From 0d684daf751bea8bbd6eb147b43245cc5a16b0f3 Mon Sep 17 00:00:00 2001
From: Li Jie <cpunion@gmail.com>
Date: Tue, 28 Jul 2026 21:23:24 +0800
Subject: [PATCH 1/8] runtime: isolate non-moving GC platform hooks

---
 ...c_baremetal.go => runtime_gc_nonmoving.go} |  5 +-
 runtime/internal/runtime/tinygogc/gc.go       | 10 ++--
 runtime/internal/runtime/tinygogc/gc_link.go  | 40 ++++++++++++--
 .../internal/runtime/tinygogc/gc_tinygo.go    | 54 +++++++++++--------
 ...efer_baremetal.go => z_defer_nonmoving.go} |  5 +-
 .../{z_gc_baremetal.go => z_gc_nonmoving.go}  | 12 ++---
 6 files changed, 81 insertions(+), 45 deletions(-)
 rename runtime/internal/lib/runtime/{runtime_gc_baremetal.go => runtime_gc_nonmoving.go} (90%)
 rename runtime/internal/runtime/{z_defer_baremetal.go => z_defer_nonmoving.go} (77%)
 rename runtime/internal/runtime/{z_gc_baremetal.go => z_gc_nonmoving.go} (74%)

diff --git a/runtime/internal/lib/runtime/runtime_gc_baremetal.go b/runtime/internal/lib/runtime/runtime_gc_nonmoving.go
similarity index 90%
rename from runtime/internal/lib/runtime/runtime_gc_baremetal.go
rename to runtime/internal/lib/runtime/runtime_gc_nonmoving.go
index f384b6d0f2..b12c146609 100644
--- a/runtime/internal/lib/runtime/runtime_gc_baremetal.go
+++ b/runtime/internal/lib/runtime/runtime_gc_nonmoving.go
@@ -1,4 +1,4 @@
-//go:build !nogc && baremetal
+//go:build baremetal && !nogc
 
 package runtime
 
@@ -9,6 +9,9 @@ import (
 )
 
 func ReadMemStats(m *runtime.MemStats) {
+	if m == nil {
+		return
+	}
 	stats := tinygogc.ReadGCStats()
 	m.Alloc = stats.Alloc
 	m.TotalAlloc = stats.TotalAlloc
diff --git a/runtime/internal/runtime/tinygogc/gc.go b/runtime/internal/runtime/tinygogc/gc.go
index b83b8569d6..2af66f6b7b 100644
--- a/runtime/internal/runtime/tinygogc/gc.go
+++ b/runtime/internal/runtime/tinygogc/gc.go
@@ -1,9 +1,7 @@
-//go:build baremetal
+//go:build baremetal && !nogc
 
 package tinygogc
 
-import "unsafe"
-
 type GCStats struct {
 	// General statistics.
 
@@ -150,6 +148,7 @@ func ReadGCStats() GCStats {
 	var heapInuse, heapIdle uint64
 
 	lock(&gcMutex)
+	lazyInit()
 
 	for block := uintptr(0); block < endBlock; block++ {
 		bstate := gcStateOf(block)
@@ -160,8 +159,7 @@ func ReadGCStats() GCStats {
 		}
 	}
 
-	stackEnd := uintptr(unsafe.Pointer(&_stackEnd))
-	stackSys := stackTop - stackEnd
+	stackInuse, stackSys := gcStackStats()
 
 	stats := GCStats{
 		Alloc:      (gcTotalBlocks - gcFreedBlocks) * uint64(bytesPerBlock),
@@ -173,7 +171,7 @@ func ReadGCStats() GCStats {
 		HeapSys:    heapInuse + heapIdle,
 		HeapIdle:   heapIdle,
 		HeapInuse:  heapInuse,
-		StackInuse: uint64(stackTop - uintptr(getsp())),
+		StackInuse: uint64(stackInuse),
 		StackSys:   uint64(stackSys),
 		GCSys:      uint64(heapEnd - uintptr(metadataStart)),
 	}
diff --git a/runtime/internal/runtime/tinygogc/gc_link.go b/runtime/internal/runtime/tinygogc/gc_link.go
index 9921cd5c7b..550341e897 100644
--- a/runtime/internal/runtime/tinygogc/gc_link.go
+++ b/runtime/internal/runtime/tinygogc/gc_link.go
@@ -1,4 +1,4 @@
-//go:build baremetal
+//go:build baremetal && !nogc
 
 package tinygogc
 
@@ -32,9 +32,6 @@ func __wrap_realloc(ptr unsafe.Pointer, size uintptr) unsafe.Pointer {
 	return Realloc(ptr, size)
 }
 
-//go:linkname getsp llgo.stackSave
-func getsp() unsafe.Pointer
-
 //go:linkname _heapStart _heapStart
 var _heapStart [0]byte
 
@@ -52,3 +49,38 @@ var _globals_start [0]byte
 
 //go:linkname _globals_end _globals_end
 var _globals_end [0]byte
+
+func gcMemoryLayout() (heapStart, heapEnd, globalsStart, globalsEnd, stackTop uintptr) {
+	// Reserve 2 KiB for libc internal allocation that cannot be wrapped.
+	return uintptr(unsafe.Pointer(&_heapStart)) + 2048,
+		uintptr(unsafe.Pointer(&_heapEnd)),
+		uintptr(unsafe.Pointer(&_globals_start)),
+		uintptr(unsafe.Pointer(&_globals_end)),
+		uintptr(unsafe.Pointer(&_stackStart))
+}
+
+func gcGrowMemory(oldHeapEnd uintptr) uintptr {
+	return oldHeapEnd
+}
+
+func gcMarkReachable() {
+	sp := uintptr(getsp())
+	if sp < stackTop {
+		markRoots(sp, stackTop)
+	}
+	if globalsStart < globalsEnd {
+		markRoots(globalsStart, globalsEnd)
+	}
+}
+
+func gcStackStats() (inuse, sys uintptr) {
+	sp := uintptr(getsp())
+	if sp < stackTop {
+		inuse = stackTop - sp
+	}
+	stackEnd := uintptr(unsafe.Pointer(&_stackEnd))
+	if stackEnd < stackTop {
+		sys = stackTop - stackEnd
+	}
+	return
+}
diff --git a/runtime/internal/runtime/tinygogc/gc_tinygo.go b/runtime/internal/runtime/tinygogc/gc_tinygo.go
index cca6f9fccd..fef3866151 100644
--- a/runtime/internal/runtime/tinygogc/gc_tinygo.go
+++ b/runtime/internal/runtime/tinygogc/gc_tinygo.go
@@ -1,4 +1,4 @@
-//go:build baremetal
+//go:build baremetal && !nogc
 
 /*
  * Copyright (c) 2018-2025 The TinyGo Authors. All rights reserved.
@@ -18,14 +18,11 @@
  */
 
 // Package tinygogc implements a conservative mark-and-sweep garbage collector
-// for baremetal environments where the standard Go runtime and bdwgc are unavailable.
+// for targets where the standard Go runtime and bdwgc are unavailable.
 //
 // This implementation is based on TinyGo's GC and is designed for resource-constrained
 // embedded systems. It uses a block-based allocator with conservative pointer scanning.
 //
-// Build tags:
-//   - baremetal: Enables this GC for baremetal targets
-//
 // Memory Layout:
 // The heap is divided into fixed-size blocks (32 bytes on 64-bit). Metadata is stored
 // at the end of the heap, using 2 bits per block to track state (free/head/tail/mark).
@@ -95,18 +92,20 @@ const (
 
 // this function MUST be initalized first, which means it's required to be initalized before runtime
 func initGC() {
-	// reserve 2K blocks for libc internal malloc, we cannot wrap those internal functions
-	heapStart = uintptr(unsafe.Pointer(&_heapStart)) + 2048
-	heapEnd = uintptr(unsafe.Pointer(&_heapEnd))
-	globalsStart = uintptr(unsafe.Pointer(&_globals_start))
-	globalsEnd = uintptr(unsafe.Pointer(&_globals_end))
+	heapStart, heapEnd, globalsStart, globalsEnd, stackTop = gcMemoryLayout()
+	if heapStart >= heapEnd {
+		gcPanic(c.Str("gc: invalid heap range"))
+	}
+	configureHeap()
+	metadataSize := heapEnd - uintptr(metadataStart)
+	c.Memset(metadataStart, 0, metadataSize)
+}
+
+func configureHeap() {
 	totalSize := heapEnd - heapStart
 	metadataSize := (totalSize + blocksPerStateByte*bytesPerBlock) / (1 + blocksPerStateByte*bytesPerBlock)
 	metadataStart = unsafe.Pointer(heapEnd - metadataSize)
 	endBlock = (uintptr(metadataStart) - heapStart) / bytesPerBlock
-	stackTop = uintptr(unsafe.Pointer(&_stackStart))
-
-	c.Memset(metadataStart, 0, metadataSize)
 }
 
 func lazyInit() {
@@ -362,12 +361,12 @@ func Realloc(ptr unsafe.Pointer, size uintptr) unsafe.Pointer {
 
 	newAlloc := Alloc(size)
 	c.Memcpy(newAlloc, ptr, oldSize)
-	free(ptr)
+	freeObject(ptr)
 
 	return newAlloc
 }
 
-func free(ptr unsafe.Pointer) {
+func freeObject(ptr unsafe.Pointer) {
 	// TODO: free blocks on request, when the compiler knows they're unused.
 }
 
@@ -555,15 +554,28 @@ func sweep() (freeBytes uintptr) {
 // growHeap tries to grow the heap size. It returns true if it succeeds, false
 // otherwise.
 func growHeap() bool {
-	// On baremetal, there is no way the heap can be grown.
-	return false
-}
+	oldHeapEnd := heapEnd
+	oldMetadataStart := metadataStart
+	oldMetadataSize := oldHeapEnd - uintptr(oldMetadataStart)
+	newHeapEnd := gcGrowMemory(oldHeapEnd)
+	if newHeapEnd <= oldHeapEnd {
+		return false
+	}
 
-func gcMarkReachable() {
-	markRoots(uintptr(getsp()), stackTop)
-	markRoots(globalsStart, globalsEnd)
+	heapEnd = newHeapEnd
+	configureHeap()
+	newMetadataSize := heapEnd - uintptr(metadataStart)
+	if newMetadataSize < oldMetadataSize {
+		gcPanic(c.Str("gc: metadata shrank while growing heap"))
+	}
+	c.Memmove(metadataStart, oldMetadataStart, oldMetadataSize)
+	c.Memset(unsafe.Add(metadataStart, oldMetadataSize), 0, newMetadataSize-oldMetadataSize)
+	return true
 }
 
 func gcResumeWorld() {
 	// Nothing to do here (single threaded).
 }
+
+//go:linkname getsp llgo.stackSave
+func getsp() unsafe.Pointer
diff --git a/runtime/internal/runtime/z_defer_baremetal.go b/runtime/internal/runtime/z_defer_nonmoving.go
similarity index 77%
rename from runtime/internal/runtime/z_defer_baremetal.go
rename to runtime/internal/runtime/z_defer_nonmoving.go
index 0af31efef4..a6c9b8467c 100644
--- a/runtime/internal/runtime/z_defer_baremetal.go
+++ b/runtime/internal/runtime/z_defer_nonmoving.go
@@ -20,9 +20,6 @@ package runtime
 
 import "unsafe"
 
-// FreeDeferNode is a no-op in baremetal environment.
-// Defer nodes become unreachable after being unlinked from the chain,
-// and tinygogc will reclaim them in the next GC cycle.
+// FreeDeferNode leaves unreachable nodes for the collector.
 func FreeDeferNode(ptr unsafe.Pointer) {
-	// no-op: let tinygogc collect
 }
diff --git a/runtime/internal/runtime/z_gc_baremetal.go b/runtime/internal/runtime/z_gc_nonmoving.go
similarity index 74%
rename from runtime/internal/runtime/z_gc_baremetal.go
rename to runtime/internal/runtime/z_gc_nonmoving.go
index 09fdb2a69d..b4de4952e3 100644
--- a/runtime/internal/runtime/z_gc_baremetal.go
+++ b/runtime/internal/runtime/z_gc_nonmoving.go
@@ -1,4 +1,4 @@
-//go:build !nogc && baremetal
+//go:build baremetal && !nogc
 
 /*
  * Copyright (c) 2024 The XGo Authors (xgo.dev). All rights reserved.
@@ -24,14 +24,12 @@ import (
 	"github.com/goplus/llgo/runtime/internal/runtime/tinygogc"
 )
 
-// AllocU allocates uninitialized memory.
 func AllocU(size uintptr) unsafe.Pointer {
 	ret := tinygogc.Alloc(size)
 	recordMemProfileAlloc(size)
 	return ret
 }
 
-// AllocZ allocates zero-initialized memory.
 func AllocZ(size uintptr) unsafe.Pointer {
 	ret := tinygogc.Alloc(size)
 	recordMemProfileAlloc(size)
@@ -45,11 +43,7 @@ func AllocRoot(size uintptr) unsafe.Pointer {
 func FreeRoot(ptr unsafe.Pointer) {
 }
 
-// AddCleanupPtr is not implemented in baremetal builds because tinygogc
-// does not support finalizers. Cleanup functions will never be called.
-//
-// Returns: a no-op cancel function
+// AddCleanupPtr is not implemented by the non-moving collector.
 func AddCleanupPtr(ptr unsafe.Pointer, cleanup func()) (cancel func()) {
-	// Not implemented: tinygogc does not support finalizers
-	return func() {} // no-op cancel
+	return func() {}
 }

From 1685873c9ccc928567fc151c093432f1cfdb4931 Mon Sep 17 00:00:00 2001
From: Li Jie <cpunion@gmail.com>
Date: Tue, 28 Jul 2026 21:24:34 +0800
Subject: [PATCH 2/8] runtime/wasm: add opt-in non-moving collector

---
 internal/build/build.go                       | 22 +++++
 internal/build/build_test.go                  | 27 +++++-
 internal/build/testdata/wasm-gc/abi.c         | 23 +++++
 internal/build/testdata/wasm-gc/abi.go        |  8 ++
 internal/build/testdata/wasm-gc/main.go       | 89 +++++++++++++++++++
 runtime/internal/clite/pthread/pthread_gc.go  |  2 +-
 .../internal/clite/pthread/pthread_nogc.go    |  2 +-
 runtime/internal/clite/tls/tls_gc.go          |  2 +-
 runtime/internal/clite/tls/tls_nogc.go        |  2 +-
 runtime/internal/lib/runtime/mfinal.go        |  2 +-
 runtime/internal/lib/runtime/mfinal_nogc.go   |  2 +-
 runtime/internal/lib/runtime/mfinal_wasm.go   |  8 ++
 runtime/internal/lib/runtime/runtime_gc.go    |  2 +-
 .../lib/runtime/runtime_gc_nonmoving.go       |  2 +-
 runtime/internal/lib/runtime/runtime_nogc.go  |  2 +-
 .../internal/runtime/tinygogc/_wrap/gc_wasm.c | 53 +++++++++++
 runtime/internal/runtime/tinygogc/gc.go       |  2 +-
 .../internal/runtime/tinygogc/gc_tinygo.go    |  2 +-
 runtime/internal/runtime/tinygogc/gc_wasm.go  | 88 ++++++++++++++++++
 .../internal/runtime/tinygogc/gc_wasm_js.go   | 74 +++++++++++++++
 .../runtime/tinygogc/gc_wasm_wasip1.go        | 30 +++++++
 runtime/internal/runtime/z_defer_gc.go        |  2 +-
 runtime/internal/runtime/z_defer_nogc.go      |  2 +-
 runtime/internal/runtime/z_defer_nonmoving.go |  2 +-
 runtime/internal/runtime/z_gc.go              |  2 +-
 runtime/internal/runtime/z_gc_nonmoving.go    |  2 +-
 runtime/internal/runtime/z_nogc.go            |  3 +-
 27 files changed, 437 insertions(+), 20 deletions(-)
 create mode 100644 internal/build/testdata/wasm-gc/abi.c
 create mode 100644 internal/build/testdata/wasm-gc/abi.go
 create mode 100644 internal/build/testdata/wasm-gc/main.go
 create mode 100644 runtime/internal/lib/runtime/mfinal_wasm.go
 create mode 100644 runtime/internal/runtime/tinygogc/_wrap/gc_wasm.c
 create mode 100644 runtime/internal/runtime/tinygogc/gc_wasm.go
 create mode 100644 runtime/internal/runtime/tinygogc/gc_wasm_js.go
 create mode 100644 runtime/internal/runtime/tinygogc/gc_wasm_wasip1.go

diff --git a/internal/build/build.go b/internal/build/build.go
index f0b08fd43d..80d61158fb 100644
--- a/internal/build/build.go
+++ b/internal/build/build.go
@@ -36,6 +36,7 @@ import (
 	"strings"
 	"sync"
 	"sync/atomic"
+	"unicode"
 
 	"golang.org/x/tools/go/ssa"
 
@@ -385,6 +386,7 @@ func Build(inv Invocation) ([]Package, error) {
 	if conf.Target != "" && export.GOARCH != "" {
 		conf.Goarch = export.GOARCH
 	}
+	applyWasmGCLinkFlags(conf, &export)
 	if conf.AppExt == "" {
 		conf.AppExt = defaultAppExt(conf)
 	}
@@ -778,6 +780,26 @@ func defaultBuildTags(goarch, target string) string {
 	return tags
 }
 
+func applyWasmGCLinkFlags(conf *Config, export *crosscompile.Export) {
+	if conf.Goos != "js" || conf.Goarch != "wasm" || !hasBuildTag(conf.Tags, "llgo_wasm_gc") {
+		return
+	}
+	if !slices.Contains(export.LDFLAGS, "-sMALLOC=none") {
+		export.LDFLAGS = append(export.LDFLAGS, "-sMALLOC=none")
+	}
+}
+
+func hasBuildTag(tags, want string) bool {
+	for _, tag := range strings.FieldsFunc(tags, func(r rune) bool {
+		return r == ',' || unicode.IsSpace(r)
+	}) {
+		if tag == want {
+			return true
+		}
+	}
+	return false
+}
+
 func effectiveTypeSizes(sizes types.Sizes, goos, goarch, target string) types.Sizes {
 	// Named wasm targets use the native wasm32 data model. The raw js/wasm
 	// entry point keeps Go's 64-bit word model and is emitted as Memory64.
diff --git a/internal/build/build_test.go b/internal/build/build_test.go
index b33332928b..6ba3f18f68 100644
--- a/internal/build/build_test.go
+++ b/internal/build/build_test.go
@@ -322,6 +322,28 @@ func TestEffectiveWasmTypeSizes(t *testing.T) {
 	}
 }
 
+func TestApplyWasmGCLinkFlags(t *testing.T) {
+	tests := []struct {
+		name string
+		conf Config
+		want bool
+	}{
+		{name: "wasm32", conf: Config{Goos: "js", Goarch: "wasm", Tags: "llgo_wasm_gc"}, want: true},
+		{name: "comma separated tags", conf: Config{Goos: "js", Goarch: "wasm", Tags: "other,llgo_wasm_gc"}, want: true},
+		{name: "default wasm", conf: Config{Goos: "js", Goarch: "wasm"}},
+		{name: "WASI", conf: Config{Goos: "wasip1", Goarch: "wasm", Tags: "llgo_wasm_gc"}},
+	}
+	for _, test := range tests {
+		t.Run(test.name, func(t *testing.T) {
+			export := crosscompile.Export{}
+			applyWasmGCLinkFlags(&test.conf, &export)
+			if got := slices.Contains(export.LDFLAGS, "-sMALLOC=none"); got != test.want {
+				t.Fatalf("MALLOC=none present = %v, want %v", got, test.want)
+			}
+		})
+	}
+}
+
 func TestWasmRuntimeAvoidsNativeHostDependencies(t *testing.T) {
 	runtimeDir := filepath.Join(env.LLGoRuntimeDir(), "internal", "lib", "runtime")
 	for _, goos := range []string{"js", "wasip1"} {
@@ -329,7 +351,7 @@ func TestWasmRuntimeAvoidsNativeHostDependencies(t *testing.T) {
 			ctx := gobuild.Default
 			ctx.GOOS = goos
 			ctx.GOARCH = "wasm"
-			ctx.BuildTags = []string{"llgo", "nogc"}
+			ctx.BuildTags = []string{"llgo", "nogc", "llgo_wasm_gc"}
 			pkg, err := ctx.ImportDir(runtimeDir, 0)
 			if err != nil {
 				t.Fatal(err)
@@ -356,8 +378,9 @@ func TestWasmRuntimeAvoidsNativeHostDependencies(t *testing.T) {
 			}
 
 			for _, name := range []string{
-				"mfinal_nogc.go",
+				"mfinal_wasm.go",
 				"runtime_baremetal.go",
+				"runtime_gc_nonmoving.go",
 				"signal_baremetal_llgo.go",
 				"time_wasm_llgo.go",
 				"unwind_wasm_llgo.go",
diff --git a/internal/build/testdata/wasm-gc/abi.c b/internal/build/testdata/wasm-gc/abi.c
new file mode 100644
index 0000000000..998721d414
--- /dev/null
+++ b/internal/build/testdata/wasm-gc/abi.c
@@ -0,0 +1,23 @@
+#include <stddef.h>
+#include <stdint.h>
+
+#if defined(__EMSCRIPTEN__)
+#include <emscripten/heap.h>
+#endif
+
+int llgo_test_gc_aligned_alloc(void) {
+#if defined(__EMSCRIPTEN__)
+	void *ptr = emscripten_builtin_memalign(65536, 257);
+	if (ptr == NULL || (uintptr_t)ptr % 65536 != 0) {
+		return 0;
+	}
+	unsigned char *bytes = ptr;
+	bytes[0] = 0x5a;
+	bytes[256] = 0xa5;
+	if (bytes[0] != 0x5a || bytes[256] != 0xa5) {
+		return 0;
+	}
+	emscripten_builtin_free(ptr);
+#endif
+	return 1;
+}
diff --git a/internal/build/testdata/wasm-gc/abi.go b/internal/build/testdata/wasm-gc/abi.go
new file mode 100644
index 0000000000..4eb18638a2
--- /dev/null
+++ b/internal/build/testdata/wasm-gc/abi.go
@@ -0,0 +1,8 @@
+package main
+
+import _ "unsafe"
+
+const LLGoFiles = "abi.c"
+
+//go:linkname testAlignedAlloc C.llgo_test_gc_aligned_alloc
+func testAlignedAlloc() int32
diff --git a/internal/build/testdata/wasm-gc/main.go b/internal/build/testdata/wasm-gc/main.go
new file mode 100644
index 0000000000..3167781a85
--- /dev/null
+++ b/internal/build/testdata/wasm-gc/main.go
@@ -0,0 +1,89 @@
+package main
+
+import "runtime"
+
+type payload struct {
+	value uint64
+}
+
+var (
+	globalRoot *payload
+	garbage    *payload
+	liveChunks [][]byte
+)
+
+func main() {
+	runtime.ReadMemStats(nil)
+	if testAlignedAlloc() == 0 {
+		panic("aligned allocation failed")
+	}
+	testRoots()
+	testReclamation()
+	testHeapGrowth()
+	println("wasm gc ok")
+}
+
+func testRoots() {
+	globalRoot = &payload{value: 0x12345678}
+	runtime.GC()
+	if globalRoot.value != 0x12345678 {
+		panic("global root was not retained")
+	}
+	globalRoot = nil
+}
+
+//go:noinline
+func allocateGarbage() {
+	for i := 0; i < 1024; i++ {
+		garbage = &payload{value: uint64(i)}
+	}
+	garbage = nil
+}
+
+func testReclamation() {
+	runtime.GC()
+	var before runtime.MemStats
+	runtime.ReadMemStats(&before)
+
+	allocateGarbage()
+	runtime.GC()
+
+	var after runtime.MemStats
+	runtime.ReadMemStats(&after)
+	if after.TotalAlloc <= before.TotalAlloc || after.Mallocs <= before.Mallocs {
+		panic("allocation statistics did not advance")
+	}
+	if after.Frees <= before.Frees {
+		panic("unreachable objects were not reclaimed")
+	}
+}
+
+func testHeapGrowth() {
+	var before runtime.MemStats
+	runtime.ReadMemStats(&before)
+
+	const (
+		chunkSize  = 1 << 20
+		chunkCount = 24
+	)
+	liveChunks = make([][]byte, 0, chunkCount)
+	for i := 0; i < chunkCount; i++ {
+		chunk := make([]byte, chunkSize)
+		chunk[0] = byte(i + 1)
+		chunk[len(chunk)-1] = byte(i + 2)
+		liveChunks = append(liveChunks, chunk)
+	}
+
+	var after runtime.MemStats
+	runtime.ReadMemStats(&after)
+	if after.HeapSys <= before.HeapSys {
+		panic("heap did not grow")
+	}
+	runtime.GC()
+	for i, chunk := range liveChunks {
+		if chunk[0] != byte(i+1) || chunk[len(chunk)-1] != byte(i+2) {
+			panic("live object was corrupted during heap growth")
+		}
+	}
+	liveChunks = nil
+}
diff --git a/runtime/internal/clite/pthread/pthread_gc.go b/runtime/internal/clite/pthread/pthread_gc.go
index 88409bc1c3..fdc067d2d2 100644
--- a/runtime/internal/clite/pthread/pthread_gc.go
+++ b/runtime/internal/clite/pthread/pthread_gc.go
@@ -1,4 +1,4 @@
-//go:build !nogc && !baremetal
+//go:build !nogc && !baremetal && !wasm
 
 /*
  * Copyright (c) 2024 The XGo Authors (xgo.dev). All rights reserved.
diff --git a/runtime/internal/clite/pthread/pthread_nogc.go b/runtime/internal/clite/pthread/pthread_nogc.go
index d61d39a3be..c72f1d597e 100644
--- a/runtime/internal/clite/pthread/pthread_nogc.go
+++ b/runtime/internal/clite/pthread/pthread_nogc.go
@@ -1,4 +1,4 @@
-//go:build nogc || baremetal
+//go:build nogc || baremetal || wasm
 
 /*
  * Copyright (c) 2024 The XGo Authors (xgo.dev). All rights reserved.
diff --git a/runtime/internal/clite/tls/tls_gc.go b/runtime/internal/clite/tls/tls_gc.go
index afd10494de..dee28069a9 100644
--- a/runtime/internal/clite/tls/tls_gc.go
+++ b/runtime/internal/clite/tls/tls_gc.go
@@ -1,4 +1,4 @@
-//go:build llgo && !baremetal && !nogc
+//go:build llgo && !baremetal && !wasm && !nogc
 
 /*
  * Copyright (c) 2025 The XGo Authors (xgo.dev). All rights reserved.
diff --git a/runtime/internal/clite/tls/tls_nogc.go b/runtime/internal/clite/tls/tls_nogc.go
index 00923d4105..4e7283b41f 100644
--- a/runtime/internal/clite/tls/tls_nogc.go
+++ b/runtime/internal/clite/tls/tls_nogc.go
@@ -1,4 +1,4 @@
-//go:build llgo && (nogc || baremetal)
+//go:build llgo && (nogc || baremetal || wasm)
 
 /*
  * Copyright (c) 2025 The XGo Authors (xgo.dev). All rights reserved.
diff --git a/runtime/internal/lib/runtime/mfinal.go b/runtime/internal/lib/runtime/mfinal.go
index a62305c8a2..70d43c918e 100644
--- a/runtime/internal/lib/runtime/mfinal.go
+++ b/runtime/internal/lib/runtime/mfinal.go
@@ -1,4 +1,4 @@
-//go:build !nogc
+//go:build !nogc && !wasm
 
 // Copyright 2009 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
diff --git a/runtime/internal/lib/runtime/mfinal_nogc.go b/runtime/internal/lib/runtime/mfinal_nogc.go
index c85111ea65..b4e55a948d 100644
--- a/runtime/internal/lib/runtime/mfinal_nogc.go
+++ b/runtime/internal/lib/runtime/mfinal_nogc.go
@@ -1,4 +1,4 @@
-//go:build nogc
+//go:build nogc && (!wasm || !llgo_wasm_gc)
 
 package runtime
 
diff --git a/runtime/internal/lib/runtime/mfinal_wasm.go b/runtime/internal/lib/runtime/mfinal_wasm.go
new file mode 100644
index 0000000000..e18f6f6b7f
--- /dev/null
+++ b/runtime/internal/lib/runtime/mfinal_wasm.go
@@ -0,0 +1,8 @@
+//go:build wasm && llgo_wasm_gc
+
+package runtime
+
+// SetFinalizer is not implemented by the initial WebAssembly collector.
+func SetFinalizer(obj any, finalizer any) {
+	_, _ = obj, finalizer
+}
diff --git a/runtime/internal/lib/runtime/runtime_gc.go b/runtime/internal/lib/runtime/runtime_gc.go
index d8656f93a4..7de1695009 100644
--- a/runtime/internal/lib/runtime/runtime_gc.go
+++ b/runtime/internal/lib/runtime/runtime_gc.go
@@ -1,4 +1,4 @@
-//go:build !nogc && !baremetal
+//go:build !nogc && !baremetal && !wasm
 
 package runtime
 
diff --git a/runtime/internal/lib/runtime/runtime_gc_nonmoving.go b/runtime/internal/lib/runtime/runtime_gc_nonmoving.go
index b12c146609..a5c79953fd 100644
--- a/runtime/internal/lib/runtime/runtime_gc_nonmoving.go
+++ b/runtime/internal/lib/runtime/runtime_gc_nonmoving.go
@@ -1,4 +1,4 @@
-//go:build baremetal && !nogc
+//go:build (baremetal && !nogc) || (wasm && llgo_wasm_gc)
 
 package runtime
 
diff --git a/runtime/internal/lib/runtime/runtime_nogc.go b/runtime/internal/lib/runtime/runtime_nogc.go
index 3f11426023..50c039b10f 100644
--- a/runtime/internal/lib/runtime/runtime_nogc.go
+++ b/runtime/internal/lib/runtime/runtime_nogc.go
@@ -1,4 +1,4 @@
-//go:build nogc
+//go:build nogc && (!wasm || !llgo_wasm_gc)
 
 package runtime
 
diff --git a/runtime/internal/runtime/tinygogc/_wrap/gc_wasm.c b/runtime/internal/runtime/tinygogc/_wrap/gc_wasm.c
new file mode 100644
index 0000000000..d6ae8fd3d4
--- /dev/null
+++ b/runtime/internal/runtime/tinygogc/_wrap/gc_wasm.c
@@ -0,0 +1,53 @@
+#include <stddef.h>
+#include <stdint.h>
+
+#if defined(__EMSCRIPTEN__)
+#include <emscripten/heap.h>
+#include <emscripten/stack.h>
+#else
+extern unsigned char __stack_high;
+#endif
+
+extern unsigned char __data_end;
+extern unsigned char __global_base;
+extern unsigned char __heap_base;
+
+#define LLGO_WASM_PAGE_SIZE 65536
+
+uintptr_t llgo_gc_globals_start(void) {
+	return (uintptr_t)&__global_base;
+}
+
+uintptr_t llgo_gc_globals_end(void) {
+	return (uintptr_t)&__data_end;
+}
+
+uintptr_t llgo_gc_heap_base(void) {
+	return (uintptr_t)&__heap_base;
+}
+
+uintptr_t llgo_gc_stack_top(void) {
+#if defined(__EMSCRIPTEN__)
+	return (uintptr_t)emscripten_stack_get_base();
+#else
+	return (uintptr_t)&__stack_high;
+#endif
+}
+
+uintptr_t llgo_gc_memory_size(void) {
+	return (uintptr_t)__builtin_wasm_memory_size(0) * LLGO_WASM_PAGE_SIZE;
+}
+
+int llgo_gc_grow_memory(uintptr_t required) {
+#if defined(__EMSCRIPTEN__)
+	return emscripten_resize_heap(required);
+#else
+	uintptr_t current = llgo_gc_memory_size();
+	if (required <= current) {
+		return 1;
+	}
+	uintptr_t pages = (required - current + LLGO_WASM_PAGE_SIZE - 1) /
+		LLGO_WASM_PAGE_SIZE;
+	return __builtin_wasm_memory_grow(0, pages) != (size_t)-1;
+#endif
+}
diff --git a/runtime/internal/runtime/tinygogc/gc.go b/runtime/internal/runtime/tinygogc/gc.go
index 2af66f6b7b..8163f7ff10 100644
--- a/runtime/internal/runtime/tinygogc/gc.go
+++ b/runtime/internal/runtime/tinygogc/gc.go
@@ -1,4 +1,4 @@
-//go:build baremetal && !nogc
+//go:build (baremetal && !nogc) || (wasm && llgo_wasm_gc)
 
 package tinygogc
 
diff --git a/runtime/internal/runtime/tinygogc/gc_tinygo.go b/runtime/internal/runtime/tinygogc/gc_tinygo.go
index fef3866151..65aceb822e 100644
--- a/runtime/internal/runtime/tinygogc/gc_tinygo.go
+++ b/runtime/internal/runtime/tinygogc/gc_tinygo.go
@@ -1,4 +1,4 @@
-//go:build baremetal && !nogc
+//go:build (baremetal && !nogc) || (wasm && llgo_wasm_gc)
 
 /*
  * Copyright (c) 2018-2025 The TinyGo Authors. All rights reserved.
diff --git a/runtime/internal/runtime/tinygogc/gc_wasm.go b/runtime/internal/runtime/tinygogc/gc_wasm.go
new file mode 100644
index 0000000000..c1b7e6300a
--- /dev/null
+++ b/runtime/internal/runtime/tinygogc/gc_wasm.go
@@ -0,0 +1,88 @@
+//go:build wasm && llgo_wasm_gc
+
+package tinygogc
+
+import (
+	_ "unsafe"
+
+	c "github.com/goplus/llgo/runtime/internal/clite"
+)
+
+const LLGoFiles = "_wrap/gc_wasm.c"
+
+const wasmPageSize = uintptr(64 << 10)
+
+func gcMemoryLayout() (heapStart, heapEnd, globalsStart, globalsEnd, stackTop uintptr) {
+	heapStart = alignUp(gcWasmHeapBase(), bytesPerBlock)
+	heapEnd = alignDown(gcWasmMemorySize(), bytesPerBlock)
+	globalsStart = gcWasmGlobalsStart()
+	globalsEnd = gcWasmGlobalsEnd()
+	stackTop = gcWasmStackTop()
+	return
+}
+
+func gcGrowMemory(oldHeapEnd uintptr) uintptr {
+	current := gcWasmMemorySize()
+	if current < oldHeapEnd {
+		return oldHeapEnd
+	}
+	growth := oldHeapEnd - heapStart
+	if growth < 1<<20 {
+		growth = 1 << 20
+	}
+	if current > ^uintptr(0)-growth {
+		return oldHeapEnd
+	}
+	required := alignUp(current+growth, wasmPageSize)
+	if gcWasmGrowMemory(required) == 0 {
+		return oldHeapEnd
+	}
+	return alignDown(gcWasmMemorySize(), bytesPerBlock)
+}
+
+func gcMarkReachable() {
+	sp := uintptr(getsp())
+	top := gcWasmStackTop()
+	if sp < top {
+		markRoots(sp, top)
+	}
+	if globalsStart < globalsEnd {
+		markRoots(globalsStart, globalsEnd)
+	}
+}
+
+func gcStackStats() (inuse, sys uintptr) {
+	sp := uintptr(getsp())
+	top := gcWasmStackTop()
+	if sp < top {
+		inuse = top - sp
+		sys = inuse
+	}
+	return
+}
+
+func alignUp(value, alignment uintptr) uintptr {
+	return (value + alignment - 1) &^ (alignment - 1)
+}
+
+func alignDown(value, alignment uintptr) uintptr {
+	return value &^ (alignment - 1)
+}
+
+//go:linkname gcWasmGlobalsStart C.llgo_gc_globals_start
+func gcWasmGlobalsStart() uintptr
+
+//go:linkname gcWasmGlobalsEnd C.llgo_gc_globals_end
+func gcWasmGlobalsEnd() uintptr
+
+//go:linkname gcWasmHeapBase C.llgo_gc_heap_base
+func gcWasmHeapBase() uintptr
+
+//go:linkname gcWasmStackTop C.llgo_gc_stack_top
+func gcWasmStackTop() uintptr
+
+//go:linkname gcWasmMemorySize C.llgo_gc_memory_size
+func gcWasmMemorySize() uintptr
+
+//go:linkname gcWasmGrowMemory C.llgo_gc_grow_memory
+func gcWasmGrowMemory(required uintptr) c.Int
diff --git a/runtime/internal/runtime/tinygogc/gc_wasm_js.go b/runtime/internal/runtime/tinygogc/gc_wasm_js.go
new file mode 100644
index 0000000000..50731fff1f
--- /dev/null
+++ b/runtime/internal/runtime/tinygogc/gc_wasm_js.go
@@ -0,0 +1,74 @@
+//go:build js && wasm && llgo_wasm_gc
+
+package tinygogc
+
+import "unsafe"
+
+func wasmCalloc(nmemb, size uintptr) unsafe.Pointer {
+	totalSize := nmemb * size
+	if nmemb != 0 && totalSize/nmemb != size {
+		return nil
+	}
+	return Alloc(totalSize)
+}
+
+func wasmMemalign(alignment, size uintptr) unsafe.Pointer {
+	if alignment < unsafe.Sizeof(uintptr(0)) || alignment&(alignment-1) != 0 {
+		return nil
+	}
+	if alignment <= bytesPerBlock {
+		return Alloc(size)
+	}
+	if size > ^uintptr(0)-(alignment-1) {
+		return nil
+	}
+	return unsafe.Pointer(alignUp(uintptr(Alloc(size+alignment-1)), alignment))
+}
+
+//export malloc
+func malloc(size uintptr) unsafe.Pointer {
+	return Alloc(size)
+}
+
+//export free
+func free(ptr unsafe.Pointer) {
+}
+
+//export calloc
+func calloc(nmemb, size uintptr) unsafe.Pointer {
+	return wasmCalloc(nmemb, size)
+}
+
+//export realloc
+func realloc(ptr unsafe.Pointer, size uintptr) unsafe.Pointer {
+	return Realloc(ptr, size)
+}
+
+//export memalign
+func memalign(alignment, size uintptr) unsafe.Pointer {
+	return wasmMemalign(alignment, size)
+}
+
+//export emscripten_builtin_malloc
+func emscripten_builtin_malloc(size uintptr) unsafe.Pointer {
+	return Alloc(size)
+}
+
+//export emscripten_builtin_free
+func emscripten_builtin_free(ptr unsafe.Pointer) {
+}
+
+//export emscripten_builtin_calloc
+func emscripten_builtin_calloc(nmemb, size uintptr) unsafe.Pointer {
+	return wasmCalloc(nmemb, size)
+}
+
+//export emscripten_builtin_realloc
+func emscripten_builtin_realloc(ptr unsafe.Pointer, size uintptr) unsafe.Pointer {
+	return Realloc(ptr, size)
+}
+
+//export emscripten_builtin_memalign
+func emscripten_builtin_memalign(alignment, size uintptr) unsafe.Pointer {
+	return wasmMemalign(alignment, size)
+}
diff --git a/runtime/internal/runtime/tinygogc/gc_wasm_wasip1.go b/runtime/internal/runtime/tinygogc/gc_wasm_wasip1.go
new file mode 100644
index 0000000000..9dd5db8874
--- /dev/null
+++ b/runtime/internal/runtime/tinygogc/gc_wasm_wasip1.go
@@ -0,0 +1,30 @@
+//go:build wasip1 && wasm && llgo_wasm_gc
+
+package tinygogc
+
+import "unsafe"
+
+const LLGoPackage = "link: -Wl,--wrap=malloc -Wl,--wrap=free -Wl,--wrap=realloc -Wl,--wrap=calloc"
+
+//export __wrap_malloc
+func __wrap_malloc(size uintptr) unsafe.Pointer {
+	return Alloc(size)
+}
+
+//export __wrap_free
+func __wrap_free(ptr unsafe.Pointer) {
+}
+
+//export __wrap_calloc
+func __wrap_calloc(nmemb, size uintptr) unsafe.Pointer {
+	totalSize := nmemb * size
+	if nmemb != 0 && totalSize/nmemb != size {
+		return nil
+	}
+	return Alloc(totalSize)
+}
+
+//export __wrap_realloc
+func __wrap_realloc(ptr unsafe.Pointer, size uintptr) unsafe.Pointer {
+	return Realloc(ptr, size)
+}
diff --git a/runtime/internal/runtime/z_defer_gc.go b/runtime/internal/runtime/z_defer_gc.go
index 88ee5eeae2..2739768e08 100644
--- a/runtime/internal/runtime/z_defer_gc.go
+++ b/runtime/internal/runtime/z_defer_gc.go
@@ -1,4 +1,4 @@
-//go:build !nogc && !baremetal
+//go:build !nogc && !baremetal && !wasm
 
 /*
  * Copyright (c) 2025 The XGo Authors (xgo.dev). All rights reserved.
diff --git a/runtime/internal/runtime/z_defer_nogc.go b/runtime/internal/runtime/z_defer_nogc.go
index e7acb7bc6d..b16c883dce 100644
--- a/runtime/internal/runtime/z_defer_nogc.go
+++ b/runtime/internal/runtime/z_defer_nogc.go
@@ -1,4 +1,4 @@
-//go:build nogc && !baremetal
+//go:build nogc && !baremetal && (!wasm || !llgo_wasm_gc)
 
 /*
  * Copyright (c) 2025 The XGo Authors (xgo.dev). All rights reserved.
diff --git a/runtime/internal/runtime/z_defer_nonmoving.go b/runtime/internal/runtime/z_defer_nonmoving.go
index a6c9b8467c..3142e3250c 100644
--- a/runtime/internal/runtime/z_defer_nonmoving.go
+++ b/runtime/internal/runtime/z_defer_nonmoving.go
@@ -1,4 +1,4 @@
-//go:build baremetal && !nogc
+//go:build (baremetal && !nogc) || (wasm && llgo_wasm_gc)
 
 /*
  * Copyright (c) 2025 The XGo Authors (xgo.dev). All rights reserved.
diff --git a/runtime/internal/runtime/z_gc.go b/runtime/internal/runtime/z_gc.go
index 4b4d144678..32ba207edc 100644
--- a/runtime/internal/runtime/z_gc.go
+++ b/runtime/internal/runtime/z_gc.go
@@ -1,4 +1,4 @@
-//go:build !nogc && !baremetal
+//go:build !nogc && !baremetal && !wasm
 
 /*
  * Copyright (c) 2024 The XGo Authors (xgo.dev). All rights reserved.
diff --git a/runtime/internal/runtime/z_gc_nonmoving.go b/runtime/internal/runtime/z_gc_nonmoving.go
index b4de4952e3..5186cb7b62 100644
--- a/runtime/internal/runtime/z_gc_nonmoving.go
+++ b/runtime/internal/runtime/z_gc_nonmoving.go
@@ -1,4 +1,4 @@
-//go:build baremetal && !nogc
+//go:build (baremetal && !nogc) || (wasm && llgo_wasm_gc)
 
 /*
  * Copyright (c) 2024 The XGo Authors (xgo.dev). All rights reserved.
diff --git a/runtime/internal/runtime/z_nogc.go b/runtime/internal/runtime/z_nogc.go
index e716ec1e94..2300034d4b 100644
--- a/runtime/internal/runtime/z_nogc.go
+++ b/runtime/internal/runtime/z_nogc.go
@@ -1,5 +1,4 @@
-//go:build nogc
-// +build nogc
+//go:build nogc && (!wasm || !llgo_wasm_gc)
 
 /*
  * Copyright (c) 2024 The XGo Authors (xgo.dev). All rights reserved.

From b6797da9cdb85c2d279d791c9ddfc082bc464ea2 Mon Sep 17 00:00:00 2001
From: Li Jie <cpunion@gmail.com>
Date: Tue, 28 Jul 2026 21:24:40 +0800
Subject: [PATCH 3/8] ci: exercise opt-in wasm collector

---
 .github/workflows/llgo.yml | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/.github/workflows/llgo.yml b/.github/workflows/llgo.yml
index dadff854d0..9bb76e6918 100644
--- a/.github/workflows/llgo.yml
+++ b/.github/workflows/llgo.yml
@@ -489,6 +489,12 @@ jobs:
           run_wasm_scheduler "$RUNNER_TEMP/wasm-scheduler.mjs"
           GOOS=wasip1 GOARCH=wasm llgo build -o "$RUNNER_TEMP/wasm-scheduler-wasip1.wasm" ./internal/build/testdata/wasm-scheduler
           run_wasi_scheduler "$RUNNER_TEMP/wasm-scheduler-wasip1.wasm"
+          GOOS=js GOARCH=wasm llgo build -tags=llgo_wasm_gc -o "$RUNNER_TEMP/wasm-gc-go.mjs" ./internal/build/testdata/wasm-gc
+          node --input-type=module -e "import Module from '$RUNNER_TEMP/wasm-gc-go.mjs'; await Module();"
+          llgo build -target wasm -tags=llgo_wasm_gc -o "$RUNNER_TEMP/wasm-gc.mjs" ./internal/build/testdata/wasm-gc
+          node --input-type=module -e "import Module from '$RUNNER_TEMP/wasm-gc.mjs'; await Module();"
+          GOOS=wasip1 GOARCH=wasm llgo build -tags=llgo_wasm_gc -o "$RUNNER_TEMP/wasm-gc-wasip1.wasm" ./internal/build/testdata/wasm-gc
           file "$RUNNER_TEMP/runtime-js.wasm" \
             "$RUNNER_TEMP/runtime-wasip1.wasm" \
-            "$RUNNER_TEMP/runtime-wasip1-threads.wasm"
+            "$RUNNER_TEMP/runtime-wasip1-threads.wasm" \
+            "$RUNNER_TEMP/wasm-gc-wasip1.wasm"

From 0c911808a6d686c3623f89de7e31dfe37aad3a1c Mon Sep 17 00:00:00 2001
From: Li Jie <cpunion@gmail.com>
Date: Tue, 28 Jul 2026 21:36:43 +0800
Subject: [PATCH 4/8] test: size wasm heap growth probe dynamically

---
 internal/build/testdata/wasm-gc/main.go | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/internal/build/testdata/wasm-gc/main.go b/internal/build/testdata/wasm-gc/main.go
index 3167781a85..d7062bcf25 100644
--- a/internal/build/testdata/wasm-gc/main.go
+++ b/internal/build/testdata/wasm-gc/main.go
@@ -62,10 +62,11 @@ func testHeapGrowth() {
 	var before runtime.MemStats
 	runtime.ReadMemStats(&before)
 
-	const (
-		chunkSize  = 1 << 20
-		chunkCount = 24
-	)
+	const chunkSize = 1 << 20
+	chunkCount := int(before.HeapSys/chunkSize) + 8
+	if chunkCount > 128 {
+		panic("initial heap is too large for the bounded growth test")
+	}
 	liveChunks = make([][]byte, 0, chunkCount)
 	for i := 0; i < chunkCount; i++ {
 		chunk := make([]byte, chunkSize)

From 40996b834377f3855e7c205e8487d676c1f39dd9 Mon Sep 17 00:00:00 2001
From: Li Jie <cpunion@gmail.com>
Date: Tue, 28 Jul 2026 22:26:44 +0800
Subject: [PATCH 5/8] build/wasm: reject GC with threaded WASI

---
 internal/build/build.go      | 24 ++++++++++++++++++------
 internal/build/build_test.go | 18 ++++++++++++++++--
 2 files changed, 34 insertions(+), 8 deletions(-)

diff --git a/internal/build/build.go b/internal/build/build.go
index 80d61158fb..a245fccbe2 100644
--- a/internal/build/build.go
+++ b/internal/build/build.go
@@ -386,7 +386,9 @@ func Build(inv Invocation) ([]Package, error) {
 	if conf.Target != "" && export.GOARCH != "" {
 		conf.Goarch = export.GOARCH
 	}
-	applyWasmGCLinkFlags(conf, &export)
+	if err := configureWasmGC(conf, &export); err != nil {
+		return nil, err
+	}
 	if conf.AppExt == "" {
 		conf.AppExt = defaultAppExt(conf)
 	}
@@ -780,13 +782,23 @@ func defaultBuildTags(goarch, target string) string {
 	return tags
 }
 
-func applyWasmGCLinkFlags(conf *Config, export *crosscompile.Export) {
-	if conf.Goos != "js" || conf.Goarch != "wasm" || !hasBuildTag(conf.Tags, "llgo_wasm_gc") {
-		return
+func configureWasmGC(conf *Config, export *crosscompile.Export) error {
+	if conf.Goarch != "wasm" || !hasBuildTag(conf.Tags, "llgo_wasm_gc") {
+		return nil
 	}
-	if !slices.Contains(export.LDFLAGS, "-sMALLOC=none") {
-		export.LDFLAGS = append(export.LDFLAGS, "-sMALLOC=none")
+	switch conf.Goos {
+	case "js":
+		if !slices.Contains(export.LDFLAGS, "-sMALLOC=none") {
+			export.LDFLAGS = append(export.LDFLAGS, "-sMALLOC=none")
+		}
+	case "wasip1":
+		if IsWasiThreadsEnabled() {
+			return errors.New("llgo_wasm_gc requires single-worker WASI (set LLGO_WASI_THREADS=0)")
+		}
+	default:
+		return fmt.Errorf("llgo_wasm_gc does not support GOOS=%s", conf.Goos)
 	}
+	return nil
 }
 
 func hasBuildTag(tags, want string) bool {
diff --git a/internal/build/build_test.go b/internal/build/build_test.go
index 6ba3f18f68..7f4dd4b936 100644
--- a/internal/build/build_test.go
+++ b/internal/build/build_test.go
@@ -322,21 +322,27 @@ func TestEffectiveWasmTypeSizes(t *testing.T) {
 	}
 }
 
-func TestApplyWasmGCLinkFlags(t *testing.T) {
+func TestConfigureWasmGC(t *testing.T) {
+	t.Setenv("LLGO_WASI_THREADS", "0")
 	tests := []struct {
 		name string
 		conf Config
 		want bool
+		err  bool
 	}{
 		{name: "wasm32", conf: Config{Goos: "js", Goarch: "wasm", Tags: "llgo_wasm_gc"}, want: true},
 		{name: "comma separated tags", conf: Config{Goos: "js", Goarch: "wasm", Tags: "other,llgo_wasm_gc"}, want: true},
 		{name: "default wasm", conf: Config{Goos: "js", Goarch: "wasm"}},
 		{name: "WASI", conf: Config{Goos: "wasip1", Goarch: "wasm", Tags: "llgo_wasm_gc"}},
+		{name: "unsupported host", conf: Config{Goos: "linux", Goarch: "wasm", Tags: "llgo_wasm_gc"}, err: true},
 	}
 	for _, test := range tests {
 		t.Run(test.name, func(t *testing.T) {
 			export := crosscompile.Export{}
-			applyWasmGCLinkFlags(&test.conf, &export)
+			err := configureWasmGC(&test.conf, &export)
+			if (err != nil) != test.err {
+				t.Fatalf("configureWasmGC error = %v, want error %v", err, test.err)
+			}
 			if got := slices.Contains(export.LDFLAGS, "-sMALLOC=none"); got != test.want {
 				t.Fatalf("MALLOC=none present = %v, want %v", got, test.want)
 			}
@@ -344,6 +350,14 @@ func TestApplyWasmGCLinkFlags(t *testing.T) {
 	}
 }
 
+func TestConfigureWasmGCRejectsWASIThreads(t *testing.T) {
+	t.Setenv("LLGO_WASI_THREADS", "1")
+	conf := Config{Goos: "wasip1", Goarch: "wasm", Tags: "llgo_wasm_gc"}
+	if err := configureWasmGC(&conf, &crosscompile.Export{}); err == nil {
+		t.Fatal("expected llgo_wasm_gc with WASI threads to fail")
+	}
+}
+
 func TestWasmRuntimeAvoidsNativeHostDependencies(t *testing.T) {
 	runtimeDir := filepath.Join(env.LLGoRuntimeDir(), "internal", "lib", "runtime")
 	for _, goos := range []string{"js", "wasip1"} {

From 44bc2f8b896c4874d4271523d2975928f7dd18c2 Mon Sep 17 00:00:00 2001
From: Li Jie <cpunion@gmail.com>
Date: Tue, 28 Jul 2026 22:29:36 +0800
Subject: [PATCH 6/8] ci: select single-worker P1 for wasm GC

---
 .github/workflows/llgo.yml | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/.github/workflows/llgo.yml b/.github/workflows/llgo.yml
index 9bb76e6918..cf6475e78d 100644
--- a/.github/workflows/llgo.yml
+++ b/.github/workflows/llgo.yml
@@ -493,7 +493,7 @@ jobs:
           node --input-type=module -e "import Module from '$RUNNER_TEMP/wasm-gc-go.mjs'; await Module();"
           llgo build -target wasm -tags=llgo_wasm_gc -o "$RUNNER_TEMP/wasm-gc.mjs" ./internal/build/testdata/wasm-gc
           node --input-type=module -e "import Module from '$RUNNER_TEMP/wasm-gc.mjs'; await Module();"
-          GOOS=wasip1 GOARCH=wasm llgo build -tags=llgo_wasm_gc -o "$RUNNER_TEMP/wasm-gc-wasip1.wasm" ./internal/build/testdata/wasm-gc
+          GOOS=wasip1 GOARCH=wasm LLGO_WASI_THREADS=0 llgo build -tags=llgo_wasm_gc -o "$RUNNER_TEMP/wasm-gc-wasip1.wasm" ./internal/build/testdata/wasm-gc
           file "$RUNNER_TEMP/runtime-js.wasm" \
             "$RUNNER_TEMP/runtime-wasip1.wasm" \
             "$RUNNER_TEMP/runtime-wasip1-threads.wasm" \

From 39bf51d6fb7b3f4908a4a0665f88391ccc106d9f Mon Sep 17 00:00:00 2001
From: Li Jie <cpunion@gmail.com>
Date: Tue, 28 Jul 2026 22:47:13 +0800
Subject: [PATCH 7/8] runtime: preserve ReadMemStats nil panic

---
 internal/build/testdata/wasm-gc/main.go              | 1 -
 runtime/internal/lib/runtime/runtime_gc_nonmoving.go | 3 ---
 2 files changed, 4 deletions(-)

diff --git a/internal/build/testdata/wasm-gc/main.go b/internal/build/testdata/wasm-gc/main.go
index d7062bcf25..f66fdd51fb 100644
--- a/internal/build/testdata/wasm-gc/main.go
+++ b/internal/build/testdata/wasm-gc/main.go
@@ -13,7 +13,6 @@ var (
 )
 
 func main() {
-	runtime.ReadMemStats(nil)
 	if testAlignedAlloc() == 0 {
 		panic("aligned allocation failed")
 	}
diff --git a/runtime/internal/lib/runtime/runtime_gc_nonmoving.go b/runtime/internal/lib/runtime/runtime_gc_nonmoving.go
index a5c79953fd..e91c06c75b 100644
--- a/runtime/internal/lib/runtime/runtime_gc_nonmoving.go
+++ b/runtime/internal/lib/runtime/runtime_gc_nonmoving.go
@@ -9,9 +9,6 @@ import (
 )
 
 func ReadMemStats(m *runtime.MemStats) {
-	if m == nil {
-		return
-	}
 	stats := tinygogc.ReadGCStats()
 	m.Alloc = stats.Alloc
 	m.TotalAlloc = stats.TotalAlloc

From 0fa359652b08c9225bb20e31a17777ec0f9d7e4b Mon Sep 17 00:00:00 2001
From: Li Jie <cpunion@gmail.com>
Date: Sat, 1 Aug 2026 18:55:57 +0800
Subject: [PATCH 8/8] ci: execute WASI collector fixture

---
 .github/workflows/llgo.yml | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/.github/workflows/llgo.yml b/.github/workflows/llgo.yml
index cf6475e78d..fbb8bf92da 100644
--- a/.github/workflows/llgo.yml
+++ b/.github/workflows/llgo.yml
@@ -494,6 +494,8 @@ jobs:
           llgo build -target wasm -tags=llgo_wasm_gc -o "$RUNNER_TEMP/wasm-gc.mjs" ./internal/build/testdata/wasm-gc
           node --input-type=module -e "import Module from '$RUNNER_TEMP/wasm-gc.mjs'; await Module();"
           GOOS=wasip1 GOARCH=wasm LLGO_WASI_THREADS=0 llgo build -tags=llgo_wasm_gc -o "$RUNNER_TEMP/wasm-gc-wasip1.wasm" ./internal/build/testdata/wasm-gc
+          wasm-tools validate --features all "$RUNNER_TEMP/wasm-gc-wasip1.wasm"
+          test "$(wasmtime run -W exceptions=y "$RUNNER_TEMP/wasm-gc-wasip1.wasm" 2>&1)" = "wasm gc ok"
           file "$RUNNER_TEMP/runtime-js.wasm" \
             "$RUNNER_TEMP/runtime-wasip1.wasm" \
             "$RUNNER_TEMP/runtime-wasip1-threads.wasm" \