Merge pull request #1415 from goplus/dependabot/github_actions/actions/checkout-6

chore(deps): bump actions/checkout from 5 to 6

.github/workflows/doc.yml

@@ -18,7 +18,7 @@ jobs:
     runs-on: ubuntu-latest
     timeout-minutes: 30
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
 
       - name: Set up Node.js
         uses: actions/setup-node@v6
@@ -47,7 +47,7 @@ jobs:
           - ubuntu-latest
     runs-on: ${{matrix.os}}
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
 
       - name: Set up Go
         uses: ./.github/actions/setup-go
@@ -84,7 +84,7 @@ jobs:
           - ubuntu-latest
     runs-on: ${{matrix.os}}
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
 
       - name: Set up Go
         uses: actions/setup-go@v6
@@ -136,7 +136,7 @@ jobs:
           - ubuntu-latest
     runs-on: ${{matrix.os}}
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
 
       - name: Set up Go
         uses: actions/setup-go@v6

.github/workflows/fmt.yml

@@ -18,7 +18,7 @@ jobs:
     runs-on: ubuntu-latest
     timeout-minutes: 30
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
 
       - name: Set up Go
         uses: ./.github/actions/setup-go

.github/workflows/go.yml

@@ -28,7 +28,7 @@ jobs:
         llvm: [19]
     runs-on: ${{matrix.os}}
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
       - name: Install dependencies
         uses: ./.github/actions/setup-deps
         with:

.github/workflows/llgo.yml

@@ -46,7 +46,7 @@ jobs:
         go: ["1.21.13", "1.22.12", "1.23.6", "1.24.2"]
     runs-on: ${{matrix.os}}
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
       - name: Install dependencies
         uses: ./.github/actions/setup-deps
         with:
@@ -61,7 +61,7 @@ jobs:
           if ${{ startsWith(matrix.os, 'macos') }}; then
             DEMO_PKG="cargs_darwin_arm64.zip"
           else
-            DEMO_PKG="cargs_linux_amd64.zip"  
+            DEMO_PKG="cargs_linux_amd64.zip"
           fi
 
           mkdir -p ./_demo/c/cargs/libs
@@ -133,6 +133,13 @@ jobs:
           chmod +x test.sh
           ./test.sh
 
+      - name: Test export with different symbol names on embedded targets
+        run: |
+          echo "Testing //export with different symbol names on embedded targets..."
+          cd _demo/embed/export
+          chmod +x verify_export.sh
+          ./verify_export.sh
+
       - name: _xtool build tests
         run: |
           cd _xtool
@@ -159,7 +166,7 @@ jobs:
         go: ["1.24.2"]
     runs-on: ${{matrix.os}}
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
       - name: Install dependencies
         uses: ./.github/actions/setup-deps
         with:
@@ -186,11 +193,15 @@ jobs:
         uses: actions/setup-go@v6
         with:
           go-version: ${{matrix.go}}
-
+      - name: Test Baremetal GC
+        if: ${{!startsWith(matrix.os, 'macos')}}
+        working-directory: runtime/internal/runtime/tinygogc
+        run: llgo test -tags testGC .
       - name: run llgo test
         run: |
           llgo test ./...
 
+
   hello:
     continue-on-error: true
     timeout-minutes: 30
@@ -201,7 +212,7 @@ jobs:
         go: ["1.21.13", "1.22.12", "1.23.6", "1.24.2"]
     runs-on: ${{matrix.os}}
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
       - name: Install dependencies
         uses: ./.github/actions/setup-deps
         with:
@@ -259,7 +270,7 @@ jobs:
         llvm: [19]
     runs-on: ${{matrix.os}}
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
       - name: Install dependencies
         uses: ./.github/actions/setup-deps
         with:

.github/workflows/release-build.yml

@@ -21,7 +21,7 @@ jobs:
       linux-cache-key: ${{ steps.cache-keys.outputs.linux-key }}
     steps:
       - name: Check out code
-        uses: actions/checkout@v5
+        uses: actions/checkout@v6
       - name: Calculate cache keys
         id: cache-keys
         run: |
@@ -33,7 +33,7 @@ jobs:
     timeout-minutes: 30
     steps:
       - name: Check out code
-        uses: actions/checkout@v5
+        uses: actions/checkout@v6
       - name: Check Linux sysroot cache
         id: cache-linux-sysroot
         uses: actions/cache/restore@v4
@@ -63,7 +63,7 @@ jobs:
     needs: [setup, populate-linux-sysroot]
     steps:
       - name: Check out code
-        uses: actions/checkout@v5
+        uses: actions/checkout@v6
       - name: Set up Release
         uses: ./.github/actions/setup-goreleaser
         with:
@@ -148,7 +148,7 @@ jobs:
             go-mod-version: "1.24"
     runs-on: ${{ matrix.os }}
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
       - name: Install dependencies
         uses: ./.github/actions/setup-deps
         with:
@@ -184,7 +184,7 @@ jobs:
     if: startsWith(github.ref, 'refs/tags/')
     steps:
       - name: Check out code
-        uses: actions/checkout@v5
+        uses: actions/checkout@v6
         with:
           fetch-depth: 0
       - name: Set up Release

.github/workflows/targets.yml

@@ -26,7 +26,7 @@ jobs:
         llvm: [19]
     runs-on: ${{matrix.os}}
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
       - name: Install dependencies
         uses: ./.github/actions/setup-deps
         with:

_demo/embed/export/main.go

@@ -0,0 +1,67 @@
+package main
+
+import (
+	"github.com/goplus/lib/c"
+)
+
+// This demo shows how to use //export with different symbol names on embedded targets.
+//
+// On embedded targets, you can export Go functions with different C symbol names.
+// This is useful for hardware interrupt handlers that require specific names.
+
+// Standard Go export - same name
+//
+//export HelloWorld
+func HelloWorld() {
+	c.Printf(c.Str("Hello from "))
+	c.Printf(c.Str("HelloWorld\n"))
+}
+
+// Embedded target export - different name
+// Go function name: interruptLPSPI2
+// Exported C symbol: LPSPI2_IRQHandler
+//
+//export LPSPI2_IRQHandler
+func interruptLPSPI2() {
+	c.Printf(c.Str("LPSPI2 interrupt "))
+	c.Printf(c.Str("handler called\n"))
+}
+
+// Embedded target export - different name
+// Go function name: systemTickHandler
+// Exported C symbol: SysTick_Handler
+//
+//export SysTick_Handler
+func systemTickHandler() {
+	c.Printf(c.Str("SysTick "))
+	c.Printf(c.Str("handler called\n"))
+}
+
+// Embedded target export - different name
+// Go function name: Add
+// Exported C symbol: AddFunc
+//
+//export AddFunc
+func Add(a, b int) int {
+	result := a + b
+	c.Printf(c.Str("AddFunc(%d, %d) = %d\n"), a, b, result)
+	return result
+}
+
+func main() {
+	c.Printf(c.Str("=== Export Demo ===\n\n"))
+
+	// Call exported functions directly from Go
+	c.Printf(c.Str("Calling HelloWorld:\n"))
+	HelloWorld()
+
+	c.Printf(c.Str("\nSimulating hardware interrupts:\n"))
+	interruptLPSPI2()
+	systemTickHandler()
+
+	c.Printf(c.Str("\nTesting function with return value:\n"))
+	result := Add(10, 20)
+	c.Printf(c.Str("Result: %d\n"), result)
+
+	c.Printf(c.Str("\n=== Demo Complete ===\n"))
+}

_demo/embed/export/verify_export.sh

@@ -0,0 +1,54 @@
+#!/bin/bash
+
+set -e
+
+echo "Building for embedded target..."
+
+# Build for embedded target as executable
+# Use llgo directly instead of llgo.sh to avoid go.mod version check
+llgo build -o test-verify --target=esp32 .
+
+echo "Checking exported symbols..."
+
+# Get exported symbols
+exported_symbols=$(nm -gU ./test-verify.elf | grep -E "(HelloWorld|LPSPI2_IRQHandler|SysTick_Handler|AddFunc)" | awk '{print $NF}')
+
+echo ""
+echo "Exported symbols:"
+echo "$exported_symbols" | awk '{print "  " $0}'
+echo ""
+
+# Check expected symbols
+expected=("HelloWorld" "LPSPI2_IRQHandler" "SysTick_Handler" "AddFunc")
+missing=""
+
+for symbol in "${expected[@]}"; do
+    if ! echo "$exported_symbols" | grep -q "^$symbol$"; then
+        missing="$missing $symbol"
+    fi
+done
+
+if [ -n "$missing" ]; then
+    echo "❌ Missing symbols:$missing"
+    exit 1
+fi
+
+echo "✅ Symbol name mapping verification:"
+echo "  HelloWorld           -> HelloWorld"
+echo "  interruptLPSPI2      -> LPSPI2_IRQHandler"
+echo "  systemTickHandler    -> SysTick_Handler"
+echo "  Add                  -> AddFunc"
+echo ""
+echo "🎉 All export symbols verified successfully!"
+echo ""
+
+echo "Testing that non-embedded target rejects different export names..."
+# Build without --target should fail with panic
+if llgo build -o test-notarget . 2>&1 | grep -q 'export comment has wrong name "LPSPI2_IRQHandler"'; then
+    echo "✅ Correctly rejected different export name on non-embedded target"
+else
+    echo "❌ Should have panicked with 'export comment has wrong name' error"
+    exit 1
+fi
+echo ""
+echo "Note: Different symbol names are only supported on embedded targets."

cl/builtin_test.go

@@ -393,10 +393,10 @@ func TestErrImport(t *testing.T) {
 
 func TestErrInitLinkname(t *testing.T) {
 	var ctx context
-	ctx.initLinkname("//llgo:link abc", func(name string) (string, bool, bool) {
+	ctx.initLinkname("//llgo:link abc", func(name string, isExport bool) (string, bool, bool) {
 		return "", false, false
 	})
-	ctx.initLinkname("//go:linkname Printf printf", func(name string) (string, bool, bool) {
+	ctx.initLinkname("//go:linkname Printf printf", func(name string, isExport bool) (string, bool, bool) {
 		return "", false, false
 	})
 	defer func() {
@@ -404,7 +404,7 @@ func TestErrInitLinkname(t *testing.T) {
 			t.Fatal("initLinkname: no error?")
 		}
 	}()
-	ctx.initLinkname("//go:linkname Printf printf", func(name string) (string, bool, bool) {
+	ctx.initLinkname("//go:linkname Printf printf", func(name string, isExport bool) (string, bool, bool) {
 		return "foo.Printf", false, name == "Printf"
 	})
 }
@@ -506,3 +506,238 @@ func TestInstantiate(t *testing.T) {
 		t.Fatal("error")
 	}
 }
+
+func TestHandleExportDiffName(t *testing.T) {
+	tests := []struct {
+		name               string
+		enableExportRename bool
+		line               string
+		fullName           string
+		inPkgName          string
+		wantHasLinkname    bool
+		wantLinkname       string
+		wantExport         string
+	}{
+		{
+			name:               "ExportDiffNames_DifferentName",
+			enableExportRename: true,
+			line:               "//export IRQ_Handler",
+			fullName:           "pkg.HandleInterrupt",
+			inPkgName:          "HandleInterrupt",
+			wantHasLinkname:    true,
+			wantLinkname:       "IRQ_Handler",
+			wantExport:         "IRQ_Handler",
+		},
+		{
+			name:               "ExportDiffNames_SameName",
+			enableExportRename: true,
+			line:               "//export SameName",
+			fullName:           "pkg.SameName",
+			inPkgName:          "SameName",
+			wantHasLinkname:    true,
+			wantLinkname:       "SameName",
+			wantExport:         "SameName",
+		},
+		{
+			name:               "ExportDiffNames_WithSpaces",
+			enableExportRename: true,
+			line:               "//export   Timer_Callback  ",
+			fullName:           "pkg.OnTimerTick",
+			inPkgName:          "OnTimerTick",
+			wantHasLinkname:    true,
+			wantLinkname:       "Timer_Callback",
+			wantExport:         "Timer_Callback",
+		},
+		{
+			name:               "ExportDiffNames_Disabled_MatchingName",
+			enableExportRename: false,
+			line:               "//export Func",
+			fullName:           "pkg.Func",
+			inPkgName:          "Func",
+			wantHasLinkname:    true,
+			wantLinkname:       "Func",
+			wantExport:         "Func",
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			// Save and restore global state
+			oldEnableExportRename := enableExportRename
+			defer func() {
+				EnableExportRename(oldEnableExportRename)
+			}()
+			EnableExportRename(tt.enableExportRename)
+
+			// Setup context
+			prog := llssa.NewProgram(nil)
+			pkg := prog.NewPackage("test", "test")
+			ctx := &context{
+				prog: prog,
+				pkg:  pkg,
+			}
+
+			// Call initLinkname with closure that mimics initLinknameByDoc behavior
+			ret := ctx.initLinkname(tt.line, func(name string, isExport bool) (string, bool, bool) {
+				return tt.fullName, false, name == tt.inPkgName || (isExport && enableExportRename)
+			})
+
+			// Verify result
+			hasLinkname := (ret == hasLinkname)
+			if hasLinkname != tt.wantHasLinkname {
+				t.Errorf("hasLinkname = %v, want %v", hasLinkname, tt.wantHasLinkname)
+			}
+
+			if tt.wantHasLinkname {
+				// Check linkname was set
+				if link, ok := prog.Linkname(tt.fullName); !ok || link != tt.wantLinkname {
+					t.Errorf("linkname = %q (ok=%v), want %q", link, ok, tt.wantLinkname)
+				}
+
+				// Check export was set
+				exports := pkg.ExportFuncs()
+				if export, ok := exports[tt.fullName]; !ok || export != tt.wantExport {
+					t.Errorf("export = %q (ok=%v), want %q", export, ok, tt.wantExport)
+				}
+			}
+		})
+	}
+}
+
+func TestInitLinknameByDocExportDiffNames(t *testing.T) {
+	tests := []struct {
+		name               string
+		enableExportRename bool
+		doc                *ast.CommentGroup
+		fullName           string
+		inPkgName          string
+		wantExported       bool // Whether the symbol should be exported with different name
+		wantLinkname       string
+		wantExport         string
+	}{
+		{
+			name:               "WithExportDiffNames_DifferentNameExported",
+			enableExportRename: true,
+			doc: &ast.CommentGroup{
+				List: []*ast.Comment{
+					{Text: "//export IRQ_Handler"},
+				},
+			},
+			fullName:     "pkg.HandleInterrupt",
+			inPkgName:    "HandleInterrupt",
+			wantExported: true,
+			wantLinkname: "IRQ_Handler",
+			wantExport:   "IRQ_Handler",
+		},
+		{
+			name:               "WithoutExportDiffNames_NotExported",
+			enableExportRename: false,
+			doc: &ast.CommentGroup{
+				List: []*ast.Comment{
+					{Text: "//export DifferentName"},
+				},
+			},
+			fullName:     "pkg.HandleInterrupt",
+			inPkgName:    "HandleInterrupt",
+			wantExported: false,
+			// Without enableExportRename, it goes through normal flow which expects same name
+			// The symbol "DifferentName" won't be found, so no export happens
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			// Without enableExportRename, export with different name will panic
+			if !tt.wantExported && !tt.enableExportRename {
+				defer func() {
+					if r := recover(); r == nil {
+						t.Error("expected panic for export with different name when enableExportRename=false")
+					}
+				}()
+			}
+
+			// Save and restore global state
+			oldEnableExportRename := enableExportRename
+			defer func() {
+				EnableExportRename(oldEnableExportRename)
+			}()
+			EnableExportRename(tt.enableExportRename)
+
+			// Setup context
+			prog := llssa.NewProgram(nil)
+			pkg := prog.NewPackage("test", "test")
+			ctx := &context{
+				prog: prog,
+				pkg:  pkg,
+			}
+
+			// Call initLinknameByDoc
+			ctx.initLinknameByDoc(tt.doc, tt.fullName, tt.inPkgName, false)
+
+			// Verify export behavior
+			exports := pkg.ExportFuncs()
+			if tt.wantExported {
+				// Should have exported the symbol with different name
+				if export, ok := exports[tt.fullName]; !ok || export != tt.wantExport {
+					t.Errorf("export = %q (ok=%v), want %q", export, ok, tt.wantExport)
+				}
+				// Check linkname was also set
+				if link, ok := prog.Linkname(tt.fullName); !ok || link != tt.wantLinkname {
+					t.Errorf("linkname = %q (ok=%v), want %q", link, ok, tt.wantLinkname)
+				}
+			}
+		})
+	}
+}
+
+func TestInitLinkExportDiffNames(t *testing.T) {
+	tests := []struct {
+		name               string
+		enableExportRename bool
+		line               string
+		wantPanic          bool
+	}{
+		{
+			name:               "ExportDiffNames_Enabled_NoError",
+			enableExportRename: true,
+			line:               "//export IRQ_Handler",
+			wantPanic:          false,
+		},
+		{
+			name:               "ExportDiffNames_Disabled_Panic",
+			enableExportRename: false,
+			line:               "//export IRQ_Handler",
+			wantPanic:          true,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			if tt.wantPanic {
+				defer func() {
+					if r := recover(); r == nil {
+						t.Error("expected panic but didn't panic")
+					}
+				}()
+			}
+
+			oldEnableExportRename := enableExportRename
+			defer func() {
+				EnableExportRename(oldEnableExportRename)
+			}()
+			EnableExportRename(tt.enableExportRename)
+
+			prog := llssa.NewProgram(nil)
+			pkg := prog.NewPackage("test", "test")
+			ctx := &context{
+				prog: prog,
+				pkg:  pkg,
+			}
+
+			ctx.initLinkname(tt.line, func(inPkgName string, isExport bool) (fullName string, isVar, ok bool) {
+				// Simulate initLinknames scenario: symbol not found (like in decl packages)
+				return "", false, false
+			})
+		})
+	}
+}

cl/compile.go

@@ -53,6 +53,11 @@ var (
 	enableDbg         bool
 	enableDbgSyms     bool
 	disableInline     bool
+
+	// enableExportRename enables //export to use different C symbol names than Go function names.
+	// This is for TinyGo compatibility when using -target flag for embedded targets.
+	// Currently, using -target implies TinyGo embedded target mode.
+	enableExportRename bool
 )
 
 // SetDebug sets debug flags.
@@ -73,6 +78,12 @@ func EnableTrace(b bool) {
 	enableCallTracing = b
 }
 
+// EnableExportRename enables or disables //export with different C symbol names.
+// This is enabled when using -target flag for TinyGo compatibility.
+func EnableExportRename(b bool) {
+	enableExportRename = b
+}
+
 // -----------------------------------------------------------------------------
 
 type instrOrValue interface {

cl/import.go

@@ -73,7 +73,7 @@ func (p *pkgSymInfo) initLinknames(ctx *context) {
 		lines := bytes.Split(b, sep)
 		for _, line := range lines {
 			if bytes.HasPrefix(line, commentPrefix) {
-				ctx.initLinkname(string(line), func(inPkgName string) (fullName string, isVar, ok bool) {
+				ctx.initLinkname(string(line), func(inPkgName string, isExport bool) (fullName string, isVar, ok bool) {
 					if sym, ok := p.syms[inPkgName]; ok && file == sym.file {
 						return sym.fullName, sym.isVar, true
 					}
@@ -277,8 +277,8 @@ func (p *context) initLinknameByDoc(doc *ast.CommentGroup, fullName, inPkgName s
 	if doc != nil {
 		for n := len(doc.List) - 1; n >= 0; n-- {
 			line := doc.List[n].Text
-			ret := p.initLinkname(line, func(name string) (_ string, _, ok bool) {
-				return fullName, isVar, name == inPkgName
+			ret := p.initLinkname(line, func(name string, isExport bool) (_ string, _, ok bool) {
+				return fullName, isVar, name == inPkgName || (isExport && enableExportRename)
 			})
 			if ret != unknownDirective {
 				return ret == hasLinkname
@@ -294,7 +294,7 @@ const (
 	unknownDirective = -1
 )
 
-func (p *context) initLinkname(line string, f func(inPkgName string) (fullName string, isVar, ok bool)) int {
+func (p *context) initLinkname(line string, f func(inPkgName string, isExport bool) (fullName string, isVar, ok bool)) int {
 	const (
 		linkname  = "//go:linkname "
 		llgolink  = "//llgo:link "
@@ -324,17 +324,24 @@ func (p *context) initLinkname(line string, f func(inPkgName string) (fullName s
 	return noDirective
 }
 
-func (p *context) initLink(line string, prefix int, export bool, f func(inPkgName string) (fullName string, isVar, ok bool)) {
+func (p *context) initLink(line string, prefix int, export bool, f func(inPkgName string, isExport bool) (fullName string, isVar, ok bool)) {
 	text := strings.TrimSpace(line[prefix:])
 	if idx := strings.IndexByte(text, ' '); idx > 0 {
 		inPkgName := text[:idx]
-		if fullName, _, ok := f(inPkgName); ok {
+		if fullName, _, ok := f(inPkgName, export); ok {
 			link := strings.TrimLeft(text[idx+1:], " ")
 			p.prog.SetLinkname(fullName, link)
 			if export {
 				p.pkg.SetExport(fullName, link)
 			}
 		} else {
+			// Export with different names already processed by initLinknameByDoc
+			if export && enableExportRename {
+				return
+			}
+			if export {
+				panic(fmt.Sprintf("export comment has wrong name %q", inPkgName))
+			}
 			fmt.Fprintln(os.Stderr, "==>", line)
 			fmt.Fprintf(os.Stderr, "llgo: linkname %s not found and ignored\n", inPkgName)
 		}

internal/build/build.go

@@ -220,6 +220,11 @@ func Do(args []string, conf *Config) ([]Package, error) {
 		conf.Goarch = export.GOARCH
 	}
 
+	// Enable different export names for TinyGo compatibility when using -target
+	if conf.Target != "" {
+		cl.EnableExportRename(true)
+	}
+
 	verbose := conf.Verbose
 	patterns := args
 	tags := "llgo,math_big_pure_go"
@@ -782,11 +787,11 @@ func linkMainPkg(ctx *context, pkg *packages.Package, pkgs []*aPackage, outputPa
 		}
 	})
 	// Generate main module file (needed for global variables even in library modes)
-	entryObjFile, err := genMainModuleFile(ctx, llssa.PkgRuntime, pkg, needRuntime, needPyInit)
+	entryPkg := genMainModule(ctx, llssa.PkgRuntime, pkg, needRuntime, needPyInit)
+	entryObjFile, err := exportObject(ctx, entryPkg.PkgPath, entryPkg.ExportFile, []byte(entryPkg.LPkg.String()))
 	if err != nil {
 		return err
 	}
-	// defer os.Remove(entryLLFile)
 	objFiles = append(objFiles, entryObjFile)
 
 	// Compile extra files from target configuration
@@ -908,118 +913,6 @@ func needStart(ctx *context) bool {
 	}
 }
 
-func genMainModuleFile(ctx *context, rtPkgPath string, pkg *packages.Package, needRuntime, needPyInit bool) (path string, err error) {
-	var (
-		pyInitDecl string
-		pyInit     string
-		rtInitDecl string
-		rtInit     string
-	)
-	mainPkgPath := pkg.PkgPath
-	if needRuntime {
-		rtInit = "call void @\"" + rtPkgPath + ".init\"()"
-		rtInitDecl = "declare void @\"" + rtPkgPath + ".init\"()"
-	}
-	if needPyInit {
-		pyInit = "call void @Py_Initialize()"
-		pyInitDecl = "declare void @Py_Initialize()"
-	}
-	declSizeT := "%size_t = type i64"
-	if is32Bits(ctx.buildConf.Goarch) {
-		declSizeT = "%size_t = type i32"
-	}
-	stdioDecl := ""
-	stdioNobuf := ""
-	if IsStdioNobuf() {
-		stdioDecl = `
-@stdout = external global ptr
-@stderr = external global ptr
-@__stdout = external global ptr
-@__stderr = external global ptr
-declare i32 @setvbuf(ptr, ptr, i32, %size_t)
-	`
-		stdioNobuf = `
-; Set stdout with no buffer
-%stdout_is_null = icmp eq ptr @stdout, null
-%stdout_ptr = select i1 %stdout_is_null, ptr @__stdout, ptr @stdout
-call i32 @setvbuf(ptr %stdout_ptr, ptr null, i32 2, %size_t 0)
-; Set stderr with no buffer
-%stderr_ptr = select i1 %stdout_is_null, ptr @__stderr, ptr @stderr
-call i32 @setvbuf(ptr %stderr_ptr, ptr null, i32 2, %size_t 0)
-	`
-	}
-	// TODO(lijie): workaround for libc-free
-	// Remove main/_start when -buildmode and libc are ready
-	startDefine := `
-define weak void @_start() {
-  ; argc = 0
-  %argc = add i32 0, 0
-  ; argv = null
-  %argv = inttoptr i64 0 to i8**
-  call i32 @main(i32 %argc, i8** %argv)
-  ret void
-}
-`
-	mainDefine := "define i32 @main(i32 noundef %0, ptr nocapture noundef readnone %1) local_unnamed_addr"
-	if !needStart(ctx) && isWasmTarget(ctx.buildConf.Goos) {
-		mainDefine = "define hidden noundef i32 @__main_argc_argv(i32 noundef %0, ptr nocapture noundef readnone %1) local_unnamed_addr"
-	}
-	if !needStart(ctx) {
-		startDefine = ""
-	}
-
-	var mainCode string
-	// For library modes (c-archive, c-shared), only generate global variables
-	if ctx.buildConf.BuildMode != BuildModeExe {
-		mainCode = `; ModuleID = 'main'
-source_filename = "main"
-@__llgo_argc = global i32 0, align 4
-@__llgo_argv = global ptr null, align 8
-`
-	} else {
-		// For executable mode, generate full main function
-		mainCode = fmt.Sprintf(`; ModuleID = 'main'
-source_filename = "main"
-%s
-@__llgo_argc = global i32 0, align 4
-@__llgo_argv = global ptr null, align 8
-%s
-%s
-%s
-declare void @"%s.init"()
-declare void @"%s.main"()
-define weak void @runtime.init() {
-  ret void
-}
-
-; TODO(lijie): workaround for syscall patch
-define weak void @"syscall.init"() {
-  ret void
-}
-
-%s
-
-%s {
-_llgo_0:
-  store i32 %%0, ptr @__llgo_argc, align 4
-  store ptr %%1, ptr @__llgo_argv, align 8
-  %s
-  %s
-  %s
-  call void @runtime.init()
-  call void @"%s.init"()
-  call void @"%s.main"()
-  ret i32 0
-}
-`, declSizeT, stdioDecl,
-			pyInitDecl, rtInitDecl, mainPkgPath, mainPkgPath,
-			startDefine, mainDefine, stdioNobuf,
-			pyInit, rtInit, mainPkgPath, mainPkgPath)
-	}
-
-	return exportObject(ctx, pkg.PkgPath+".main", pkg.ExportFile+"-main", []byte(mainCode))
-}
-
 func is32Bits(goarch string) bool {
 	return goarch == "386" || goarch == "arm" || goarch == "mips" || goarch == "wasm"
 }

internal/build/build_test.go

@@ -159,3 +159,8 @@ func runBinary(t *testing.T, path string, args ...string) string {
 	}
 	return string(output)
 }
+
+func TestRunPrintfWithStdioNobuf(t *testing.T) {
+	t.Setenv(llgoStdioNobuf, "1")
+	mockRun([]string{"../../cl/_testdata/printf"}, &Config{Mode: ModeRun})
+}

internal/build/main_module.go

@@ -0,0 +1,231 @@
+//go:build !llgo
+// +build !llgo
+
+/*
+ * Copyright (c) 2024 The GoPlus Authors (goplus.org). All rights reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+// Package build contains the llgo compiler build orchestration logic.
+//
+// The main_module.go file generates the entry point module for llgo programs,
+// which contains the main() function, initialization sequence, and global
+// variables like argc/argv. This module is generated differently depending on
+// BuildMode (exe, c-archive, c-shared).
+
+package build
+
+import (
+	"go/token"
+	"go/types"
+
+	"github.com/goplus/llgo/internal/packages"
+	llvm "github.com/goplus/llvm"
+
+	llssa "github.com/goplus/llgo/ssa"
+)
+
+// genMainModule generates the main entry module for an llgo program.
+//
+// The module contains argc/argv globals and, for executable build modes,
+// the entry function that wires initialization and main. For C archive or
+// shared library modes, only the globals are emitted.
+func genMainModule(ctx *context, rtPkgPath string, pkg *packages.Package, needRuntime, needPyInit bool) Package {
+	prog := ctx.prog
+	mainPkg := prog.NewPackage("", pkg.ID+".main")
+
+	argcVar := mainPkg.NewVarEx("__llgo_argc", prog.Pointer(prog.Int32()))
+	argcVar.Init(prog.Zero(prog.Int32()))
+
+	argvValueType := prog.Pointer(prog.CStr())
+	argvVar := mainPkg.NewVarEx("__llgo_argv", prog.Pointer(argvValueType))
+	argvVar.InitNil()
+
+	exportFile := pkg.ExportFile
+	if exportFile == "" {
+		exportFile = pkg.PkgPath
+	}
+	mainAPkg := &aPackage{
+		Package: &packages.Package{
+			PkgPath:    pkg.PkgPath + ".main",
+			ExportFile: exportFile + "-main",
+		},
+		LPkg: mainPkg,
+	}
+
+	if ctx.buildConf.BuildMode != BuildModeExe {
+		return mainAPkg
+	}
+
+	runtimeStub := defineWeakNoArgStub(mainPkg, "runtime.init")
+	// TODO(lijie): workaround for syscall patch
+	defineWeakNoArgStub(mainPkg, "syscall.init")
+
+	var pyInit llssa.Function
+	if needPyInit {
+		pyInit = declareNoArgFunc(mainPkg, "Py_Initialize")
+	}
+
+	var rtInit llssa.Function
+	if needRuntime {
+		rtInit = declareNoArgFunc(mainPkg, rtPkgPath+".init")
+	}
+
+	mainInit := declareNoArgFunc(mainPkg, pkg.PkgPath+".init")
+	mainMain := declareNoArgFunc(mainPkg, pkg.PkgPath+".main")
+
+	entryFn := defineEntryFunction(ctx, mainPkg, argcVar, argvVar, argvValueType, runtimeStub, mainInit, mainMain, pyInit, rtInit)
+
+	if needStart(ctx) {
+		defineStart(mainPkg, entryFn, argvValueType)
+	}
+
+	return mainAPkg
+}
+
+// defineEntryFunction creates the program's entry function. The name is
+// "main" for standard targets, or "__main_argc_argv" with hidden visibility
+// for WASM targets that don't require _start.
+//
+// The entry stores argc/argv, optionally disables stdio buffering, runs
+// initialization hooks (Python, runtime, package init), and finally calls
+// main.main before returning 0.
+func defineEntryFunction(ctx *context, pkg llssa.Package, argcVar, argvVar llssa.Global, argvType llssa.Type, runtimeStub, mainInit, mainMain llssa.Function, pyInit, rtInit llssa.Function) llssa.Function {
+	prog := pkg.Prog
+	entryName := "main"
+	if !needStart(ctx) && isWasmTarget(ctx.buildConf.Goos) {
+		entryName = "__main_argc_argv"
+	}
+	sig := newEntrySignature(argvType.RawType())
+	fn := pkg.NewFunc(entryName, sig, llssa.InC)
+	fnVal := pkg.Module().NamedFunction(entryName)
+	if entryName != "main" {
+		fnVal.SetVisibility(llvm.HiddenVisibility)
+		fnVal.SetUnnamedAddr(true)
+	}
+	b := fn.MakeBody(1)
+	b.Store(argcVar.Expr, fn.Param(0))
+	b.Store(argvVar.Expr, fn.Param(1))
+	if IsStdioNobuf() {
+		emitStdioNobuf(b, pkg, ctx.buildConf.Goos)
+	}
+	if pyInit != nil {
+		b.Call(pyInit.Expr)
+	}
+	if rtInit != nil {
+		b.Call(rtInit.Expr)
+	}
+	b.Call(runtimeStub.Expr)
+	b.Call(mainInit.Expr)
+	b.Call(mainMain.Expr)
+	b.Return(prog.IntVal(0, prog.Int32()))
+	return fn
+}
+
+func defineStart(pkg llssa.Package, entry llssa.Function, argvType llssa.Type) {
+	fn := pkg.NewFunc("_start", llssa.NoArgsNoRet, llssa.InC)
+	pkg.Module().NamedFunction("_start").SetLinkage(llvm.WeakAnyLinkage)
+	b := fn.MakeBody(1)
+	prog := pkg.Prog
+	b.Call(entry.Expr, prog.IntVal(0, prog.Int32()), prog.Nil(argvType))
+	b.Return()
+}
+
+func declareNoArgFunc(pkg llssa.Package, name string) llssa.Function {
+	return pkg.NewFunc(name, llssa.NoArgsNoRet, llssa.InC)
+}
+
+func defineWeakNoArgStub(pkg llssa.Package, name string) llssa.Function {
+	fn := pkg.NewFunc(name, llssa.NoArgsNoRet, llssa.InC)
+	pkg.Module().NamedFunction(name).SetLinkage(llvm.WeakAnyLinkage)
+	b := fn.MakeBody(1)
+	b.Return()
+	return fn
+}
+
+const (
+	// ioNoBuf represents the _IONBF flag for setvbuf (no buffering)
+	ioNoBuf = 2
+)
+
+// emitStdioNobuf generates code to disable buffering on stdout and stderr
+// when the LLGO_STDIO_NOBUF environment variable is set. Only Darwin uses
+// the alternate `__stdoutp`/`__stderrp` symbols; other targets rely on the
+// standard `stdout`/`stderr` globals.
+func emitStdioNobuf(b llssa.Builder, pkg llssa.Package, goos string) {
+	prog := pkg.Prog
+	streamType := prog.VoidPtr()
+	streamPtrType := prog.Pointer(streamType)
+
+	stdoutName := "stdout"
+	stderrName := "stderr"
+	if goos == "darwin" {
+		stdoutName = "__stdoutp"
+		stderrName = "__stderrp"
+	}
+	stdout := declareExternalPtrGlobal(pkg, stdoutName, streamPtrType)
+	stderr := declareExternalPtrGlobal(pkg, stderrName, streamPtrType)
+	stdoutPtr := b.Load(stdout)
+	stderrPtr := b.Load(stderr)
+	sizeType := prog.Uintptr()
+	setvbuf := declareSetvbuf(pkg, streamPtrType, prog.CStr(), prog.Int32(), sizeType)
+
+	noBufMode := prog.IntVal(ioNoBuf, prog.Int32())
+	zeroSize := prog.Zero(sizeType)
+	nullBuf := prog.Nil(prog.CStr())
+
+	b.Call(setvbuf.Expr, stdoutPtr, nullBuf, noBufMode, zeroSize)
+	b.Call(setvbuf.Expr, stderrPtr, nullBuf, noBufMode, zeroSize)
+}
+
+func declareExternalPtrGlobal(pkg llssa.Package, name string, valueType llssa.Type) llssa.Expr {
+	global := pkg.NewVarEx(name, valueType)
+	pkg.Module().NamedGlobal(name).SetLinkage(llvm.ExternalLinkage)
+	return global.Expr
+}
+
+func declareSetvbuf(pkg llssa.Package, streamPtrType, bufPtrType, intType, sizeType llssa.Type) llssa.Function {
+	sig := newSignature(
+		[]types.Type{
+			streamPtrType.RawType(),
+			bufPtrType.RawType(),
+			intType.RawType(),
+			sizeType.RawType(),
+		},
+		[]types.Type{intType.RawType()},
+	)
+	return pkg.NewFunc("setvbuf", sig, llssa.InC)
+}
+
+func tupleOf(tys ...types.Type) *types.Tuple {
+	if len(tys) == 0 {
+		return types.NewTuple()
+	}
+	vars := make([]*types.Var, len(tys))
+	for i, t := range tys {
+		vars[i] = types.NewParam(token.NoPos, nil, "", t)
+	}
+	return types.NewTuple(vars...)
+}
+
+func newSignature(params []types.Type, results []types.Type) *types.Signature {
+	return types.NewSignatureType(nil, nil, nil, tupleOf(params...), tupleOf(results...), false)
+}
+
+func newEntrySignature(argvType types.Type) *types.Signature {
+	return newSignature(
+		[]types.Type{types.Typ[types.Int32], argvType},
+		[]types.Type{types.Typ[types.Int32]},
+	)
+}

internal/build/main_module_test.go

@@ -0,0 +1,70 @@
+//go:build !llgo
+// +build !llgo
+
+package build
+
+import (
+	"strings"
+	"testing"
+
+	"github.com/goplus/llvm"
+
+	"github.com/goplus/llgo/internal/packages"
+	llssa "github.com/goplus/llgo/ssa"
+)
+
+func init() {
+	llssa.Initialize(llssa.InitAll)
+}
+
+func TestGenMainModuleExecutable(t *testing.T) {
+	llvm.InitializeAllTargets()
+	t.Setenv(llgoStdioNobuf, "")
+	ctx := &context{
+		prog: llssa.NewProgram(nil),
+		buildConf: &Config{
+			BuildMode: BuildModeExe,
+			Goos:      "linux",
+			Goarch:    "amd64",
+		},
+	}
+	pkg := &packages.Package{PkgPath: "example.com/foo", ExportFile: "foo.a"}
+	mod := genMainModule(ctx, llssa.PkgRuntime, pkg, true, true)
+	if mod.ExportFile != "foo.a-main" {
+		t.Fatalf("unexpected export file: %s", mod.ExportFile)
+	}
+	ir := mod.LPkg.String()
+	checks := []string{
+		"define i32 @main(",
+		"call void @Py_Initialize()",
+		"call void @\"example.com/foo.init\"()",
+		"define weak void @_start()",
+	}
+	for _, want := range checks {
+		if !strings.Contains(ir, want) {
+			t.Fatalf("main module IR missing %q:\n%s", want, ir)
+		}
+	}
+}
+
+func TestGenMainModuleLibrary(t *testing.T) {
+	llvm.InitializeAllTargets()
+	t.Setenv(llgoStdioNobuf, "")
+	ctx := &context{
+		prog: llssa.NewProgram(nil),
+		buildConf: &Config{
+			BuildMode: BuildModeCArchive,
+			Goos:      "linux",
+			Goarch:    "amd64",
+		},
+	}
+	pkg := &packages.Package{PkgPath: "example.com/foo", ExportFile: "foo.a"}
+	mod := genMainModule(ctx, llssa.PkgRuntime, pkg, false, false)
+	ir := mod.LPkg.String()
+	if strings.Contains(ir, "define i32 @main") {
+		t.Fatalf("library mode should not emit main function:\n%s", ir)
+	}
+	if !strings.Contains(ir, "@__llgo_argc = global i32 0") {
+		t.Fatalf("library mode missing argc global:\n%s", ir)
+	}
+}

runtime/internal/clite/pthread/pthread_gc.go

@@ -1,5 +1,4 @@
-//go:build !nogc
-// +build !nogc
+//go:build !nogc && !baremetal
 
 /*
  * Copyright (c) 2024 The GoPlus Authors (goplus.org). All rights reserved.

runtime/internal/clite/pthread/pthread_nogc.go

@@ -1,5 +1,4 @@
-//go:build nogc
-// +build nogc
+//go:build nogc || baremetal
 
 /*
  * Copyright (c) 2024 The GoPlus Authors (goplus.org). All rights reserved.

runtime/internal/clite/tls/tls_common.go

@@ -1,4 +1,4 @@
-//go:build llgo
+//go:build llgo && !baremetal
 
 /*
  * Copyright (c) 2025 The GoPlus Authors (goplus.org). All rights reserved.

runtime/internal/clite/tls/tls_gc.go

@@ -1,4 +1,4 @@
-//go:build llgo && !nogc
+//go:build llgo && !baremetal && !nogc
 
 /*
  * Copyright (c) 2025 The GoPlus Authors (goplus.org). All rights reserved.

runtime/internal/clite/tls/tls_nogc.go

@@ -1,4 +1,4 @@
-//go:build llgo && nogc
+//go:build llgo && (nogc || baremetal)
 
 /*
  * Copyright (c) 2025 The GoPlus Authors (goplus.org). All rights reserved.

runtime/internal/clite/tls/tls_stub.go

@@ -1,4 +1,4 @@
-//go:build !llgo
+//go:build !llgo || baremetal
 
 /*
  * Copyright (c) 2025 The GoPlus Authors (goplus.org). All rights reserved.

runtime/internal/lib/runtime/runtime2.go

@@ -4,8 +4,6 @@
 
 package runtime
 
-import "runtime"
-
 // Layout of in-memory per-function information prepared by linker
 // See https://golang.org/s/go12symtab.
 // Keep in sync with linker (../cmd/link/internal/ld/pcln.go:/pclntab)
@@ -30,10 +28,6 @@ func StopTrace() {
 	panic("todo: runtime.StopTrace")
 }
 
-func ReadMemStats(m *runtime.MemStats) {
-	panic("todo: runtime.ReadMemStats")
-}
-
 func SetMutexProfileFraction(rate int) int {
 	panic("todo: runtime.SetMutexProfileFraction")
 }

runtime/internal/lib/runtime/runtime_gc.go

@@ -1,8 +1,16 @@
-//go:build !nogc
+//go:build !nogc && !baremetal
 
 package runtime
 
-import "github.com/goplus/llgo/runtime/internal/clite/bdwgc"
+import (
+	"runtime"
+
+	"github.com/goplus/llgo/runtime/internal/clite/bdwgc"
+)
+
+func ReadMemStats(m *runtime.MemStats) {
+	panic("todo: runtime.ReadMemStats")
+}
 
 func GC() {
 	bdwgc.Gcollect()

runtime/internal/lib/runtime/runtime_gc_baremetal.go

@@ -0,0 +1,29 @@
+//go:build !nogc && baremetal
+
+package runtime
+
+import (
+	"runtime"
+
+	"github.com/goplus/llgo/runtime/internal/runtime/tinygogc"
+)
+
+func ReadMemStats(m *runtime.MemStats) {
+	stats := tinygogc.ReadGCStats()
+	m.Alloc = stats.Alloc
+	m.TotalAlloc = stats.TotalAlloc
+	m.Sys = stats.Sys
+	m.Mallocs = stats.Mallocs
+	m.Frees = stats.Frees
+	m.HeapAlloc = stats.HeapAlloc
+	m.HeapSys = stats.HeapSys
+	m.HeapIdle = stats.HeapIdle
+	m.HeapInuse = stats.HeapInuse
+	m.StackInuse = stats.StackInuse
+	m.StackSys = stats.StackSys
+	m.GCSys = stats.GCSys
+}
+
+func GC() {
+	tinygogc.GC()
+}

runtime/internal/runtime/tinygogc/gc.go

@@ -0,0 +1,184 @@
+//go:build baremetal || testGC
+
+package tinygogc
+
+import "unsafe"
+
+type GCStats struct {
+	// General statistics.
+
+	// Alloc is bytes of allocated heap objects.
+	//
+	// This is the same as HeapAlloc (see below).
+	Alloc uint64
+
+	// TotalAlloc is cumulative bytes allocated for heap objects.
+	//
+	// TotalAlloc increases as heap objects are allocated, but
+	// unlike Alloc and HeapAlloc, it does not decrease when
+	// objects are freed.
+	TotalAlloc uint64
+
+	// Sys is the total bytes of memory obtained from the OS.
+	//
+	// Sys is the sum of the XSys fields below. Sys measures the
+	// virtual address space reserved by the Go runtime for the
+	// heap, stacks, and other internal data structures. It's
+	// likely that not all of the virtual address space is backed
+	// by physical memory at any given moment, though in general
+	// it all was at some point.
+	Sys uint64
+
+	// Mallocs is the cumulative count of heap objects allocated.
+	// The number of live objects is Mallocs - Frees.
+	Mallocs uint64
+
+	// Frees is the cumulative count of heap objects freed.
+	Frees uint64
+
+	// Heap memory statistics.
+	//
+	// Interpreting the heap statistics requires some knowledge of
+	// how Go organizes memory. Go divides the virtual address
+	// space of the heap into "spans", which are contiguous
+	// regions of memory 8K or larger. A span may be in one of
+	// three states:
+	//
+	// An "idle" span contains no objects or other data. The
+	// physical memory backing an idle span can be released back
+	// to the OS (but the virtual address space never is), or it
+	// can be converted into an "in use" or "stack" span.
+	//
+	// An "in use" span contains at least one heap object and may
+	// have free space available to allocate more heap objects.
+	//
+	// A "stack" span is used for goroutine stacks. Stack spans
+	// are not considered part of the heap. A span can change
+	// between heap and stack memory; it is never used for both
+	// simultaneously.
+
+	// HeapAlloc is bytes of allocated heap objects.
+	//
+	// "Allocated" heap objects include all reachable objects, as
+	// well as unreachable objects that the garbage collector has
+	// not yet freed. Specifically, HeapAlloc increases as heap
+	// objects are allocated and decreases as the heap is swept
+	// and unreachable objects are freed. Sweeping occurs
+	// incrementally between GC cycles, so these two processes
+	// occur simultaneously, and as a result HeapAlloc tends to
+	// change smoothly (in contrast with the sawtooth that is
+	// typical of stop-the-world garbage collectors).
+	HeapAlloc uint64
+
+	// HeapSys is bytes of heap memory obtained from the OS.
+	//
+	// HeapSys measures the amount of virtual address space
+	// reserved for the heap. This includes virtual address space
+	// that has been reserved but not yet used, which consumes no
+	// physical memory, but tends to be small, as well as virtual
+	// address space for which the physical memory has been
+	// returned to the OS after it became unused (see HeapReleased
+	// for a measure of the latter).
+	//
+	// HeapSys estimates the largest size the heap has had.
+	HeapSys uint64
+
+	// HeapIdle is bytes in idle (unused) spans.
+	//
+	// Idle spans have no objects in them. These spans could be
+	// (and may already have been) returned to the OS, or they can
+	// be reused for heap allocations, or they can be reused as
+	// stack memory.
+	//
+	// HeapIdle minus HeapReleased estimates the amount of memory
+	// that could be returned to the OS, but is being retained by
+	// the runtime so it can grow the heap without requesting more
+	// memory from the OS. If this difference is significantly
+	// larger than the heap size, it indicates there was a recent
+	// transient spike in live heap size.
+	HeapIdle uint64
+
+	// HeapInuse is bytes in in-use spans.
+	//
+	// In-use spans have at least one object in them. These spans
+	// can only be used for other objects of roughly the same
+	// size.
+	//
+	// HeapInuse minus HeapAlloc estimates the amount of memory
+	// that has been dedicated to particular size classes, but is
+	// not currently being used. This is an upper bound on
+	// fragmentation, but in general this memory can be reused
+	// efficiently.
+	HeapInuse uint64
+
+	// Stack memory statistics.
+	//
+	// Stacks are not considered part of the heap, but the runtime
+	// can reuse a span of heap memory for stack memory, and
+	// vice-versa.
+
+	// StackInuse is bytes in stack spans.
+	//
+	// In-use stack spans have at least one stack in them. These
+	// spans can only be used for other stacks of the same size.
+	//
+	// There is no StackIdle because unused stack spans are
+	// returned to the heap (and hence counted toward HeapIdle).
+	StackInuse uint64
+
+	// StackSys is bytes of stack memory obtained from the OS.
+	//
+	// StackSys is StackInuse, plus any memory obtained directly
+	// from the OS for OS thread stacks.
+	//
+	// In non-cgo programs this metric is currently equal to StackInuse
+	// (but this should not be relied upon, and the value may change in
+	// the future).
+	//
+	// In cgo programs this metric includes OS thread stacks allocated
+	// directly from the OS. Currently, this only accounts for one stack in
+	// c-shared and c-archive build modes and other sources of stacks from
+	// the OS (notably, any allocated by C code) are not currently measured.
+	// Note this too may change in the future.
+	StackSys uint64
+
+	// GCSys is bytes of memory in garbage collection metadata.
+	GCSys uint64
+}
+
+func ReadGCStats() GCStats {
+	var heapInuse, heapIdle uint64
+
+	lock(&gcMutex)
+
+	for block := uintptr(0); block < endBlock; block++ {
+		bstate := gcStateOf(block)
+		if bstate == blockStateFree {
+			heapIdle += uint64(bytesPerBlock)
+		} else {
+			heapInuse += uint64(bytesPerBlock)
+		}
+	}
+
+	stackEnd := uintptr(unsafe.Pointer(&_stackEnd))
+	stackSys := stackTop - stackEnd
+
+	stats := GCStats{
+		Alloc:      (gcTotalBlocks - gcFreedBlocks) * uint64(bytesPerBlock),
+		TotalAlloc: gcTotalAlloc,
+		Sys:        uint64(heapEnd - heapStart),
+		Mallocs:    gcMallocs,
+		Frees:      gcFrees,
+		HeapAlloc:  (gcTotalBlocks - gcFreedBlocks) * uint64(bytesPerBlock),
+		HeapSys:    heapInuse + heapIdle,
+		HeapIdle:   heapIdle,
+		HeapInuse:  heapInuse,
+		StackInuse: uint64(stackTop - uintptr(getsp())),
+		StackSys:   uint64(stackSys),
+		GCSys:      uint64(heapEnd - uintptr(metadataStart)),
+	}
+
+	unlock(&gcMutex)
+
+	return stats
+}

runtime/internal/runtime/tinygogc/gc_link.go

@@ -0,0 +1,54 @@
+//go:build !testGC
+
+package tinygogc
+
+import (
+	"unsafe"
+	_ "unsafe"
+)
+
+// LLGoPackage instructs the LLGo linker to wrap C standard library memory allocation
+// functions (malloc, realloc, calloc) so they use the tinygogc allocator instead.
+// This ensures all memory allocations go through the GC, including C library calls.
+const LLGoPackage = "link: --wrap=malloc --wrap=realloc --wrap=calloc"
+
+//export __wrap_malloc
+func __wrap_malloc(size uintptr) unsafe.Pointer {
+	return Alloc(size)
+}
+
+//export __wrap_calloc
+func __wrap_calloc(nmemb, size uintptr) unsafe.Pointer {
+	totalSize := nmemb * size
+	// Check for multiplication overflow
+	if nmemb != 0 && totalSize/nmemb != size {
+		return nil // Overflow
+	}
+	return Alloc(totalSize)
+}
+
+//export __wrap_realloc
+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
+
+//go:linkname _heapEnd _heapEnd
+var _heapEnd [0]byte
+
+//go:linkname _stackStart _stack_top
+var _stackStart [0]byte
+
+//go:linkname _stackEnd _stack_end
+var _stackEnd [0]byte
+
+//go:linkname _globals_start _globals_start
+var _globals_start [0]byte
+
+//go:linkname _globals_end _globals_end
+var _globals_end [0]byte

runtime/internal/runtime/tinygogc/gc_test.go

@@ -0,0 +1,25 @@
+//go:build testGC
+
+package tinygogc
+
+import (
+	_ "unsafe"
+)
+
+var currentStack uintptr
+
+func getsp() uintptr {
+	return currentStack
+}
+
+var _heapStart [0]byte
+
+var _heapEnd [0]byte
+
+var _stackStart [0]byte
+
+var _stackEnd [0]byte
+
+var _globals_start [0]byte
+
+var _globals_end [0]byte

runtime/internal/runtime/tinygogc/gc_tinygo.go

@@ -0,0 +1,570 @@
+//go:build baremetal || testGC
+
+/*
+ * Copyright (c) 2018-2025 The TinyGo Authors. All rights reserved.
+ * Copyright (c) 2024 The GoPlus Authors (goplus.org). All rights reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+// Package tinygogc implements a conservative mark-and-sweep garbage collector
+// for baremetal environments 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
+//   - testGC: Enables testing mode with mock implementations
+//
+// 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).
+package tinygogc
+
+import (
+	"unsafe"
+
+	c "github.com/goplus/llgo/runtime/internal/clite"
+)
+
+const gcDebug = false
+
+// blockState stores the four states in which a block can be. It is two bits in
+// size.
+const (
+	blockStateFree uint8 = 0 // 00
+	blockStateHead uint8 = 1 // 01
+	blockStateTail uint8 = 2 // 10
+	blockStateMark uint8 = 3 // 11
+	blockStateMask uint8 = 3 // 11
+)
+
+// The byte value of a block where every block is a 'tail' block.
+const blockStateByteAllTails = 0 |
+	uint8(blockStateTail<<(stateBits*3)) |
+	uint8(blockStateTail<<(stateBits*2)) |
+	uint8(blockStateTail<<(stateBits*1)) |
+	uint8(blockStateTail<<(stateBits*0))
+
+var (
+	heapStart     uintptr        // start address of heap area
+	heapEnd       uintptr        // end address of heap area
+	globalsStart  uintptr        // start address of global variable area
+	globalsEnd    uintptr        // end address of global variable area
+	stackTop      uintptr        // the top of stack
+	endBlock      uintptr        // GC end block index
+	metadataStart unsafe.Pointer // start address of GC metadata
+
+	nextAlloc     uintptr // the next block that should be tried by the allocator
+	gcTotalAlloc  uint64  // total number of bytes allocated
+	gcTotalBlocks uint64  // total number of allocated blocks
+	gcMallocs     uint64  // total number of allocations
+	gcFrees       uint64  // total number of objects freed
+	gcFreedBlocks uint64  // total number of freed blocks
+
+	// stackOverflow is a flag which is set when the GC scans too deep while marking.
+	// After it is set, all marked allocations must be re-scanned.
+	markStackOverflow bool
+
+	// zeroSizedAlloc is just a sentinel that gets returned when allocating 0 bytes.
+	zeroSizedAlloc uint8
+
+	gcMutex  mutex // gcMutex protects GC related variables
+	isGCInit bool  // isGCInit indicates GC initialization state
+)
+
+// Some globals + constants for the entire GC.
+
+const (
+	wordsPerBlock      = 4 // number of pointers in an allocated block
+	bytesPerBlock      = wordsPerBlock * unsafe.Sizeof(heapStart)
+	stateBits          = 2 // how many bits a block state takes (see blockState type)
+	blocksPerStateByte = 8 / stateBits
+	markStackSize      = 8 * unsafe.Sizeof((*int)(nil)) // number of to-be-marked blocks to queue before forcing a rescan
+)
+
+// 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))
+	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() {
+	if !isGCInit {
+		initGC()
+		isGCInit = true
+	}
+}
+
+func gcPanic(s *c.Char) {
+	c.Printf(c.Str("%s"), s)
+	c.Exit(2)
+}
+
+// blockFromAddr returns a block given an address somewhere in the heap (which
+// might not be heap-aligned).
+func blockFromAddr(addr uintptr) uintptr {
+	if addr < heapStart || addr >= uintptr(metadataStart) {
+		gcPanic(c.Str("gc: trying to get block from invalid address"))
+	}
+	return (addr - heapStart) / bytesPerBlock
+}
+
+// Return a pointer to the start of the allocated object.
+func gcPointerOf(blockAddr uintptr) unsafe.Pointer {
+	return unsafe.Pointer(gcAddressOf(blockAddr))
+}
+
+// Return the address of the start of the allocated object.
+func gcAddressOf(blockAddr uintptr) uintptr {
+	addr := heapStart + blockAddr*bytesPerBlock
+	if addr > uintptr(metadataStart) {
+		gcPanic(c.Str("gc: block pointing inside metadata"))
+	}
+	return addr
+}
+
+// findHead returns the head (first block) of an object, assuming the block
+// points to an allocated object. It returns the same block if this block
+// already points to the head.
+func gcFindHead(blockAddr uintptr) uintptr {
+	for {
+		// Optimization: check whether the current block state byte (which
+		// contains the state of multiple blocks) is composed entirely of tail
+		// blocks. If so, we can skip back to the last block in the previous
+		// state byte.
+		// This optimization speeds up findHead for pointers that point into a
+		// large allocation.
+		stateByte := gcStateByteOf(blockAddr)
+		if stateByte == blockStateByteAllTails {
+			blockAddr -= (blockAddr % blocksPerStateByte) + 1
+			continue
+		}
+
+		// Check whether we've found a non-tail block, which means we found the
+		// head.
+		state := gcStateFromByte(blockAddr, stateByte)
+		if state != blockStateTail {
+			break
+		}
+		blockAddr--
+	}
+	if gcStateOf(blockAddr) != blockStateHead && gcStateOf(blockAddr) != blockStateMark {
+		gcPanic(c.Str("gc: found tail without head"))
+	}
+	return blockAddr
+}
+
+// findNext returns the first block just past the end of the tail. This may or
+// may not be the head of an object.
+func gcFindNext(blockAddr uintptr) uintptr {
+	if gcStateOf(blockAddr) == blockStateHead || gcStateOf(blockAddr) == blockStateMark {
+		blockAddr++
+	}
+	for gcAddressOf(blockAddr) < uintptr(metadataStart) && gcStateOf(blockAddr) == blockStateTail {
+		blockAddr++
+	}
+	return blockAddr
+}
+
+func gcStateByteOf(blockAddr uintptr) byte {
+	return *(*uint8)(unsafe.Add(metadataStart, blockAddr/blocksPerStateByte))
+}
+
+// Return the block state given a state byte. The state byte must have been
+// obtained using b.stateByte(), otherwise the result is incorrect.
+func gcStateFromByte(blockAddr uintptr, stateByte byte) uint8 {
+	return uint8(stateByte>>((blockAddr%blocksPerStateByte)*stateBits)) & blockStateMask
+}
+
+// State returns the current block state.
+func gcStateOf(blockAddr uintptr) uint8 {
+	return gcStateFromByte(blockAddr, gcStateByteOf(blockAddr))
+}
+
+// setState sets the current block to the given state, which must contain more
+// bits than the current state. Allowed transitions: from free to any state and
+// from head to mark.
+func gcSetState(blockAddr uintptr, newState uint8) {
+	stateBytePtr := (*uint8)(unsafe.Add(metadataStart, blockAddr/blocksPerStateByte))
+	*stateBytePtr |= uint8(newState << ((blockAddr % blocksPerStateByte) * stateBits))
+	if gcStateOf(blockAddr) != newState {
+		gcPanic(c.Str("gc: setState() was not successful"))
+	}
+}
+
+// markFree sets the block state to free, no matter what state it was in before.
+func gcMarkFree(blockAddr uintptr) {
+	stateBytePtr := (*uint8)(unsafe.Add(metadataStart, blockAddr/blocksPerStateByte))
+	*stateBytePtr &^= uint8(blockStateMask << ((blockAddr % blocksPerStateByte) * stateBits))
+	if gcStateOf(blockAddr) != blockStateFree {
+		gcPanic(c.Str("gc: markFree() was not successful"))
+	}
+	*(*[wordsPerBlock]uintptr)(unsafe.Pointer(gcAddressOf(blockAddr))) = [wordsPerBlock]uintptr{}
+}
+
+// unmark changes the state of the block from mark to head. It must be marked
+// before calling this function.
+func gcUnmark(blockAddr uintptr) {
+	if gcStateOf(blockAddr) != blockStateMark {
+		gcPanic(c.Str("gc: unmark() on a block that is not marked"))
+	}
+	clearMask := blockStateMask ^ blockStateHead // the bits to clear from the state
+	stateBytePtr := (*uint8)(unsafe.Add(metadataStart, blockAddr/blocksPerStateByte))
+	*stateBytePtr &^= uint8(clearMask << ((blockAddr % blocksPerStateByte) * stateBits))
+	if gcStateOf(blockAddr) != blockStateHead {
+		gcPanic(c.Str("gc: unmark() was not successful"))
+	}
+}
+
+func isOnHeap(ptr uintptr) bool {
+	return ptr >= heapStart && ptr < uintptr(metadataStart)
+}
+
+func isPointer(ptr uintptr) bool {
+	// TODO: implement precise GC
+	return isOnHeap(ptr)
+}
+
+// alloc tries to find some free space on the heap, possibly doing a garbage
+// collection cycle if needed. If no space is free, it panics.
+//
+//go:noinline
+func Alloc(size uintptr) unsafe.Pointer {
+	if size == 0 {
+		return unsafe.Pointer(&zeroSizedAlloc)
+	}
+	lock(&gcMutex)
+	lazyInit()
+
+	gcTotalAlloc += uint64(size)
+	gcMallocs++
+
+	neededBlocks := (size + (bytesPerBlock - 1)) / bytesPerBlock
+	gcTotalBlocks += uint64(neededBlocks)
+
+	// Continue looping until a run of free blocks has been found that fits the
+	// requested size.
+	index := nextAlloc
+	numFreeBlocks := uintptr(0)
+	heapScanCount := uint8(0)
+	for {
+		if index == nextAlloc {
+			if heapScanCount == 0 {
+				heapScanCount = 1
+			} else if heapScanCount == 1 {
+				// The entire heap has been searched for free memory, but none
+				// could be found. Run a garbage collection cycle to reclaim
+				// free memory and try again.
+				heapScanCount = 2
+				freeBytes := gc()
+				heapSize := uintptr(metadataStart) - heapStart
+				if freeBytes < heapSize/3 {
+					// Ensure there is at least 33% headroom.
+					// This percentage was arbitrarily chosen, and may need to
+					// be tuned in the future.
+					growHeap()
+				}
+			} else {
+				// Even after garbage collection, no free memory could be found.
+				// Try to increase heap size.
+				if growHeap() {
+					// Success, the heap was increased in size. Try again with a
+					// larger heap.
+				} else {
+					// Unfortunately the heap could not be increased. This
+					// happens on baremetal systems for example (where all
+					// available RAM has already been dedicated to the heap).
+					gcPanic(c.Str("out of memory"))
+				}
+			}
+		}
+
+		// Wrap around the end of the heap.
+		if index == endBlock {
+			index = 0
+			// Reset numFreeBlocks as allocations cannot wrap.
+			numFreeBlocks = 0
+			// In rare cases, the initial heap might be so small that there are
+			// no blocks at all. In this case, it's better to jump back to the
+			// start of the loop and try again, until the GC realizes there is
+			// no memory and grows the heap.
+			// This can sometimes happen on WebAssembly, where the initial heap
+			// is created by whatever is left on the last memory page.
+			continue
+		}
+
+		// Is the block we're looking at free?
+		if gcStateOf(index) != blockStateFree {
+			// This block is in use. Try again from this point.
+			numFreeBlocks = 0
+			index++
+			continue
+		}
+		numFreeBlocks++
+		index++
+
+		// Are we finished?
+		if numFreeBlocks == neededBlocks {
+			// Found a big enough range of free blocks!
+			nextAlloc = index
+			thisAlloc := index - neededBlocks
+
+			// Set the following blocks as being allocated.
+			gcSetState(thisAlloc, blockStateHead)
+			for i := thisAlloc + 1; i != nextAlloc; i++ {
+				gcSetState(i, blockStateTail)
+			}
+			unlock(&gcMutex)
+			// Return a pointer to this allocation.
+			return c.Memset(gcPointerOf(thisAlloc), 0, size)
+		}
+	}
+}
+
+func Realloc(ptr unsafe.Pointer, size uintptr) unsafe.Pointer {
+	if ptr == nil {
+		return Alloc(size)
+	}
+	lock(&gcMutex)
+	lazyInit()
+	unlock(&gcMutex)
+
+	ptrAddress := uintptr(ptr)
+	endOfTailAddress := gcAddressOf(gcFindNext(blockFromAddr(ptrAddress)))
+
+	// this might be a few bytes longer than the original size of
+	// ptr, because we align to full blocks of size bytesPerBlock
+	oldSize := endOfTailAddress - ptrAddress
+	if size <= oldSize {
+		return ptr
+	}
+
+	newAlloc := Alloc(size)
+	c.Memcpy(newAlloc, ptr, oldSize)
+	free(ptr)
+
+	return newAlloc
+}
+
+func free(ptr unsafe.Pointer) {
+	// TODO: free blocks on request, when the compiler knows they're unused.
+}
+
+func GC() uintptr {
+	lock(&gcMutex)
+	freeBytes := gc()
+	unlock(&gcMutex)
+	return freeBytes
+}
+
+// runGC performs a garbage collection cycle. It is the internal implementation
+// of the runtime.GC() function. The difference is that it returns the number of
+// free bytes in the heap after the GC is finished.
+func gc() (freeBytes uintptr) {
+	lazyInit()
+
+	if gcDebug {
+		println("running collection cycle...")
+	}
+
+	// Mark phase: mark all reachable objects, recursively.
+	gcMarkReachable()
+
+	finishMark()
+
+	// If we're using threads, resume all other threads before starting the
+	// sweep.
+	gcResumeWorld()
+
+	// Sweep phase: free all non-marked objects and unmark marked objects for
+	// the next collection cycle.
+	freeBytes = sweep()
+
+	return
+}
+
+// markRoots reads all pointers from start to end (exclusive) and if they look
+// like a heap pointer and are unmarked, marks them and scans that object as
+// well (recursively). The start and end parameters must be valid pointers and
+// must be aligned.
+func markRoots(start, end uintptr) {
+	if start >= end {
+		gcPanic(c.Str("gc: unexpected range to mark"))
+	}
+	// Reduce the end bound to avoid reading too far on platforms where pointer alignment is smaller than pointer size.
+	// If the size of the range is 0, then end will be slightly below start after this.
+	end -= unsafe.Sizeof(end) - unsafe.Alignof(end)
+
+	for addr := start; addr < end; addr += unsafe.Alignof(addr) {
+		root := *(*uintptr)(unsafe.Pointer(addr))
+		markRoot(addr, root)
+	}
+}
+
+// startMark starts the marking process on a root and all of its children.
+func startMark(root uintptr) {
+	var stack [markStackSize]uintptr
+	stack[0] = root
+	gcSetState(root, blockStateMark)
+	stackLen := 1
+	for stackLen > 0 {
+		// Pop a block off of the stack.
+		stackLen--
+		block := stack[stackLen]
+
+		start, end := gcAddressOf(block), gcAddressOf(gcFindNext(block))
+
+		for addr := start; addr != end; addr += unsafe.Alignof(addr) {
+			// Load the word.
+			word := *(*uintptr)(unsafe.Pointer(addr))
+
+			if !isPointer(word) {
+				// Not a heap pointer.
+				continue
+			}
+
+			// Find the corresponding memory block.
+			referencedBlock := blockFromAddr(word)
+
+			if gcStateOf(referencedBlock) == blockStateFree {
+				// The to-be-marked object doesn't actually exist.
+				// This is probably a false positive.
+				continue
+			}
+
+			// Move to the block's head.
+			referencedBlock = gcFindHead(referencedBlock)
+
+			if gcStateOf(referencedBlock) == blockStateMark {
+				// The block has already been marked by something else.
+				continue
+			}
+
+			// Mark block.
+			gcSetState(referencedBlock, blockStateMark)
+
+			if stackLen == len(stack) {
+				// The stack is full.
+				// It is necessary to rescan all marked blocks once we are done.
+				markStackOverflow = true
+				if gcDebug {
+					println("gc stack overflowed")
+				}
+				continue
+			}
+
+			// Push the pointer onto the stack to be scanned later.
+			stack[stackLen] = referencedBlock
+			stackLen++
+		}
+	}
+}
+
+// finishMark finishes the marking process by processing all stack overflows.
+func finishMark() {
+	for markStackOverflow {
+		// Re-mark all blocks.
+		markStackOverflow = false
+		for block := uintptr(0); block < endBlock; block++ {
+			if gcStateOf(block) != blockStateMark {
+				// Block is not marked, so we do not need to rescan it.
+				continue
+			}
+
+			// Re-mark the block.
+			startMark(block)
+		}
+	}
+}
+
+// mark a GC root at the address addr.
+func markRoot(addr, root uintptr) {
+	if isOnHeap(root) {
+		block := blockFromAddr(root)
+		if gcStateOf(block) == blockStateFree {
+			// The to-be-marked object doesn't actually exist.
+			// This could either be a dangling pointer (oops!) but most likely
+			// just a false positive.
+			return
+		}
+		head := gcFindHead(block)
+
+		if gcStateOf(head) != blockStateMark {
+			startMark(head)
+		}
+	}
+}
+
+// Sweep goes through all memory and frees unmarked
+// It returns how many bytes are free in the heap after the sweep.
+func sweep() (freeBytes uintptr) {
+	freeCurrentObject := false
+	var freed uint64
+
+	for block := uintptr(0); block < endBlock; block++ {
+		switch gcStateOf(block) {
+		case blockStateHead:
+			// Unmarked head. Free it, including all tail blocks following it.
+			gcMarkFree(block)
+			freeCurrentObject = true
+			gcFrees++
+			freed++
+		case blockStateTail:
+			if freeCurrentObject {
+				// This is a tail object following an unmarked head.
+				// Free it now.
+				gcMarkFree(block)
+				freed++
+			}
+		case blockStateMark:
+			// This is a marked object. The next tail blocks must not be freed,
+			// but the mark bit must be removed so the next GC cycle will
+			// collect this object if it is unreferenced then.
+			gcUnmark(block)
+			freeCurrentObject = false
+		case blockStateFree:
+			freeBytes += bytesPerBlock
+		}
+	}
+	gcFreedBlocks += freed
+	freeBytes += uintptr(freed) * bytesPerBlock
+	return
+}
+
+// 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
+}
+
+func gcMarkReachable() {
+	markRoots(uintptr(getsp()), stackTop)
+	markRoots(globalsStart, globalsEnd)
+}
+
+func gcResumeWorld() {
+	// Nothing to do here (single threaded).
+}

runtime/internal/runtime/tinygogc/mutex.go

@@ -0,0 +1,8 @@
+package tinygogc
+
+// TODO(MeteorsLiu): mutex lock for baremetal GC
+type mutex struct{}
+
+func lock(m *mutex) {}
+
+func unlock(m *mutex) {}

runtime/internal/runtime/tinygogc/pc_mock_test.go

@@ -0,0 +1,604 @@
+//go:build testGC
+
+package tinygogc
+
+import (
+	"testing"
+	"unsafe"
+
+	c "github.com/goplus/llgo/runtime/internal/clite"
+)
+
+const (
+	// Mock a typical embedded system with 128KB RAM
+	mockHeapSize     = 128 * 1024 // 128KB
+	mockGlobalsSize  = 4 * 1024   // 4KB for globals
+	mockStackSize    = 8 * 1024   // 8KB for stack
+	mockReservedSize = 2048       // 2KB reserved as in real implementation
+)
+
+type testObject struct {
+	data [4]uintptr
+}
+
+// mockGCEnv provides a controlled root environment for GC testing
+type mockGCEnv struct {
+	memory       []byte
+	heapStart    uintptr
+	heapEnd      uintptr
+	globalsStart uintptr
+	globalsEnd   uintptr
+	stackStart   uintptr
+	stackEnd     uintptr
+	// Controlled root sets for testing
+	rootObjects []unsafe.Pointer
+	// Original GC state to restore
+	originalHeapStart     uintptr
+	originalHeapEnd       uintptr
+	originalGlobalsStart  uintptr
+	originalGlobalsEnd    uintptr
+	originalStackTop      uintptr
+	originalEndBlock      uintptr
+	originalMetadataStart unsafe.Pointer
+	originalNextAlloc     uintptr
+	originalIsGCInit      bool
+	// Mock mode flag
+	mockMode bool
+}
+
+// createMockGCEnv creates a completely isolated GC environment
+func createMockGCEnv() *mockGCEnv {
+	totalMemory := mockHeapSize + mockGlobalsSize + mockStackSize
+	memory := make([]byte, totalMemory)
+	baseAddr := uintptr(unsafe.Pointer(&memory[0]))
+
+	env := &mockGCEnv{
+		memory:       memory,
+		globalsStart: baseAddr,
+		globalsEnd:   baseAddr + mockGlobalsSize,
+		heapStart:    baseAddr + mockGlobalsSize + mockReservedSize,
+		heapEnd:      baseAddr + mockGlobalsSize + mockHeapSize,
+		stackStart:   baseAddr + mockGlobalsSize + mockHeapSize,
+		stackEnd:     baseAddr + uintptr(totalMemory),
+		rootObjects:  make([]unsafe.Pointer, 0),
+		mockMode:     false,
+	}
+
+	return env
+}
+
+// setupMockGC initializes the GC with mock memory layout using initGC's logic
+func (env *mockGCEnv) setupMockGC() {
+	// Save original GC state
+	env.originalHeapStart = heapStart
+	env.originalHeapEnd = heapEnd
+	env.originalGlobalsStart = globalsStart
+	env.originalGlobalsEnd = globalsEnd
+	env.originalStackTop = stackTop
+	env.originalEndBlock = endBlock
+	env.originalMetadataStart = metadataStart
+	env.originalNextAlloc = nextAlloc
+	env.originalIsGCInit = isGCInit
+
+	// Set currentStack for getsp()
+	currentStack = env.stackStart
+
+	// Apply initGC's logic with our mock memory layout
+	// This is the same logic as initGC() but with our mock addresses
+	heapStart = env.heapStart + 2048 // reserve 2K blocks like initGC does
+	heapEnd = env.heapEnd
+	globalsStart = env.globalsStart
+	globalsEnd = env.globalsEnd
+	stackTop = env.stackEnd
+
+	totalSize := heapEnd - heapStart
+	metadataSize := (totalSize + blocksPerStateByte*bytesPerBlock) / (1 + blocksPerStateByte*bytesPerBlock)
+	metadataStart = unsafe.Pointer(heapEnd - metadataSize)
+	endBlock = (uintptr(metadataStart) - heapStart) / bytesPerBlock
+
+	// Clear metadata using memset like initGC does
+	c.Memset(metadataStart, 0, metadataSize)
+
+	// Reset allocator state and all GC statistics for clean test environment
+	nextAlloc = 0
+	isGCInit = true
+
+	// Reset all GC statistics to start from clean state
+	gcTotalAlloc = 0
+	gcTotalBlocks = 0
+	gcMallocs = 0
+	gcFrees = 0
+	gcFreedBlocks = 0
+	markStackOverflow = false
+}
+
+// restoreOriginalGC restores the original GC state
+func (env *mockGCEnv) restoreOriginalGC() {
+	heapStart = env.originalHeapStart
+	heapEnd = env.originalHeapEnd
+	globalsStart = env.originalGlobalsStart
+	globalsEnd = env.originalGlobalsEnd
+	stackTop = env.originalStackTop
+	endBlock = env.originalEndBlock
+	metadataStart = env.originalMetadataStart
+	nextAlloc = env.originalNextAlloc
+	isGCInit = false
+}
+
+// enableMockMode enables mock root scanning mode
+func (env *mockGCEnv) enableMockMode() {
+	env.mockMode = true
+}
+
+// disableMockMode disables mock root scanning mode
+func (env *mockGCEnv) disableMockMode() {
+	env.mockMode = false
+}
+
+// addRoot adds an object to the controlled root set
+func (env *mockGCEnv) addRoot(ptr unsafe.Pointer) {
+	env.rootObjects = append(env.rootObjects, ptr)
+}
+
+// clearRoots removes all objects from the controlled root set
+func (env *mockGCEnv) clearRoots() {
+	env.rootObjects = env.rootObjects[:0]
+}
+
+// mockMarkReachable replaces gcMarkReachable when in mock mode
+func (env *mockGCEnv) mockMarkReachable() {
+	if !env.mockMode {
+		// Use original logic
+		markRoots(uintptr(getsp()), stackTop)
+		markRoots(globalsStart, globalsEnd)
+		return
+	}
+
+	// Mock mode: only scan our controlled roots
+	for _, root := range env.rootObjects {
+		addr := uintptr(root)
+		markRoot(addr, addr)
+	}
+}
+
+// runMockGC runs standard GC but with controlled root scanning
+func (env *mockGCEnv) runMockGC() uintptr {
+	lock(&gcMutex)
+	defer unlock(&gcMutex)
+
+	lazyInit()
+
+	if gcDebug {
+		println("running mock collection cycle...")
+	}
+
+	// Mark phase: use our mock root scanning
+	env.mockMarkReachable()
+	finishMark()
+
+	// Resume world (no-op in single threaded)
+	gcResumeWorld()
+
+	// Sweep phase: use standard sweep logic
+	return sweep()
+}
+
+// createTestObjects creates a network of objects for testing reachability
+func createTestObjects(env *mockGCEnv) []*testObject {
+	// Allocate several test objects
+	objects := make([]*testObject, 0, 10)
+
+	// Dependencies Graph
+	// root1 -> child1 -> grandchild1 -> child2
+	// root1 -> child2 -> grandchild1
+
+	// Create root objects (reachable from stack/globals)
+	root1 := (*testObject)(Alloc(unsafe.Sizeof(testObject{})))
+	root2 := (*testObject)(Alloc(unsafe.Sizeof(testObject{})))
+	objects = append(objects, root1, root2)
+
+	// Create objects reachable from root1
+	child1 := (*testObject)(Alloc(unsafe.Sizeof(testObject{})))
+	child2 := (*testObject)(Alloc(unsafe.Sizeof(testObject{})))
+	root1.data[0] = uintptr(unsafe.Pointer(child1))
+	root1.data[1] = uintptr(unsafe.Pointer(child2))
+	objects = append(objects, child1, child2)
+
+	// Create objects reachable from child1
+	grandchild1 := (*testObject)(Alloc(unsafe.Sizeof(testObject{})))
+	child1.data[0] = uintptr(unsafe.Pointer(grandchild1))
+	objects = append(objects, grandchild1)
+
+	// Create circular reference between child2 and grandchild1
+	child2.data[0] = uintptr(unsafe.Pointer(grandchild1))
+	grandchild1.data[0] = uintptr(unsafe.Pointer(child2))
+
+	// Create unreachable objects (garbage)
+	garbage1 := (*testObject)(Alloc(unsafe.Sizeof(testObject{})))
+	garbage2 := (*testObject)(Alloc(unsafe.Sizeof(testObject{})))
+	// Create circular reference in garbage
+	garbage1.data[0] = uintptr(unsafe.Pointer(garbage2))
+	garbage2.data[0] = uintptr(unsafe.Pointer(garbage1))
+	objects = append(objects, garbage1, garbage2)
+
+	return objects
+}
+
+func TestMockGCBasicAllocation(t *testing.T) {
+	env := createMockGCEnv()
+	env.setupMockGC()
+	defer env.restoreOriginalGC()
+
+	// Test basic allocation
+	ptr1 := Alloc(32)
+	if ptr1 == nil {
+		t.Fatal("Failed to allocate 32 bytes")
+	}
+
+	ptr2 := Alloc(64)
+	if ptr2 == nil {
+		t.Fatal("Failed to allocate 64 bytes")
+	}
+
+	// Verify pointers are within heap bounds
+	addr1 := uintptr(ptr1)
+	addr2 := uintptr(ptr2)
+
+	if addr1 < heapStart || addr1 >= uintptr(metadataStart) {
+		t.Errorf("ptr1 %x not within heap bounds [%x, %x)", addr1, heapStart, uintptr(metadataStart))
+	}
+
+	if addr2 < heapStart || addr2 >= uintptr(metadataStart) {
+		t.Errorf("ptr2 %x not within heap bounds [%x, %x)", addr2, heapStart, uintptr(metadataStart))
+	}
+
+	t.Logf("Allocated ptr1 at %x, ptr2 at %x", addr1, addr2)
+	t.Logf("Heap bounds: [%x, %x)", heapStart, uintptr(metadataStart))
+}
+
+func TestMockGCReachabilityAndSweep(t *testing.T) {
+	env := createMockGCEnv()
+	env.setupMockGC()
+	defer env.restoreOriginalGC()
+
+	// Track initial stats
+	initialMallocs := gcMallocs
+	initialFrees := gcFrees
+
+	// Create test object network
+	objects := createTestObjects(env)
+
+	// Add first 2 objects as roots using mock control
+	env.enableMockMode()
+	env.addRoot(unsafe.Pointer(objects[0])) // root1
+	env.addRoot(unsafe.Pointer(objects[1])) // root2
+
+	t.Logf("Created %d objects, 2 are roots", len(objects))
+	t.Logf("Mallocs: %d", gcMallocs-initialMallocs)
+
+	// Verify all objects are initially allocated
+	for i, obj := range objects {
+		addr := uintptr(unsafe.Pointer(obj))
+		block := blockFromAddr(addr)
+		state := gcStateOf(block)
+		if state != blockStateHead {
+			t.Errorf("Object %d at %x has state %d, expected %d (HEAD)", i, addr, state, blockStateHead)
+		}
+	}
+
+	// Perform GC with controlled root scanning
+	freedBytes := env.runMockGC()
+	t.Logf("Freed %d bytes during GC", freedBytes)
+	t.Logf("Frees: %d (delta: %d)", gcFrees, gcFrees-initialFrees)
+
+	// Verify reachable objects are still allocated
+	reachableObjects := []unsafe.Pointer{
+		unsafe.Pointer(objects[0]), // root1
+		unsafe.Pointer(objects[1]), // root2
+		unsafe.Pointer(objects[2]), // child1 (reachable from root1)
+		unsafe.Pointer(objects[3]), // child2 (reachable from root1)
+		unsafe.Pointer(objects[4]), // grandchild1 (reachable from child1, child2)
+	}
+
+	for i, obj := range reachableObjects {
+		addr := uintptr(obj)
+		block := blockFromAddr(addr)
+		state := gcStateOf(block)
+		if state != blockStateHead {
+			t.Errorf("Reachable object %d at %x has state %d, expected %d (HEAD)", i, addr, state, blockStateHead)
+		}
+	}
+
+	// Verify unreachable objects are freed
+	unreachableObjects := []unsafe.Pointer{
+		unsafe.Pointer(objects[5]), // garbage1
+		unsafe.Pointer(objects[6]), // garbage2
+	}
+
+	for i, obj := range unreachableObjects {
+		addr := uintptr(obj)
+		block := blockFromAddr(addr)
+		state := gcStateOf(block)
+		if state != blockStateFree {
+			t.Errorf("Unreachable object %d at %x has state %d, expected %d (FREE)", i, addr, state, blockStateFree)
+		}
+	}
+
+	// Verify some memory was actually freed
+	if freedBytes == 0 {
+		t.Error("Expected some memory to be freed, but freed 0 bytes")
+	}
+
+	if gcFrees == initialFrees {
+		t.Error("Expected some objects to be freed, but free count didn't change")
+	}
+
+	// Clear refs to make grandchild1 unreachable
+	objects[2].data[0] = 0 // child1 -> grandchild1
+	objects[3].data[0] = 0 // child2 -> grandchild1
+
+	// Run GC again with same roots
+	freedBytes = env.runMockGC()
+
+	// child2 should still be reachable (through root1)
+	blockAddr := blockFromAddr(uintptr(unsafe.Pointer(objects[3])))
+	state := gcStateOf(blockAddr)
+	if state != blockStateHead {
+		t.Errorf("Object child2 at %x has state %d, expected %d (HEAD)", blockAddr, state, blockStateHead)
+	}
+
+	// grandchild1 should now be unreachable and freed
+	blockAddr = blockFromAddr(uintptr(unsafe.Pointer(objects[4])))
+	state = gcStateOf(blockAddr)
+	if state != blockStateFree {
+		t.Errorf("Object grandchild1 at %x has state %d, expected %d (FREE)", blockAddr, state, blockStateFree)
+	}
+}
+
+func TestMockGCMemoryPressure(t *testing.T) {
+	env := createMockGCEnv()
+	env.setupMockGC()
+	defer env.restoreOriginalGC()
+
+	// Calculate available heap space
+	heapSize := uintptr(metadataStart) - heapStart
+	blockSize := bytesPerBlock
+	maxBlocks := heapSize / blockSize
+
+	t.Logf("Heap size: %d bytes, Block size: %d bytes, Max blocks: %d",
+		heapSize, blockSize, maxBlocks)
+
+	// Allocate until we trigger GC
+	var allocations []unsafe.Pointer
+	allocSize := uintptr(32) // Small allocations
+
+	// Allocate about 80% of heap to trigger GC pressure
+	targetAllocations := int(maxBlocks * 4 / 5) // 80% capacity
+
+	for i := 0; i < targetAllocations; i++ {
+		ptr := Alloc(allocSize)
+		if ptr == nil {
+			t.Fatalf("Failed to allocate at iteration %d", i)
+		}
+		allocations = append(allocations, ptr)
+	}
+
+	initialMallocs := gcMallocs
+	t.Logf("Allocated %d objects (%d mallocs total)", len(allocations), initialMallocs)
+
+	// Enable mock mode and keep only half the allocations as roots
+	env.enableMockMode()
+	keepCount := len(allocations) / 2
+	for i := 0; i < keepCount; i++ {
+		env.addRoot(allocations[i])
+	}
+
+	t.Logf("Keeping %d objects as roots, %d should be freed", keepCount, len(allocations)-keepCount)
+
+	// Force GC with controlled roots
+	freeBytes := env.runMockGC()
+
+	t.Logf("GC freed %d bytes", freeBytes)
+	t.Logf("Objects freed: %d", gcFrees)
+
+	// Try to allocate more after GC
+	for i := 0; i < 10; i++ {
+		ptr := Alloc(allocSize)
+		if ptr == nil {
+			t.Fatalf("Failed to allocate after GC at iteration %d", i)
+		}
+	}
+
+	t.Log("Successfully allocated more objects after GC")
+}
+
+func TestMockGCStats(t *testing.T) {
+	env := createMockGCEnv()
+	env.setupMockGC()
+	defer env.restoreOriginalGC()
+
+	// Get initial stats
+	initialStats := ReadGCStats()
+	t.Logf("Initial stats - Mallocs: %d, Frees: %d, TotalAlloc: %d, Alloc: %d",
+		initialStats.Mallocs, initialStats.Frees, initialStats.TotalAlloc, initialStats.Alloc)
+
+	// Verify basic system stats
+	expectedSys := uint64(env.heapEnd - env.heapStart - 2048)
+	if initialStats.Sys != expectedSys {
+		t.Errorf("Expected Sys %d, got %d", expectedSys, initialStats.Sys)
+	}
+
+	expectedGCSys := uint64(env.heapEnd - uintptr(metadataStart))
+	if initialStats.GCSys != expectedGCSys {
+		t.Errorf("Expected GCSys %d, got %d", expectedGCSys, initialStats.GCSys)
+	}
+
+	// Allocate some objects
+	var allocations []unsafe.Pointer
+	allocSize := uintptr(64)
+	numAllocs := 10
+
+	for i := 0; i < numAllocs; i++ {
+		ptr := Alloc(allocSize)
+		if ptr == nil {
+			t.Fatalf("Failed to allocate at iteration %d", i)
+		}
+		allocations = append(allocations, ptr)
+	}
+
+	// Check stats after allocation
+	afterAllocStats := ReadGCStats()
+	t.Logf("After allocation - Mallocs: %d, Frees: %d, TotalAlloc: %d, Alloc: %d",
+		afterAllocStats.Mallocs, afterAllocStats.Frees, afterAllocStats.TotalAlloc, afterAllocStats.Alloc)
+
+	// Verify allocation stats increased
+	if afterAllocStats.Mallocs <= initialStats.Mallocs {
+		t.Errorf("Expected Mallocs to increase from %d, got %d", initialStats.Mallocs, afterAllocStats.Mallocs)
+	}
+
+	if afterAllocStats.TotalAlloc <= initialStats.TotalAlloc {
+		t.Errorf("Expected TotalAlloc to increase from %d, got %d", initialStats.TotalAlloc, afterAllocStats.TotalAlloc)
+	}
+
+	if afterAllocStats.Alloc <= initialStats.Alloc {
+		t.Errorf("Expected Alloc to increase from %d, got %d", initialStats.Alloc, afterAllocStats.Alloc)
+	}
+
+	// Verify Alloc and HeapAlloc are the same
+	if afterAllocStats.Alloc != afterAllocStats.HeapAlloc {
+		t.Errorf("Expected Alloc (%d) to equal HeapAlloc (%d)", afterAllocStats.Alloc, afterAllocStats.HeapAlloc)
+	}
+
+	// Perform GC with controlled roots - keep only half the allocations
+	env.enableMockMode()
+	keepCount := len(allocations) / 2
+	for i := 0; i < keepCount; i++ {
+		env.addRoot(allocations[i])
+	}
+
+	freedBytes := env.runMockGC()
+	t.Logf("GC freed %d bytes", freedBytes)
+
+	// Check stats after GC
+	afterGCStats := ReadGCStats()
+	t.Logf("After GC - Mallocs: %d, Frees: %d, TotalAlloc: %d, Alloc: %d",
+		afterGCStats.Mallocs, afterGCStats.Frees, afterGCStats.TotalAlloc, afterGCStats.Alloc)
+
+	// Verify GC stats
+	if afterGCStats.Frees <= afterAllocStats.Frees {
+		t.Errorf("Expected Frees to increase from %d, got %d", afterAllocStats.Frees, afterGCStats.Frees)
+	}
+
+	// TotalAlloc should not decrease (cumulative)
+	if afterGCStats.TotalAlloc != afterAllocStats.TotalAlloc {
+		t.Errorf("Expected TotalAlloc to remain %d after GC, got %d", afterAllocStats.TotalAlloc, afterGCStats.TotalAlloc)
+	}
+
+	// Alloc should decrease (freed objects)
+	if afterGCStats.Alloc >= afterAllocStats.Alloc {
+		t.Errorf("Expected Alloc to decrease from %d after GC, got %d", afterAllocStats.Alloc, afterGCStats.Alloc)
+	}
+
+	// Verify heap statistics consistency
+	if afterGCStats.HeapSys != afterGCStats.HeapInuse+afterGCStats.HeapIdle {
+		t.Errorf("Expected HeapSys (%d) to equal HeapInuse (%d) + HeapIdle (%d)",
+			afterGCStats.HeapSys, afterGCStats.HeapInuse, afterGCStats.HeapIdle)
+	}
+
+	// Verify live objects calculation
+	expectedLiveObjects := afterGCStats.Mallocs - afterGCStats.Frees
+	t.Logf("Live objects: %d (Mallocs: %d - Frees: %d)", expectedLiveObjects, afterGCStats.Mallocs, afterGCStats.Frees)
+
+	// The number of live objects should be reasonable (we kept half the allocations plus some overhead)
+	if expectedLiveObjects < uint64(keepCount) {
+		t.Errorf("Expected at least %d live objects, got %d", keepCount, expectedLiveObjects)
+	}
+
+	// Test stack statistics
+	if afterGCStats.StackInuse > afterGCStats.StackSys {
+		t.Errorf("StackInuse (%d) should not exceed StackSys (%d)", afterGCStats.StackInuse, afterGCStats.StackSys)
+	}
+}
+
+func TestMockGCCircularReferences(t *testing.T) {
+	env := createMockGCEnv()
+	env.setupMockGC()
+	defer env.restoreOriginalGC()
+
+	type Node struct {
+		data [3]uintptr
+		next uintptr
+	}
+
+	// Create a circular linked list
+	nodes := make([]*Node, 5)
+	for i := range nodes {
+		nodes[i] = (*Node)(Alloc(unsafe.Sizeof(Node{})))
+		nodes[i].data[0] = uintptr(i) // Store index as data
+	}
+
+	// Link them in a circle
+	for i := range nodes {
+		nextIdx := (i + 1) % len(nodes)
+		nodes[i].next = uintptr(unsafe.Pointer(nodes[nextIdx]))
+	}
+
+	t.Logf("Created circular list of %d nodes", len(nodes))
+
+	// Initially all should be allocated
+	for i, node := range nodes {
+		addr := uintptr(unsafe.Pointer(node))
+		block := blockFromAddr(addr)
+		state := gcStateOf(block)
+		if state != blockStateHead {
+			t.Errorf("Node %d at %x has state %d, expected %d", i, addr, state, blockStateHead)
+		}
+	}
+
+	// Test 1: With root references - objects should NOT be freed
+	env.enableMockMode()
+	// Add the first node as root (keeps entire circle reachable)
+	env.addRoot(unsafe.Pointer(nodes[0]))
+
+	freeBytes := env.runMockGC()
+	t.Logf("GC with root reference freed %d bytes", freeBytes)
+
+	// All nodes should still be allocated since they're reachable through the root
+	for i, node := range nodes {
+		addr := uintptr(unsafe.Pointer(node))
+		block := blockFromAddr(addr)
+		state := gcStateOf(block)
+		if state != blockStateHead {
+			t.Errorf("Node %d at %x should still be allocated, but has state %d", i, addr, state)
+		}
+	}
+
+	// Test 2: Without root references - all circular objects should be freed
+	env.clearRoots() // Remove all root references
+
+	freeBytes = env.runMockGC()
+	t.Logf("GC without roots freed %d bytes", freeBytes)
+
+	// All nodes should now be freed since they're not reachable from any roots
+	expectedFreed := uintptr(len(nodes)) * ((unsafe.Sizeof(Node{}) + bytesPerBlock - 1) / bytesPerBlock) * bytesPerBlock
+
+	if freeBytes < expectedFreed {
+		t.Errorf("Expected at least %d bytes freed, got %d", expectedFreed, freeBytes)
+	}
+
+	// Verify all nodes are actually freed
+	for i, node := range nodes {
+		addr := uintptr(unsafe.Pointer(node))
+		block := blockFromAddr(addr)
+		state := gcStateOf(block)
+		if state != blockStateFree {
+			t.Errorf("Node %d at %x should be freed, but has state %d", i, addr, state)
+		}
+	}
+
+	// Verify we can allocate new objects in the freed space
+	newPtr := Alloc(unsafe.Sizeof(Node{}))
+	if newPtr == nil {
+		t.Error("Failed to allocate after freeing circular references")
+	}
+}

runtime/internal/runtime/z_defer_gc.go

@@ -1,4 +1,4 @@
-//go:build !nogc
+//go:build !nogc && !baremetal
 
 /*
  * Copyright (c) 2025 The GoPlus Authors (goplus.org). All rights reserved.

runtime/internal/runtime/z_defer_nogc.go

@@ -1,4 +1,4 @@
-//go:build nogc
+//go:build nogc || baremetal
 
 /*
  * Copyright (c) 2025 The GoPlus Authors (goplus.org). All rights reserved.

runtime/internal/runtime/z_gc.go

@@ -1,5 +1,4 @@
-//go:build !nogc
-// +build !nogc
+//go:build !nogc && !baremetal
 
 /*
  * Copyright (c) 2024 The GoPlus Authors (goplus.org). All rights reserved.

runtime/internal/runtime/z_gc_baremetal.go

@@ -0,0 +1,35 @@
+//go:build !nogc && baremetal
+
+/*
+ * Copyright (c) 2024 The GoPlus Authors (goplus.org). All rights reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package runtime
+
+import (
+	"unsafe"
+
+	"github.com/goplus/llgo/runtime/internal/runtime/tinygogc"
+)
+
+// AllocU allocates uninitialized memory.
+func AllocU(size uintptr) unsafe.Pointer {
+	return tinygogc.Alloc(size)
+}
+
+// AllocZ allocates zero-initialized memory.
+func AllocZ(size uintptr) unsafe.Pointer {
+	return tinygogc.Alloc(size)
+}

targets/esp32-riscv.app.elf.ld

@@ -1,6 +1,4 @@
-__stack = ORIGIN(dram_seg) + LENGTH(dram_seg);
-__MIN_STACK_SIZE = 0x1000;
-_stack_top = __stack;
+_heapEnd = ORIGIN(dram_seg) + LENGTH(dram_seg);
 
 /* Default entry point */
 ENTRY(_start)
@@ -94,6 +92,12 @@ SECTIONS
     _iram_end = .;
   } > iram_seg
 
+  .stack (NOLOAD) :
+  {
+    . += 16K;
+    __stack = .;
+  } > dram_seg
+
   /**
    * This section is required to skip .iram0.text area because iram0_0_seg and
    * dram0_0_seg reflect the same address space on different buses.
@@ -148,7 +152,7 @@ SECTIONS
   } > dram_seg
 
   /* Check if data + heap + stack exceeds RAM limit */
-  ASSERT(_end <= __stack - __MIN_STACK_SIZE, "region DRAM overflowed by .data and .bss sections")
+  ASSERT(_end <= _heapEnd, "region DRAM overflowed by .data and .bss sections")
 
   /* Stabs debugging sections.  */
   .stab          0 : { *(.stab) }
@@ -193,3 +197,8 @@ SECTIONS
   .gnu.attributes 0 : { KEEP (*(.gnu.attributes)) }
   /DISCARD/ : { *(.note.GNU-stack) *(.gnu_debuglink) *(.gnu.lto_*) }
 }
+
+_globals_start = _data_start;
+_globals_end = _end;
+_heapStart = _end;
+_stack_top = __stack;

targets/esp32.app.elf.ld

@@ -1,5 +1,4 @@
-__stack = ORIGIN(dram_seg) + LENGTH(dram_seg);
-__MIN_STACK_SIZE = 0x2000;
+_heapEnd = ORIGIN(dram_seg) + LENGTH(dram_seg);
 
 ENTRY(_start)
 SECTIONS
@@ -26,6 +25,14 @@ SECTIONS
      the same address within the page on the next page up.  */
   . = ALIGN (CONSTANT (MAXPAGESIZE)) - ((CONSTANT (MAXPAGESIZE) - .) & (CONSTANT (MAXPAGESIZE) - 1)); . = DATA_SEGMENT_ALIGN (CONSTANT (MAXPAGESIZE), CONSTANT (COMMONPAGESIZE));
 
+  .stack (NOLOAD) :
+  {
+    _stack_end = .;
+    . = ALIGN(16);
+    . += 16K;
+    __stack = .;
+  }
+
 
   .rodata    :
   {
@@ -116,7 +123,7 @@ SECTIONS
   . = DATA_SEGMENT_END (.);
 
   /* Check if data + heap + stack exceeds RAM limit */
-  ASSERT(. <= __stack - __MIN_STACK_SIZE, "region DRAM overflowed by .data and .bss sections")
+  ASSERT(. <= _heapEnd, "region DRAM overflowed by .data and .bss sections")
 
   /* Stabs debugging sections.  */
   .stab          0 : { *(.stab) }
@@ -165,4 +172,7 @@ SECTIONS
 
 _sbss = __bss_start;
 _ebss = _end;
-
+_globals_start = _data_start;
+_globals_end = _end;
+_heapStart = _end;
+_stack_top = __stack;

targets/esp32.memory.elf.ld

@@ -19,8 +19,8 @@ MEMORY
 /* 64k at the end of DRAM, after ROM bootloader stack
  * or entire DRAM (for QEMU only)
  */
-  dram_seg (RW) : org = 0x3FFF0000 ,
-                  len = 0x10000
+  dram_seg (RW) : org = 0x3ffae000 ,
+                  len = 0x52000
 }
 
 INCLUDE "targets/esp32.app.elf.ld";