builder: add strlen to wasm builtins

LLVM 22 can replace string-scanning loops with calls to strlen during
optimization. Add the implementation to wasmbuiltins and invalidate
cached archives.

Add an optimized wasm-unknown smoke test that exercises the reflect
name-decoding path which exposed the missing symbol.

builder/wasmbuiltins.go

@@ -43,11 +43,11 @@ var libWasmBuiltins = Library{
 	sourceDir: func() string { return filepath.Join(goenv.Get("TINYGOROOT"), "lib/wasi-libc") },
 	librarySources: func(target string, _ bool) ([]string, error) {
 		return []string{
-			// memory builtins needed for llvm.memcpy.*, llvm.memmove.*, and
+			// Memory builtins needed for LLVM intrinsics and library calls.
-			// llvm.memset.* LLVM intrinsics.
 			"libc-top-half/musl/src/string/memcpy.c",
 			"libc-top-half/musl/src/string/memmove.c",
 			"libc-top-half/musl/src/string/memset.c",
+			"libc-top-half/musl/src/string/strlen.c",
 
 			// exp, exp2, and log are needed for LLVM math builtin functions
 			// like llvm.exp.*.

compileopts/config.go

@@ -25,6 +25,7 @@ import (
 var libVersions = map[string]int{
 	"musl":         3,
 	"bdwgc":        2,
+	"wasmbuiltins": 1,
 }
 
 // Config keeps all configuration affecting the build in a single struct.

make/smoketest.mk

@@ -576,6 +576,7 @@ ifneq ($(WASM), 0)
 	$(TINYGO) build -size short -o $(SMOKE_OUT).wasm -target=wasm                examples/wasm/export
 	$(TINYGO) build -size short -o $(SMOKE_OUT).wasm -target=wasm                examples/wasm/main
 	$(TINYGO) build -size short -o $(SMOKE_OUT).wasm -target=wasm-unknown        examples/hello-wasm-unknown
+	$(TINYGO) build -size short -o $(SMOKE_OUT).wasm -target=wasm-unknown -opt=2 ./testdata/wasm-unknown-opt
 endif
 
 smoketest-flags: SMOKE_OUT = build/smoke/flags

testdata/wasm-unknown-opt/main.go

@@ -0,0 +1,15 @@
+package main
+
+import "reflect"
+
+type value struct {
+	Field int
+}
+
+//go:wasmexport typeNameLength
+func typeNameLength() uint32 {
+	return uint32(len(reflect.TypeOf(value{}).String()))
+}
+
+func main() {
+}