/Right Clock (Frame Sync)
+	I2S_DOUT_PIN = IO15 // Data Out to Speaker (ES8311)
+	I2S_DSIN_PIN = IO16 // Data In from Microphone (ES7210)
+)
+
+// SD Card pins (SD/MMC mode)
+const (
+	SDCARD_CMD_PIN = IO14
+	SDCARD_CLK_PIN = IO11
+	SDCARD_D0_PIN  = IO9
+	SDCARD_D1_PIN  = IO13
+	SDCARD_D2_PIN  = IO42
+	SDCARD_D3_PIN  = IO12
+	SDCARD_PWR_PIN = IO43 // SD Card Power
+)
+
+// USB pins (native USB)
+const (
+	USB_DPPIN = IO20 // USB D+
+	USB_DMPIN = IO19 // USB D-
+)
+
+// Touch interrupt
+const TOUCH_INT_PIN = IO3
+
+// Power amplifier control
+const POWER_AMP_PIN = IO46

src/machine/board_waveshare-rp2040-zero.go

@@ -41,6 +41,40 @@ const (
 	D29 Pin = GPIO29
 )
 
+// GPIO pin aliases
+const (
+	GP0  Pin = GPIO0
+	GP1  Pin = GPIO1
+	GP2  Pin = GPIO2
+	GP3  Pin = GPIO3
+	GP4  Pin = GPIO4
+	GP5  Pin = GPIO5
+	GP6  Pin = GPIO6
+	GP7  Pin = GPIO7
+	GP8  Pin = GPIO8
+	GP9  Pin = GPIO9
+	GP10 Pin = GPIO10
+	GP11 Pin = GPIO11
+	GP12 Pin = GPIO12
+	GP13 Pin = GPIO13
+	GP14 Pin = GPIO14
+	GP15 Pin = GPIO15
+	GP16 Pin = GPIO16
+	GP17 Pin = GPIO17
+	GP18 Pin = GPIO18
+	GP19 Pin = GPIO19
+	GP20 Pin = GPIO20
+	GP21 Pin = GPIO21
+	GP22 Pin = GPIO22
+	GP23 Pin = GPIO23
+	GP24 Pin = GPIO24
+	GP25 Pin = GPIO25
+	GP26 Pin = GPIO26
+	GP27 Pin = GPIO27
+	GP28 Pin = GPIO28
+	GP29 Pin = GPIO29
+)
+
 // Analog pins
 const (
 	A0 Pin = D26

src/machine/board_xiao-esp32c6.go

@@ -0,0 +1,57 @@
+//go:build xiao_esp32c6
+
+// This file contains the pin mappings for the Seeed XIAO ESP32C6 board.
+//
+// Seeed Studio XIAO ESP32C6 is an IoT mini development board based on
+// the Espressif ESP32-C6 WiFi 6 / Bluetooth 5 / 802.15.4 chip.
+//
+// - https://www.seeedstudio.com/Seeed-Studio-XIAO-ESP32C6-p-5884.html
+// - https://wiki.seeedstudio.com/xiao_esp32c6_getting_started/
+
+package machine
+
+// Digital Pins
+const (
+	D0  = GPIO0
+	D1  = GPIO1
+	D2  = GPIO2
+	D3  = GPIO21
+	D4  = GPIO22
+	D5  = GPIO23
+	D6  = GPIO16
+	D7  = GPIO17
+	D8  = GPIO19
+	D9  = GPIO20
+	D10 = GPIO18
+)
+
+// Analog pins
+const (
+	A0 = GPIO0
+	A1 = GPIO1
+	A2 = GPIO2
+)
+
+// UART pins
+const (
+	UART_TX_PIN = GPIO16
+	UART_RX_PIN = GPIO17
+)
+
+// I2C pins
+const (
+	SDA_PIN = GPIO22
+	SCL_PIN = GPIO23
+)
+
+// SPI pins
+const (
+	SPI_SCK_PIN = GPIO19
+	SPI_SDI_PIN = GPIO20
+	SPI_SDO_PIN = GPIO18
+)
+
+// Onboard LEDs
+const (
+	LED = GPIO15
+)

src/machine/i2c.go

@@ -1,4 +1,4 @@
-//go:build !baremetal || atmega || nrf || sam || stm32 || fe310 || k210 || rp2040 || rp2350 || mimxrt1062 || (esp32c3 && !m5stamp_c3) || esp32 || esp32s3
+//go:build !baremetal || atmega || nrf || sam || stm32 || fe310 || k210 || rp2040 || rp2350 || mimxrt1062 || (esp32c3 && !m5stamp_c3) || esp32 || esp32c6 || esp32s3
 
 package machine
 

src/machine/machine_atsamd21_usb.go

@@ -23,19 +23,6 @@ const (
 	NumberOfUSBEndpoints = 8
 )
 
-var (
-	endPoints = []uint32{
-		usb.CONTROL_ENDPOINT:  usb.ENDPOINT_TYPE_CONTROL,
-		usb.CDC_ENDPOINT_ACM:  (usb.ENDPOINT_TYPE_INTERRUPT | usb.EndpointIn),
-		usb.CDC_ENDPOINT_OUT:  (usb.ENDPOINT_TYPE_BULK | usb.EndpointOut),
-		usb.CDC_ENDPOINT_IN:   (usb.ENDPOINT_TYPE_BULK | usb.EndpointIn),
-		usb.HID_ENDPOINT_IN:   (usb.ENDPOINT_TYPE_DISABLE), // Interrupt In
-		usb.HID_ENDPOINT_OUT:  (usb.ENDPOINT_TYPE_DISABLE), // Interrupt Out
-		usb.MIDI_ENDPOINT_IN:  (usb.ENDPOINT_TYPE_DISABLE), // Bulk In
-		usb.MIDI_ENDPOINT_OUT: (usb.ENDPOINT_TYPE_DISABLE), // Bulk Out
-	}
-)
-
 // Configure the USB peripheral. The config is here for compatibility with the UART interface.
 func (dev *USBDevice) Configure(config UARTConfig) {
 	if dev.initcomplete {
@@ -188,7 +175,7 @@ func handleUSBIRQ(intr interrupt.Interrupt) {
 
 	// Now the actual transfer handlers, ignore endpoint number 0 (setup)
 	var i uint32
-	for i = 1; i < uint32(len(endPoints)); i++ {
+	for i = 1; i < NumberOfUSBEndpoints; i++ {
 		// Check if endpoint has a pending interrupt
 		epFlags := getEPINTFLAG(i)
 		setEPINTFLAG(i, epFlags)
@@ -206,6 +193,8 @@ func handleUSBIRQ(intr interrupt.Interrupt) {
 }
 
 func initEndpoint(ep, config uint32) {
+	// Note: Both IN (Bank 1) and OUT (Bank 0) configurations share the same EPCFG register.
+	// We must use getEPCFG(ep) | ... to avoid clearing/disabling the opposite direction.
 	switch config {
 	case usb.ENDPOINT_TYPE_INTERRUPT | usb.EndpointIn:
 		// set packet size
@@ -215,7 +204,7 @@ func initEndpoint(ep, config uint32) {
 		usbEndpointDescriptors[ep].DeviceDescBank[1].ADDR.Set(uint32(uintptr(unsafe.Pointer(&udd_ep_in_cache_buffer[ep]))))
 
 		// set endpoint type
-		setEPCFG(ep, ((usb.ENDPOINT_TYPE_INTERRUPT + 1) << sam.USB_DEVICE_EPCFG_EPTYPE1_Pos))
+		setEPCFG(ep, getEPCFG(ep)|((usb.ENDPOINT_TYPE_INTERRUPT+1)<<sam.USB_DEVICE_EPCFG_EPTYPE1_Pos))
 
 		setEPINTENSET(ep, sam.USB_DEVICE_EPINTENSET_TRCPT1)
 
@@ -227,7 +216,7 @@ func initEndpoint(ep, config uint32) {
 		usbEndpointDescriptors[ep].DeviceDescBank[0].ADDR.Set(uint32(uintptr(unsafe.Pointer(&udd_ep_out_cache_buffer[ep]))))
 
 		// set endpoint type
-		setEPCFG(ep, ((usb.ENDPOINT_TYPE_BULK + 1) << sam.USB_DEVICE_EPCFG_EPTYPE0_Pos))
+		setEPCFG(ep, getEPCFG(ep)|((usb.ENDPOINT_TYPE_BULK+1)<<sam.USB_DEVICE_EPCFG_EPTYPE0_Pos))
 
 		// receive interrupts when current transfer complete
 		setEPINTENSET(ep, sam.USB_DEVICE_EPINTENSET_TRCPT0)
@@ -246,7 +235,7 @@ func initEndpoint(ep, config uint32) {
 		usbEndpointDescriptors[ep].DeviceDescBank[0].ADDR.Set(uint32(uintptr(unsafe.Pointer(&udd_ep_out_cache_buffer[ep]))))
 
 		// set endpoint type
-		setEPCFG(ep, ((usb.ENDPOINT_TYPE_INTERRUPT + 1) << sam.USB_DEVICE_EPCFG_EPTYPE0_Pos))
+		setEPCFG(ep, getEPCFG(ep)|((usb.ENDPOINT_TYPE_INTERRUPT+1)<<sam.USB_DEVICE_EPCFG_EPTYPE0_Pos))
 
 		// receive interrupts when current transfer complete
 		setEPINTENSET(ep, sam.USB_DEVICE_EPINTENSET_TRCPT0)
@@ -265,7 +254,7 @@ func initEndpoint(ep, config uint32) {
 		usbEndpointDescriptors[ep].DeviceDescBank[1].ADDR.Set(uint32(uintptr(unsafe.Pointer(&udd_ep_in_cache_buffer[ep]))))
 
 		// set endpoint type
-		setEPCFG(ep, ((usb.ENDPOINT_TYPE_BULK + 1) << sam.USB_DEVICE_EPCFG_EPTYPE1_Pos))
+		setEPCFG(ep, getEPCFG(ep)|((usb.ENDPOINT_TYPE_BULK+1)<<sam.USB_DEVICE_EPCFG_EPTYPE1_Pos))
 
 		// NAK on endpoint IN, the bank is not yet filled in.
 		setEPSTATUSCLR(ep, sam.USB_DEVICE_EPSTATUSCLR_BK1RDY)
@@ -663,3 +652,19 @@ func setEPINTENSET(ep uint32, val uint8) {
 		return
 	}
 }
+
+func (dev *USBDevice) SetStallEPIn(ep uint32) {
+	setEPSTATUSSET(ep, sam.USB_DEVICE_EPSTATUSSET_STALLRQ1)
+}
+
+func (dev *USBDevice) SetStallEPOut(ep uint32) {
+	setEPSTATUSSET(ep, sam.USB_DEVICE_EPSTATUSSET_STALLRQ0)
+}
+
+func (dev *USBDevice) ClearStallEPIn(ep uint32) {
+	setEPSTATUSCLR(ep, sam.USB_DEVICE_EPSTATUSCLR_STALLRQ1)
+}
+
+func (dev *USBDevice) ClearStallEPOut(ep uint32) {
+	setEPSTATUSCLR(ep, sam.USB_DEVICE_EPSTATUSCLR_STALLRQ0)
+}

src/machine/machine_atsamd51_usb.go

@@ -23,19 +23,6 @@ const (
 	NumberOfUSBEndpoints = 8
 )
 
-var (
-	endPoints = []uint32{
-		usb.CONTROL_ENDPOINT:  usb.ENDPOINT_TYPE_CONTROL,
-		usb.CDC_ENDPOINT_ACM:  (usb.ENDPOINT_TYPE_INTERRUPT | usb.EndpointIn),
-		usb.CDC_ENDPOINT_OUT:  (usb.ENDPOINT_TYPE_BULK | usb.EndpointOut),
-		usb.CDC_ENDPOINT_IN:   (usb.ENDPOINT_TYPE_BULK | usb.EndpointIn),
-		usb.HID_ENDPOINT_IN:   (usb.ENDPOINT_TYPE_DISABLE), // Interrupt In
-		usb.HID_ENDPOINT_OUT:  (usb.ENDPOINT_TYPE_DISABLE), // Interrupt Out
-		usb.MIDI_ENDPOINT_IN:  (usb.ENDPOINT_TYPE_DISABLE), // Bulk In
-		usb.MIDI_ENDPOINT_OUT: (usb.ENDPOINT_TYPE_DISABLE), // Bulk Out
-	}
-)
-
 // Configure the USB peripheral. The config is here for compatibility with the UART interface.
 func (dev *USBDevice) Configure(config UARTConfig) {
 	if dev.initcomplete {
@@ -191,7 +178,7 @@ func handleUSBIRQ(intr interrupt.Interrupt) {
 
 	// Now the actual transfer handlers, ignore endpoint number 0 (setup)
 	var i uint32
-	for i = 1; i < uint32(len(endPoints)); i++ {
+	for i = 1; i < NumberOfUSBEndpoints; i++ {
 		// Check if endpoint has a pending interrupt
 		epFlags := getEPINTFLAG(i)
 		setEPINTFLAG(i, epFlags)
@@ -209,6 +196,8 @@ func handleUSBIRQ(intr interrupt.Interrupt) {
 }
 
 func initEndpoint(ep, config uint32) {
+	// Note: Both IN (Bank 1) and OUT (Bank 0) configurations share the same EPCFG register.
+	// We must use getEPCFG(ep) | ... to avoid clearing/disabling the opposite direction.
 	switch config {
 	case usb.ENDPOINT_TYPE_INTERRUPT | usb.EndpointIn:
 		// set packet size
@@ -218,7 +207,7 @@ func initEndpoint(ep, config uint32) {
 		usbEndpointDescriptors[ep].DeviceDescBank[1].ADDR.Set(uint32(uintptr(unsafe.Pointer(&udd_ep_in_cache_buffer[ep]))))
 
 		// set endpoint type
-		setEPCFG(ep, ((usb.ENDPOINT_TYPE_INTERRUPT + 1) << sam.USB_DEVICE_ENDPOINT_EPCFG_EPTYPE1_Pos))
+		setEPCFG(ep, getEPCFG(ep)|((usb.ENDPOINT_TYPE_INTERRUPT+1)<<sam.USB_DEVICE_ENDPOINT_EPCFG_EPTYPE1_Pos))
 
 		setEPINTENSET(ep, sam.USB_DEVICE_ENDPOINT_EPINTENSET_TRCPT1)
 
@@ -230,7 +219,7 @@ func initEndpoint(ep, config uint32) {
 		usbEndpointDescriptors[ep].DeviceDescBank[0].ADDR.Set(uint32(uintptr(unsafe.Pointer(&udd_ep_out_cache_buffer[ep]))))
 
 		// set endpoint type
-		setEPCFG(ep, ((usb.ENDPOINT_TYPE_BULK + 1) << sam.USB_DEVICE_ENDPOINT_EPCFG_EPTYPE0_Pos))
+		setEPCFG(ep, getEPCFG(ep)|((usb.ENDPOINT_TYPE_BULK+1)<<sam.USB_DEVICE_ENDPOINT_EPCFG_EPTYPE0_Pos))
 
 		// receive interrupts when current transfer complete
 		setEPINTENSET(ep, sam.USB_DEVICE_ENDPOINT_EPINTENSET_TRCPT0)
@@ -249,7 +238,7 @@ func initEndpoint(ep, config uint32) {
 		usbEndpointDescriptors[ep].DeviceDescBank[0].ADDR.Set(uint32(uintptr(unsafe.Pointer(&udd_ep_out_cache_buffer[ep]))))
 
 		// set endpoint type
-		setEPCFG(ep, ((usb.ENDPOINT_TYPE_INTERRUPT + 1) << sam.USB_DEVICE_ENDPOINT_EPCFG_EPTYPE0_Pos))
+		setEPCFG(ep, getEPCFG(ep)|((usb.ENDPOINT_TYPE_INTERRUPT+1)<<sam.USB_DEVICE_ENDPOINT_EPCFG_EPTYPE0_Pos))
 
 		// receive interrupts when current transfer complete
 		setEPINTENSET(ep, sam.USB_DEVICE_ENDPOINT_EPINTENSET_TRCPT0)
@@ -268,7 +257,7 @@ func initEndpoint(ep, config uint32) {
 		usbEndpointDescriptors[ep].DeviceDescBank[1].ADDR.Set(uint32(uintptr(unsafe.Pointer(&udd_ep_in_cache_buffer[ep]))))
 
 		// set endpoint type
-		setEPCFG(ep, ((usb.ENDPOINT_TYPE_BULK + 1) << sam.USB_DEVICE_ENDPOINT_EPCFG_EPTYPE1_Pos))
+		setEPCFG(ep, getEPCFG(ep)|((usb.ENDPOINT_TYPE_BULK+1)<<sam.USB_DEVICE_ENDPOINT_EPCFG_EPTYPE1_Pos))
 
 		// NAK on endpoint IN, the bank is not yet filled in.
 		setEPSTATUSCLR(ep, sam.USB_DEVICE_ENDPOINT_EPSTATUSCLR_BK1RDY)
@@ -494,3 +483,19 @@ func setEPINTENCLR(ep uint32, val uint8) {
 func setEPINTENSET(ep uint32, val uint8) {
 	sam.USB_DEVICE.DEVICE_ENDPOINT[ep].EPINTENSET.Set(val)
 }
+
+func (dev *USBDevice) SetStallEPIn(ep uint32) {
+	setEPSTATUSSET(ep, sam.USB_DEVICE_ENDPOINT_EPSTATUSSET_STALLRQ1)
+}
+
+func (dev *USBDevice) SetStallEPOut(ep uint32) {
+	setEPSTATUSSET(ep, sam.USB_DEVICE_ENDPOINT_EPSTATUSSET_STALLRQ0)
+}
+
+func (dev *USBDevice) ClearStallEPIn(ep uint32) {
+	setEPSTATUSCLR(ep, sam.USB_DEVICE_ENDPOINT_EPSTATUSCLR_STALLRQ1)
+}
+
+func (dev *USBDevice) ClearStallEPOut(ep uint32) {
+	setEPSTATUSCLR(ep, sam.USB_DEVICE_ENDPOINT_EPSTATUSCLR_STALLRQ0)
+}

src/machine/machine_esp32.go

@@ -295,16 +295,33 @@ var DefaultUART = UART0
 
 var (
 	UART0  = &_UART0
-	_UART0 = UART{Bus: esp.UART0, Buffer: NewRingBuffer()}
+	_UART0 = UART{
+		Bus:          esp.UART0,
+		Buffer:       NewRingBuffer(),
+		TXRXSignal:   14,
+		RTSCTSSignal: 15,
+	}
 	UART1  = &_UART1
-	_UART1 = UART{Bus: esp.UART1, Buffer: NewRingBuffer()}
+	_UART1 = UART{
+		Bus:          esp.UART1,
+		Buffer:       NewRingBuffer(),
+		TXRXSignal:   17,
+		RTSCTSSignal: 18,
+	}
 	UART2  = &_UART2
-	_UART2 = UART{Bus: esp.UART2, Buffer: NewRingBuffer()}
+	_UART2 = UART{
+		Bus:          esp.UART2,
+		Buffer:       NewRingBuffer(),
+		TXRXSignal:   198,
+		RTSCTSSignal: 199,
+	}
 )
 
 type UART struct {
-	Bus    *esp.UART_Type
-	Buffer *RingBuffer
+	Bus          *esp.UART_Type
+	Buffer       *RingBuffer
+	TXRXSignal   uint32
+	RTSCTSSignal uint32
 }
 
 func (uart *UART) Configure(config UARTConfig) {
@@ -312,6 +329,22 @@ func (uart *UART) Configure(config UARTConfig) {
 		config.BaudRate = 115200
 	}
 	uart.Bus.CLKDIV.Set(peripheralClock / config.BaudRate)
+
+	if config.RX != NoPin {
+		config.RX.configure(PinConfig{Mode: PinInputPullup}, uart.TXRXSignal)
+	}
+
+	if config.TX != NoPin {
+		config.TX.configure(PinConfig{Mode: PinOutput}, uart.TXRXSignal)
+	}
+
+	if config.RTS != NoPin {
+		config.RTS.configure(PinConfig{Mode: PinOutput}, uart.RTSCTSSignal)
+	}
+
+	if config.CTS != NoPin {
+		config.CTS.configure(PinConfig{Mode: PinInputPullup}, uart.RTSCTSSignal)
+	}
 }
 
 func (uart *UART) writeByte(b byte) error {
@@ -319,6 +352,7 @@ func (uart *UART) writeByte(b byte) error {
 		// Read UART_TXFIFO_CNT from the status register, which indicates how
 		// many bytes there are in the transmit buffer. Wait until there are
 		// less than 128 bytes in this buffer (the default buffer size).
+		gosched()
 	}
 	// Write to the TX_FIFO register.
 	(*volatile.Register8)(unsafe.Add(unsafe.Pointer(uart.Bus), 0x200C0000)).Set(b)

src/machine/machine_esp32c3_i2c.go

@@ -19,3 +19,10 @@ var (
 		useExt1: false,
 	}
 )
+
+// enableI2C0PeriphClock enables the I2C0 peripheral clock via SYSTEM.
+func enableI2C0PeriphClock() {
+	esp.SYSTEM.SetPERIP_RST_EN0_I2C_EXT0_RST(1)
+	esp.SYSTEM.SetPERIP_CLK_EN0_I2C_EXT0_CLK_EN(1)
+	esp.SYSTEM.SetPERIP_RST_EN0_I2C_EXT0_RST(0)
+}

src/machine/machine_esp32c6.go

@@ -0,0 +1,546 @@
+//go:build esp32c6
+
+package machine
+
+import (
+	"device/esp"
+	"device/riscv"
+	"errors"
+	"runtime/interrupt"
+	"runtime/volatile"
+	"sync"
+	"unsafe"
+)
+
+const deviceName = esp.Device
+const maxPin = 31
+const cpuInterruptFromPin = 6
+
+// CPUFrequency returns the current CPU frequency of the chip.
+// Currently it is a fixed frequency but it may allow changing in the future.
+func CPUFrequency() uint32 {
+	return 160e6 // 160MHz
+}
+
+const (
+	PinOutput PinMode = iota
+	PinInput
+	PinInputPullup
+	PinInputPulldown
+	PinAnalog
+)
+
+const (
+	GPIO0  Pin = 0
+	GPIO1  Pin = 1
+	GPIO2  Pin = 2
+	GPIO3  Pin = 3
+	GPIO4  Pin = 4
+	GPIO5  Pin = 5
+	GPIO6  Pin = 6
+	GPIO7  Pin = 7
+	GPIO8  Pin = 8
+	GPIO9  Pin = 9
+	GPIO10 Pin = 10
+	GPIO11 Pin = 11
+	GPIO12 Pin = 12
+	GPIO13 Pin = 13
+	GPIO14 Pin = 14
+	GPIO15 Pin = 15
+	GPIO16 Pin = 16
+	GPIO17 Pin = 17
+	GPIO18 Pin = 18
+	GPIO19 Pin = 19
+	GPIO20 Pin = 20
+	GPIO21 Pin = 21
+	GPIO22 Pin = 22
+	GPIO23 Pin = 23
+	GPIO24 Pin = 24
+	GPIO25 Pin = 25
+	GPIO26 Pin = 26
+	GPIO27 Pin = 27
+	GPIO28 Pin = 28
+	GPIO29 Pin = 29
+	GPIO30 Pin = 30
+)
+
+const (
+	ADC0 Pin = GPIO0
+	ADC1 Pin = GPIO1
+	ADC2 Pin = GPIO2
+	ADC3 Pin = GPIO3
+	ADC4 Pin = GPIO4
+	ADC5 Pin = GPIO5
+	ADC6 Pin = GPIO6
+)
+
+type PinChange uint8
+
+// Pin change interrupt constants for SetInterrupt.
+const (
+	PinRising PinChange = iota + 1
+	PinFalling
+	PinToggle
+)
+
+// Configure this pin with the given configuration.
+func (p Pin) Configure(config PinConfig) {
+	if p == NoPin {
+		// This simplifies pin configuration in peripherals such as SPI.
+		return
+	}
+
+	var muxConfig uint32
+
+	// Configure this pin as a GPIO pin.
+	const function = 1 // function 1 is GPIO for every pin
+	muxConfig |= function << esp.IO_MUX_GPIO_MCU_SEL_Pos
+
+	// FUN_IE: disable for PinAnalog (high-Z for ADC)
+	if config.Mode != PinAnalog {
+		muxConfig |= esp.IO_MUX_GPIO_FUN_IE
+	}
+
+	// Set drive strength: 0 is lowest, 3 is highest.
+	muxConfig |= 2 << esp.IO_MUX_GPIO_FUN_DRV_Pos
+
+	// Select pull mode (no pulls for PinAnalog).
+	if config.Mode == PinInputPullup {
+		muxConfig |= esp.IO_MUX_GPIO_FUN_WPU
+	} else if config.Mode == PinInputPulldown {
+		muxConfig |= esp.IO_MUX_GPIO_FUN_WPD
+	}
+
+	// Configure the pad with the given IO mux configuration.
+	p.mux().Set(muxConfig)
+
+	// Set the output signal to the simple GPIO output.
+	p.outFunc().Set(0x80)
+
+	switch config.Mode {
+	case PinOutput:
+		// Set the 'output enable' bit.
+		esp.GPIO.ENABLE_W1TS.Set(1 << p)
+	case PinInput, PinInputPullup, PinInputPulldown, PinAnalog:
+		// Clear the 'output enable' bit.
+		esp.GPIO.ENABLE_W1TC.Set(1 << p)
+	}
+}
+
+// configure is the same as Configure, but allows setting a specific GPIO matrix signal.
+func (p Pin) configure(config PinConfig, signal uint32) {
+	p.Configure(config)
+	if signal == 256 {
+		return
+	}
+	if config.Mode == PinOutput {
+		p.outFunc().Set(signal)
+	} else {
+		inFunc(signal).Set(esp.GPIO_FUNC_IN_SEL_CFG_SEL | uint32(p))
+	}
+}
+
+func initI2CExt1Clock() {}
+
+// outFunc returns the FUNCx_OUT_SEL_CFG register used for configuring the
+// output function selection.
+func (p Pin) outFunc() *volatile.Register32 {
+	return (*volatile.Register32)(unsafe.Add(unsafe.Pointer(&esp.GPIO.FUNC0_OUT_SEL_CFG), uintptr(p)*4))
+}
+
+func (p Pin) pinReg() *volatile.Register32 {
+	return (*volatile.Register32)(unsafe.Pointer((uintptr(unsafe.Pointer(&esp.GPIO.PIN0)) + uintptr(p)*4)))
+}
+
+// inFunc returns the FUNCy_IN_SEL_CFG register used for configuring the input
+// function selection.
+func inFunc(signal uint32) *volatile.Register32 {
+	return (*volatile.Register32)(unsafe.Add(unsafe.Pointer(&esp.GPIO.FUNC0_IN_SEL_CFG), uintptr(signal)*4))
+}
+
+// mux returns the I/O mux configuration register corresponding to the given
+// GPIO pin.
+func (p Pin) mux() *volatile.Register32 {
+	return (*volatile.Register32)(unsafe.Add(unsafe.Pointer(&esp.IO_MUX.GPIO0), uintptr(p)*4))
+}
+
+// pin returns the PIN register corresponding to the given GPIO pin.
+func (p Pin) pin() *volatile.Register32 {
+	return (*volatile.Register32)(unsafe.Add(unsafe.Pointer(&esp.GPIO.PIN0), uintptr(p)*4))
+}
+
+// Set the pin to high or low.
+// Warning: only use this on an output pin!
+func (p Pin) Set(value bool) {
+	if value {
+		reg, mask := p.portMaskSet()
+		reg.Set(mask)
+	} else {
+		reg, mask := p.portMaskClear()
+		reg.Set(mask)
+	}
+}
+
+// Get returns the current value of a GPIO pin when configured as an input or as
+// an output.
+func (p Pin) Get() bool {
+	reg := &esp.GPIO.IN
+	return (reg.Get()>>p)&1 > 0
+}
+
+// Return the register and mask to enable a given GPIO pin. This can be used to
+// implement bit-banged drivers.
+//
+// Warning: only use this on an output pin!
+func (p Pin) PortMaskSet() (*uint32, uint32) {
+	reg, mask := p.portMaskSet()
+	return &reg.Reg, mask
+}
+
+// Return the register and mask to disable a given GPIO pin. This can be used to
+// implement bit-banged drivers.
+//
+// Warning: only use this on an output pin!
+func (p Pin) PortMaskClear() (*uint32, uint32) {
+	reg, mask := p.portMaskClear()
+	return &reg.Reg, mask
+}
+
+func (p Pin) portMaskSet() (*volatile.Register32, uint32) {
+	return &esp.GPIO.OUT_W1TS, 1 << p
+}
+
+func (p Pin) portMaskClear() (*volatile.Register32, uint32) {
+	return &esp.GPIO.OUT_W1TC, 1 << p
+}
+
+// SetInterrupt sets an interrupt to be executed when a particular pin changes
+// state. The pin should already be configured as an input, including a pull up
+// or down if no external pull is provided.
+//
+// You can pass a nil func to unset the pin change interrupt. If you do so,
+// the change parameter is ignored and can be set to any value (such as 0).
+// If the pin is already configured with a callback, you must first unset
+// this pins interrupt before you can set a new callback.
+func (p Pin) SetInterrupt(change PinChange, callback func(Pin)) (err error) {
+	if p >= maxPin {
+		return ErrInvalidInputPin
+	}
+
+	if callback == nil {
+		// Disable this pin interrupt
+		p.pin().ClearBits(esp.GPIO_PIN_INT_TYPE_Msk | esp.GPIO_PIN_INT_ENA_Msk)
+
+		if pinCallbacks[p] != nil {
+			pinCallbacks[p] = nil
+		}
+		return nil
+	}
+
+	if pinCallbacks[p] != nil {
+		// The pin was already configured.
+		// To properly re-configure a pin, unset it first and set a new
+		// configuration.
+		return ErrNoPinChangeChannel
+	}
+	pinCallbacks[p] = callback
+
+	onceSetupPinInterrupt.Do(func() {
+		err = setupPinInterrupt()
+	})
+	if err != nil {
+		return err
+	}
+
+	p.pin().Set(
+		(p.pin().Get() & ^uint32(esp.GPIO_PIN_INT_TYPE_Msk|esp.GPIO_PIN_INT_ENA_Msk)) |
+			uint32(change)<<esp.GPIO_PIN_INT_TYPE_Pos | uint32(1)<<esp.GPIO_PIN_INT_ENA_Pos)
+
+	return nil
+}
+
+var (
+	pinCallbacks          [maxPin]func(Pin)
+	onceSetupPinInterrupt sync.Once
+)
+
+func setupPinInterrupt() error {
+	esp.INTERRUPT_CORE0.GPIO_INTERRUPT_PRO_MAP.Set(cpuInterruptFromPin)
+	return interrupt.New(cpuInterruptFromPin, func(interrupt.Interrupt) {
+		status := esp.GPIO.STATUS.Get()
+		// Clear before processing so new edges during callbacks are not lost.
+		esp.GPIO.STATUS_W1TC.Set(status)
+		for i, mask := 0, uint32(1); i < maxPin; i, mask = i+1, mask<<1 {
+			if (status&mask) != 0 && pinCallbacks[i] != nil {
+				pinCallbacks[i](Pin(i))
+			}
+		}
+	}).Enable()
+}
+
+var (
+	DefaultUART = UART0
+
+	UART0  = &_UART0
+	_UART0 = UART{Bus: esp.UART0, Buffer: NewRingBuffer()}
+	UART1  = &_UART1
+	_UART1 = UART{Bus: esp.UART1, Buffer: NewRingBuffer()}
+
+	onceUart            = sync.Once{}
+	errSamePins         = errors.New("UART: invalid pin combination")
+	errWrongUART        = errors.New("UART: unsupported UARTn")
+	errWrongBitSize     = errors.New("UART: invalid data size")
+	errWrongStopBitSize = errors.New("UART: invalid bit size")
+)
+
+type UART struct {
+	Bus                  *esp.UART_Type
+	Buffer               *RingBuffer
+	ParityErrorDetected  bool // set when parity error detected
+	DataErrorDetected    bool // set when data corruption detected
+	DataOverflowDetected bool // set when data overflow detected in UART FIFO buffer or RingBuffer
+}
+
+const (
+	defaultDataBits = 8
+	defaultStopBit  = 1
+	defaultParity   = ParityNone
+
+	uartInterrupts = esp.UART_INT_ENA_RXFIFO_FULL_INT_ENA |
+		esp.UART_INT_ENA_PARITY_ERR_INT_ENA |
+		esp.UART_INT_ENA_FRM_ERR_INT_ENA |
+		esp.UART_INT_ENA_RXFIFO_OVF_INT_ENA |
+		esp.UART_INT_ENA_GLITCH_DET_INT_ENA
+
+	pplClockFreq = 80e6
+)
+
+type registerSet struct {
+	interruptMapReg  *volatile.Register32
+	gpioMatrixSignal uint32
+}
+
+func (uart *UART) Configure(config UARTConfig) error {
+	if config.BaudRate == 0 {
+		config.BaudRate = 115200
+	}
+	if config.TX == config.RX {
+		return errSamePins
+	}
+	switch {
+	case uart.Bus == esp.UART0:
+		return uart.configure(config, registerSet{
+			interruptMapReg:  &esp.INTERRUPT_CORE0.UART0_INTR_MAP,
+			gpioMatrixSignal: 6,
+		})
+	case uart.Bus == esp.UART1:
+		return uart.configure(config, registerSet{
+			interruptMapReg:  &esp.INTERRUPT_CORE0.UART1_INTR_MAP,
+			gpioMatrixSignal: 9,
+		})
+	}
+	return errWrongUART
+}
+
+func (uart *UART) configure(config UARTConfig, regs registerSet) error {
+	initUARTClock(uart.Bus)
+
+	// - disable TX/RX clock to make sure the UART transmitter or receiver is not at work during configuration
+	uart.Bus.SetCLK_CONF_TX_SCLK_EN(0)
+	uart.Bus.SetCLK_CONF_RX_SCLK_EN(0)
+
+	// - default clock source: 1=XTAL_CLK, 2=RC_FAST_CLK, 3=FOSC_CLK
+	//   On C6, SCLK_SEL=1 selects XTAL (40 MHz). Use FOSC (80 MHz) for
+	//   better baud-rate accuracy.
+	uart.Bus.SetCLK_CONF_SCLK_SEL(3) // FOSC_CLK (80 MHz)
+	// reset divisor of the divider via UART_SCLK_DIV_NUM, UART_SCLK_DIV_A, and UART_SCLK_DIV_B
+	uart.Bus.SetCLK_CONF_SCLK_DIV_NUM(0)
+	uart.Bus.SetCLK_CONF_SCLK_DIV_A(0)
+	uart.Bus.SetCLK_CONF_SCLK_DIV_B(0)
+
+	uart.SetBaudRate(config.BaudRate)
+	uart.SetFormat(defaultDataBits, defaultStopBit, defaultParity)
+
+	// - set UART mode
+	uart.Bus.SetRS485_CONF_RS485_EN(0)
+	uart.Bus.SetRS485_CONF_RS485TX_RX_EN(0)
+	uart.Bus.SetRS485_CONF_RS485RXBY_TX_EN(0)
+	uart.Bus.SetCONF0_IRDA_EN(0)
+	// - disable hw-flow control
+	uart.Bus.SetCONF0_TX_FLOW_EN(0)
+
+	// synchronize values into Core Clock
+	uart.Bus.SetREG_UPDATE(1)
+
+	uart.setupPins(config, regs)
+	uart.configureInterrupt(regs.interruptMapReg)
+	uart.enableTransmitter()
+	uart.enableReceiver()
+
+	// Start TX/RX
+	uart.Bus.SetCLK_CONF_TX_SCLK_EN(1)
+	uart.Bus.SetCLK_CONF_RX_SCLK_EN(1)
+	return nil
+}
+
+func (uart *UART) SetFormat(dataBits, stopBits int, parity UARTParity) error {
+	if dataBits < 5 {
+		return errWrongBitSize
+	}
+	if stopBits > 1 {
+		return errWrongStopBitSize
+	}
+	// - data length
+	uart.Bus.SetCONF0_BIT_NUM(uint32(dataBits - 5))
+	// - stop bit
+	uart.Bus.SetCONF0_STOP_BIT_NUM(uint32(stopBits))
+	// - parity check
+	switch parity {
+	case ParityNone:
+		uart.Bus.SetCONF0_PARITY_EN(0)
+	case ParityEven:
+		uart.Bus.SetCONF0_PARITY_EN(1)
+		uart.Bus.SetCONF0_PARITY(0)
+	case ParityOdd:
+		uart.Bus.SetCONF0_PARITY_EN(1)
+		uart.Bus.SetCONF0_PARITY(1)
+	}
+	return nil
+}
+
+func initUARTClock(bus *esp.UART_Type) {
+	// On ESP32-C6, UART clock is controlled via PCR (Peripheral Clock Reset).
+	switch bus {
+	case esp.UART0:
+		esp.PCR.SetUART0_CONF_UART0_CLK_EN(1)
+		esp.PCR.SetUART0_CONF_UART0_RST_EN(0) // ensure not in reset
+		bus.SetCLK_CONF_RST_CORE(1)
+		esp.PCR.SetUART0_CONF_UART0_RST_EN(1)
+		esp.PCR.SetUART0_CONF_UART0_RST_EN(0)
+		bus.SetCLK_CONF_RST_CORE(0)
+		// Configure SCLK divisor in PCR
+		esp.PCR.SetUART0_SCLK_CONF_UART0_SCLK_DIV_NUM(0)
+		esp.PCR.SetUART0_SCLK_CONF_UART0_SCLK_DIV_A(0)
+		esp.PCR.SetUART0_SCLK_CONF_UART0_SCLK_DIV_B(0)
+	case esp.UART1:
+		esp.PCR.SetUART1_CONF_UART1_CLK_EN(1)
+		esp.PCR.SetUART1_CONF_UART1_RST_EN(0)
+		bus.SetCLK_CONF_RST_CORE(1)
+		esp.PCR.SetUART1_CONF_UART1_RST_EN(1)
+		esp.PCR.SetUART1_CONF_UART1_RST_EN(0)
+		bus.SetCLK_CONF_RST_CORE(0)
+		esp.PCR.SetUART1_SCLK_CONF_UART1_SCLK_DIV_NUM(0)
+		esp.PCR.SetUART1_SCLK_CONF_UART1_SCLK_DIV_A(0)
+		esp.PCR.SetUART1_SCLK_CONF_UART1_SCLK_DIV_B(0)
+	}
+	// wait for Core Clock to ready for configuration
+	for bus.GetREG_UPDATE() > 0 {
+		riscv.Asm("nop")
+	}
+}
+
+func (uart *UART) SetBaudRate(baudRate uint32) {
+	// based on esp-idf
+	max_div := uint32((1 << 12) - 1)
+	sclk_div := (pplClockFreq + (max_div * baudRate) - 1) / (max_div * baudRate)
+	clk_div := (pplClockFreq << 4) / (baudRate * sclk_div)
+	uart.Bus.SetCLKDIV(clk_div >> 4)
+	uart.Bus.SetCLKDIV_FRAG(clk_div & 0xf)
+	// On C6, the SCLK divisor is in the PCR register.
+	switch uart.Bus {
+	case esp.UART0:
+		esp.PCR.SetUART0_SCLK_CONF_UART0_SCLK_DIV_NUM(sclk_div - 1)
+	case esp.UART1:
+		esp.PCR.SetUART1_SCLK_CONF_UART1_SCLK_DIV_NUM(sclk_div - 1)
+	}
+}
+
+func (uart *UART) setupPins(config UARTConfig, regs registerSet) {
+	config.RX.Configure(PinConfig{Mode: PinInputPullup})
+	config.TX.Configure(PinConfig{Mode: PinInputPullup})
+
+	// link TX with GPIO signal X (technical reference manual, GPIO matrix)
+	config.TX.outFunc().Set(regs.gpioMatrixSignal)
+	// link RX with GPIO signal X and route signals via GPIO matrix
+	inFunc(regs.gpioMatrixSignal).Set(esp.GPIO_FUNC_IN_SEL_CFG_SEL | uint32(config.RX))
+}
+
+func (uart *UART) configureInterrupt(intrMapReg *volatile.Register32) {
+	// Disable all UART interrupts
+	uart.Bus.INT_ENA.ClearBits(0x0ffff)
+
+	intrMapReg.Set(7)
+	onceUart.Do(func() {
+		_ = interrupt.New(7, func(i interrupt.Interrupt) {
+			UART0.serveInterrupt(0)
+			UART1.serveInterrupt(1)
+		}).Enable()
+	})
+}
+
+func (uart *UART) serveInterrupt(num int) {
+	// get interrupt status
+	interrutFlag := uart.Bus.INT_ST.Get()
+	if (interrutFlag & uartInterrupts) == 0 {
+		return
+	}
+
+	// block UART interrupts while processing
+	uart.Bus.INT_ENA.ClearBits(uartInterrupts)
+
+	if interrutFlag&esp.UART_INT_ENA_RXFIFO_FULL_INT_ENA > 0 {
+		for uart.Bus.GetSTATUS_RXFIFO_CNT() > 0 {
+			b := uart.Bus.GetFIFO_RXFIFO_RD_BYTE()
+			if !uart.Buffer.Put(byte(b & 0xff)) {
+				uart.DataOverflowDetected = true
+			}
+		}
+	}
+	if interrutFlag&esp.UART_INT_ENA_PARITY_ERR_INT_ENA > 0 {
+		uart.ParityErrorDetected = true
+	}
+	if 0 != interrutFlag&esp.UART_INT_ENA_FRM_ERR_INT_ENA {
+		uart.DataErrorDetected = true
+	}
+	if 0 != interrutFlag&esp.UART_INT_ENA_RXFIFO_OVF_INT_ENA {
+		uart.DataOverflowDetected = true
+	}
+	if 0 != interrutFlag&esp.UART_INT_ENA_GLITCH_DET_INT_ENA {
+		uart.DataErrorDetected = true
+	}
+
+	// Clear the UART interrupt status
+	uart.Bus.INT_CLR.SetBits(interrutFlag)
+	uart.Bus.INT_CLR.ClearBits(interrutFlag)
+	// Enable interrupts
+	uart.Bus.INT_ENA.Set(uartInterrupts)
+}
+
+const uart_empty_thresh_default = 10
+
+func (uart *UART) enableTransmitter() {
+	uart.Bus.SetCONF0_TXFIFO_RST(1)
+	uart.Bus.SetCONF0_TXFIFO_RST(0)
+	uart.Bus.SetCONF1_TXFIFO_EMPTY_THRHD(uart_empty_thresh_default)
+}
+
+func (uart *UART) enableReceiver() {
+	uart.Bus.SetCONF0_RXFIFO_RST(1)
+	uart.Bus.SetCONF0_RXFIFO_RST(0)
+	uart.Bus.SetCONF1_RXFIFO_FULL_THRHD(1)
+	uart.Bus.SetINT_ENA_RXFIFO_FULL_INT_ENA(1)
+	uart.Bus.SetINT_ENA_FRM_ERR_INT_ENA(1)
+	uart.Bus.SetINT_ENA_PARITY_ERR_INT_ENA(1)
+	uart.Bus.SetINT_ENA_GLITCH_DET_INT_ENA(1)
+	uart.Bus.SetINT_ENA_RXFIFO_OVF_INT_ENA(1)
+}
+
+func (uart *UART) writeByte(b byte) error {
+	for (uart.Bus.STATUS.Get()&esp.UART_STATUS_TXFIFO_CNT_Msk)>>esp.UART_STATUS_TXFIFO_CNT_Pos >= 128 {
+		// Wait until there is space in the transmit buffer.
+	}
+	uart.Bus.FIFO.Set(uint32(b))
+	return nil
+}
+
+func (uart *UART) flush() {}

src/machine/machine_esp32c6_i2c.go

@@ -0,0 +1,37 @@
+//go:build esp32c6
+
+package machine
+
+import (
+	"device/esp"
+)
+
+// GPIO matrix signal indices for I2C0 on ESP32-C6.
+const (
+	I2CEXT0_SCL_OUT_IDX = 45
+	I2CEXT0_SDA_OUT_IDX = 46
+)
+
+var (
+	I2C0 = &I2C{
+		Bus:     esp.I2C0,
+		funcSCL: I2CEXT0_SCL_OUT_IDX,
+		funcSDA: I2CEXT0_SDA_OUT_IDX,
+		useExt1: false,
+	}
+)
+
+// enableI2C0PeriphClock enables the I2C0 peripheral clock via PCR.
+func enableI2C0PeriphClock() {
+	// Enable the APB/bus clock for the I2C0 registers and pulse the reset.
+	esp.PCR.SetI2C0_CONF_I2C0_CLK_EN(1)
+	esp.PCR.SetI2C0_CONF_I2C0_RST_EN(1)
+	esp.PCR.SetI2C0_CONF_I2C0_RST_EN(0)
+
+	// On the ESP32-C6 the I2C functional (source) clock is gated and selected
+	// in PCR.
+	// Select the XTAL (40 MHz) source and enable the clock gate, otherwise SCL
+	// is never driven and no bytes are clocked onto the bus.
+	esp.PCR.SetI2C_SCLK_CONF_I2C_SCLK_SEL(i2cClkSource)
+	esp.PCR.SetI2C_SCLK_CONF_I2C_SCLK_EN(1)
+}

src/machine/machine_esp32c6_usb.go

@@ -0,0 +1,250 @@
+//go:build esp32c6
+
+package machine
+
+import (
+	"device/esp"
+	"errors"
+	"machine/usb"
+	"machine/usb/descriptor"
+	"runtime/interrupt"
+)
+
+// USB Serial/JTAG Controller
+// The ESP32-C6 has the same built-in USB Serial/JTAG hardware IP as the
+// ESP32-C3. The only difference at the machine level is how the peripheral
+// clock is enabled: C3 uses SYSTEM.PERIP_CLK_EN0, while C6 uses the PCR
+// (Peripheral Clock Reset) block.
+
+const cpuInterruptFromUSB = 10
+
+type USB_DEVICE struct {
+	Bus       *esp.USB_DEVICE_Type
+	Buffer    *RingBuffer
+	txPending bool // unflushed data in the EP1 TX FIFO
+	txStalled bool // set when flushAndWait fails (no host reading); cleared when FIFO becomes writable
+}
+
+var (
+	_USBCDC = &USB_DEVICE{
+		Bus:    esp.USB_DEVICE,
+		Buffer: NewRingBuffer(),
+	}
+
+	USBCDC Serialer = _USBCDC
+)
+
+var (
+	errUSBWrongSize            = errors.New("USB: invalid write size")
+	errUSBCouldNotWriteAllData = errors.New("USB: could not write all data")
+)
+
+type Serialer interface {
+	WriteByte(c byte) error
+	Write(data []byte) (n int, err error)
+	Configure(config UARTConfig) error
+	Buffered() int
+	ReadByte() (byte, error)
+	DTR() bool
+	RTS() bool
+}
+
+var usbConfigured bool
+
+// USBDevice provides a stub USB device for the ESP32-C6. The hardware
+// only supports a fixed-function CDC-ACM serial port, so the programmable
+// USB device features are no-ops.
+type USBDevice struct {
+	initcomplete         bool
+	InitEndpointComplete bool
+}
+
+var USBDev = &USBDevice{}
+
+func (dev *USBDevice) SetStallEPIn(ep uint32)    {}
+func (dev *USBDevice) SetStallEPOut(ep uint32)   {}
+func (dev *USBDevice) ClearStallEPIn(ep uint32)  {}
+func (dev *USBDevice) ClearStallEPOut(ep uint32) {}
+
+// initUSB is intentionally empty — the interp phase evaluates init()
+// functions at compile time and cannot access hardware registers.
+// Actual hardware setup is deferred to the first Configure() call.
+func initUSB() {}
+
+// Configure initialises the USB Serial/JTAG controller clock, pads, and
+// interrupt so that received data is buffered automatically.
+func (usbdev *USB_DEVICE) Configure(config UARTConfig) error {
+	if usbConfigured {
+		return nil
+	}
+	usbConfigured = true
+
+	// Enable the USB_DEVICE peripheral clock via PCR (C6 uses PCR instead
+	// of SYSTEM.PERIP_CLK_EN0 that C3 used).
+	esp.PCR.SetUSB_DEVICE_CONF_USB_DEVICE_CLK_EN(1)
+	esp.PCR.SetUSB_DEVICE_CONF_USB_DEVICE_RST_EN(0)
+
+	// Ensure internal PHY is selected and USB pads are enabled.
+	usbdev.Bus.SetCONF0_PHY_SEL(0)
+	usbdev.Bus.SetCONF0_USB_PAD_ENABLE(1)
+	usbdev.Bus.SetCONF0_DP_PULLUP(1)
+
+	// Clear any pending interrupts.
+	usbdev.Bus.INT_CLR.Set(0xFFFFFFFF)
+
+	// Enable the RX-packet-received interrupt.
+	usbdev.Bus.SetINT_ENA_SERIAL_OUT_RECV_PKT_INT_ENA(1)
+
+	// Map the USB peripheral interrupt to CPU interrupt cpuInterruptFromUSB.
+	esp.INTERRUPT_CORE0.SetUSB_INTR_MAP(cpuInterruptFromUSB)
+
+	_ = interrupt.New(cpuInterruptFromUSB, func(interrupt.Interrupt) {
+		_USBCDC.handleInterrupt()
+	}).Enable()
+
+	return nil
+}
+
+// ensureConfigured triggers lazy initialization on first use.
+func (usbdev *USB_DEVICE) ensureConfigured() {
+	if !usbConfigured {
+		usbdev.Configure(UARTConfig{})
+	}
+}
+
+// handleInterrupt drains the hardware RX FIFO into the software ring buffer.
+func (usbdev *USB_DEVICE) handleInterrupt() {
+	intStatus := usbdev.Bus.INT_ST.Get()
+
+	// Disable the RX interrupt to prevent re-triggering while we drain.
+	usbdev.Bus.SetINT_ENA_SERIAL_OUT_RECV_PKT_INT_ENA(0)
+
+	if intStatus&esp.USB_DEVICE_INT_ST_SERIAL_OUT_RECV_PKT_INT_ST != 0 {
+		for usbdev.Bus.GetEP1_CONF_SERIAL_OUT_EP_DATA_AVAIL() != 0 {
+			b := byte(usbdev.Bus.EP1.Get())
+			usbdev.Buffer.Put(b)
+		}
+		usbdev.Bus.SetINT_CLR_SERIAL_OUT_RECV_PKT_INT_CLR(1)
+	}
+
+	// Re-enable the RX interrupt.
+	usbdev.Bus.SetINT_ENA_SERIAL_OUT_RECV_PKT_INT_ENA(1)
+}
+
+func (usbdev *USB_DEVICE) WriteByte(c byte) error {
+	usbdev.ensureConfigured()
+	if usbdev.Bus.GetEP1_CONF_SERIAL_IN_EP_DATA_FREE() == 0 {
+		if usbdev.txStalled {
+			return errUSBCouldNotWriteAllData
+		}
+		if !usbdev.flushAndWait() {
+			usbdev.txStalled = true
+			return errUSBCouldNotWriteAllData
+		}
+	}
+	usbdev.txStalled = false
+
+	usbdev.Bus.EP1.Set(uint32(c))
+
+	if c == '\n' {
+		usbdev.flush()
+		usbdev.txPending = false
+	} else {
+		usbdev.txPending = true
+	}
+
+	return nil
+}
+
+func (usbdev *USB_DEVICE) Write(data []byte) (n int, err error) {
+	usbdev.ensureConfigured()
+	if len(data) == 0 {
+		return 0, nil
+	}
+
+	for i, c := range data {
+		if usbdev.Bus.GetEP1_CONF_SERIAL_IN_EP_DATA_FREE() == 0 {
+			if usbdev.txStalled {
+				return i, errUSBCouldNotWriteAllData
+			}
+			if !usbdev.flushAndWait() {
+				usbdev.txStalled = true
+				return i, errUSBCouldNotWriteAllData
+			}
+		}
+		usbdev.txStalled = false
+		usbdev.Bus.EP1.Set(uint32(c))
+	}
+
+	usbdev.flush()
+	usbdev.txPending = false
+	return len(data), nil
+}
+
+// Buffered returns the number of bytes waiting in the receive ring buffer.
+func (usbdev *USB_DEVICE) Buffered() int {
+	usbdev.ensureConfigured()
+	if usbdev.txPending {
+		usbdev.flush()
+		usbdev.txPending = false
+	}
+	return int(usbdev.Buffer.Used())
+}
+
+// ReadByte returns a byte from the receive ring buffer.
+func (usbdev *USB_DEVICE) ReadByte() (byte, error) {
+	b, ok := usbdev.Buffer.Get()
+	if !ok {
+		return 0, nil
+	}
+	return b, nil
+}
+
+func (usbdev *USB_DEVICE) DTR() bool {
+	return false
+}
+
+func (usbdev *USB_DEVICE) RTS() bool {
+	return false
+}
+
+// flush signals WR_DONE to tell the hardware to send the data that has
+// been written to the EP1 FIFO.
+func (usbdev *USB_DEVICE) flush() {
+	usbdev.Bus.SetEP1_CONF_WR_DONE(1)
+}
+
+// flushAndWait signals WR_DONE and waits for the EP1 FIFO to become
+// writable again. Returns false if the FIFO is still locked after the
+// timeout (no host reading).
+func (usbdev *USB_DEVICE) flushAndWait() bool {
+	usbdev.Bus.SetEP1_CONF_WR_DONE(1)
+	for i := 0; i < 50000; i++ {
+		if usbdev.Bus.GetEP1_CONF_SERIAL_IN_EP_DATA_FREE() != 0 {
+			return true
+		}
+	}
+	return false
+}
+
+// FlushSerial flushes any pending USB serial TX data.
+func FlushSerial() {
+	if _USBCDC.txPending {
+		_USBCDC.flush()
+		_USBCDC.txPending = false
+	}
+}
+
+// ConfigureUSBEndpoint is a no-op on ESP32-C6 — the hardware does not
+// support programmable USB endpoints.
+func ConfigureUSBEndpoint(desc descriptor.Descriptor, epSettings []usb.EndpointConfig, setup []usb.SetupConfig) {
+}
+
+// SendZlp is a no-op on ESP32-C6.
+func SendZlp() {
+}
+
+// SendUSBInPacket is a no-op on ESP32-C6.
+func SendUSBInPacket(ep uint32, data []byte) bool {
+	return false
+}

src/machine/machine_esp32s3_i2c.go

@@ -33,3 +33,10 @@ func initI2CExt1Clock() {
 	esp.SYSTEM.SetPERIP_CLK_EN0_I2C_EXT1_CLK_EN(1)
 	esp.SYSTEM.SetPERIP_RST_EN0_I2C_EXT1_RST(0)
 }
+
+// enableI2C0PeriphClock enables the I2C0 peripheral clock via SYSTEM.
+func enableI2C0PeriphClock() {
+	esp.SYSTEM.SetPERIP_RST_EN0_I2C_EXT0_RST(1)
+	esp.SYSTEM.SetPERIP_CLK_EN0_I2C_EXT0_CLK_EN(1)
+	esp.SYSTEM.SetPERIP_RST_EN0_I2C_EXT0_RST(0)
+}

src/machine/machine_esp32xx_i2c.go

@@ -1,4 +1,4 @@
-//go:build (esp32c3 || esp32s3) && !m5stamp_c3
+//go:build (esp32c3 || esp32c6 || esp32s3) && !m5stamp_c3
 
 package machine
 
@@ -53,9 +53,7 @@ func (i2c *I2C) Configure(config I2CConfig) error {
 //go:inline
 func (i2c *I2C) initClock(config I2CConfig) {
 	if !i2c.useExt1 {
-		esp.SYSTEM.SetPERIP_RST_EN0_I2C_EXT0_RST(1)
-		esp.SYSTEM.SetPERIP_CLK_EN0_I2C_EXT0_CLK_EN(1)
-		esp.SYSTEM.SetPERIP_RST_EN0_I2C_EXT0_RST(0)
+		enableI2C0PeriphClock()
 	} else {
 		initI2CExt1Clock()
 	}

src/machine/machine_nrf.go

@@ -145,7 +145,7 @@ func (p Pin) SetInterrupt(change PinChange, callback func(Pin)) error {
 
 	// Set and enable the GPIOTE interrupt. It's not a problem if this happens
 	// more than once.
-	interrupt.New(nrf.IRQ_GPIOTE, func(interrupt.Interrupt) {
+	intr := interrupt.New(nrf.IRQ_GPIOTE, func(interrupt.Interrupt) {
 		for i := range nrf.GPIOTE.EVENTS_IN {
 			if nrf.GPIOTE.EVENTS_IN[i].Get() != 0 {
 				nrf.GPIOTE.EVENTS_IN[i].Set(0)
@@ -153,7 +153,9 @@ func (p Pin) SetInterrupt(change PinChange, callback func(Pin)) error {
 				pinCallbacks[i](pin)
 			}
 		}
-	}).Enable()
+	})
+	intr.SetPriority(0x40) // interrupt priority 2 (highest priority not reserved by the SoftDevice)
+	intr.Enable()
 
 	// Everything was configured correctly.
 	return nil

src/machine/machine_nrf52840_usb.go

@@ -22,17 +22,6 @@ var (
 	epinen      uint32
 	epouten     uint32
 	easyDMABusy volatile.Register8
-
-	endPoints = []uint32{
-		usb.CONTROL_ENDPOINT:  usb.ENDPOINT_TYPE_CONTROL,
-		usb.CDC_ENDPOINT_ACM:  (usb.ENDPOINT_TYPE_INTERRUPT | usb.EndpointIn),
-		usb.CDC_ENDPOINT_OUT:  (usb.ENDPOINT_TYPE_BULK | usb.EndpointOut),
-		usb.CDC_ENDPOINT_IN:   (usb.ENDPOINT_TYPE_BULK | usb.EndpointIn),
-		usb.HID_ENDPOINT_IN:   (usb.ENDPOINT_TYPE_DISABLE), // Interrupt In
-		usb.HID_ENDPOINT_OUT:  (usb.ENDPOINT_TYPE_DISABLE), // Interrupt Out
-		usb.MIDI_ENDPOINT_IN:  (usb.ENDPOINT_TYPE_DISABLE), // Bulk In
-		usb.MIDI_ENDPOINT_OUT: (usb.ENDPOINT_TYPE_DISABLE), // Bulk Out
-	}
 )
 
 // enterCriticalSection is used to protect access to easyDMA - only one thing
@@ -183,7 +172,7 @@ func handleUSBIRQ(interrupt.Interrupt) {
 		epDataStatus := nrf.USBD.EPDATASTATUS.Get()
 		nrf.USBD.EPDATASTATUS.Set(epDataStatus)
 		var i uint32
-		for i = 1; i < uint32(len(endPoints)); i++ {
+		for i = 1; i < NumberOfUSBEndpoints; i++ {
 			// Check if endpoint has a pending interrupt
 			inDataDone := epDataStatus&(nrf.USBD_EPDATASTATUS_EPIN1<<(i-1)) > 0
 			outDataDone := epDataStatus&(nrf.USBD_EPDATASTATUS_EPOUT1<<(i-1)) > 0
@@ -202,7 +191,7 @@ func handleUSBIRQ(interrupt.Interrupt) {
 	}
 
 	// ENDEPOUT[n] events
-	for i := 0; i < len(endPoints); i++ {
+	for i := 0; i < NumberOfUSBEndpoints; i++ {
 		if nrf.USBD.EVENTS_ENDEPOUT[i].Get() > 0 {
 			nrf.USBD.EVENTS_ENDEPOUT[i].Set(0)
 			buf := handleEndpointRx(uint32(i))
@@ -378,3 +367,19 @@ func ReceiveUSBControlPacket() ([cdcLineInfoSize]byte, error) {
 
 	return b, nil
 }
+
+func (dev *USBDevice) SetStallEPIn(ep uint32) {
+	nrf.USBD.EPSTALL.Set(ep | nrf.USBD_EPSTALL_IO | nrf.USBD_EPSTALL_STALL)
+}
+
+func (dev *USBDevice) SetStallEPOut(ep uint32) {
+	nrf.USBD.EPSTALL.Set(ep | nrf.USBD_EPSTALL_STALL)
+}
+
+func (dev *USBDevice) ClearStallEPIn(ep uint32) {
+	nrf.USBD.EPSTALL.Set(ep | nrf.USBD_EPSTALL_IO)
+}
+
+func (dev *USBDevice) ClearStallEPOut(ep uint32) {
+	nrf.USBD.EPSTALL.Set(ep)
+}

src/machine/machine_rp2040_usb.go

@@ -90,6 +90,7 @@ func handleUSBIRQ(intr interrupt.Interrupt) {
 		}
 
 		s2 := rp.USBCTRL_REGS.BUFF_STATUS.Get()
+		rp.USBCTRL_REGS.BUFF_STATUS.Set(s2)
 
 		// OUT (PC -> rp2040)
 		for i := 0; i < 16; i++ {
@@ -110,7 +111,6 @@ func handleUSBIRQ(intr interrupt.Interrupt) {
 			}
 		}
 
-		rp.USBCTRL_REGS.BUFF_STATUS.Set(s2)
 	}
 
 	// Bus is reset
@@ -128,7 +128,7 @@ func handleUSBSetAddress(setup usb.Setup) bool {
 	const ackTimeout = 570
 
 	rp.USBCTRL_REGS.SIE_STATUS.Set(rp.USBCTRL_REGS_SIE_STATUS_ACK_REC)
-	sendUSBPacket(0, []byte{})
+	sendUSBPacket(0, nil)
 
 	// Wait for transfer to complete with a timeout.
 	t := timer.timeElapsed()

src/machine/machine_rp2350_rom.go

@@ -155,9 +155,7 @@ static bool pico_processor_state_is_nonsecure(void) {
 
 #define BOOTROM_FUNC_TABLE_OFFSET 0x14
 
-// todo remove this (or #ifdef it for A1/A2)
-#define BOOTROM_IS_A2() ((*(volatile uint8_t *)0x13) == 2)
-#define BOOTROM_WELL_KNOWN_PTR_SIZE (BOOTROM_IS_A2() ? 2 : 4)
+#define BOOTROM_WELL_KNOWN_PTR_SIZE 2
 
 #define BOOTROM_VTABLE_OFFSET 0x00
 #define BOOTROM_TABLE_LOOKUP_OFFSET     (BOOTROM_FUNC_TABLE_OFFSET + BOOTROM_WELL_KNOWN_PTR_SIZE)
@@ -229,11 +227,12 @@ void reset_usb_boot(uint32_t usb_activity_gpio_pin_mask, uint32_t disable_interf
 // https://github.com/raspberrypi/pico-sdk
 // src/rp2350/hardware_regs/include/hardware/regs/qmi.h
 
-#define QMI_DIRECT_CSR_EN_BITS      0x00000001
-#define QMI_DIRECT_CSR_RXEMPTY_BITS 0x00010000
-#define QMI_DIRECT_CSR_TXFULL_BITS  0x00000400
-#define QMI_M1_WFMT_RESET           0x00001000
-#define QMI_M1_WCMD_RESET           0x0000a002
+#define QMI_DIRECT_CSR_EN_BITS          0x00000001
+#define QMI_DIRECT_CSR_ASSERT_CS0N_BITS 0x00000004
+#define QMI_DIRECT_CSR_RXEMPTY_BITS     0x00010000
+#define QMI_DIRECT_CSR_TXFULL_BITS      0x00000400
+#define QMI_M1_WFMT_RESET               0x00001000
+#define QMI_M1_WCMD_RESET               0x0000a002
 
 
 // https://github.com/raspberrypi/pico-sdk
@@ -406,13 +405,11 @@ static ram_func void flash_rp2350_restore_qmi_cs1(const flash_rp2350_qmi_save_st
 }
 
 void ram_func flash_cs_force(bool high) {
-    uint32_t field_val = high ?
-        IO_QSPI_GPIO_QSPI_SS_CTRL_OUTOVER_VALUE_HIGH :
-        IO_QSPI_GPIO_QSPI_SS_CTRL_OUTOVER_VALUE_LOW;
-    hw_write_masked(&io_qspi_hw->io[1].ctrl,
-        field_val << IO_QSPI_GPIO_QSPI_SS_CTRL_OUTOVER_LSB,
-        IO_QSPI_GPIO_QSPI_SS_CTRL_OUTOVER_BITS
-    );
+    if (high) {
+        hw_clear_bits(&qmi_hw->direct_csr, QMI_DIRECT_CSR_ASSERT_CS0N_BITS);
+    } else {
+        hw_set_bits(&qmi_hw->direct_csr, QMI_DIRECT_CSR_ASSERT_CS0N_BITS);
+    }
 }
 
 // Adapted from flash_range_program()

src/machine/machine_rp2350_usb.go

@@ -93,6 +93,7 @@ func handleUSBIRQ(intr interrupt.Interrupt) {
 		}
 
 		s2 := rp.USB.BUFF_STATUS.Get()
+		rp.USB.BUFF_STATUS.Set(s2)
 
 		// OUT (PC -> rp2350)
 		for i := 0; i < 16; i++ {
@@ -113,7 +114,6 @@ func handleUSBIRQ(intr interrupt.Interrupt) {
 			}
 		}
 
-		rp.USB.BUFF_STATUS.Set(s2)
 	}
 
 	// Bus is reset

src/machine/machine_rp2_2040.go

@@ -130,11 +130,11 @@ func (spi *SPI) validPins(config SPIConfig) error {
 	var okSDI, okSDO, okSCK bool
 	switch spi.Bus {
 	case rp.SPI0:
-		okSDI = config.SDI == 0 || config.SDI == 4 || config.SDI == 16 || config.SDI == 20
+		okSDI = config.SDI == NoPin || config.SDI == 0 || config.SDI == 4 || config.SDI == 16 || config.SDI == 20
 		okSDO = config.SDO == 3 || config.SDO == 7 || config.SDO == 19 || config.SDO == 23
 		okSCK = config.SCK == 2 || config.SCK == 6 || config.SCK == 18 || config.SCK == 22
 	case rp.SPI1:
-		okSDI = config.SDI == 8 || config.SDI == 12 || config.SDI == 24 || config.SDI == 28
+		okSDI = config.SDI == NoPin || config.SDI == 8 || config.SDI == 12 || config.SDI == 24 || config.SDI == 28
 		okSDO = config.SDO == 11 || config.SDO == 15 || config.SDO == 27
 		okSCK = config.SCK == 10 || config.SCK == 14 || config.SCK == 26
 	}

src/machine/machine_rp2_2350a.go

@@ -21,11 +21,11 @@ func (spi *SPI) validPins(config SPIConfig) error {
 	var okSDI, okSDO, okSCK bool
 	switch spi.Bus {
 	case rp.SPI0:
-		okSDI = config.SDI == 0 || config.SDI == 4 || config.SDI == 16 || config.SDI == 20
+		okSDI = config.SDI == NoPin || config.SDI == 0 || config.SDI == 4 || config.SDI == 16 || config.SDI == 20
 		okSDO = config.SDO == 3 || config.SDO == 7 || config.SDO == 19 || config.SDO == 23
 		okSCK = config.SCK == 2 || config.SCK == 6 || config.SCK == 18 || config.SCK == 22
 	case rp.SPI1:
-		okSDI = config.SDI == 8 || config.SDI == 12 || config.SDI == 24 || config.SDI == 28
+		okSDI = config.SDI == NoPin || config.SDI == 8 || config.SDI == 12 || config.SDI == 24 || config.SDI == 28
 		okSDO = config.SDO == 11 || config.SDO == 15 || config.SDO == 27
 		okSCK = config.SCK == 10 || config.SCK == 14 || config.SCK == 26
 	}

src/machine/machine_rp2_2350b.go

@@ -55,11 +55,11 @@ func (spi *SPI) validPins(config SPIConfig) error {
 	var okSDI, okSDO, okSCK bool
 	switch spi.Bus {
 	case rp.SPI0:
-		okSDI = config.SDI == 0 || config.SDI == 4 || config.SDI == 16 || config.SDI == 20 || config.SDI == 32 || config.SDI == 36
+		okSDI = config.SDI == NoPin || config.SDI == 0 || config.SDI == 4 || config.SDI == 16 || config.SDI == 20 || config.SDI == 32 || config.SDI == 36
 		okSDO = config.SDO == 3 || config.SDO == 7 || config.SDO == 19 || config.SDO == 23 || config.SDO == 35 || config.SDO == 39
 		okSCK = config.SCK == 2 || config.SCK == 6 || config.SCK == 18 || config.SCK == 22 || config.SCK == 34 || config.SCK == 38
 	case rp.SPI1:
-		okSDI = config.SDI == 8 || config.SDI == 12 || config.SDI == 24 || config.SDI == 28 || config.SDI == 40 || config.SDI == 44
+		okSDI = config.SDI == NoPin || config.SDI == 8 || config.SDI == 12 || config.SDI == 24 || config.SDI == 28 || config.SDI == 40 || config.SDI == 44
 		okSDO = config.SDO == 11 || config.SDO == 15 || config.SDO == 27 || config.SDO == 31 || config.SDO == 43 || config.SDO == 47
 		okSCK = config.SCK == 10 || config.SCK == 14 || config.SCK == 26 || config.SCK == 30 || config.SCK == 42 || config.SCK == 46
 	}

src/machine/machine_rp2_spi.go

@@ -174,7 +174,9 @@ func (spi *SPI) Configure(config SPIConfig) error {
 	// SPI pin configuration
 	config.SCK.setFunc(fnSPI)
 	config.SDO.setFunc(fnSPI)
-	config.SDI.setFunc(fnSPI)
+	if config.SDI != NoPin {
+		config.SDI.setFunc(fnSPI)
+	}
 
 	return spi.initSPI(config)
 }

src/machine/machine_rp2_usb.go

@@ -16,53 +16,60 @@ var (
 		data   []byte
 		pid    uint32
 	}
-
-	endPoints = []uint32{
-		usb.CONTROL_ENDPOINT:  usb.ENDPOINT_TYPE_CONTROL,
-		usb.CDC_ENDPOINT_ACM:  (usb.ENDPOINT_TYPE_INTERRUPT | usb.EndpointIn),
-		usb.CDC_ENDPOINT_OUT:  (usb.ENDPOINT_TYPE_BULK | usb.EndpointOut),
-		usb.CDC_ENDPOINT_IN:   (usb.ENDPOINT_TYPE_BULK | usb.EndpointIn),
-		usb.HID_ENDPOINT_IN:   (usb.ENDPOINT_TYPE_DISABLE), // Interrupt In
-		usb.HID_ENDPOINT_OUT:  (usb.ENDPOINT_TYPE_DISABLE), // Interrupt Out
-		usb.MIDI_ENDPOINT_IN:  (usb.ENDPOINT_TYPE_DISABLE), // Bulk In
-		usb.MIDI_ENDPOINT_OUT: (usb.ENDPOINT_TYPE_DISABLE), // Bulk Out
-	}
 )
 
 func initEndpoint(ep, config uint32) {
 	val := uint32(usbEpControlEnable) | uint32(usbEpControlInterruptPerBuff)
+
+	// Each endpoint has 128 bytes of DPRAM buffer space allocated (2 * usbBufferLen).
+	// To support bidirectional configurations using the same endpoint number,
+	// we allocate the first 64 bytes (Buffer0) to OUT transfers, and the remaining
+	// 64 bytes (Buffer1) to IN transfers by shifting the IN offset by usbBufferLen.
 	offset := ep*2*usbBufferLen + 0x100
-	val |= offset
 
 	// Bulk and interrupt endpoints must have their Packet ID reset to DATA0 when un-stalled.
-	epXPIDReset[ep] = false // Default to false in case an endpoint is re-initialized.
+	// Since both directions share the same ep, we reset their PID flags independently.
+	if (config & usb.EndpointIn) != 0 {
+		epXPIDResetIn[ep] = false
+	} else {
+		epXPIDResetOut[ep] = false
+	}
 
 	switch config {
 	case usb.ENDPOINT_TYPE_INTERRUPT | usb.EndpointIn:
+		epXPIDResetIn[ep] = true
+		epXdata0In[ep] = false
+		val |= offset + usbBufferLen
 		val |= usbEpControlEndpointTypeInterrupt
 		_usbDPSRAM.EPxControl[ep].In.Set(val)
-		epXPIDReset[ep] = true
 
 	case usb.ENDPOINT_TYPE_BULK | usb.EndpointOut:
+		epXPIDResetOut[ep] = true
+		epXdata0Out[ep] = false
+		val |= offset
 		val |= usbEpControlEndpointTypeBulk
 		_usbDPSRAM.EPxControl[ep].Out.Set(val)
 		_usbDPSRAM.EPxBufferControl[ep].Out.Set(usbBufferLen & usbBuf0CtrlLenMask)
 		_usbDPSRAM.EPxBufferControl[ep].Out.SetBits(usbBuf0CtrlAvail)
-		epXPIDReset[ep] = true
 
 	case usb.ENDPOINT_TYPE_INTERRUPT | usb.EndpointOut:
+		epXPIDResetOut[ep] = true
+		epXdata0Out[ep] = false
+		val |= offset
 		val |= usbEpControlEndpointTypeInterrupt
 		_usbDPSRAM.EPxControl[ep].Out.Set(val)
 		_usbDPSRAM.EPxBufferControl[ep].Out.Set(usbBufferLen & usbBuf0CtrlLenMask)
 		_usbDPSRAM.EPxBufferControl[ep].Out.SetBits(usbBuf0CtrlAvail)
-		epXPIDReset[ep] = true
 
 	case usb.ENDPOINT_TYPE_BULK | usb.EndpointIn:
+		epXPIDResetIn[ep] = true
+		epXdata0In[ep] = false
+		val |= offset + usbBufferLen
 		val |= usbEpControlEndpointTypeBulk
 		_usbDPSRAM.EPxControl[ep].In.Set(val)
-		epXPIDReset[ep] = true
 
 	case usb.ENDPOINT_TYPE_CONTROL:
+		val |= offset
 		val |= usbEpControlEndpointTypeControl
 		_usbDPSRAM.EPxBufferControl[ep].Out.Set(usbBuf0CtrlData1Pid)
 		_usbDPSRAM.EPxBufferControl[ep].Out.SetBits(usbBuf0CtrlAvail)
@@ -90,7 +97,7 @@ func sendUSBPacket(ep uint32, data []byte) {
 		} else {
 			sendOnEP0DATADONE.offset = 0
 		}
-		epXdata0[ep] = true
+		epXdata0In[ep] = true
 	}
 
 	sendViaEPIn(ep, data, count)
@@ -127,21 +134,31 @@ func handleEndpointRx(ep uint32) []byte {
 // AckUsbOutTransfer is called to acknowledge the completion of a USB OUT transfer.
 func AckUsbOutTransfer(ep uint32) {
 	ep = ep & 0x7F
-	setEPDataPID(ep, !epXdata0[ep])
+	setEPDataPIDOut(ep, !epXdata0Out[ep])
 }
 
-// Set the USB endpoint Packet ID to DATA0 or DATA1.
-func setEPDataPID(ep uint32, dataOne bool) {
-	epXdata0[ep] = dataOne
-	if epXdata0[ep] || ep == 0 {
+// Set the USB endpoint Packet ID to DATA0 or DATA1 for OUT direction.
+func setEPDataPIDOut(ep uint32, dataOne bool) {
+	epXdata0Out[ep] = dataOne
+	if epXdata0Out[ep] || ep == 0 {
 		_usbDPSRAM.EPxBufferControl[ep].Out.SetBits(usbBuf0CtrlData1Pid)
 	}
 
 	_usbDPSRAM.EPxBufferControl[ep].Out.SetBits(usbBuf0CtrlAvail)
 }
 
+// Set the USB endpoint Packet ID to DATA0 or DATA1 for IN direction.
+func setEPDataPIDIn(ep uint32, dataOne bool) {
+	epXdata0In[ep] = dataOne
+	if epXdata0In[ep] || ep == 0 {
+		_usbDPSRAM.EPxBufferControl[ep].In.SetBits(usbBuf0CtrlData1Pid)
+	}
+
+	_usbDPSRAM.EPxBufferControl[ep].In.SetBits(usbBuf0CtrlAvail)
+}
+
 func SendZlp() {
-	sendUSBPacket(0, []byte{})
+	sendUSBPacket(0, nil)
 }
 
 func sendViaEPIn(ep uint32, data []byte, count int) {
@@ -149,15 +166,19 @@ func sendViaEPIn(ep uint32, data []byte, count int) {
 	val := uint32(count) | usbBuf0CtrlAvail
 
 	// DATA0 or DATA1
-	epXdata0[ep&0x7F] = !epXdata0[ep&0x7F]
-	if !epXdata0[ep&0x7F] {
+	epXdata0In[ep&0x7F] = !epXdata0In[ep&0x7F]
+	if !epXdata0In[ep&0x7F] {
 		val |= usbBuf0CtrlData1Pid
 	}
 
 	// Mark as full
 	val |= usbBuf0CtrlFull
 
-	copy(_usbDPSRAM.EPxBuffer[ep&0x7F].Buffer0[:], data[:count])
+	if (ep & 0x7F) == 0 {
+		copy(_usbDPSRAM.EPxBuffer[0].Buffer0[:], data[:count])
+	} else {
+		copy(_usbDPSRAM.EPxBuffer[ep&0x7F].Buffer1[:], data[:count])
+	}
 	_usbDPSRAM.EPxBufferControl[ep&0x7F].In.Set(val)
 }
 
@@ -189,9 +210,9 @@ func (dev *USBDevice) ClearStallEPIn(ep uint32) {
 	ep = ep & 0x7F
 	val := uint32(usbBuf0CtrlStall)
 	_usbDPSRAM.EPxBufferControl[ep].In.ClearBits(val)
-	if epXPIDReset[ep] {
+	if epXPIDResetIn[ep] {
 		// Reset the PID to DATA0
-		setEPDataPID(ep, false)
+		setEPDataPIDIn(ep, false)
 	}
 }
 
@@ -200,9 +221,9 @@ func (dev *USBDevice) ClearStallEPOut(ep uint32) {
 	ep = ep & 0x7F
 	val := uint32(usbBuf0CtrlStall)
 	_usbDPSRAM.EPxBufferControl[ep].Out.ClearBits(val)
-	if epXPIDReset[ep] {
+	if epXPIDResetOut[ep] {
 		// Reset the PID to DATA0
-		setEPDataPID(ep, false)
+		setEPDataPIDOut(ep, false)
 	}
 }
 
@@ -230,10 +251,12 @@ type usbBuffer struct {
 }
 
 var (
-	_usbDPSRAM  = (*usbDPSRAM)(unsafe.Pointer(uintptr(0x50100000)))
-	epXdata0    [16]bool
-	epXPIDReset [16]bool
-	setupBytes  [8]byte
+	_usbDPSRAM     = (*usbDPSRAM)(unsafe.Pointer(uintptr(0x50100000)))
+	epXdata0In     [16]bool
+	epXdata0Out    [16]bool
+	epXPIDResetIn  [16]bool
+	epXPIDResetOut [16]bool
+	setupBytes     [8]byte
 )
 
 func (d *usbDPSRAM) setupBytes() []byte {

src/machine/machine_stm32_uart.go

@@ -76,13 +76,15 @@ func (uart *UART) handleInterrupt(interrupt.Interrupt) {
 		uart.Receive(byte((uart.rxReg.Get() & 0xFF)))
 	}
 
-	// Clear overrun error (ORE, bit 3) to prevent an interrupt storm.
-	if s&0x8 != 0 {
+	// Clear error flags (ORE=bit3, NE=bit2, FE=bit1, PE=bit0) to prevent
+	// an interrupt storm and ensure the USART can continue receiving.
+	if s&0xF != 0 {
 		if uart.errClearReg != nil {
-			// Newer USART peripherals: clear ORE via the ICR register.
-			uart.errClearReg.Set(0x8) // ORECF
+			// Newer USART peripherals (L0, L4, L5, G0, F7, U5, WL, etc.):
+			// clear all error flags via ICR (ORECF|NECF|FECF|PECF = bits 3:0).
+			uart.errClearReg.Set(s & 0xF)
 		} else if s&0x20 == 0 {
-			// Older USART (F1/F4): ORE is cleared by reading SR then DR.
+			// Older USART (F1/F4): errors are cleared by reading SR then DR.
 			// SR was already read above. If RXNE was set, DR was read in
 			// the Receive path. Otherwise do a dummy DR read to complete
 			// the clearing sequence.
@@ -91,20 +93,20 @@ func (uart *UART) handleInterrupt(interrupt.Interrupt) {
 	}
 }
 
-// SetBaudRate sets the communication speed for the UART. Defer to chip-specific
-// routines for calculation
-func (uart *UART) SetBaudRate(br uint32) {
-	divider := uart.getBaudRateDivisor(br)
-	uart.Bus.BRR.Set(divider)
-}
-
 // WriteByte writes a byte of data to the UART.
 func (uart *UART) writeByte(c byte) error {
-	uart.txReg.Set(uint32(c))
-
+	// Wait for the transmit data register to be empty before writing, so we
+	// don't overwrite a byte that hasn't moved to the shift register yet.
 	for !uart.statusReg.HasBits(uart.txEmptyFlag) {
 	}
+	uart.txReg.Set(uint32(c))
 	return nil
 }
 
-func (uart *UART) flush() {}
+// flush waits until the USART shift register has finished transmitting the
+// last byte (TC = Transmission Complete, bit 6). Without this, Write() returns
+// while the final byte is still clocking out on the wire.
+func (uart *UART) flush() {
+	for !uart.statusReg.HasBits(1 << 6) { // TC bit
+	}
+}

src/machine/machine_stm32_uart_setbaudrate.go

@@ -0,0 +1,13 @@
+//go:build stm32 && !stm32u585
+
+package machine
+
+// SetBaudRate sets the communication speed for the UART. Defers to
+// chip-specific getBaudRateDivisor for the divisor calculation.
+//
+// On STM32U585 this function is overridden in machine_stm32u585.go because
+// the U5 family requires UE=0 to write BRR.
+func (uart *UART) SetBaudRate(br uint32) {
+	divider := uart.getBaudRateDivisor(br)
+	uart.Bus.BRR.Set(divider)
+}

src/machine/machine_stm32u5.go

@@ -256,6 +256,7 @@ func enableAltFuncClock(bus unsafe.Pointer) {
 		stm32.RCC.APB1ENR2.SetBits(stm32.RCC_APB1ENR2_I2C4EN)
 	case unsafe.Pointer(stm32.USART1): // USART1 clock enable
 		stm32.RCC.APB2ENR.SetBits(stm32.RCC_APB2ENR_USART1EN)
+		_ = stm32.RCC.APB2ENR.Get() // readback: ensure clock is active before accessing USART1 registers
 	case unsafe.Pointer(stm32.USART2): // USART2 clock enable
 		stm32.RCC.APB1ENR1.SetBits(stm32.RCC_APB1ENR1_USART2EN)
 	case unsafe.Pointer(stm32.USART3): // USART3 clock enable

src/machine/machine_stm32u585.go

@@ -8,14 +8,14 @@ import (
 )
 
 func CPUFrequency() uint32 {
-	return 4_000_000
+	return 160_000_000
 }
 
 // Internal use: configured speed of the APB1 and APB2 timers, this should be kept
 // in sync with any changes to runtime package which configures the oscillators
 // and clock frequencies
-const APB1_TIM_FREQ = 4e6 // 4MHz (MSI default)
-const APB2_TIM_FREQ = 4e6 // 4MHz (MSI default)
+const APB1_TIM_FREQ = 160e6 // 160MHz (PLL1: MSIS 4MHz × 80 / 1 / 2)
+const APB2_TIM_FREQ = 160e6 // 160MHz (PLL1: MSIS 4MHz × 80 / 1 / 2)
 
 //---------- UART related code
 
@@ -55,10 +55,21 @@ func (uart *UART) isLPUART1() bool {
 // NOTE: keep this in sync with the runtime/runtime_stm32u5.go clock init code
 func (uart *UART) getBaudRateDivisor(baudRate uint32) uint32 {
 	if uart.isLPUART1() {
-		// LPUART uses BRR = 256 * fclk / baud
-		return (256 * CPUFrequency()) / baudRate
+		// LPUART uses BRR = 256 * fclk / baud.
+		// Use 64-bit arithmetic to avoid overflow: at 160 MHz,
+		// 256 * 160_000_000 = 40_960_000_000 which exceeds uint32 max.
+		return uint32(uint64(256) * uint64(CPUFrequency()) / uint64(baudRate))
 	}
-	return CPUFrequency() / baudRate
+	// USART requires BRR >= 16 for 16x oversampling (OVER8=0).
+	// A divisor below 16 is invalid per the STM32 reference manual and causes
+	// undefined hardware behaviour — in practice the receiver fires ORE/RXNE
+	// interrupts at an impossible rate, completely starving the CPU.
+	const minBRR = 16
+	divisor := CPUFrequency() / baudRate
+	if divisor < minBRR {
+		divisor = minBRR
+	}
+	return divisor
 }
 
 // Register names vary by ST processor, these are for STM U5
@@ -70,6 +81,24 @@ func (uart *UART) setRegisters() {
 	uart.errClearReg = &uart.Bus.ICR
 }
 
+// SetBaudRate overrides the shared implementation for STM32U5. On this
+// family the BRR register is read-only while UE=1 (USART enabled), so the
+// USART must be briefly disabled to change the baud rate. This matters when
+// the servo library (or any code) calls SetBaudRate after Configure has
+// already enabled the USART.
+func (uart *UART) SetBaudRate(br uint32) {
+	cr1 := uart.Bus.CR1.Get()
+	if cr1&stm32.USART_CR1_UE != 0 {
+		// Disable the USART so BRR becomes writable.
+		uart.Bus.CR1.Set(cr1 &^ stm32.USART_CR1_UE)
+	}
+	uart.Bus.BRR.Set(uart.getBaudRateDivisor(br))
+	if cr1&stm32.USART_CR1_UE != 0 {
+		// Restore CR1 exactly as it was (re-enables USART, TE, RE, etc.).
+		uart.Bus.CR1.Set(cr1)
+	}
+}
+
 //---------- SPI related types and code
 
 // SPI on the STM32U5 using the new SPIv2 peripheral

src/machine/serial-rtt.go

@@ -71,16 +71,18 @@ type rttSerial struct {
 	rttControlBlock
 }
 
+var terminalByteString = []byte("Terminal\x00")
+
 func (s *rttSerial) Configure(config UARTConfig) error {
 	s.maxNumUpBuffers = rttMaxNumUpBuffers
 	s.maxNumDownBuffers = rttMaxNumDownBuffers
 
-	s.buffersUp[0].name = &[]byte("Terminal\x00")[0]
+	s.buffersUp[0].name = &terminalByteString[0]
 	s.buffersUp[0].buffer = &rttBufferUpData[0]
 	s.buffersUp[0].bufferSize = rttBufferSizeUp
 	s.buffersUp[0].flags = rttModeNoBlockSkip
 
-	s.buffersDown[0].name = &[]byte("Terminal\x00")[0]
+	s.buffersDown[0].name = &terminalByteString[0]
 	s.buffersDown[0].buffer = &rttBufferDownData[0]
 	s.buffersDown[0].bufferSize = rttBufferSizeDown
 	s.buffersDown[0].flags = rttModeNoBlockSkip

src/machine/usb.go

@@ -14,9 +14,21 @@ type USBDevice struct {
 	InitEndpointComplete bool
 }
 
+type usbEndpointEntry struct {
+	Endpoint uint32
+	Config   uint32
+}
+
 var (
 	USBDev = &USBDevice{}
 	USBCDC Serialer
+
+	endPoints = []usbEndpointEntry{
+		{
+			Endpoint: usb.CONTROL_ENDPOINT,
+			Config:   usb.ENDPOINT_TYPE_CONTROL,
+		},
+	}
 )
 
 func initUSB() {
@@ -196,17 +208,18 @@ func sendDescriptorString(data string, maxLen uint16) {
 
 	// Clamp the length.
 	maxEncBytes := min(len(usb_trans_buffer), len(udd_ep_control_cache_buffer), int(maxLen))
-	data = data[:min(len(data), (maxEncBytes-2)/2)]
-
 	// Write the header.
-	buf := usb_trans_buffer[:2*len(data)+2]
+	buf := usb_trans_buffer[:min(2*len(data)+2, maxEncBytes)]
 	hdr, body := buf[:2], buf[2:]
-	hdr[0] = byte(len(buf))
+
+	// hdr[0] (bLength) should convey the "original total string length" before being limited by the host's maxLen.
+	hdr[0] = byte(2*len(data) + 2)
 	hdr[1] = descriptor.TypeString
 
 	// Convert the string to UTF16.
 	// NOTE: Using range here would cause the length to disagree when multibyte codepoints are present.
-	for i := 0; i < len(data); i++ {
+	limit := min(len(data), len(body)/2)
+	for i := 0; i < limit; i++ {
 		body[2*i] = byte(data[i])
 		body[2*i+1] = 0
 	}
@@ -276,8 +289,11 @@ func handleStandardSetup(setup usb.Setup) bool {
 
 	case usb.SET_CONFIGURATION:
 		if setup.BmRequestType&usb.REQUEST_RECIPIENT == usb.REQUEST_DEVICE {
-			for i := 1; i < len(endPoints); i++ {
-				initEndpoint(uint32(i), endPoints[i])
+			for _, entry := range endPoints {
+				if entry.Endpoint == usb.CONTROL_ENDPOINT {
+					continue
+				}
+				initEndpoint(uint32(entry.Endpoint), entry.Config)
 			}
 
 			usbConfiguration = setup.WValueL
@@ -358,12 +374,18 @@ func ConfigureUSBEndpoint(desc descriptor.Descriptor, epSettings []usb.EndpointC
 
 	for _, ep := range epSettings {
 		if ep.IsIn {
-			endPoints[ep.Index] = uint32(ep.Type | usb.EndpointIn)
+			endPoints = append(endPoints, usbEndpointEntry{
+				Endpoint: uint32(ep.Index),
+				Config:   uint32(ep.Type | usb.EndpointIn),
+			})
 			if ep.TxHandler != nil {
 				usbTxHandler[ep.Index] = ep.TxHandler
 			}
 		} else {
-			endPoints[ep.Index] = uint32(ep.Type | usb.EndpointOut)
+			endPoints = append(endPoints, usbEndpointEntry{
+				Endpoint: uint32(ep.Index),
+				Config:   uint32(ep.Type | usb.EndpointOut),
+			})
 			if ep.RxHandler != nil {
 				usbRxHandler[ep.Index] = func(b []byte) bool {
 					ep.RxHandler(b)

src/machine/usb/cdc/cdc.go

@@ -2,10 +2,14 @@
 
 package cdc
 
+import (
+	"machine/usb"
+)
+
 const (
-	cdcEndpointACM = 1
-	cdcEndpointOut = 2
-	cdcEndpointIn  = 3
+	cdcEndpointACM = usb.CDC_ENDPOINT_ACM
+	cdcEndpointOut = usb.CDC_ENDPOINT_OUT
+	cdcEndpointIn  = usb.CDC_ENDPOINT_IN
 )
 
 // New returns USBCDC struct.

src/machine/usb/cdc/usbcdc.go

@@ -26,11 +26,23 @@ type cdcLineInfo struct {
 
 // USBCDC is the USB CDC aka serial over USB interface.
 type USBCDC struct {
-	tx       ring512
-	rx       ring512
+	tx ring512
+	rx ring512
+
+	// inflight is the number of bytes currently submitted to the USB IN endpoint.
 	inflight atomic.Uint32
-	rbuf     [1]byte
-	wbuf     [1]byte
+
+	// txActive is the TX-pump ownership flag: 0 = idle, 1 = a pump owns the TX
+	// path. Claimed once (kickTx, CAS 0->1), held across every in-flight packet
+	// and the TX-complete IRQ, and released only when the ring drains. While it
+	// is set, kickTx's CAS fails and no second pump starts, which serializes the
+	// pump against Write across cores. Same model as Linux NAPI_STATE_SCHED:
+	// held across completion, dropped only with a recheck
+	// (Documentation/networking/napi.rst).
+	txActive atomic.Uint32
+
+	rbuf [1]byte
+	wbuf [1]byte
 }
 
 var (
@@ -81,7 +93,7 @@ func (usbcdc *USBCDC) Configure(config machine.UARTConfig) error {
 
 // Flush flushes buffered data.
 func (usbcdc *USBCDC) Flush() {
-	for usbcdc.tx.Used() > 0 {
+	for usbcdc.tx.Used() > 0 || usbcdc.txActive.Load() != 0 {
 		gosched()
 	}
 }
@@ -105,33 +117,59 @@ func (usbcdc *USBCDC) Write(data []byte) (n int, err error) {
 	return n, nil
 }
 
-// kickTx starts a transfer if none is in flight. Called from main context only.
+// kickTx claims the TX pump for a producer. This CAS is the only start-from-idle
+// edge; if it fails, a pump already owns the path and will drain what we just
+// enqueued -- see the recheck in sendFromRing.
 func (usbcdc *USBCDC) kickTx() {
-	if usbcdc.inflight.Load() > 0 {
-		return // txhandler will chain the next packet.
+	if !usbcdc.txActive.CompareAndSwap(0, 1) {
+		return
 	}
 	usbcdc.sendFromRing()
 }
 
 func (usbcdc *USBCDC) txhandler() {
+	// TX-complete IRQ. The pump is still owned here (txActive stayed 1 across the
+	// in-flight packet), so continue WITHOUT re-claiming -- pairs with the CAS in
+	// kickTx. A CAS here would see the flag already set, bail, and stall the chain.
 	inflight := usbcdc.inflight.Load()
-	usbcdc.inflight.Store(0)
+	if inflight == 0 {
+		return
+	}
 	usbcdc.tx.Discard(inflight)
+	usbcdc.inflight.Store(0)
 	usbcdc.sendFromRing()
 }
 
-// sendFromRing sends one USB packet from the ring and sets inflight.
-// Called from kickTx (main) or txhandler (ISR), but never concurrently
-// because kickTx only runs when inflight==0 and txhandler only runs
-// when inflight>0.
+// sendFromRing runs one step of the TX pump: submit one IN packet, or release the
+// pump if the ring is empty. Precondition: txActive == 1 (from kickTx's CAS, or
+// still held from the previous packet when entered via txhandler).
 func (usbcdc *USBCDC) sendFromRing() {
-	d1, _ := usbcdc.tx.Peek()
-	if len(d1) == 0 {
-		return
+	for {
+		d1, _ := usbcdc.tx.Peek()
+		if len(d1) == 0 {
+			// Release the pump, then re-scan the ring: closes the missed-wakeup
+			// race where Write Put()s data and kickTx's CAS then fails (txActive
+			// still set), leaving the data for this pump to drain. The Store(0)
+			// is ordered before the Used() load -- and, in the producer, Put()
+			// before its CAS -- by the sequential consistency of Go's atomics, so
+			// neither side misses the other (assumes the ring's accesses are
+			// atomic too). cf. napi_complete_done() clearing NAPI_STATE_SCHED
+			// then rechecking.
+			usbcdc.txActive.Store(0)
+			if usbcdc.tx.Used() == 0 {
+				return // ring empty and pump released; done
+			}
+			if !usbcdc.txActive.CompareAndSwap(0, 1) {
+				return // another producer re-claimed the pump; let it run
+			}
+			continue // re-claimed; re-peek and keep pumping
+		}
+
+		chunk := d1[:min(usb.EndpointPacketSize, len(d1))]
+		usbcdc.inflight.Store(uint32(len(chunk)))
+		machine.SendUSBInPacket(cdcEndpointIn, chunk)
+		return // in flight; txActive stays set, txhandler continues
 	}
-	chunk := d1[:min(usb.EndpointPacketSize, len(d1))]
-	usbcdc.inflight.Store(uint32(len(chunk)))
-	machine.SendUSBInPacket(cdcEndpointIn, chunk)
 }
 
 // WriteByte writes a byte of data to the USB CDC interface.

src/machine/usb/descriptor/cdc.go

@@ -150,6 +150,9 @@ var InterfaceCDCData = InterfaceType{
 	data: interfaceCDCData[:],
 }
 
+// EP1 IN : CDC Call Management
+// EP2 OUT: CDC OUT
+// EP2 IN : CDC IN
 var CDC = Descriptor{
 	Device: DeviceCDC.Bytes(),
 	Configuration: Append([][]byte{
@@ -160,9 +163,9 @@ var CDC = Descriptor{
 		ClassSpecificCDCCallManagement.Bytes(),
 		ClassSpecificCDCACM.Bytes(),
 		ClassSpecificCDCUnion.Bytes(),
-		EndpointEP1IN.Bytes(),
+		EndpointIN(EndpointEP1, TransferTypeInterrupt, 0x10, 0x10).Bytes(),
 		InterfaceCDCData.Bytes(),
-		EndpointEP2OUT.Bytes(),
-		EndpointEP3IN.Bytes(),
+		EndpointOUT(EndpointEP2, TransferTypeBulk, 0x40, 0x00).Bytes(),
+		EndpointIN(EndpointEP2, TransferTypeBulk, 0x40, 0x00).Bytes(),
 	}),
 }

src/machine/usb/descriptor/endpoint.go

@@ -15,104 +15,44 @@ const (
 	TransferTypeInterrupt
 )
 
-var endpointEP1IN = [endpointTypeLen]byte{
-	endpointTypeLen,
-	TypeEndpoint,
-	0x81, // EndpointAddress
-	0x03, // Attributes
-	0x10, // MaxPacketSizeL
-	0x00, // MaxPacketSizeH
-	0x10, // Interval
+type EndpointNumber uint8
+
+const (
+	EndpointEP1 EndpointNumber = iota
+	EndpointEP2
+	EndpointEP3
+	EndpointEP4
+)
+
+const (
+	maxEndpoints = 4
+)
+
+var (
+	endpointEPIn  = [maxEndpoints][endpointTypeLen]byte{}
+	endpointEPOut = [maxEndpoints][endpointTypeLen]byte{}
+)
+
+func EndpointIN(ep EndpointNumber, transferType uint8, maxPacketSize uint16, interval uint8) EndpointType {
+	e := EndpointType{data: endpointEPIn[ep][:]}
+	e.Length(endpointTypeLen)
+	e.Type(TypeEndpoint)
+	e.EndpointAddress(uint8(ep+1) | 0x80) // EndpointNumber is 0-based, addresses are 1-based
+	e.Attributes(transferType)
+	e.MaxPacketSize(maxPacketSize)
+	e.Interval(interval)
+	return e
 }
 
-var EndpointEP1IN = EndpointType{
-	data: endpointEP1IN[:],
-}
-
-var endpointEP2OUT = [endpointTypeLen]byte{
-	endpointTypeLen,
-	TypeEndpoint,
-	0x02, // EndpointAddress
-	0x02, // Attributes
-	0x40, // MaxPacketSizeL
-	0x00, // MaxPacketSizeH
-	0x00, // Interval
-}
-
-var EndpointEP2OUT = EndpointType{
-	data: endpointEP2OUT[:],
-}
-
-var endpointEP3IN = [endpointTypeLen]byte{
-	endpointTypeLen,
-	TypeEndpoint,
-	0x83, // EndpointAddress
-	0x02, // Attributes
-	0x40, // MaxPacketSizeL
-	0x00, // MaxPacketSizeH
-	0x00, // Interval
-}
-
-var EndpointEP3IN = EndpointType{
-	data: endpointEP3IN[:],
-}
-
-var endpointEP4IN = [endpointTypeLen]byte{
-	endpointTypeLen,
-	TypeEndpoint,
-	0x84, // EndpointAddress
-	0x03, // Attributes
-	0x40, // MaxPacketSizeL
-	0x00, // MaxPacketSizeH
-	0x01, // Interval
-}
-
-var EndpointEP4IN = EndpointType{
-	data: endpointEP4IN[:],
-}
-
-var endpointEP5OUT = [endpointTypeLen]byte{
-	endpointTypeLen,
-	TypeEndpoint,
-	0x05, // EndpointAddress
-	0x03, // Attributes
-	0x40, // MaxPacketSizeL
-	0x00, // MaxPacketSizeH
-	0x01, // Interval
-}
-
-var EndpointEP5OUT = EndpointType{
-	data: endpointEP5OUT[:],
-}
-
-// Mass Storage Class bulk in endpoint
-var endpointMSCIN = [endpointTypeLen]byte{
-	endpointTypeLen,
-	TypeEndpoint,
-	0x86,             // EndpointAddress
-	TransferTypeBulk, // Attributes
-	0x40,             // MaxPacketSizeL (64 bytes)
-	0x00,             // MaxPacketSizeH
-	0x00,             // Interval
-}
-
-var EndpointMSCIN = EndpointType{
-	data: endpointMSCIN[:],
-}
-
-// Mass Storage Class bulk out endpoint
-var endpointMSCOUT = [endpointTypeLen]byte{
-	endpointTypeLen,
-	TypeEndpoint,
-	0x07,             // EndpointAddress
-	TransferTypeBulk, // Attributes
-	0x40,             // MaxPacketSizeL (64 bytes)
-	0x00,             // MaxPacketSizeH
-	0x00,             // Interval
-}
-
-var EndpointMSCOUT = EndpointType{
-	data: endpointMSCOUT[:],
+func EndpointOUT(ep EndpointNumber, transferType uint8, maxPacketSize uint16, interval uint8) EndpointType {
+	e := EndpointType{data: endpointEPOut[ep][:]}
+	e.Length(endpointTypeLen)
+	e.Type(TypeEndpoint)
+	e.EndpointAddress(uint8(ep + 1)) // EndpointNumber is 0-based, addresses are 1-based
+	e.Attributes(transferType)
+	e.MaxPacketSize(maxPacketSize)
+	e.Interval(interval)
+	return e
 }
 
 const (

src/machine/usb/descriptor/hid.go

@@ -111,6 +111,11 @@ var ClassHID = ClassHIDType{
 	data: classHID[:],
 }
 
+// EP1 IN : CDC Call Management
+// EP2 OUT: CDC OUT
+// EP2 IN : CDC IN
+// EP3 OUT: HID OUT
+// EP3 IN : HID IN
 var CDCHID = Descriptor{
 	Device: DeviceCDC.Bytes(),
 	Configuration: Append([][]byte{
@@ -121,14 +126,14 @@ var CDCHID = Descriptor{
 		ClassSpecificCDCACM.Bytes(),
 		ClassSpecificCDCUnion.Bytes(),
 		ClassSpecificCDCCallManagement.Bytes(),
-		EndpointEP1IN.Bytes(),
+		EndpointIN(EndpointEP1, TransferTypeInterrupt, 0x10, 0x10).Bytes(),
 		InterfaceCDCData.Bytes(),
-		EndpointEP2OUT.Bytes(),
-		EndpointEP3IN.Bytes(),
+		EndpointOUT(EndpointEP2, TransferTypeBulk, 0x40, 0x00).Bytes(),
+		EndpointIN(EndpointEP2, TransferTypeBulk, 0x40, 0x00).Bytes(),
 		InterfaceHID.Bytes(),
 		ClassHID.Bytes(),
-		EndpointEP4IN.Bytes(),
-		EndpointEP5OUT.Bytes(),
+		EndpointIN(EndpointEP3, TransferTypeInterrupt, 0x40, 0x01).Bytes(),
+		EndpointOUT(EndpointEP3, TransferTypeInterrupt, 0x40, 0x01).Bytes(),
 	}),
 	HID: map[uint16][]byte{
 		2: Append([][]byte{ // Update ClassLength in classHID whenever the array length is modified!

src/machine/usb/descriptor/joystick.go

@@ -121,6 +121,11 @@ var JoystickDefaultHIDReport = Append([][]byte{
 // CDCJoystick requires that you append the JoystickDescriptor
 // to the Configuration before using. This is in order to support
 // custom configurations.
+// EP1 IN : CDC Call Management
+// EP2 OUT: CDC OUT
+// EP2 IN : CDC IN
+// EP3 OUT: HID OUT
+// EP3 IN : HID IN
 var CDCJoystick = Descriptor{
 	Device: DeviceJoystick.Bytes(),
 	Configuration: Append([][]byte{
@@ -131,14 +136,14 @@ var CDCJoystick = Descriptor{
 		ClassSpecificCDCACM.Bytes(),
 		ClassSpecificCDCUnion.Bytes(),
 		ClassSpecificCDCCallManagement.Bytes(),
-		EndpointEP1IN.Bytes(),
+		EndpointIN(EndpointEP1, TransferTypeInterrupt, 0x10, 0x10).Bytes(),
 		InterfaceCDCData.Bytes(),
-		EndpointEP2OUT.Bytes(),
-		EndpointEP3IN.Bytes(),
+		EndpointOUT(EndpointEP2, TransferTypeBulk, 0x40, 0x00).Bytes(),
+		EndpointIN(EndpointEP2, TransferTypeBulk, 0x40, 0x00).Bytes(),
 		InterfaceHIDJoystick.Bytes(),
 		ClassHIDJoystick.Bytes(),
-		EndpointEP4IN.Bytes(),
-		EndpointEP5OUT.Bytes(),
+		EndpointIN(EndpointEP3, TransferTypeInterrupt, 0x40, 0x01).Bytes(),
+		EndpointOUT(EndpointEP3, TransferTypeInterrupt, 0x40, 0x01).Bytes(),
 	}),
 	HID: map[uint16][]byte{},
 }