support bfm = BFM_InLibC

cl/blockctx.go

@@ -206,6 +206,7 @@ type blockCtx struct {
 	file     *token.File
 	curfn    *funcCtx
 	curflow  flowCtx
+	bfm      BFMode
 	multiFileCtl
 	testMain bool
 }

cl/codebuild.go

@@ -77,15 +77,26 @@ func decl_builtin(ctx *blockCtx) {
 	if err != nil {
 		log.Panicln("decl_builtin decode error:", err)
 	}
+	bfm := ctx.bfm
 	pkg := ctx.pkg.Types
 	scope := pkg.Scope()
 	for fn, proto := range fns {
 		t := toType(ctx, &cast.Type{QualType: strings.ReplaceAll(proto, "size_t", "unsigned long")}, 0)
+		switch bfm {
+		case BFM_InLibC:
+			fn = "X" + fn
+		case BFM_FromLibC:
+			panic("TODO: import builtin from libc")
+		}
 		scope.Insert(types.NewFunc(token.NoPos, pkg, fn, t.(*types.Signature)))
 	}
 	for _, o := range builtin_overloads {
 		fns := make([]types.Object, len(o.overloads))
 		for i, item := range o.overloads {
+			switch bfm {
+			case BFM_InLibC:
+				item = "X" + item
+			}
 			fns[i] = pkg.Scope().Lookup(item)
 		}
 		scope.Insert(gox.NewOverloadFunc(token.NoPos, pkg, o.name, fns...))

cl/compile.go

@@ -100,6 +100,16 @@ func (p *nodeInterp) LoadExpr(v goast.Node) (code string, pos token.Position) {
 
 // -----------------------------------------------------------------------------
 
+type BFMode int8
+
+const (
+	BFM_Default  BFMode = iota
+	BFM_InLibC          // define builtin functions in libc
+	BFM_FromLibC        // import builtin functions from libc
+)
+
+// -----------------------------------------------------------------------------
+
 type PkgInfo struct {
 	typdecls map[string]*gox.TypeDecl
 	extfns   map[string]none // external functions which are used
@@ -166,6 +176,9 @@ type Config struct {
 	// PublicFrom specifies header files to fetch public symbols.
 	PublicFrom []string
 
+	// BuiltinFuncMode sets compiling mode of builtin functions.
+	BuiltinFuncMode BFMode
+
 	// NeedPkgInfo allows to check dependencies and write them to c2go_autogen.go file.
 	NeedPkgInfo bool
 
@@ -249,6 +262,7 @@ func loadFile(p *gox.Package, conf *Config, file *ast.Node) (pi *PkgInfo, err er
 		public:   conf.Public,
 		srcfile:  conf.SrcFile,
 		src:      conf.Src,
+		bfm:      conf.BuiltinFuncMode,
 		testMain: conf.TestMain,
 	}
 	ctx.initMultiFileCtl(p, conf)

proj.go

@@ -74,6 +74,8 @@ type c2goConf struct {
 	dir         string            `json:"-"`
 	public      map[string]string `json:"-"`
 	needPkgInfo bool              `json:"-"`
+
+	InLibC bool `json:"libc"`
 }
 
 var json = jsoniter.ConfigCompatibleWithStandardLibrary
@@ -255,6 +257,10 @@ func execProjFile(infile string, conf *c2goConf, flags int) {
 			Run("", pkgDir, flags, nil)
 		}
 	}
+	var bfm cl.BFMode
+	if conf.InLibC {
+		bfm = cl.BFM_InLibC
+	}
 	_, err = cl.NewPackage("", conf.Target.Name, doc, &cl.Config{
 		SrcFile:     outfile,
 		ProcDepPkg:  procDepPkg,
@@ -267,6 +273,8 @@ func execProjFile(infile string, conf *c2goConf, flags int) {
 		Ignored:     conf.Source.Ignore.Names,
 		Reused:      &conf.Reused,
 		TestMain:    (flags & FlagTestMain) != 0,
+		// BuiltinFuncMode: compiling mode of builtin functions
+		BuiltinFuncMode: bfm,
 	})
 	check(err)
 }

testdata/libc/c2go.cfg

@@ -27,5 +27,6 @@
         "dirs": ["../printf", "../qsort"],
         "files": ["../strlen/strlen.c", "./src/foo.c", "./src/foo2.c"]
     },
-    "include": ["./src"]
+    "include": ["./src"],
+    "libc": true
 }

testdata/libc/c2go.pub

@@ -1,3 +1,7 @@
+__builtin___memcpy_chk
+__builtin_object_size
+__builtin_bswap32
+__builtin_bswap64
 printf
 strlen
 qsort QSort

testdata/libc/libc.go

@@ -64,21 +64,21 @@ func memcpy(dst unsafe.Pointer, src unsafe.Pointer, n c.SizeT) unsafe.Pointer {
 	return dst
 }
 
-func __builtin___memcpy_chk(dst unsafe.Pointer, src unsafe.Pointer, n c.SizeT, elem c.SizeT) unsafe.Pointer {
+func X__builtin___memcpy_chk(dst unsafe.Pointer, src unsafe.Pointer, n c.SizeT, elem c.SizeT) unsafe.Pointer {
 	copy(sliceOf(dst, n), sliceOf(src, n))
 	return dst
 }
 
-func __builtin_object_size(unsafe.Pointer, int32) c.SizeT {
+func X__builtin_object_size(unsafe.Pointer, int32) c.SizeT {
 	return 1
 }
 
-func __builtin_bswap32(v uint32) uint32 {
+func X__builtin_bswap32(v uint32) uint32 {
 	log.Panicln("__builtin_bswap32: notimpl")
 	return v
 }
 
-func __builtin_bswap64(v uint64) uint64 {
+func X__builtin_bswap64(v uint64) uint64 {
 	log.Panicln("__builtin_bswap32: notimpl")
 	return v
 }