[Based on #2197] runtime/wasm: add experimental Go-style resumable ABI

.github/actions/setup-binaryen/action.yml

@@ -0,0 +1,40 @@
+name: "Setup Binaryen"
+description: "Install a pinned Binaryen release"
+inputs:
+  version:
+    description: "Binaryen release version"
+    required: false
+    default: "131"
+
+runs:
+  using: "composite"
+  steps:
+    - name: Install Binaryen
+      shell: bash
+      run: |
+        set -euo pipefail
+
+        version="${{ inputs.version }}"
+        case "$(uname -s):$(uname -m)" in
+          Linux:x86_64) platform="x86_64-linux" ;;
+          Linux:aarch64|Linux:arm64) platform="aarch64-linux" ;;
+          Darwin:x86_64) platform="x86_64-macos" ;;
+          Darwin:arm64) platform="arm64-macos" ;;
+          *)
+            echo "Unsupported Binaryen host: $(uname -s) $(uname -m)" >&2
+            exit 1
+            ;;
+        esac
+
+        archive="binaryen-version_${version}-${platform}.tar.gz"
+        base_url="https://github.com/WebAssembly/binaryen/releases/download/version_${version}"
+        cd "$RUNNER_TEMP"
+        curl --retry 3 --retry-all-errors -fsSLO "${base_url}/${archive}"
+        curl --retry 3 --retry-all-errors -fsSLO "${base_url}/${archive}.sha256"
+        if command -v sha256sum >/dev/null; then
+          sha256sum --check "${archive}.sha256"
+        else
+          shasum -a 256 --check "${archive}.sha256"
+        fi
+        tar -xzf "$archive" -C "$RUNNER_TEMP"
+        echo "$RUNNER_TEMP/binaryen-version_${version}/bin" >> "$GITHUB_PATH"

.github/workflows/build-cache.yml

@@ -33,6 +33,9 @@ jobs:
       - name: Set up Go
         uses: ./.github/actions/setup-go
 
+      - name: Set up Binaryen
+        uses: ./.github/actions/setup-binaryen
+
       - name: Install wamr (for wasm tests)
         if: startsWith(matrix.os, 'macos')
         run: |

.github/workflows/llgo.yml

@@ -364,6 +364,9 @@ jobs:
       - name: Set up Go for building llgo
         uses: ./.github/actions/setup-go
 
+      - name: Set up Binaryen
+        uses: ./.github/actions/setup-binaryen
+
       - name: Install wamr
         run: |
           git clone --branch WAMR-2.4.4 --depth 1 https://github.com/bytecodealliance/wasm-micro-runtime.git
@@ -412,6 +415,24 @@ jobs:
         with:
           version: "4.0.21"
 
+      - name: Set up Node.js
+        uses: actions/setup-node@v7
+        with:
+          node-version: "25"
+
+      - name: Set up Binaryen
+        uses: ./.github/actions/setup-binaryen
+
+      - name: Set up Wasmtime
+        uses: bytecodealliance/actions/wasmtime/setup@v1
+        with:
+          version: "39.0.1"
+
+      - name: Set up wasm-tools
+        uses: bytecodealliance/actions/wasm-tools/setup@v1
+        with:
+          version: "1.243.0"
+
       - name: Set up Go for building llgo
         uses: ./.github/actions/setup-go
 
@@ -428,6 +449,51 @@ jobs:
       - name: Build standard runtime for wasm
         shell: bash
         run: |
+          run_wasm_scheduler() {
+            local module="$1"
+            local output
+            node --input-type=module -e "import Module from '$module'; await Module();"
+            if output=$(node --input-type=module -e "import Module from '$module'; await Module({preRun: [module => { module.ENV.LLGO_WASM_SCHEDULER_DEADLOCK = '1'; }]});" 2>&1); then
+              echo "deadlock scheduler fixture unexpectedly succeeded"
+              return 1
+            fi
+            grep -Fq "fatal error: all goroutines are asleep - deadlock!" <<<"$output"
+          }
+
+          run_wasi_scheduler() {
+            local module="$1"
+            local output
+            wasm-tools validate --features all "$module"
+            output=$(wasmtime run -W exceptions=y "$module" 2>&1)
+            grep -Fq "wasm scheduler ok" <<<"$output"
+            if output=$(wasmtime run -W exceptions=y \
+              --env LLGO_WASM_SCHEDULER_DEADLOCK=1 "$module" 2>&1); then
+              echo "deadlock scheduler fixture unexpectedly succeeded"
+              return 1
+            fi
+            grep -Fq "fatal error: all goroutines are asleep - deadlock!" <<<"$output"
+          }
+
           GOOS=js GOARCH=wasm llgo build -o "$RUNNER_TEMP/runtime-js.wasm" ./internal/build/testdata/wasm-runtime
           GOOS=wasip1 GOARCH=wasm llgo build -o "$RUNNER_TEMP/runtime-wasip1.wasm" ./internal/build/testdata/wasm-runtime
-          file "$RUNNER_TEMP/runtime-js.wasm" "$RUNNER_TEMP/runtime-wasip1.wasm"
+          LLGO_WASI_THREADS=1 GOOS=wasip1 GOARCH=wasm llgo build \
+            -o "$RUNNER_TEMP/runtime-wasip1-threads.wasm" ./internal/build/testdata/wasm-runtime
+          test "$(wasmtime run -W exceptions=y "$RUNNER_TEMP/runtime-wasip1.wasm" 2>&1)" = "wasip1"
+          GOOS=js GOARCH=wasm llgo build -o "$RUNNER_TEMP/wasm-scheduler-go.mjs" ./internal/build/testdata/wasm-scheduler
+          run_wasm_scheduler "$RUNNER_TEMP/wasm-scheduler-go.mjs"
+          llgo build -target wasm -o "$RUNNER_TEMP/wasm-scheduler.mjs" ./internal/build/testdata/wasm-scheduler
+          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 "$RUNNER_TEMP/wasm-scheduler-wasip1.wasm"
+          LLGO_WASM_RESUME=1 GOOS=js GOARCH=wasm llgo build \
+            -o "$RUNNER_TEMP/wasm-resume-scheduler-go.mjs" ./internal/build/testdata/wasm-scheduler
+          run_wasm_scheduler "$RUNNER_TEMP/wasm-resume-scheduler-go.mjs"
+          LLGO_WASM_RESUME=1 llgo build -target wasm \
+            -o "$RUNNER_TEMP/wasm-resume-scheduler.mjs" ./internal/build/testdata/wasm-scheduler
+          run_wasm_scheduler "$RUNNER_TEMP/wasm-resume-scheduler.mjs"
+          LLGO_WASM_RESUME=1 GOOS=wasip1 GOARCH=wasm llgo build \
+            -o "$RUNNER_TEMP/wasm-resume-scheduler-wasip1.wasm" ./internal/build/testdata/wasm-scheduler
+          run_wasi_scheduler "$RUNNER_TEMP/wasm-resume-scheduler-wasip1.wasm"
+          file "$RUNNER_TEMP/runtime-js.wasm" \
+            "$RUNNER_TEMP/runtime-wasip1.wasm" \
+            "$RUNNER_TEMP/runtime-wasip1-threads.wasm"

.github/workflows/targets.yml

@@ -27,6 +27,11 @@ jobs:
         with:
           llvm-version: ${{matrix.llvm}}
 
+      - name: Set up Emscripten
+        uses: emscripten-core/setup-emsdk@v15
+        with:
+          version: "4.0.21"
+
       - name: Set up Go for build
         uses: ./.github/actions/setup-go
 

internal/build/build.go

@@ -298,9 +298,6 @@ func Do(args []string, conf *Config) ([]Package, error) {
 	if conf.Goarch == "" {
 		conf.Goarch = runtime.GOARCH
 	}
-	if conf.AppExt == "" {
-		conf.AppExt = defaultAppExt(conf)
-	}
 	if conf.BuildMode == "" {
 		conf.BuildMode = BuildModeExe
 	}
@@ -339,6 +336,12 @@ func Do(args []string, conf *Config) ([]Package, error) {
 	if conf.Target != "" && export.GOARCH != "" {
 		conf.Goarch = export.GOARCH
 	}
+	if err := configureWasmResume(conf, &export); err != nil {
+		return nil, err
+	}
+	if conf.AppExt == "" {
+		conf.AppExt = defaultAppExt(conf)
+	}
 	if err := validateLinkOptions(conf, &export); err != nil {
 		return nil, err
 	}
@@ -393,6 +396,7 @@ func Do(args []string, conf *Config) ([]Package, error) {
 	}
 
 	prog := llssa.NewProgram(target)
+	prog.EnableWasmResumeABI(IsWasmResumeEnabled())
 	prog.DisableBoundsChecks(conf.DisableBoundsChecks)
 	if conf.Mode != ModeGen {
 		// ModeGen callers (llgen and the golden suites) read LPkg.String()
@@ -418,10 +422,7 @@ func Do(args []string, conf *Config) ([]Package, error) {
 	// final-PC sites for sidecar construction.
 	prog.EnableFuncInfoSites(shouldEnablePCLNSites(conf, funcInfo, emitDebugInfo))
 	sizes := func(sizes types.Sizes, compiler, arch string) types.Sizes {
-		if arch == "wasm" {
-			sizes = &types.StdSizes{WordSize: 4, MaxAlign: 4}
-		}
-		return prog.TypeSizes(sizes)
+		return prog.TypeSizes(effectiveTypeSizes(sizes, conf.Goos, arch, conf.Target))
 	}
 	dedup := packages.NewDeduper()
 	var syntaxErr error
@@ -727,16 +728,22 @@ func DefaultBuildTags(goarch, target string) string {
 
 func defaultBuildTags(goarch, target string) string {
 	tags := "llgo,math_big_pure_go,purego"
-	// Raw GOOS/GOARCH wasm builds do not have a target configuration that
-	// selects a collector. BDWGC is not available in either wasm host, so use
-	// the supported collector-free runtime unless a named target supplies its
-	// own runtime configuration.
-	if goarch == "wasm" && target == "" {
+	// BDWGC is unavailable in both wasm hosts.
+	if goarch == "wasm" {
 		tags += ",nogc"
 	}
 	return tags
 }
 
+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.
+	if goarch == "wasm" && (target != "" || goos != "js") {
+		return &types.StdSizes{WordSize: 4, MaxAlign: 4}
+	}
+	return sizes
+}
+
 func allowMissingFunctionBodies(initial []*packages.Package) {
 	for _, pkg := range initial {
 		hasMissingBody := false
@@ -1327,6 +1334,9 @@ func linkMainPkg(ctx *context, pkg *packages.Package, pkgs []*aPackage, outputPa
 		pcLineInfo:    pcLineInfo,
 		funcInfoStubs: funcInfoStubs,
 	})
+	if err := lowerWasmResumeModule(ctx, entryPkg.LPkg.Module()); err != nil {
+		return fmt.Errorf("entry main: %w", err)
+	}
 	entryObjFile, err := exportObject(ctx, "entry_main", entryPkg.ExportFile, entryPkg.LPkg)
 	if err != nil {
 		return err
@@ -1359,12 +1369,15 @@ func linkMainPkg(ctx *context, pkg *packages.Package, pkgs []*aPackage, outputPa
 	}
 	linkArgs = append(linkArgs, cSharedExportArgs(ctx, linkedOrder)...)
 
-	err = linkObjFiles(ctx, outputPath, linkInputs, linkArgs, verbose)
+	linkOutput, err := prepareWasmLinkOutput(ctx.buildConf, &ctx.crossCompile, outputPath)
 	if err != nil {
 		return err
 	}
-
-	return nil
+	defer cleanupWasmLinkOutput(linkOutput, outputPath)
+	if err := linkObjFiles(ctx, linkOutput, linkInputs, linkArgs, verbose); err != nil {
+		return err
+	}
+	return publishWasmLinkOutput(ctx, linkOutput, outputPath, verbose)
 }
 
 func linkedModuleGlobals(pkgs []Package) map[string]none {
@@ -1722,6 +1735,9 @@ func buildPkg(ctx *context, aPkg *aPackage, verbose bool) error {
 		return nil
 	}
 
+	if err := lowerWasmResumeModule(ctx, ret.Module()); err != nil {
+		return fmt.Errorf("%s: %w", pkgPath, err)
+	}
 	ctx.cTransformer.SetSkipFuncs(cabiSkipFuncsForPlan9Asm(ctx, pkgPath, ret.Module()))
 	llabi.LowerLargeAggregates(ctx.prog.TargetData(), ret.Module())
 	ctx.cTransformer.TransformModule(ret.Path(), ret.Module())
@@ -2282,6 +2298,7 @@ const llgoFuncInfoSites = "LLGO_FUNCINFO_SITES"
 const llgoTrace = "LLGO_TRACE"
 const llgoOptimize = "LLGO_OPTIMIZE"
 const llgoWasmRuntime = "LLGO_WASM_RUNTIME"
+const llgoWasmResume = "LLGO_WASM_RESUME"
 const llgoWasiThreads = "LLGO_WASI_THREADS"
 const llgoStdioNobuf = "LLGO_STDIO_NOBUF"
 const llgoFullRpath = "LLGO_FULL_RPATH"
@@ -2360,7 +2377,11 @@ func llvmPassPipeline(level optlevel.Level, ltoMode lto.Mode) string {
 }
 
 func IsWasiThreadsEnabled() bool {
-	return isEnvOn(llgoWasiThreads, true)
+	return isEnvOn(llgoWasiThreads, false)
+}
+
+func IsWasmResumeEnabled() bool {
+	return isEnvOn(llgoWasmResume, false)
 }
 
 func IsFullRpathEnabled() bool {

internal/build/build_test.go

@@ -109,7 +109,7 @@ func TestDefaultBuildTags(t *testing.T) {
 	}{
 		{name: "native", goarch: "arm64", want: base},
 		{name: "raw wasm", goarch: "wasm", want: base + ",nogc"},
-		{name: "configured wasm target", goarch: "wasm", target: "wasip1", want: base},
+		{name: "configured wasm target", goarch: "wasm", target: "wasip1", want: base + ",nogc"},
 	} {
 		t.Run(test.name, func(t *testing.T) {
 			if got := defaultBuildTags(test.goarch, test.target); got != test.want {
@@ -119,6 +119,30 @@ func TestDefaultBuildTags(t *testing.T) {
 	}
 }
 
+func TestEffectiveWasmTypeSizes(t *testing.T) {
+	goSizes := types.SizesFor("gc", "wasm")
+	for _, test := range []struct {
+		name   string
+		goos   string
+		target string
+		want   int64
+	}{
+		{name: "Go js wasm", goos: "js", want: 8},
+		{name: "configured wasm", goos: "js", target: "wasm", want: 4},
+		{name: "WASI compatibility", goos: "wasip1", want: 4},
+	} {
+		t.Run(test.name, func(t *testing.T) {
+			got := effectiveTypeSizes(goSizes, test.goos, "wasm", test.target)
+			if size := got.Sizeof(types.Typ[types.Uintptr]); size != test.want {
+				t.Fatalf("uintptr size = %d, want %d", size, test.want)
+			}
+		})
+	}
+	if got := effectiveTypeSizes(goSizes, "linux", "amd64", ""); got != goSizes {
+		t.Fatal("native type sizes changed")
+	}
+}
+
 func TestWasmRuntimeAvoidsNativeHostDependencies(t *testing.T) {
 	runtimeDir := filepath.Join(env.LLGoRuntimeDir(), "internal", "lib", "runtime")
 	for _, goos := range []string{"js", "wasip1"} {
@@ -836,6 +860,17 @@ func TestApplyBuildModeCompileFlags(t *testing.T) {
 	applyBuildModeCompileFlags(BuildModeCShared, nil)
 }
 
+func TestWASIThreadsAreOptIn(t *testing.T) {
+	t.Setenv(llgoWasiThreads, "")
+	if IsWasiThreadsEnabled() {
+		t.Fatal("WASI threads are enabled by default")
+	}
+	t.Setenv(llgoWasiThreads, "1")
+	if !IsWasiThreadsEnabled() {
+		t.Fatal("WASI threads opt-in was ignored")
+	}
+}
+
 func TestCHeaderPackagesExcludesStandardRuntime(t *testing.T) {
 	prog := llssa.NewProgram(nil)
 	defer prog.Dispose()

internal/build/collect.go

@@ -85,6 +85,7 @@ func (c *context) collectEnvInputs(m *manifestBuilder) {
 		llgoTrace,
 		llgoOptimize,
 		llgoWasmRuntime,
+		llgoWasmResume,
 		llgoWasiThreads,
 		llgoStdioNobuf,
 		llgoFullRpath,