avr: use compiler-rt

Be able to run `tinygo gdb -target=arduino examples/serial` and debug a
program with the power of a real debugger.

Note that this only works on LLVM 11 because older versions have a bug
in the AVR backend that cause it to produce invalid debug information:
https://reviews.llvm.org/D74213.

builder/builtins.go

@@ -16,8 +16,10 @@ var genericBuiltins = []string{
 	"addvsi3.c",
 	"addvti3.c",
 	"apple_versioning.c",
+	"ashlsi3.c",
 	"ashldi3.c",
 	"ashlti3.c",
+	"ashrsi3.c",
 	"ashrdi3.c",
 	"ashrti3.c",
 	"bswapdi2.c",
@@ -72,7 +74,9 @@ var genericBuiltins = []string{
 	"floatunsisf.c",
 	"floatuntidf.c",
 	"floatuntisf.c",
-	//"int_util.c",
+	"fp_mode.c",
+	"int_util.c",
+	"lshrsi3.c",
 	"lshrdi3.c",
 	"lshrti3.c",
 	"moddi3.c",
@@ -86,6 +90,7 @@ var genericBuiltins = []string{
 	"muloti4.c",
 	"mulsc3.c",
 	"mulsf3.c",
+	"mulsi3.c",
 	"multi3.c",
 	"multf3.c",
 	"mulvdi3.c",
@@ -108,6 +113,7 @@ var genericBuiltins = []string{
 	"powidf2.c",
 	"powisf2.c",
 	"powitf2.c",
+	"powixf2.c",
 	"subdf3.c",
 	"subsf3.c",
 	"subvdi3.c",
@@ -159,7 +165,7 @@ var aeabiBuiltins = []string{
 var CompilerRT = Library{
 	name:      "compiler-rt",
 	cflags:    func() []string { return []string{"-Werror", "-Wall", "-std=c11", "-nostdlibinc"} },
-	sourceDir: "lib/compiler-rt/lib/builtins",
+	sourceDir: "llvm-project.master/compiler-rt/lib/builtins",
 	sources: func(target string) []string {
 		builtins := append([]string{}, genericBuiltins...) // copy genericBuiltins
 		if strings.HasPrefix(target, "arm") || strings.HasPrefix(target, "thumb") {

builder/library.go

@@ -74,6 +74,9 @@ func (l *Library) Load(target string) (path string, err error) {
 	if strings.HasPrefix(target, "riscv32-") {
 		args = append(args, "-march=rv32imac", "-mabi=ilp32", "-fforce-enable-int128")
 	}
+	if strings.HasPrefix(target, "avr-") {
+		args = append(args, "-mdouble=64", "-mmcu=atmega1284p")
+	}
 
 	// Compile all sources.
 	var objs []string

cgo/libclang_config.go

@@ -1,5 +1,5 @@
 // +build !byollvm
-// +build !llvm9
+// +build !llvm9,!llvm11
 
 package cgo
 

cgo/libclang_config_llvm11.go

@@ -0,0 +1,14 @@
+// +build !byollvm
+// +build llvm11
+
+package cgo
+
+/*
+#cgo linux   CFLAGS:  -I/usr/lib/llvm-11/include
+#cgo darwin  CFLAGS:  -I/usr/local/opt/llvm@11/include
+#cgo freebsd CFLAGS:  -I/usr/local/llvm11/include
+#cgo linux   LDFLAGS: -L/usr/lib/llvm-11/lib -lclang
+#cgo darwin  LDFLAGS: -L/usr/local/opt/llvm@11/lib -lclang -lffi
+#cgo freebsd LDFLAGS: -L/usr/local/llvm11/lib -lclang
+*/
+import "C"

go.mod

@@ -10,5 +10,5 @@ require (
 	github.com/marcinbor85/gohex v0.0.0-20200531091804-343a4b548892
 	go.bug.st/serial v1.0.0
 	golang.org/x/tools v0.0.0-20200216192241-b320d3a0f5a2
-	tinygo.org/x/go-llvm v0.0.0-20200503225853-345b2947b59d
+	tinygo.org/x/go-llvm v0.0.0-20200503224449-70c558526021
 )

go.sum

@@ -46,5 +46,5 @@ golang.org/x/xerrors v0.0.0-20191011141410-1b5146add898 h1:/atklqdjdhuosWIl6AIbO
 golang.org/x/xerrors v0.0.0-20191011141410-1b5146add898/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
 gopkg.in/yaml.v2 v2.2.2/go.mod h1:hI93XBmqTisBFMUTm0b8Fm+jr3Dg1NNxqwp+5A1VGuI=
-tinygo.org/x/go-llvm v0.0.0-20200503225853-345b2947b59d h1:hcX7vpB067GWM/EH4sGGOti0PMgIx+0bbZwUXctOIvE=
+tinygo.org/x/go-llvm v0.0.0-20200503224449-70c558526021 h1:d8T98WXGjrTgDmMXgxa6nb9EAYXGXwnzXygnJl6d+ac=
-tinygo.org/x/go-llvm v0.0.0-20200503225853-345b2947b59d/go.mod h1:fv1F0BSNpxMfCL0zF3M4OPFbgYHnhtB6ST0HvUtu/LE=
+tinygo.org/x/go-llvm v0.0.0-20200503224449-70c558526021/go.mod h1:fv1F0BSNpxMfCL0zF3M4OPFbgYHnhtB6ST0HvUtu/LE=

main.go

@@ -310,10 +310,12 @@ func FlashGDB(pkgName string, ocdOutput bool, options *compileopts.Options) erro
 		switch gdbInterface {
 		case "msd", "command", "":
 			if len(config.Target.Emulator) != 0 {
-				// Assume QEMU as an emulator.
 				if config.Target.Emulator[0] == "mgba" {
 					gdbInterface = "mgba"
+				} else if config.Target.Emulator[0] == "simavr" {
+					gdbInterface = "simavr"
 				} else {
+					// Assume QEMU as an emulator.
 					gdbInterface = "qemu"
 				}
 			} else if openocdInterface != "" && config.Target.OpenOCDTarget != "" {
@@ -379,6 +381,14 @@ func FlashGDB(pkgName string, ocdOutput bool, options *compileopts.Options) erro
 			daemon = exec.Command(config.Target.Emulator[0], args...)
 			daemon.Stdout = os.Stdout
 			daemon.Stderr = os.Stderr
+		case "simavr":
+			gdbCommands = append(gdbCommands, "target remote :1234")
+
+			// Run in an emulator.
+			args := append(config.Target.Emulator[1:], "-g", tmppath)
+			daemon = exec.Command(config.Target.Emulator[0], args...)
+			daemon.Stdout = os.Stdout
+			daemon.Stderr = os.Stderr
 		case "msd":
 			return errors.New("gdb is not supported for drag-and-drop programmable devices")
 		default:

src/internal/task/task_stack_avr.go

@@ -4,7 +4,7 @@ package task
 
 import "unsafe"
 
-const stackSize = 256
+const stackSize = 1024
 
 // calleeSavedRegs is the list of registers that must be saved and restored when
 // switching between tasks. Also see scheduler_avr.S that relies on the

targets/arduino.json

@@ -2,8 +2,8 @@
 	"inherits": ["atmega328p"],
 	"build-tags": ["arduino"],
 	"ldflags": [
-		"-Wl,--defsym=_bootloader_size=512",
+		"--defsym=_bootloader_size=512",
-		"-Wl,--defsym=_stack_size=512"
+		"--defsym=_stack_size=512"
 	],
 	"flash-command": "avrdude -c arduino -p atmega328p -P {port} -U flash:w:{hex}:i"
 }

targets/atmega1284p.json

@@ -7,9 +7,8 @@
         "-mmcu=atmega1284p"
     ],
     "ldflags": [
-        "-mmcu=avr51",
+        "--defsym=_bootloader_size=0",
-        "-Wl,--defsym=_bootloader_size=0",
+        "--defsym=_stack_size=512"
-        "-Wl,--defsym=_stack_size=512"
     ],
     "linkerscript": "src/device/avr/atmega1284p.ld",
     "extra-files": [

targets/atmega328p.json

@@ -7,7 +7,7 @@
 		"-mmcu=atmega328p"
 	],
 	"ldflags": [
-		"-mmcu=avr5"
+		"-mavr5"
 	],
 	"linkerscript": "src/device/avr/atmega328p.ld",
 	"extra-files": [

targets/avr.S

@@ -2,6 +2,30 @@
 ; in Go.
 ; The reset vector is device-specific and is generated by tools/gen-device-avr.py.
 
+#ifndef xl
+#define xl r26
+#endif
+
+#ifndef xh
+#define xh r27
+#endif
+
+#ifndef yl
+#define yl r28
+#endif
+
+#ifndef yh
+#define yh r29
+#endif
+
+#ifndef zl
+#define zl r30
+#endif
+
+#ifndef zh
+#define zh r31
+#endif
+
 ; Startup code
 .section .text.__vector_RESET
 .global  __vector_RESET

targets/avr.json

@@ -2,15 +2,24 @@
 	"build-tags": ["avr", "baremetal", "linux", "arm"],
 	"goos": "linux",
 	"goarch": "arm",
-	"compiler": "avr-gcc",
+	"compiler": "clang",
 	"gc": "conservative",
-	"linker": "avr-gcc",
+	"linker": "llvm-build.master/bin/ld.lld",
 	"scheduler": "none",
+	"rtlib": "compiler-rt",
+	"libc": "picolibc",
+	"cflags": [
+		"--target=avr-atmel-none",
+		"-g",
+		"-Werror",
+		"-Qunused-arguments"
+	],
 	"ldflags": [
 		"-T", "targets/avr.ld",
-		"-Wl,--gc-sections"
+		"--gc-sections"
 	],
 	"extra-files": [
 		"src/runtime/scheduler_avr.S"
-	]
+	],
+	"gdb": "avr-gdb"
 }

targets/avr.ld

@@ -5,17 +5,22 @@ MEMORY
     RAM (xrw)       : ORIGIN = 0x800000 + __ram_start, LENGTH = __ram_size
 }
 
+ENTRY(main)
+
 SECTIONS
 {
-    .text :
+    .text : ALIGN(2)
     {
         KEEP(*(.vectors))
         KEEP(*(.text.__vector_RESET))
         KEEP(*(.text.main)) /* main must follow the reset handler */
+        *(.text)
         *(.text.*)
         *(.rodata)
         *(.rodata.*)
-    }
+        *(.progmem.data)
+        . = ALIGN(16); /* required because of lld (not sure why) */
+    } > FLASH_TEXT
 
     .stack (NOLOAD) :
     {
@@ -29,7 +34,7 @@ SECTIONS
     {
         _sdata = .;        /* used by startup code */
         *(.data)
-        *(.data*)
+        *(.data.*)
         _edata = .;        /* used by startup code */
     } >RAM AT>FLASH_TEXT
 
@@ -37,7 +42,7 @@ SECTIONS
     {
         _sbss = .;         /* used by startup code */
         *(.bss)
-        *(.bss*)
+        *(.bss.*)
         *(COMMON)
         _ebss = .;         /* used by startup code */
     } >RAM

tools/gen-device-avr/gen-device-avr.go

@@ -407,7 +407,7 @@ __vector_default:
 .endm
 
 ; The interrupt vector of this device. Must be placed at address 0 by the linker.
-.section .vectors
+.section .vectors, "a", %progbits
 .global  __vectors
 `))
 	err = t.Execute(out, device.metadata)