libgo: Add sources for go, cgo, and gofmt commands.

The new commands are not yet built.  That will be done
separately.

Also include a few changes to go/build to support them.

From-SVN: r219272

7 files changed, 4973 insertions, 0 deletions

diff --git a/libgo/go/cmd/cgo/ast.go b/libgo/go/cmd/cgo/ast.go
new file mode 100644
index 0000000..7757efa
--- /dev/null
+++ b/libgo/go/cmd/cgo/ast.go
@@ -0,0 +1,460 @@
+// Copyright 2009 The Go Authors.  All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Parse input AST and prepare Prog structure.
+
+package main
+
+import (
+	"fmt"
+	"go/ast"
+	"go/parser"
+	"go/scanner"
+	"go/token"
+	"os"
+	"path/filepath"
+	"strings"
+)
+
+func parse(name string, flags parser.Mode) *ast.File {
+	ast1, err := parser.ParseFile(fset, name, nil, flags)
+	if err != nil {
+		if list, ok := err.(scanner.ErrorList); ok {
+			// If err is a scanner.ErrorList, its String will print just
+			// the first error and then (+n more errors).
+			// Instead, turn it into a new Error that will return
+			// details for all the errors.
+			for _, e := range list {
+				fmt.Fprintln(os.Stderr, e)
+			}
+			os.Exit(2)
+		}
+		fatalf("parsing %s: %s", name, err)
+	}
+	return ast1
+}
+
+func sourceLine(n ast.Node) int {
+	return fset.Position(n.Pos()).Line
+}
+
+// ReadGo populates f with information learned from reading the
+// Go source file with the given file name.  It gathers the C preamble
+// attached to the import "C" comment, a list of references to C.xxx,
+// a list of exported functions, and the actual AST, to be rewritten and
+// printed.
+func (f *File) ReadGo(name string) {
+	// Create absolute path for file, so that it will be used in error
+	// messages and recorded in debug line number information.
+	// This matches the rest of the toolchain. See golang.org/issue/5122.
+	if aname, err := filepath.Abs(name); err == nil {
+		name = aname
+	}
+
+	// Two different parses: once with comments, once without.
+	// The printer is not good enough at printing comments in the
+	// right place when we start editing the AST behind its back,
+	// so we use ast1 to look for the doc comments on import "C"
+	// and on exported functions, and we use ast2 for translating
+	// and reprinting.
+	ast1 := parse(name, parser.ParseComments)
+	ast2 := parse(name, 0)
+
+	f.Package = ast1.Name.Name
+	f.Name = make(map[string]*Name)
+
+	// In ast1, find the import "C" line and get any extra C preamble.
+	sawC := false
+	for _, decl := range ast1.Decls {
+		d, ok := decl.(*ast.GenDecl)
+		if !ok {
+			continue
+		}
+		for _, spec := range d.Specs {
+			s, ok := spec.(*ast.ImportSpec)
+			if !ok || string(s.Path.Value) != `"C"` {
+				continue
+			}
+			sawC = true
+			if s.Name != nil {
+				error_(s.Path.Pos(), `cannot rename import "C"`)
+			}
+			cg := s.Doc
+			if cg == nil && len(d.Specs) == 1 {
+				cg = d.Doc
+			}
+			if cg != nil {
+				f.Preamble += fmt.Sprintf("#line %d %q\n", sourceLine(cg), name)
+				f.Preamble += commentText(cg) + "\n"
+			}
+		}
+	}
+	if !sawC {
+		error_(token.NoPos, `cannot find import "C"`)
+	}
+
+	// In ast2, strip the import "C" line.
+	w := 0
+	for _, decl := range ast2.Decls {
+		d, ok := decl.(*ast.GenDecl)
+		if !ok {
+			ast2.Decls[w] = decl
+			w++
+			continue
+		}
+		ws := 0
+		for _, spec := range d.Specs {
+			s, ok := spec.(*ast.ImportSpec)
+			if !ok || string(s.Path.Value) != `"C"` {
+				d.Specs[ws] = spec
+				ws++
+			}
+		}
+		if ws == 0 {
+			continue
+		}
+		d.Specs = d.Specs[0:ws]
+		ast2.Decls[w] = d
+		w++
+	}
+	ast2.Decls = ast2.Decls[0:w]
+
+	// Accumulate pointers to uses of C.x.
+	if f.Ref == nil {
+		f.Ref = make([]*Ref, 0, 8)
+	}
+	f.walk(ast2, "prog", (*File).saveRef)
+
+	// Accumulate exported functions.
+	// The comments are only on ast1 but we need to
+	// save the function bodies from ast2.
+	// The first walk fills in ExpFunc, and the
+	// second walk changes the entries to
+	// refer to ast2 instead.
+	f.walk(ast1, "prog", (*File).saveExport)
+	f.walk(ast2, "prog", (*File).saveExport2)
+
+	f.Comments = ast1.Comments
+	f.AST = ast2
+}
+
+// Like ast.CommentGroup's Text method but preserves
+// leading blank lines, so that line numbers line up.
+func commentText(g *ast.CommentGroup) string {
+	if g == nil {
+		return ""
+	}
+	var pieces []string
+	for _, com := range g.List {
+		c := string(com.Text)
+		// Remove comment markers.
+		// The parser has given us exactly the comment text.
+		switch c[1] {
+		case '/':
+			//-style comment (no newline at the end)
+			c = c[2:] + "\n"
+		case '*':
+			/*-style comment */
+			c = c[2 : len(c)-2]
+		}
+		pieces = append(pieces, c)
+	}
+	return strings.Join(pieces, "")
+}
+
+// Save references to C.xxx for later processing.
+func (f *File) saveRef(x interface{}, context string) {
+	n, ok := x.(*ast.Expr)
+	if !ok {
+		return
+	}
+	if sel, ok := (*n).(*ast.SelectorExpr); ok {
+		// For now, assume that the only instance of capital C is
+		// when used as the imported package identifier.
+		// The parser should take care of scoping in the future,
+		// so that we will be able to distinguish a "top-level C"
+		// from a local C.
+		if l, ok := sel.X.(*ast.Ident); ok && l.Name == "C" {
+			if context == "as2" {
+				context = "expr"
+			}
+			if context == "embed-type" {
+				error_(sel.Pos(), "cannot embed C type")
+			}
+			goname := sel.Sel.Name
+			if goname == "errno" {
+				error_(sel.Pos(), "cannot refer to errno directly; see documentation")
+				return
+			}
+			if goname == "_CMalloc" {
+				error_(sel.Pos(), "cannot refer to C._CMalloc; use C.malloc")
+				return
+			}
+			if goname == "malloc" {
+				goname = "_CMalloc"
+			}
+			name := f.Name[goname]
+			if name == nil {
+				name = &Name{
+					Go: goname,
+				}
+				f.Name[goname] = name
+			}
+			f.Ref = append(f.Ref, &Ref{
+				Name:    name,
+				Expr:    n,
+				Context: context,
+			})
+			return
+		}
+	}
+}
+
+// If a function should be exported add it to ExpFunc.
+func (f *File) saveExport(x interface{}, context string) {
+	n, ok := x.(*ast.FuncDecl)
+	if !ok {
+		return
+	}
+
+	if n.Doc == nil {
+		return
+	}
+	for _, c := range n.Doc.List {
+		if !strings.HasPrefix(string(c.Text), "//export ") {
+			continue
+		}
+
+		name := strings.TrimSpace(string(c.Text[9:]))
+		if name == "" {
+			error_(c.Pos(), "export missing name")
+		}
+
+		if name != n.Name.Name {
+			error_(c.Pos(), "export comment has wrong name %q, want %q", name, n.Name.Name)
+		}
+
+		f.ExpFunc = append(f.ExpFunc, &ExpFunc{
+			Func:    n,
+			ExpName: name,
+		})
+		break
+	}
+}
+
+// Make f.ExpFunc[i] point at the Func from this AST instead of the other one.
+func (f *File) saveExport2(x interface{}, context string) {
+	n, ok := x.(*ast.FuncDecl)
+	if !ok {
+		return
+	}
+
+	for _, exp := range f.ExpFunc {
+		if exp.Func.Name.Name == n.Name.Name {
+			exp.Func = n
+			break
+		}
+	}
+}
+
+// walk walks the AST x, calling visit(f, x, context) for each node.
+func (f *File) walk(x interface{}, context string, visit func(*File, interface{}, string)) {
+	visit(f, x, context)
+	switch n := x.(type) {
+	case *ast.Expr:
+		f.walk(*n, context, visit)
+
+	// everything else just recurs
+	default:
+		error_(token.NoPos, "unexpected type %T in walk", x, visit)
+		panic("unexpected type")
+
+	case nil:
+
+	// These are ordered and grouped to match ../../pkg/go/ast/ast.go
+	case *ast.Field:
+		if len(n.Names) == 0 && context == "field" {
+			f.walk(&n.Type, "embed-type", visit)
+		} else {
+			f.walk(&n.Type, "type", visit)
+		}
+	case *ast.FieldList:
+		for _, field := range n.List {
+			f.walk(field, context, visit)
+		}
+	case *ast.BadExpr:
+	case *ast.Ident:
+	case *ast.Ellipsis:
+	case *ast.BasicLit:
+	case *ast.FuncLit:
+		f.walk(n.Type, "type", visit)
+		f.walk(n.Body, "stmt", visit)
+	case *ast.CompositeLit:
+		f.walk(&n.Type, "type", visit)
+		f.walk(n.Elts, "expr", visit)
+	case *ast.ParenExpr:
+		f.walk(&n.X, context, visit)
+	case *ast.SelectorExpr:
+		f.walk(&n.X, "selector", visit)
+	case *ast.IndexExpr:
+		f.walk(&n.X, "expr", visit)
+		f.walk(&n.Index, "expr", visit)
+	case *ast.SliceExpr:
+		f.walk(&n.X, "expr", visit)
+		if n.Low != nil {
+			f.walk(&n.Low, "expr", visit)
+		}
+		if n.High != nil {
+			f.walk(&n.High, "expr", visit)
+		}
+	case *ast.TypeAssertExpr:
+		f.walk(&n.X, "expr", visit)
+		f.walk(&n.Type, "type", visit)
+	case *ast.CallExpr:
+		if context == "as2" {
+			f.walk(&n.Fun, "call2", visit)
+		} else {
+			f.walk(&n.Fun, "call", visit)
+		}
+		f.walk(n.Args, "expr", visit)
+	case *ast.StarExpr:
+		f.walk(&n.X, context, visit)
+	case *ast.UnaryExpr:
+		f.walk(&n.X, "expr", visit)
+	case *ast.BinaryExpr:
+		f.walk(&n.X, "expr", visit)
+		f.walk(&n.Y, "expr", visit)
+	case *ast.KeyValueExpr:
+		f.walk(&n.Key, "expr", visit)
+		f.walk(&n.Value, "expr", visit)
+
+	case *ast.ArrayType:
+		f.walk(&n.Len, "expr", visit)
+		f.walk(&n.Elt, "type", visit)
+	case *ast.StructType:
+		f.walk(n.Fields, "field", visit)
+	case *ast.FuncType:
+		f.walk(n.Params, "param", visit)
+		if n.Results != nil {
+			f.walk(n.Results, "param", visit)
+		}
+	case *ast.InterfaceType:
+		f.walk(n.Methods, "field", visit)
+	case *ast.MapType:
+		f.walk(&n.Key, "type", visit)
+		f.walk(&n.Value, "type", visit)
+	case *ast.ChanType:
+		f.walk(&n.Value, "type", visit)
+
+	case *ast.BadStmt:
+	case *ast.DeclStmt:
+		f.walk(n.Decl, "decl", visit)
+	case *ast.EmptyStmt:
+	case *ast.LabeledStmt:
+		f.walk(n.Stmt, "stmt", visit)
+	case *ast.ExprStmt:
+		f.walk(&n.X, "expr", visit)
+	case *ast.SendStmt:
+		f.walk(&n.Chan, "expr", visit)
+		f.walk(&n.Value, "expr", visit)
+	case *ast.IncDecStmt:
+		f.walk(&n.X, "expr", visit)
+	case *ast.AssignStmt:
+		f.walk(n.Lhs, "expr", visit)
+		if len(n.Lhs) == 2 && len(n.Rhs) == 1 {
+			f.walk(n.Rhs, "as2", visit)
+		} else {
+			f.walk(n.Rhs, "expr", visit)
+		}
+	case *ast.GoStmt:
+		f.walk(n.Call, "expr", visit)
+	case *ast.DeferStmt:
+		f.walk(n.Call, "expr", visit)
+	case *ast.ReturnStmt:
+		f.walk(n.Results, "expr", visit)
+	case *ast.BranchStmt:
+	case *ast.BlockStmt:
+		f.walk(n.List, context, visit)
+	case *ast.IfStmt:
+		f.walk(n.Init, "stmt", visit)
+		f.walk(&n.Cond, "expr", visit)
+		f.walk(n.Body, "stmt", visit)
+		f.walk(n.Else, "stmt", visit)
+	case *ast.CaseClause:
+		if context == "typeswitch" {
+			context = "type"
+		} else {
+			context = "expr"
+		}
+		f.walk(n.List, context, visit)
+		f.walk(n.Body, "stmt", visit)
+	case *ast.SwitchStmt:
+		f.walk(n.Init, "stmt", visit)
+		f.walk(&n.Tag, "expr", visit)
+		f.walk(n.Body, "switch", visit)
+	case *ast.TypeSwitchStmt:
+		f.walk(n.Init, "stmt", visit)
+		f.walk(n.Assign, "stmt", visit)
+		f.walk(n.Body, "typeswitch", visit)
+	case *ast.CommClause:
+		f.walk(n.Comm, "stmt", visit)
+		f.walk(n.Body, "stmt", visit)
+	case *ast.SelectStmt:
+		f.walk(n.Body, "stmt", visit)
+	case *ast.ForStmt:
+		f.walk(n.Init, "stmt", visit)
+		f.walk(&n.Cond, "expr", visit)
+		f.walk(n.Post, "stmt", visit)
+		f.walk(n.Body, "stmt", visit)
+	case *ast.RangeStmt:
+		f.walk(&n.Key, "expr", visit)
+		f.walk(&n.Value, "expr", visit)
+		f.walk(&n.X, "expr", visit)
+		f.walk(n.Body, "stmt", visit)
+
+	case *ast.ImportSpec:
+	case *ast.ValueSpec:
+		f.walk(&n.Type, "type", visit)
+		f.walk(n.Values, "expr", visit)
+	case *ast.TypeSpec:
+		f.walk(&n.Type, "type", visit)
+
+	case *ast.BadDecl:
+	case *ast.GenDecl:
+		f.walk(n.Specs, "spec", visit)
+	case *ast.FuncDecl:
+		if n.Recv != nil {
+			f.walk(n.Recv, "param", visit)
+		}
+		f.walk(n.Type, "type", visit)
+		if n.Body != nil {
+			f.walk(n.Body, "stmt", visit)
+		}
+
+	case *ast.File:
+		f.walk(n.Decls, "decl", visit)
+
+	case *ast.Package:
+		for _, file := range n.Files {
+			f.walk(file, "file", visit)
+		}
+
+	case []ast.Decl:
+		for _, d := range n {
+			f.walk(d, context, visit)
+		}
+	case []ast.Expr:
+		for i := range n {
+			f.walk(&n[i], context, visit)
+		}
+	case []ast.Stmt:
+		for _, s := range n {
+			f.walk(s, context, visit)
+		}
+	case []ast.Spec:
+		for _, s := range n {
+			f.walk(s, context, visit)
+		}
+	}
+}
diff --git a/libgo/go/cmd/cgo/doc.go b/libgo/go/cmd/cgo/doc.go
new file mode 100644
index 0000000..69c7ce8
--- /dev/null
+++ b/libgo/go/cmd/cgo/doc.go
@@ -0,0 +1,748 @@
+// Copyright 2009 The Go Authors.  All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+/*
+
+Cgo enables the creation of Go packages that call C code.
+
+Using cgo with the go command
+
+To use cgo write normal Go code that imports a pseudo-package "C".
+The Go code can then refer to types such as C.size_t, variables such
+as C.stdout, or functions such as C.putchar.
+
+If the import of "C" is immediately preceded by a comment, that
+comment, called the preamble, is used as a header when compiling
+the C parts of the package.  For example:
+
+	// #include <stdio.h>
+	// #include <errno.h>
+	import "C"
+
+See $GOROOT/misc/cgo/stdio and $GOROOT/misc/cgo/gmp for examples.  See
+"C? Go? Cgo!" for an introduction to using cgo:
+http://golang.org/doc/articles/c_go_cgo.html.
+
+CFLAGS, CPPFLAGS, CXXFLAGS and LDFLAGS may be defined with pseudo #cgo
+directives within these comments to tweak the behavior of the C or C++
+compiler.  Values defined in multiple directives are concatenated
+together.  The directive can include a list of build constraints limiting its
+effect to systems satisfying one of the constraints
+(see http://golang.org/pkg/go/build/#hdr-Build_Constraints for details about the constraint syntax).
+For example:
+
+	// #cgo CFLAGS: -DPNG_DEBUG=1
+	// #cgo amd64 386 CFLAGS: -DX86=1
+	// #cgo LDFLAGS: -lpng
+	// #include <png.h>
+	import "C"
+
+Alternatively, CPPFLAGS and LDFLAGS may be obtained via the pkg-config
+tool using a '#cgo pkg-config:' directive followed by the package names.
+For example:
+
+	// #cgo pkg-config: png cairo
+	// #include <png.h>
+	import "C"
+
+When building, the CGO_CFLAGS, CGO_CPPFLAGS, CGO_CXXFLAGS and
+CGO_LDFLAGS environment variables are added to the flags derived from
+these directives.  Package-specific flags should be set using the
+directives, not the environment variables, so that builds work in
+unmodified environments.
+
+All the cgo CPPFLAGS and CFLAGS directives in a package are concatenated and
+used to compile C files in that package.  All the CPPFLAGS and CXXFLAGS
+directives in a package are concatenated and used to compile C++ files in that
+package.  All the LDFLAGS directives in any package in the program are
+concatenated and used at link time.  All the pkg-config directives are
+concatenated and sent to pkg-config simultaneously to add to each appropriate
+set of command-line flags.
+
+When the Go tool sees that one or more Go files use the special import
+"C", it will look for other non-Go files in the directory and compile
+them as part of the Go package.  Any .c, .s, or .S files will be
+compiled with the C compiler.  Any .cc, .cpp, or .cxx files will be
+compiled with the C++ compiler.  Any .h, .hh, .hpp, or .hxx files will
+not be compiled separately, but, if these header files are changed,
+the C and C++ files will be recompiled.  The default C and C++
+compilers may be changed by the CC and CXX environment variables,
+respectively; those environment variables may include command line
+options.
+
+To enable cgo during cross compiling builds, set the CGO_ENABLED
+environment variable to 1 when building the Go tools with make.bash.
+Also, set CC_FOR_TARGET to the C cross compiler for the target.  CC will
+be used for compiling for the host.
+
+After the Go tools are built, when running the go command, CC_FOR_TARGET is
+ignored.  The value of CC_FOR_TARGET when running make.bash is the default
+compiler.  However, you can set the environment variable CC, not CC_FOR_TARGET,
+to control the compiler when running the go tool.
+
+CXX_FOR_TARGET works in a similar way for C++ code.
+
+Go references to C
+
+Within the Go file, C's struct field names that are keywords in Go
+can be accessed by prefixing them with an underscore: if x points at a C
+struct with a field named "type", x._type accesses the field.
+C struct fields that cannot be expressed in Go, such as bit fields
+or misaligned data, are omitted in the Go struct, replaced by
+appropriate padding to reach the next field or the end of the struct.
+
+The standard C numeric types are available under the names
+C.char, C.schar (signed char), C.uchar (unsigned char),
+C.short, C.ushort (unsigned short), C.int, C.uint (unsigned int),
+C.long, C.ulong (unsigned long), C.longlong (long long),
+C.ulonglong (unsigned long long), C.float, C.double.
+The C type void* is represented by Go's unsafe.Pointer.
+
+To access a struct, union, or enum type directly, prefix it with
+struct_, union_, or enum_, as in C.struct_stat.
+
+As Go doesn't have support for C's union type in the general case,
+C's union types are represented as a Go byte array with the same length.
+
+Go structs cannot embed fields with C types.
+
+Cgo translates C types into equivalent unexported Go types.
+Because the translations are unexported, a Go package should not
+expose C types in its exported API: a C type used in one Go package
+is different from the same C type used in another.
+
+Any C function (even void functions) may be called in a multiple
+assignment context to retrieve both the return value (if any) and the
+C errno variable as an error (use _ to skip the result value if the
+function returns void).  For example:
+
+	n, err := C.sqrt(-1)
+	_, err := C.voidFunc()
+
+Calling C function pointers is currently not supported, however you can
+declare Go variables which hold C function pointers and pass them
+back and forth between Go and C. C code may call function pointers
+received from Go. For example:
+
+	package main
+
+	// typedef int (*intFunc) ();
+	//
+	// int
+	// bridge_int_func(intFunc f)
+	// {
+	//		return f();
+	// }
+	//
+	// int fortytwo()
+	// {
+	//	    return 42;
+	// }
+	import "C"
+	import "fmt"
+
+	func main() {
+		f := C.intFunc(C.fortytwo)
+		fmt.Println(int(C.bridge_int_func(f)))
+		// Output: 42
+	}
+
+In C, a function argument written as a fixed size array
+actually requires a pointer to the first element of the array.
+C compilers are aware of this calling convention and adjust
+the call accordingly, but Go cannot.  In Go, you must pass
+the pointer to the first element explicitly: C.f(&x[0]).
+
+A few special functions convert between Go and C types
+by making copies of the data.  In pseudo-Go definitions:
+
+	// Go string to C string
+	// The C string is allocated in the C heap using malloc.
+	// It is the caller's responsibility to arrange for it to be
+	// freed, such as by calling C.free (be sure to include stdlib.h
+	// if C.free is needed).
+	func C.CString(string) *C.char
+
+	// C string to Go string
+	func C.GoString(*C.char) string
+
+	// C string, length to Go string
+	func C.GoStringN(*C.char, C.int) string
+
+	// C pointer, length to Go []byte
+	func C.GoBytes(unsafe.Pointer, C.int) []byte
+
+C references to Go
+
+Go functions can be exported for use by C code in the following way:
+
+	//export MyFunction
+	func MyFunction(arg1, arg2 int, arg3 string) int64 {...}
+
+	//export MyFunction2
+	func MyFunction2(arg1, arg2 int, arg3 string) (int64, *C.char) {...}
+
+They will be available in the C code as:
+
+	extern int64 MyFunction(int arg1, int arg2, GoString arg3);
+	extern struct MyFunction2_return MyFunction2(int arg1, int arg2, GoString arg3);
+
+found in the _cgo_export.h generated header, after any preambles
+copied from the cgo input files. Functions with multiple
+return values are mapped to functions returning a struct.
+Not all Go types can be mapped to C types in a useful way.
+
+Using //export in a file places a restriction on the preamble:
+since it is copied into two different C output files, it must not
+contain any definitions, only declarations. Definitions must be
+placed in preambles in other files, or in C source files.
+
+Using cgo directly
+
+Usage:
+	go tool cgo [cgo options] [-- compiler options] file.go
+
+Cgo transforms the input file.go into four output files: two Go source
+files, a C file for 6c (or 8c or 5c), and a C file for gcc.
+
+The compiler options are passed through uninterpreted when
+invoking the C compiler to compile the C parts of the package.
+
+The following options are available when running cgo directly:
+
+	-dynimport file
+		Write list of symbols imported by file. Write to
+		-dynout argument or to standard output. Used by go
+		build when building a cgo package.
+	-dynout file
+		Write -dynimport output to file.
+	-dynlinker
+		Write dynamic linker as part of -dynimport output.
+	-godefs
+		Write out input file in Go syntax replacing C package
+		names with real values. Used to generate files in the
+		syscall package when bootstrapping a new target.
+	-cdefs
+		Like -godefs, but write file in C syntax.
+		Used to generate files in the runtime package when
+		bootstrapping a new target.
+	-objdir directory
+		Put all generated files in directory.
+	-gccgo
+		Generate output for the gccgo compiler rather than the
+		gc compiler.
+	-gccgoprefix prefix
+		The -fgo-prefix option to be used with gccgo.
+	-gccgopkgpath path
+		The -fgo-pkgpath option to be used with gccgo.
+	-import_runtime_cgo
+		If set (which it is by default) import runtime/cgo in
+		generated output.
+	-import_syscall
+		If set (which it is by default) import syscall in
+		generated output.
+	-debug-define
+		Debugging option. Print #defines.
+	-debug-gcc
+		Debugging option. Trace C compiler execution and output.
+*/
+package main
+
+/*
+Implementation details.
+
+Cgo provides a way for Go programs to call C code linked into the same
+address space. This comment explains the operation of cgo.
+
+Cgo reads a set of Go source files and looks for statements saying
+import "C". If the import has a doc comment, that comment is
+taken as literal C code to be used as a preamble to any C code
+generated by cgo. A typical preamble #includes necessary definitions:
+
+	// #include <stdio.h>
+	import "C"
+
+For more details about the usage of cgo, see the documentation
+comment at the top of this file.
+
+Understanding C
+
+Cgo scans the Go source files that import "C" for uses of that
+package, such as C.puts. It collects all such identifiers. The next
+step is to determine each kind of name. In C.xxx the xxx might refer
+to a type, a function, a constant, or a global variable. Cgo must
+decide which.
+
+The obvious thing for cgo to do is to process the preamble, expanding
+#includes and processing the corresponding C code. That would require
+a full C parser and type checker that was also aware of any extensions
+known to the system compiler (for example, all the GNU C extensions) as
+well as the system-specific header locations and system-specific
+pre-#defined macros. This is certainly possible to do, but it is an
+enormous amount of work.
+
+Cgo takes a different approach. It determines the meaning of C
+identifiers not by parsing C code but by feeding carefully constructed
+programs into the system C compiler and interpreting the generated
+error messages, debug information, and object files. In practice,
+parsing these is significantly less work and more robust than parsing
+C source.
+
+Cgo first invokes gcc -E -dM on the preamble, in order to find out
+about simple #defines for constants and the like. These are recorded
+for later use.
+
+Next, cgo needs to identify the kinds for each identifier. For the
+identifiers C.foo and C.bar, cgo generates this C program:
+
+	<preamble>
+	#line 1 "not-declared"
+	void __cgo_f_xxx_1(void) { __typeof__(foo) *__cgo_undefined__; }
+	#line 1 "not-type"
+	void __cgo_f_xxx_2(void) { foo *__cgo_undefined__; }
+	#line 1 "not-const"
+	void __cgo_f_xxx_3(void) { enum { __cgo_undefined__ = (foo)*1 }; }
+	#line 2 "not-declared"
+	void __cgo_f_xxx_1(void) { __typeof__(bar) *__cgo_undefined__; }
+	#line 2 "not-type"
+	void __cgo_f_xxx_2(void) { bar *__cgo_undefined__; }
+	#line 2 "not-const"
+	void __cgo_f_xxx_3(void) { enum { __cgo_undefined__ = (bar)*1 }; }
+
+This program will not compile, but cgo can use the presence or absence
+of an error message on a given line to deduce the information it
+needs. The program is syntactically valid regardless of whether each
+name is a type or an ordinary identifier, so there will be no syntax
+errors that might stop parsing early.
+
+An error on not-declared:1 indicates that foo is undeclared.
+An error on not-type:1 indicates that foo is not a type (if declared at all, it is an identifier).
+An error on not-const:1 indicates that foo is not an integer constant.
+
+The line number specifies the name involved. In the example, 1 is foo and 2 is bar.
+
+Next, cgo must learn the details of each type, variable, function, or
+constant. It can do this by reading object files. If cgo has decided
+that t1 is a type, v2 and v3 are variables or functions, and c4, c5,
+and c6 are constants, it generates:
+
+	<preamble>
+	__typeof__(t1) *__cgo__1;
+	__typeof__(v2) *__cgo__2;
+	__typeof__(v3) *__cgo__3;
+	__typeof__(c4) *__cgo__4;
+	enum { __cgo_enum__4 = c4 };
+	__typeof__(c5) *__cgo__5;
+	enum { __cgo_enum__5 = c5 };
+	__typeof__(c6) *__cgo__6;
+	enum { __cgo_enum__6 = c6 };
+
+	long long __cgo_debug_data[] = {
+		0, // t1
+		0, // v2
+		0, // v3
+		c4,
+		c5,
+		c6,
+		1
+	};
+
+and again invokes the system C compiler, to produce an object file
+containing debug information. Cgo parses the DWARF debug information
+for __cgo__N to learn the type of each identifier. (The types also
+distinguish functions from global variables.) If using a standard gcc,
+cgo can parse the DWARF debug information for the __cgo_enum__N to
+learn the identifier's value. The LLVM-based gcc on OS X emits
+incomplete DWARF information for enums; in that case cgo reads the
+constant values from the __cgo_debug_data from the object file's data
+segment.
+
+At this point cgo knows the meaning of each C.xxx well enough to start
+the translation process.
+
+Translating Go
+
+[The rest of this comment refers to 6g and 6c, the Go and C compilers
+that are part of the amd64 port of the gc Go toolchain. Everything here
+applies to another architecture's compilers as well.]
+
+Given the input Go files x.go and y.go, cgo generates these source
+files:
+
+	x.cgo1.go       # for 6g
+	y.cgo1.go       # for 6g
+	_cgo_gotypes.go # for 6g
+	_cgo_defun.c    # for 6c
+	x.cgo2.c        # for gcc
+	y.cgo2.c        # for gcc
+	_cgo_export.c   # for gcc
+	_cgo_main.c     # for gcc
+
+The file x.cgo1.go is a copy of x.go with the import "C" removed and
+references to C.xxx replaced with names like _Cfunc_xxx or _Ctype_xxx.
+The definitions of those identifiers, written as Go functions, types,
+or variables, are provided in _cgo_gotypes.go.
+
+Here is a _cgo_gotypes.go containing definitions for C.flush (provided
+in the preamble) and C.puts (from stdio):
+
+	type _Ctype_char int8
+	type _Ctype_int int32
+	type _Ctype_void [0]byte
+
+	func _Cfunc_CString(string) *_Ctype_char
+	func _Cfunc_flush() _Ctype_void
+	func _Cfunc_puts(*_Ctype_char) _Ctype_int
+
+For functions, cgo only writes an external declaration in the Go
+output. The implementation is in a combination of C for 6c (meaning
+any gc-toolchain compiler) and C for gcc.
+
+The 6c file contains the definitions of the functions. They all have
+similar bodies that invoke runtime·cgocall to make a switch from the
+Go runtime world to the system C (GCC-based) world.
+
+For example, here is the definition of _Cfunc_puts:
+
+	void _cgo_be59f0f25121_Cfunc_puts(void*);
+
+	void
+	·_Cfunc_puts(struct{uint8 x[1];}p)
+	{
+		runtime·cgocall(_cgo_be59f0f25121_Cfunc_puts, &p);
+	}
+
+The hexadecimal number is a hash of cgo's input, chosen to be
+deterministic yet unlikely to collide with other uses. The actual
+function _cgo_be59f0f25121_Cfunc_puts is implemented in a C source
+file compiled by gcc, the file x.cgo2.c:
+
+	void
+	_cgo_be59f0f25121_Cfunc_puts(void *v)
+	{
+		struct {
+			char* p0;
+			int r;
+			char __pad12[4];
+		} __attribute__((__packed__, __gcc_struct__)) *a = v;
+		a->r = puts((void*)a->p0);
+	}
+
+It extracts the arguments from the pointer to _Cfunc_puts's argument
+frame, invokes the system C function (in this case, puts), stores the
+result in the frame, and returns.
+
+Linking
+
+Once the _cgo_export.c and *.cgo2.c files have been compiled with gcc,
+they need to be linked into the final binary, along with the libraries
+they might depend on (in the case of puts, stdio). 6l has been
+extended to understand basic ELF files, but it does not understand ELF
+in the full complexity that modern C libraries embrace, so it cannot
+in general generate direct references to the system libraries.
+
+Instead, the build process generates an object file using dynamic
+linkage to the desired libraries. The main function is provided by
+_cgo_main.c:
+
+	int main() { return 0; }
+	void crosscall2(void(*fn)(void*, int), void *a, int c) { }
+	void _cgo_allocate(void *a, int c) { }
+	void _cgo_panic(void *a, int c) { }
+
+The extra functions here are stubs to satisfy the references in the C
+code generated for gcc. The build process links this stub, along with
+_cgo_export.c and *.cgo2.c, into a dynamic executable and then lets
+cgo examine the executable. Cgo records the list of shared library
+references and resolved names and writes them into a new file
+_cgo_import.c, which looks like:
+
+	#pragma cgo_dynamic_linker "/lib64/ld-linux-x86-64.so.2"
+	#pragma cgo_import_dynamic puts puts#GLIBC_2.2.5 "libc.so.6"
+	#pragma cgo_import_dynamic __libc_start_main __libc_start_main#GLIBC_2.2.5 "libc.so.6"
+	#pragma cgo_import_dynamic stdout stdout#GLIBC_2.2.5 "libc.so.6"
+	#pragma cgo_import_dynamic fflush fflush#GLIBC_2.2.5 "libc.so.6"
+	#pragma cgo_import_dynamic _ _ "libpthread.so.0"
+	#pragma cgo_import_dynamic _ _ "libc.so.6"
+
+In the end, the compiled Go package, which will eventually be
+presented to 6l as part of a larger program, contains:
+
+	_go_.6        # 6g-compiled object for _cgo_gotypes.go *.cgo1.go
+	_cgo_defun.6  # 6c-compiled object for _cgo_defun.c
+	_all.o        # gcc-compiled object for _cgo_export.c, *.cgo2.c
+	_cgo_import.6 # 6c-compiled object for _cgo_import.c
+
+The final program will be a dynamic executable, so that 6l can avoid
+needing to process arbitrary .o files. It only needs to process the .o
+files generated from C files that cgo writes, and those are much more
+limited in the ELF or other features that they use.
+
+In essence, the _cgo_import.6 file includes the extra linking
+directives that 6l is not sophisticated enough to derive from _all.o
+on its own. Similarly, the _all.o uses dynamic references to real
+system object code because 6l is not sophisticated enough to process
+the real code.
+
+The main benefits of this system are that 6l remains relatively simple
+(it does not need to implement a complete ELF and Mach-O linker) and
+that gcc is not needed after the package is compiled. For example,
+package net uses cgo for access to name resolution functions provided
+by libc. Although gcc is needed to compile package net, gcc is not
+needed to link programs that import package net.
+
+Runtime
+
+When using cgo, Go must not assume that it owns all details of the
+process. In particular it needs to coordinate with C in the use of
+threads and thread-local storage. The runtime package, in its own
+(6c-compiled) C code, declares a few uninitialized (default bss)
+variables:
+
+	bool	runtime·iscgo;
+	void	(*libcgo_thread_start)(void*);
+	void	(*initcgo)(G*);
+
+Any package using cgo imports "runtime/cgo", which provides
+initializations for these variables. It sets iscgo to 1, initcgo to a
+gcc-compiled function that can be called early during program startup,
+and libcgo_thread_start to a gcc-compiled function that can be used to
+create a new thread, in place of the runtime's usual direct system
+calls.
+
+Internal and External Linking
+
+The text above describes "internal" linking, in which 6l parses and
+links host object files (ELF, Mach-O, PE, and so on) into the final
+executable itself. Keeping 6l simple means we cannot possibly
+implement the full semantics of the host linker, so the kinds of
+objects that can be linked directly into the binary is limited (other
+code can only be used as a dynamic library). On the other hand, when
+using internal linking, 6l can generate Go binaries by itself.
+
+In order to allow linking arbitrary object files without requiring
+dynamic libraries, cgo will soon support an "external" linking mode
+too. In external linking mode, 6l does not process any host object
+files. Instead, it collects all the Go code and writes a single go.o
+object file containing it. Then it invokes the host linker (usually
+gcc) to combine the go.o object file and any supporting non-Go code
+into a final executable. External linking avoids the dynamic library
+requirement but introduces a requirement that the host linker be
+present to create such a binary.
+
+Most builds both compile source code and invoke the linker to create a
+binary. When cgo is involved, the compile step already requires gcc, so
+it is not problematic for the link step to require gcc too.
+
+An important exception is builds using a pre-compiled copy of the
+standard library. In particular, package net uses cgo on most systems,
+and we want to preserve the ability to compile pure Go code that
+imports net without requiring gcc to be present at link time. (In this
+case, the dynamic library requirement is less significant, because the
+only library involved is libc.so, which can usually be assumed
+present.)
+
+This conflict between functionality and the gcc requirement means we
+must support both internal and external linking, depending on the
+circumstances: if net is the only cgo-using package, then internal
+linking is probably fine, but if other packages are involved, so that there
+are dependencies on libraries beyond libc, external linking is likely
+to work better. The compilation of a package records the relevant
+information to support both linking modes, leaving the decision
+to be made when linking the final binary.
+
+Linking Directives
+
+In either linking mode, package-specific directives must be passed
+through to 6l. These are communicated by writing #pragma directives
+in a C source file compiled by 6c. The directives are copied into the .6 object file
+and then processed by the linker.
+
+The directives are:
+
+#pragma cgo_import_dynamic <local> [<remote> ["<library>"]]
+
+	In internal linking mode, allow an unresolved reference to
+	<local>, assuming it will be resolved by a dynamic library
+	symbol. The optional <remote> specifies the symbol's name and
+	possibly version in the dynamic library, and the optional "<library>"
+	names the specific library where the symbol should be found.
+
+	In the <remote>, # or @ can be used to introduce a symbol version.
+
+	Examples:
+	#pragma cgo_import_dynamic puts
+	#pragma cgo_import_dynamic puts puts#GLIBC_2.2.5
+	#pragma cgo_import_dynamic puts puts#GLIBC_2.2.5 "libc.so.6"
+
+	A side effect of the cgo_import_dynamic directive with a
+	library is to make the final binary depend on that dynamic
+	library. To get the dependency without importing any specific
+	symbols, use _ for local and remote.
+
+	Example:
+	#pragma cgo_import_dynamic _ _ "libc.so.6"
+
+	For compatibility with current versions of SWIG,
+	#pragma dynimport is an alias for #pragma cgo_import_dynamic.
+
+#pragma cgo_dynamic_linker "<path>"
+
+	In internal linking mode, use "<path>" as the dynamic linker
+	in the final binary. This directive is only needed from one
+	package when constructing a binary; by convention it is
+	supplied by runtime/cgo.
+
+	Example:
+	#pragma cgo_dynamic_linker "/lib/ld-linux.so.2"
+
+#pragma cgo_export_dynamic <local> <remote>
+
+	In internal linking mode, put the Go symbol
+	named <local> into the program's exported symbol table as
+	<remote>, so that C code can refer to it by that name. This
+	mechanism makes it possible for C code to call back into Go or
+	to share Go's data.
+
+	For compatibility with current versions of SWIG,
+	#pragma dynexport is an alias for #pragma cgo_export_dynamic.
+
+#pragma cgo_import_static <local>
+
+	In external linking mode, allow unresolved references to
+	<local> in the go.o object file prepared for the host linker,
+	under the assumption that <local> will be supplied by the
+	other object files that will be linked with go.o.
+
+	Example:
+	#pragma cgo_import_static puts_wrapper
+
+#pragma cgo_export_static <local> <remote>
+
+	In external linking mode, put the Go symbol
+	named <local> into the program's exported symbol table as
+	<remote>, so that C code can refer to it by that name. This
+	mechanism makes it possible for C code to call back into Go or
+	to share Go's data.
+
+#pragma cgo_ldflag "<arg>"
+
+	In external linking mode, invoke the host linker (usually gcc)
+	with "<arg>" as a command-line argument following the .o files.
+	Note that the arguments are for "gcc", not "ld".
+
+	Example:
+	#pragma cgo_ldflag "-lpthread"
+	#pragma cgo_ldflag "-L/usr/local/sqlite3/lib"
+
+A package compiled with cgo will include directives for both
+internal and external linking; the linker will select the appropriate
+subset for the chosen linking mode.
+
+Example
+
+As a simple example, consider a package that uses cgo to call C.sin.
+The following code will be generated by cgo:
+
+	// compiled by 6g
+
+	type _Ctype_double float64
+	func _Cfunc_sin(_Ctype_double) _Ctype_double
+
+	// compiled by 6c
+
+	#pragma cgo_import_dynamic sin sin#GLIBC_2.2.5 "libm.so.6"
+
+	#pragma cgo_import_static _cgo_gcc_Cfunc_sin
+	#pragma cgo_ldflag "-lm"
+
+	void _cgo_gcc_Cfunc_sin(void*);
+
+	void
+	·_Cfunc_sin(struct{uint8 x[16];}p)
+	{
+		runtime·cgocall(_cgo_gcc_Cfunc_sin, &p);
+	}
+
+	// compiled by gcc, into foo.cgo2.o
+
+	void
+	_cgo_gcc_Cfunc_sin(void *v)
+	{
+		struct {
+			double p0;
+			double r;
+		} __attribute__((__packed__)) *a = v;
+		a->r = sin(a->p0);
+	}
+
+What happens at link time depends on whether the final binary is linked
+using the internal or external mode. If other packages are compiled in
+"external only" mode, then the final link will be an external one.
+Otherwise the link will be an internal one.
+
+The directives in the 6c-compiled file are used according to the kind
+of final link used.
+
+In internal mode, 6l itself processes all the host object files, in
+particular foo.cgo2.o. To do so, it uses the cgo_import_dynamic and
+cgo_dynamic_linker directives to learn that the otherwise undefined
+reference to sin in foo.cgo2.o should be rewritten to refer to the
+symbol sin with version GLIBC_2.2.5 from the dynamic library
+"libm.so.6", and the binary should request "/lib/ld-linux.so.2" as its
+runtime dynamic linker.
+
+In external mode, 6l does not process any host object files, in
+particular foo.cgo2.o. It links together the 6g- and 6c-generated
+object files, along with any other Go code, into a go.o file. While
+doing that, 6l will discover that there is no definition for
+_cgo_gcc_Cfunc_sin, referred to by the 6c-compiled source file. This
+is okay, because 6l also processes the cgo_import_static directive and
+knows that _cgo_gcc_Cfunc_sin is expected to be supplied by a host
+object file, so 6l does not treat the missing symbol as an error when
+creating go.o. Indeed, the definition for _cgo_gcc_Cfunc_sin will be
+provided to the host linker by foo2.cgo.o, which in turn will need the
+symbol 'sin'. 6l also processes the cgo_ldflag directives, so that it
+knows that the eventual host link command must include the -lm
+argument, so that the host linker will be able to find 'sin' in the
+math library.
+
+6l Command Line Interface
+
+The go command and any other Go-aware build systems invoke 6l
+to link a collection of packages into a single binary. By default, 6l will
+present the same interface it does today:
+
+	6l main.a
+
+produces a file named 6.out, even if 6l does so by invoking the host
+linker in external linking mode.
+
+By default, 6l will decide the linking mode as follows: if the only
+packages using cgo are those on a whitelist of standard library
+packages (net, os/user, runtime/cgo), 6l will use internal linking
+mode. Otherwise, there are non-standard cgo packages involved, and 6l
+will use external linking mode. The first rule means that a build of
+the godoc binary, which uses net but no other cgo, can run without
+needing gcc available. The second rule means that a build of a
+cgo-wrapped library like sqlite3 can generate a standalone executable
+instead of needing to refer to a dynamic library. The specific choice
+can be overridden using a command line flag: 6l -linkmode=internal or
+6l -linkmode=external.
+
+In an external link, 6l will create a temporary directory, write any
+host object files found in package archives to that directory (renamed
+to avoid conflicts), write the go.o file to that directory, and invoke
+the host linker. The default value for the host linker is $CC, split
+into fields, or else "gcc". The specific host linker command line can
+be overridden using command line flags: 6l -extld=clang
+-extldflags='-ggdb -O3'.  If any package in a build includes a .cc or
+other file compiled by the C++ compiler, the go tool will use the
+-extld option to set the host linker to the C++ compiler.
+
+These defaults mean that Go-aware build systems can ignore the linking
+changes and keep running plain '6l' and get reasonable results, but
+they can also control the linking details if desired.
+
+*/
diff --git a/libgo/go/cmd/cgo/gcc.go b/libgo/go/cmd/cgo/gcc.go
new file mode 100644
index 0000000..f55cfba
--- /dev/null
+++ b/libgo/go/cmd/cgo/gcc.go
@@ -0,0 +1,1728 @@
+// Copyright 2009 The Go Authors.  All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Annotate Ref in Prog with C types by parsing gcc debug output.
+// Conversion of debug output to Go types.
+
+package main
+
+import (
+	"bytes"
+	"debug/dwarf"
+	"debug/elf"
+	"debug/macho"
+	"debug/pe"
+	"encoding/binary"
+	"errors"
+	"flag"
+	"fmt"
+	"go/ast"
+	"go/parser"
+	"go/token"
+	"os"
+	"strconv"
+	"strings"
+	"unicode"
+	"unicode/utf8"
+)
+
+var debugDefine = flag.Bool("debug-define", false, "print relevant #defines")
+var debugGcc = flag.Bool("debug-gcc", false, "print gcc invocations")
+
+var nameToC = map[string]string{
+	"schar":         "signed char",
+	"uchar":         "unsigned char",
+	"ushort":        "unsigned short",
+	"uint":          "unsigned int",
+	"ulong":         "unsigned long",
+	"longlong":      "long long",
+	"ulonglong":     "unsigned long long",
+	"complexfloat":  "float complex",
+	"complexdouble": "double complex",
+}
+
+// cname returns the C name to use for C.s.
+// The expansions are listed in nameToC and also
+// struct_foo becomes "struct foo", and similarly for
+// union and enum.
+func cname(s string) string {
+	if t, ok := nameToC[s]; ok {
+		return t
+	}
+
+	if strings.HasPrefix(s, "struct_") {
+		return "struct " + s[len("struct_"):]
+	}
+	if strings.HasPrefix(s, "union_") {
+		return "union " + s[len("union_"):]
+	}
+	if strings.HasPrefix(s, "enum_") {
+		return "enum " + s[len("enum_"):]
+	}
+	if strings.HasPrefix(s, "sizeof_") {
+		return "sizeof(" + cname(s[len("sizeof_"):]) + ")"
+	}
+	return s
+}
+
+// DiscardCgoDirectives processes the import C preamble, and discards
+// all #cgo CFLAGS and LDFLAGS directives, so they don't make their
+// way into _cgo_export.h.
+func (f *File) DiscardCgoDirectives() {
+	linesIn := strings.Split(f.Preamble, "\n")
+	linesOut := make([]string, 0, len(linesIn))
+	for _, line := range linesIn {
+		l := strings.TrimSpace(line)
+		if len(l) < 5 || l[:4] != "#cgo" || !unicode.IsSpace(rune(l[4])) {
+			linesOut = append(linesOut, line)
+		} else {
+			linesOut = append(linesOut, "")
+		}
+	}
+	f.Preamble = strings.Join(linesOut, "\n")
+}
+
+// addToFlag appends args to flag.  All flags are later written out onto the
+// _cgo_flags file for the build system to use.
+func (p *Package) addToFlag(flag string, args []string) {
+	p.CgoFlags[flag] = append(p.CgoFlags[flag], args...)
+	if flag == "CFLAGS" {
+		// We'll also need these when preprocessing for dwarf information.
+		p.GccOptions = append(p.GccOptions, args...)
+	}
+}
+
+// splitQuoted splits the string s around each instance of one or more consecutive
+// white space characters while taking into account quotes and escaping, and
+// returns an array of substrings of s or an empty list if s contains only white space.
+// Single quotes and double quotes are recognized to prevent splitting within the
+// quoted region, and are removed from the resulting substrings. If a quote in s
+// isn't closed err will be set and r will have the unclosed argument as the
+// last element.  The backslash is used for escaping.
+//
+// For example, the following string:
+//
+//     `a b:"c d" 'e''f'  "g\""`
+//
+// Would be parsed as:
+//
+//     []string{"a", "b:c d", "ef", `g"`}
+//
+func splitQuoted(s string) (r []string, err error) {
+	var args []string
+	arg := make([]rune, len(s))
+	escaped := false
+	quoted := false
+	quote := '\x00'
+	i := 0
+	for _, r := range s {
+		switch {
+		case escaped:
+			escaped = false
+		case r == '\\':
+			escaped = true
+			continue
+		case quote != 0:
+			if r == quote {
+				quote = 0
+				continue
+			}
+		case r == '"' || r == '\'':
+			quoted = true
+			quote = r
+			continue
+		case unicode.IsSpace(r):
+			if quoted || i > 0 {
+				quoted = false
+				args = append(args, string(arg[:i]))
+				i = 0
+			}
+			continue
+		}
+		arg[i] = r
+		i++
+	}
+	if quoted || i > 0 {
+		args = append(args, string(arg[:i]))
+	}
+	if quote != 0 {
+		err = errors.New("unclosed quote")
+	} else if escaped {
+		err = errors.New("unfinished escaping")
+	}
+	return args, err
+}
+
+var safeBytes = []byte(`+-.,/0123456789:=ABCDEFGHIJKLMNOPQRSTUVWXYZ\_abcdefghijklmnopqrstuvwxyz`)
+
+func safeName(s string) bool {
+	if s == "" {
+		return false
+	}
+	for i := 0; i < len(s); i++ {
+		if c := s[i]; c < 0x80 && bytes.IndexByte(safeBytes, c) < 0 {
+			return false
+		}
+	}
+	return true
+}
+
+// Translate rewrites f.AST, the original Go input, to remove
+// references to the imported package C, replacing them with
+// references to the equivalent Go types, functions, and variables.
+func (p *Package) Translate(f *File) {
+	for _, cref := range f.Ref {
+		// Convert C.ulong to C.unsigned long, etc.
+		cref.Name.C = cname(cref.Name.Go)
+	}
+	p.loadDefines(f)
+	needType := p.guessKinds(f)
+	if len(needType) > 0 {
+		p.loadDWARF(f, needType)
+	}
+	p.rewriteRef(f)
+}
+
+// loadDefines coerces gcc into spitting out the #defines in use
+// in the file f and saves relevant renamings in f.Name[name].Define.
+func (p *Package) loadDefines(f *File) {
+	var b bytes.Buffer
+	b.WriteString(f.Preamble)
+	b.WriteString(builtinProlog)
+	stdout := p.gccDefines(b.Bytes())
+
+	for _, line := range strings.Split(stdout, "\n") {
+		if len(line) < 9 || line[0:7] != "#define" {
+			continue
+		}
+
+		line = strings.TrimSpace(line[8:])
+
+		var key, val string
+		spaceIndex := strings.Index(line, " ")
+		tabIndex := strings.Index(line, "\t")
+
+		if spaceIndex == -1 && tabIndex == -1 {
+			continue
+		} else if tabIndex == -1 || (spaceIndex != -1 && spaceIndex < tabIndex) {
+			key = line[0:spaceIndex]
+			val = strings.TrimSpace(line[spaceIndex:])
+		} else {
+			key = line[0:tabIndex]
+			val = strings.TrimSpace(line[tabIndex:])
+		}
+
+		if n := f.Name[key]; n != nil {
+			if *debugDefine {
+				fmt.Fprintf(os.Stderr, "#define %s %s\n", key, val)
+			}
+			n.Define = val
+		}
+	}
+}
+
+// guessKinds tricks gcc into revealing the kind of each
+// name xxx for the references C.xxx in the Go input.
+// The kind is either a constant, type, or variable.
+func (p *Package) guessKinds(f *File) []*Name {
+	// Determine kinds for names we already know about,
+	// like #defines or 'struct foo', before bothering with gcc.
+	var names, needType []*Name
+	for _, n := range f.Name {
+		// If we've already found this name as a #define
+		// and we can translate it as a constant value, do so.
+		if n.Define != "" {
+			isConst := false
+			if _, err := strconv.Atoi(n.Define); err == nil {
+				isConst = true
+			} else if n.Define[0] == '"' || n.Define[0] == '\'' {
+				if _, err := parser.ParseExpr(n.Define); err == nil {
+					isConst = true
+				}
+			}
+			if isConst {
+				n.Kind = "const"
+				// Turn decimal into hex, just for consistency
+				// with enum-derived constants.  Otherwise
+				// in the cgo -godefs output half the constants
+				// are in hex and half are in whatever the #define used.
+				i, err := strconv.ParseInt(n.Define, 0, 64)
+				if err == nil {
+					n.Const = fmt.Sprintf("%#x", i)
+				} else {
+					n.Const = n.Define
+				}
+				continue
+			}
+
+			if isName(n.Define) {
+				n.C = n.Define
+			}
+		}
+
+		needType = append(needType, n)
+
+		// If this is a struct, union, or enum type name, no need to guess the kind.
+		if strings.HasPrefix(n.C, "struct ") || strings.HasPrefix(n.C, "union ") || strings.HasPrefix(n.C, "enum ") {
+			n.Kind = "type"
+			continue
+		}
+
+		// Otherwise, we'll need to find out from gcc.
+		names = append(names, n)
+	}
+
+	// Bypass gcc if there's nothing left to find out.
+	if len(names) == 0 {
+		return needType
+	}
+
+	// Coerce gcc into telling us whether each name is a type, a value, or undeclared.
+	// For names, find out whether they are integer constants.
+	// We used to look at specific warning or error messages here, but that tied the
+	// behavior too closely to specific versions of the compilers.
+	// Instead, arrange that we can infer what we need from only the presence or absence
+	// of an error on a specific line.
+	//
+	// For each name, we generate these lines, where xxx is the index in toSniff plus one.
+	//
+	//	#line xxx "not-declared"
+	//	void __cgo_f_xxx_1(void) { __typeof__(name) *__cgo_undefined__; }
+	//	#line xxx "not-type"
+	//	void __cgo_f_xxx_2(void) { name *__cgo_undefined__; }
+	//	#line xxx "not-const"
+	//	void __cgo_f_xxx_3(void) { enum { __cgo_undefined__ = (name)*1 }; }
+	//
+	// If we see an error at not-declared:xxx, the corresponding name is not declared.
+	// If we see an error at not-type:xxx, the corresponding name is a type.
+	// If we see an error at not-const:xxx, the corresponding name is not an integer constant.
+	// If we see no errors, we assume the name is an expression but not a constant
+	// (so a variable or a function).
+	//
+	// The specific input forms are chosen so that they are valid C syntax regardless of
+	// whether name denotes a type or an expression.
+
+	var b bytes.Buffer
+	b.WriteString(f.Preamble)
+	b.WriteString(builtinProlog)
+
+	for i, n := range names {
+		fmt.Fprintf(&b, "#line %d \"not-declared\"\n"+
+			"void __cgo_f_%d_1(void) { __typeof__(%s) *__cgo_undefined__; }\n"+
+			"#line %d \"not-type\"\n"+
+			"void __cgo_f_%d_2(void) { %s *__cgo_undefined__; }\n"+
+			"#line %d \"not-const\"\n"+
+			"void __cgo_f_%d_3(void) { enum { __cgo__undefined__ = (%s)*1 }; }\n",
+			i+1, i+1, n.C,
+			i+1, i+1, n.C,
+			i+1, i+1, n.C)
+	}
+	fmt.Fprintf(&b, "#line 1 \"completed\"\n"+
+		"int __cgo__1 = __cgo__2;\n")
+
+	stderr := p.gccErrors(b.Bytes())
+	if stderr == "" {
+		fatalf("%s produced no output\non input:\n%s", p.gccBaseCmd()[0], b.Bytes())
+	}
+
+	completed := false
+	sniff := make([]int, len(names))
+	const (
+		notType = 1 << iota
+		notConst
+	)
+	for _, line := range strings.Split(stderr, "\n") {
+		if !strings.Contains(line, ": error:") {
+			// we only care about errors.
+			// we tried to turn off warnings on the command line, but one never knows.
+			continue
+		}
+
+		c1 := strings.Index(line, ":")
+		if c1 < 0 {
+			continue
+		}
+		c2 := strings.Index(line[c1+1:], ":")
+		if c2 < 0 {
+			continue
+		}
+		c2 += c1 + 1
+
+		filename := line[:c1]
+		i, _ := strconv.Atoi(line[c1+1 : c2])
+		i--
+		if i < 0 || i >= len(names) {
+			continue
+		}
+
+		switch filename {
+		case "completed":
+			// Strictly speaking, there is no guarantee that seeing the error at completed:1
+			// (at the end of the file) means we've seen all the errors from earlier in the file,
+			// but usually it does. Certainly if we don't see the completed:1 error, we did
+			// not get all the errors we expected.
+			completed = true
+
+		case "not-declared":
+			error_(token.NoPos, "%s", strings.TrimSpace(line[c2+1:]))
+		case "not-type":
+			sniff[i] |= notType
+		case "not-const":
+			sniff[i] |= notConst
+		}
+	}
+
+	if !completed {
+		fatalf("%s did not produce error at completed:1\non input:\n%s", p.gccBaseCmd()[0], b.Bytes())
+	}
+
+	for i, n := range names {
+		switch sniff[i] {
+		case 0:
+			error_(token.NoPos, "could not determine kind of name for C.%s", fixGo(n.Go))
+		case notType:
+			n.Kind = "const"
+		case notConst:
+			n.Kind = "type"
+		case notConst | notType:
+			n.Kind = "not-type"
+		}
+	}
+	if nerrors > 0 {
+		fatalf("unresolved names")
+	}
+
+	needType = append(needType, names...)
+	return needType
+}
+
+// loadDWARF parses the DWARF debug information generated
+// by gcc to learn the details of the constants, variables, and types
+// being referred to as C.xxx.
+func (p *Package) loadDWARF(f *File, names []*Name) {
+	// Extract the types from the DWARF section of an object
+	// from a well-formed C program.  Gcc only generates DWARF info
+	// for symbols in the object file, so it is not enough to print the
+	// preamble and hope the symbols we care about will be there.
+	// Instead, emit
+	//	__typeof__(names[i]) *__cgo__i;
+	// for each entry in names and then dereference the type we
+	// learn for __cgo__i.
+	var b bytes.Buffer
+	b.WriteString(f.Preamble)
+	b.WriteString(builtinProlog)
+	for i, n := range names {
+		fmt.Fprintf(&b, "__typeof__(%s) *__cgo__%d;\n", n.C, i)
+		if n.Kind == "const" {
+			fmt.Fprintf(&b, "enum { __cgo_enum__%d = %s };\n", i, n.C)
+		}
+	}
+
+	// Apple's LLVM-based gcc does not include the enumeration
+	// names and values in its DWARF debug output.  In case we're
+	// using such a gcc, create a data block initialized with the values.
+	// We can read them out of the object file.
+	fmt.Fprintf(&b, "long long __cgodebug_data[] = {\n")
+	for _, n := range names {
+		if n.Kind == "const" {
+			fmt.Fprintf(&b, "\t%s,\n", n.C)
+		} else {
+			fmt.Fprintf(&b, "\t0,\n")
+		}
+	}
+	// for the last entry, we can not use 0, otherwise
+	// in case all __cgodebug_data is zero initialized,
+	// LLVM-based gcc will place the it in the __DATA.__common
+	// zero-filled section (our debug/macho doesn't support
+	// this)
+	fmt.Fprintf(&b, "\t1\n")
+	fmt.Fprintf(&b, "};\n")
+
+	d, bo, debugData := p.gccDebug(b.Bytes())
+	enumVal := make([]int64, len(debugData)/8)
+	for i := range enumVal {
+		enumVal[i] = int64(bo.Uint64(debugData[i*8:]))
+	}
+
+	// Scan DWARF info for top-level TagVariable entries with AttrName __cgo__i.
+	types := make([]dwarf.Type, len(names))
+	enums := make([]dwarf.Offset, len(names))
+	nameToIndex := make(map[*Name]int)
+	for i, n := range names {
+		nameToIndex[n] = i
+	}
+	nameToRef := make(map[*Name]*Ref)
+	for _, ref := range f.Ref {
+		nameToRef[ref.Name] = ref
+	}
+	r := d.Reader()
+	for {
+		e, err := r.Next()
+		if err != nil {
+			fatalf("reading DWARF entry: %s", err)
+		}
+		if e == nil {
+			break
+		}
+		switch e.Tag {
+		case dwarf.TagEnumerationType:
+			offset := e.Offset
+			for {
+				e, err := r.Next()
+				if err != nil {
+					fatalf("reading DWARF entry: %s", err)
+				}
+				if e.Tag == 0 {
+					break
+				}
+				if e.Tag == dwarf.TagEnumerator {
+					entryName := e.Val(dwarf.AttrName).(string)
+					if strings.HasPrefix(entryName, "__cgo_enum__") {
+						n, _ := strconv.Atoi(entryName[len("__cgo_enum__"):])
+						if 0 <= n && n < len(names) {
+							enums[n] = offset
+						}
+					}
+				}
+			}
+		case dwarf.TagVariable:
+			name, _ := e.Val(dwarf.AttrName).(string)
+			typOff, _ := e.Val(dwarf.AttrType).(dwarf.Offset)
+			if name == "" || typOff == 0 {
+				fatalf("malformed DWARF TagVariable entry")
+			}
+			if !strings.HasPrefix(name, "__cgo__") {
+				break
+			}
+			typ, err := d.Type(typOff)
+			if err != nil {
+				fatalf("loading DWARF type: %s", err)
+			}
+			t, ok := typ.(*dwarf.PtrType)
+			if !ok || t == nil {
+				fatalf("internal error: %s has non-pointer type", name)
+			}
+			i, err := strconv.Atoi(name[7:])
+			if err != nil {
+				fatalf("malformed __cgo__ name: %s", name)
+			}
+			if enums[i] != 0 {
+				t, err := d.Type(enums[i])
+				if err != nil {
+					fatalf("loading DWARF type: %s", err)
+				}
+				types[i] = t
+			} else {
+				types[i] = t.Type
+			}
+		}
+		if e.Tag != dwarf.TagCompileUnit {
+			r.SkipChildren()
+		}
+	}
+
+	// Record types and typedef information.
+	var conv typeConv
+	conv.Init(p.PtrSize, p.IntSize)
+	for i, n := range names {
+		if types[i] == nil {
+			continue
+		}
+		pos := token.NoPos
+		if ref, ok := nameToRef[n]; ok {
+			pos = ref.Pos()
+		}
+		f, fok := types[i].(*dwarf.FuncType)
+		if n.Kind != "type" && fok {
+			n.Kind = "func"
+			n.FuncType = conv.FuncType(f, pos)
+		} else {
+			n.Type = conv.Type(types[i], pos)
+			if enums[i] != 0 && n.Type.EnumValues != nil {
+				k := fmt.Sprintf("__cgo_enum__%d", i)
+				n.Kind = "const"
+				n.Const = fmt.Sprintf("%#x", n.Type.EnumValues[k])
+				// Remove injected enum to ensure the value will deep-compare
+				// equally in future loads of the same constant.
+				delete(n.Type.EnumValues, k)
+			}
+			// Prefer debug data over DWARF debug output, if we have it.
+			if n.Kind == "const" && i < len(enumVal) {
+				n.Const = fmt.Sprintf("%#x", enumVal[i])
+			}
+		}
+		conv.FinishType(pos)
+	}
+}
+
+// mangleName does name mangling to translate names
+// from the original Go source files to the names
+// used in the final Go files generated by cgo.
+func (p *Package) mangleName(n *Name) {
+	// When using gccgo variables have to be
+	// exported so that they become global symbols
+	// that the C code can refer to.
+	prefix := "_C"
+	if *gccgo && n.IsVar() {
+		prefix = "C"
+	}
+	n.Mangle = prefix + n.Kind + "_" + n.Go
+}
+
+// rewriteRef rewrites all the C.xxx references in f.AST to refer to the
+// Go equivalents, now that we have figured out the meaning of all
+// the xxx.  In *godefs or *cdefs mode, rewriteRef replaces the names
+// with full definitions instead of mangled names.
+func (p *Package) rewriteRef(f *File) {
+	// Keep a list of all the functions, to remove the ones
+	// only used as expressions and avoid generating bridge
+	// code for them.
+	functions := make(map[string]bool)
+
+	// Assign mangled names.
+	for _, n := range f.Name {
+		if n.Kind == "not-type" {
+			n.Kind = "var"
+		}
+		if n.Mangle == "" {
+			p.mangleName(n)
+		}
+		if n.Kind == "func" {
+			functions[n.Go] = false
+		}
+	}
+
+	// Now that we have all the name types filled in,
+	// scan through the Refs to identify the ones that
+	// are trying to do a ,err call.  Also check that
+	// functions are only used in calls.
+	for _, r := range f.Ref {
+		if r.Name.Kind == "const" && r.Name.Const == "" {
+			error_(r.Pos(), "unable to find value of constant C.%s", fixGo(r.Name.Go))
+		}
+		var expr ast.Expr = ast.NewIdent(r.Name.Mangle) // default
+		switch r.Context {
+		case "call", "call2":
+			if r.Name.Kind != "func" {
+				if r.Name.Kind == "type" {
+					r.Context = "type"
+					expr = r.Name.Type.Go
+					break
+				}
+				error_(r.Pos(), "call of non-function C.%s", fixGo(r.Name.Go))
+				break
+			}
+			functions[r.Name.Go] = true
+			if r.Context == "call2" {
+				if r.Name.Go == "_CMalloc" {
+					error_(r.Pos(), "no two-result form for C.malloc")
+					break
+				}
+				// Invent new Name for the two-result function.
+				n := f.Name["2"+r.Name.Go]
+				if n == nil {
+					n = new(Name)
+					*n = *r.Name
+					n.AddError = true
+					n.Mangle = "_C2func_" + n.Go
+					f.Name["2"+r.Name.Go] = n
+				}
+				expr = ast.NewIdent(n.Mangle)
+				r.Name = n
+				break
+			}
+		case "expr":
+			if r.Name.Kind == "func" {
+				// Function is being used in an expression, to e.g. pass around a C function pointer.
+				// Create a new Name for this Ref which causes the variable to be declared in Go land.
+				fpName := "fp_" + r.Name.Go
+				name := f.Name[fpName]
+				if name == nil {
+					name = &Name{
+						Go:   fpName,
+						C:    r.Name.C,
+						Kind: "fpvar",
+						Type: &Type{Size: p.PtrSize, Align: p.PtrSize, C: c("void*"), Go: ast.NewIdent("unsafe.Pointer")},
+					}
+					p.mangleName(name)
+					f.Name[fpName] = name
+				}
+				r.Name = name
+				expr = ast.NewIdent(name.Mangle)
+			} else if r.Name.Kind == "type" {
+				// Okay - might be new(T)
+				expr = r.Name.Type.Go
+			} else if r.Name.Kind == "var" {
+				expr = &ast.StarExpr{Star: (*r.Expr).Pos(), X: expr}
+			}
+
+		case "type":
+			if r.Name.Kind != "type" {
+				error_(r.Pos(), "expression C.%s used as type", fixGo(r.Name.Go))
+			} else if r.Name.Type == nil {
+				// Use of C.enum_x, C.struct_x or C.union_x without C definition.
+				// GCC won't raise an error when using pointers to such unknown types.
+				error_(r.Pos(), "type C.%s: undefined C type '%s'", fixGo(r.Name.Go), r.Name.C)
+			} else {
+				expr = r.Name.Type.Go
+			}
+		default:
+			if r.Name.Kind == "func" {
+				error_(r.Pos(), "must call C.%s", fixGo(r.Name.Go))
+			}
+		}
+		if *godefs || *cdefs {
+			// Substitute definition for mangled type name.
+			if id, ok := expr.(*ast.Ident); ok {
+				if t := typedef[id.Name]; t != nil {
+					expr = t.Go
+				}
+				if id.Name == r.Name.Mangle && r.Name.Const != "" {
+					expr = ast.NewIdent(r.Name.Const)
+				}
+			}
+		}
+
+		// Copy position information from old expr into new expr,
+		// in case expression being replaced is first on line.
+		// See golang.org/issue/6563.
+		pos := (*r.Expr).Pos()
+		switch x := expr.(type) {
+		case *ast.Ident:
+			expr = &ast.Ident{NamePos: pos, Name: x.Name}
+		}
+
+		*r.Expr = expr
+	}
+
+	// Remove functions only used as expressions, so their respective
+	// bridge functions are not generated.
+	for name, used := range functions {
+		if !used {
+			delete(f.Name, name)
+		}
+	}
+}
+
+// gccBaseCmd returns the start of the compiler command line.
+// It uses $CC if set, or else $GCC, or else the compiler recorded
+// during the initial build as defaultCC.
+// defaultCC is defined in zdefaultcc.go, written by cmd/dist.
+func (p *Package) gccBaseCmd() []string {
+	// Use $CC if set, since that's what the build uses.
+	if ret := strings.Fields(os.Getenv("CC")); len(ret) > 0 {
+		return ret
+	}
+	// Try $GCC if set, since that's what we used to use.
+	if ret := strings.Fields(os.Getenv("GCC")); len(ret) > 0 {
+		return ret
+	}
+	return strings.Fields(defaultCC)
+}
+
+// gccMachine returns the gcc -m flag to use, either "-m32", "-m64" or "-marm".
+func (p *Package) gccMachine() []string {
+	switch goarch {
+	case "amd64":
+		return []string{"-m64"}
+	case "386":
+		return []string{"-m32"}
+	case "arm":
+		return []string{"-marm"} // not thumb
+	}
+	return nil
+}
+
+func gccTmp() string {
+	return *objDir + "_cgo_.o"
+}
+
+// gccCmd returns the gcc command line to use for compiling
+// the input.
+func (p *Package) gccCmd() []string {
+	c := append(p.gccBaseCmd(),
+		"-w",          // no warnings
+		"-Wno-error",  // warnings are not errors
+		"-o"+gccTmp(), // write object to tmp
+		"-gdwarf-2",   // generate DWARF v2 debugging symbols
+		"-c",          // do not link
+		"-xc",         // input language is C
+	)
+	if strings.Contains(c[0], "clang") {
+		c = append(c,
+			"-ferror-limit=0",
+			// Apple clang version 1.7 (tags/Apple/clang-77) (based on LLVM 2.9svn)
+			// doesn't have -Wno-unneeded-internal-declaration, so we need yet another
+			// flag to disable the warning. Yes, really good diagnostics, clang.
+			"-Wno-unknown-warning-option",
+			"-Wno-unneeded-internal-declaration",
+			"-Wno-unused-function",
+			"-Qunused-arguments",
+			// Clang embeds prototypes for some builtin functions,
+			// like malloc and calloc, but all size_t parameters are
+			// incorrectly typed unsigned long. We work around that
+			// by disabling the builtin functions (this is safe as
+			// it won't affect the actual compilation of the C code).
+			// See: http://golang.org/issue/6506.
+			"-fno-builtin",
+		)
+	}
+
+	c = append(c, p.GccOptions...)
+	c = append(c, p.gccMachine()...)
+	c = append(c, "-") //read input from standard input
+	return c
+}
+
+// gccDebug runs gcc -gdwarf-2 over the C program stdin and
+// returns the corresponding DWARF data and, if present, debug data block.
+func (p *Package) gccDebug(stdin []byte) (*dwarf.Data, binary.ByteOrder, []byte) {
+	runGcc(stdin, p.gccCmd())
+
+	isDebugData := func(s string) bool {
+		// Some systems use leading _ to denote non-assembly symbols.
+		return s == "__cgodebug_data" || s == "___cgodebug_data"
+	}
+
+	if f, err := macho.Open(gccTmp()); err == nil {
+		defer f.Close()
+		d, err := f.DWARF()
+		if err != nil {
+			fatalf("cannot load DWARF output from %s: %v", gccTmp(), err)
+		}
+		var data []byte
+		if f.Symtab != nil {
+			for i := range f.Symtab.Syms {
+				s := &f.Symtab.Syms[i]
+				if isDebugData(s.Name) {
+					// Found it.  Now find data section.
+					if i := int(s.Sect) - 1; 0 <= i && i < len(f.Sections) {
+						sect := f.Sections[i]
+						if sect.Addr <= s.Value && s.Value < sect.Addr+sect.Size {
+							if sdat, err := sect.Data(); err == nil {
+								data = sdat[s.Value-sect.Addr:]
+							}
+						}
+					}
+				}
+			}
+		}
+		return d, f.ByteOrder, data
+	}
+
+	if f, err := elf.Open(gccTmp()); err == nil {
+		defer f.Close()
+		d, err := f.DWARF()
+		if err != nil {
+			fatalf("cannot load DWARF output from %s: %v", gccTmp(), err)
+		}
+		var data []byte
+		symtab, err := f.Symbols()
+		if err == nil {
+			for i := range symtab {
+				s := &symtab[i]
+				if isDebugData(s.Name) {
+					// Found it.  Now find data section.
+					if i := int(s.Section); 0 <= i && i < len(f.Sections) {
+						sect := f.Sections[i]
+						if sect.Addr <= s.Value && s.Value < sect.Addr+sect.Size {
+							if sdat, err := sect.Data(); err == nil {
+								data = sdat[s.Value-sect.Addr:]
+							}
+						}
+					}
+				}
+			}
+		}
+		return d, f.ByteOrder, data
+	}
+
+	if f, err := pe.Open(gccTmp()); err == nil {
+		defer f.Close()
+		d, err := f.DWARF()
+		if err != nil {
+			fatalf("cannot load DWARF output from %s: %v", gccTmp(), err)
+		}
+		var data []byte
+		for _, s := range f.Symbols {
+			if isDebugData(s.Name) {
+				if i := int(s.SectionNumber) - 1; 0 <= i && i < len(f.Sections) {
+					sect := f.Sections[i]
+					if s.Value < sect.Size {
+						if sdat, err := sect.Data(); err == nil {
+							data = sdat[s.Value:]
+						}
+					}
+				}
+			}
+		}
+		return d, binary.LittleEndian, data
+	}
+
+	fatalf("cannot parse gcc output %s as ELF, Mach-O, PE object", gccTmp())
+	panic("not reached")
+}
+
+// gccDefines runs gcc -E -dM -xc - over the C program stdin
+// and returns the corresponding standard output, which is the
+// #defines that gcc encountered while processing the input
+// and its included files.
+func (p *Package) gccDefines(stdin []byte) string {
+	base := append(p.gccBaseCmd(), "-E", "-dM", "-xc")
+	base = append(base, p.gccMachine()...)
+	stdout, _ := runGcc(stdin, append(append(base, p.GccOptions...), "-"))
+	return stdout
+}
+
+// gccErrors runs gcc over the C program stdin and returns
+// the errors that gcc prints.  That is, this function expects
+// gcc to fail.
+func (p *Package) gccErrors(stdin []byte) string {
+	// TODO(rsc): require failure
+	args := p.gccCmd()
+
+	if *debugGcc {
+		fmt.Fprintf(os.Stderr, "$ %s <<EOF\n", strings.Join(args, " "))
+		os.Stderr.Write(stdin)
+		fmt.Fprint(os.Stderr, "EOF\n")
+	}
+	stdout, stderr, _ := run(stdin, args)
+	if *debugGcc {
+		os.Stderr.Write(stdout)
+		os.Stderr.Write(stderr)
+	}
+	return string(stderr)
+}
+
+// runGcc runs the gcc command line args with stdin on standard input.
+// If the command exits with a non-zero exit status, runGcc prints
+// details about what was run and exits.
+// Otherwise runGcc returns the data written to standard output and standard error.
+// Note that for some of the uses we expect useful data back
+// on standard error, but for those uses gcc must still exit 0.
+func runGcc(stdin []byte, args []string) (string, string) {
+	if *debugGcc {
+		fmt.Fprintf(os.Stderr, "$ %s <<EOF\n", strings.Join(args, " "))
+		os.Stderr.Write(stdin)
+		fmt.Fprint(os.Stderr, "EOF\n")
+	}
+	stdout, stderr, ok := run(stdin, args)
+	if *debugGcc {
+		os.Stderr.Write(stdout)
+		os.Stderr.Write(stderr)
+	}
+	if !ok {
+		os.Stderr.Write(stderr)
+		os.Exit(2)
+	}
+	return string(stdout), string(stderr)
+}
+
+// A typeConv is a translator from dwarf types to Go types
+// with equivalent memory layout.
+type typeConv struct {
+	// Cache of already-translated or in-progress types.
+	m       map[dwarf.Type]*Type
+	typedef map[string]ast.Expr
+
+	// Map from types to incomplete pointers to those types.
+	ptrs map[dwarf.Type][]*Type
+
+	// Fields to be processed by godefsField after completing pointers.
+	todoFlds [][]*ast.Field
+
+	// Predeclared types.
+	bool                                   ast.Expr
+	byte                                   ast.Expr // denotes padding
+	int8, int16, int32, int64              ast.Expr
+	uint8, uint16, uint32, uint64, uintptr ast.Expr
+	float32, float64                       ast.Expr
+	complex64, complex128                  ast.Expr
+	void                                   ast.Expr
+	unsafePointer                          ast.Expr
+	string                                 ast.Expr
+	goVoid                                 ast.Expr // _Ctype_void, denotes C's void
+
+	ptrSize int64
+	intSize int64
+}
+
+var tagGen int
+var typedef = make(map[string]*Type)
+var goIdent = make(map[string]*ast.Ident)
+
+func (c *typeConv) Init(ptrSize, intSize int64) {
+	c.ptrSize = ptrSize
+	c.intSize = intSize
+	c.m = make(map[dwarf.Type]*Type)
+	c.ptrs = make(map[dwarf.Type][]*Type)
+	c.bool = c.Ident("bool")
+	c.byte = c.Ident("byte")
+	c.int8 = c.Ident("int8")
+	c.int16 = c.Ident("int16")
+	c.int32 = c.Ident("int32")
+	c.int64 = c.Ident("int64")
+	c.uint8 = c.Ident("uint8")
+	c.uint16 = c.Ident("uint16")
+	c.uint32 = c.Ident("uint32")
+	c.uint64 = c.Ident("uint64")
+	c.uintptr = c.Ident("uintptr")
+	c.float32 = c.Ident("float32")
+	c.float64 = c.Ident("float64")
+	c.complex64 = c.Ident("complex64")
+	c.complex128 = c.Ident("complex128")
+	c.unsafePointer = c.Ident("unsafe.Pointer")
+	c.void = c.Ident("void")
+	c.string = c.Ident("string")
+	c.goVoid = c.Ident("_Ctype_void")
+}
+
+// base strips away qualifiers and typedefs to get the underlying type
+func base(dt dwarf.Type) dwarf.Type {
+	for {
+		if d, ok := dt.(*dwarf.QualType); ok {
+			dt = d.Type
+			continue
+		}
+		if d, ok := dt.(*dwarf.TypedefType); ok {
+			dt = d.Type
+			continue
+		}
+		break
+	}
+	return dt
+}
+
+// Map from dwarf text names to aliases we use in package "C".
+var dwarfToName = map[string]string{
+	"long int":               "long",
+	"long unsigned int":      "ulong",
+	"unsigned int":           "uint",
+	"short unsigned int":     "ushort",
+	"short int":              "short",
+	"long long int":          "longlong",
+	"long long unsigned int": "ulonglong",
+	"signed char":            "schar",
+	"float complex":          "complexfloat",
+	"double complex":         "complexdouble",
+}
+
+const signedDelta = 64
+
+// String returns the current type representation.  Format arguments
+// are assembled within this method so that any changes in mutable
+// values are taken into account.
+func (tr *TypeRepr) String() string {
+	if len(tr.Repr) == 0 {
+		return ""
+	}
+	if len(tr.FormatArgs) == 0 {
+		return tr.Repr
+	}
+	return fmt.Sprintf(tr.Repr, tr.FormatArgs...)
+}
+
+// Empty returns true if the result of String would be "".
+func (tr *TypeRepr) Empty() bool {
+	return len(tr.Repr) == 0
+}
+
+// Set modifies the type representation.
+// If fargs are provided, repr is used as a format for fmt.Sprintf.
+// Otherwise, repr is used unprocessed as the type representation.
+func (tr *TypeRepr) Set(repr string, fargs ...interface{}) {
+	tr.Repr = repr
+	tr.FormatArgs = fargs
+}
+
+// FinishType completes any outstanding type mapping work.
+// In particular, it resolves incomplete pointer types and also runs
+// godefsFields on any new struct types.
+func (c *typeConv) FinishType(pos token.Pos) {
+	// Completing one pointer type might produce more to complete.
+	// Keep looping until they're all done.
+	for len(c.ptrs) > 0 {
+		for dtype := range c.ptrs {
+			// Note Type might invalidate c.ptrs[dtype].
+			t := c.Type(dtype, pos)
+			for _, ptr := range c.ptrs[dtype] {
+				ptr.Go.(*ast.StarExpr).X = t.Go
+				ptr.C.Set("%s*", t.C)
+			}
+			delete(c.ptrs, dtype)
+		}
+	}
+
+	// Now that pointer types are completed, we can invoke godefsFields
+	// to rewrite struct definitions.
+	for _, fld := range c.todoFlds {
+		godefsFields(fld)
+	}
+	c.todoFlds = nil
+}
+
+// Type returns a *Type with the same memory layout as
+// dtype when used as the type of a variable or a struct field.
+func (c *typeConv) Type(dtype dwarf.Type, pos token.Pos) *Type {
+	if t, ok := c.m[dtype]; ok {
+		if t.Go == nil {
+			fatalf("%s: type conversion loop at %s", lineno(pos), dtype)
+		}
+		return t
+	}
+
+	// clang won't generate DW_AT_byte_size for pointer types,
+	// so we have to fix it here.
+	if dt, ok := base(dtype).(*dwarf.PtrType); ok && dt.ByteSize == -1 {
+		dt.ByteSize = c.ptrSize
+	}
+
+	t := new(Type)
+	t.Size = dtype.Size() // note: wrong for array of pointers, corrected below
+	t.Align = -1
+	t.C = &TypeRepr{Repr: dtype.Common().Name}
+	c.m[dtype] = t
+
+	switch dt := dtype.(type) {
+	default:
+		fatalf("%s: unexpected type: %s", lineno(pos), dtype)
+
+	case *dwarf.AddrType:
+		if t.Size != c.ptrSize {
+			fatalf("%s: unexpected: %d-byte address type - %s", lineno(pos), t.Size, dtype)
+		}
+		t.Go = c.uintptr
+		t.Align = t.Size
+
+	case *dwarf.ArrayType:
+		if dt.StrideBitSize > 0 {
+			// Cannot represent bit-sized elements in Go.
+			t.Go = c.Opaque(t.Size)
+			break
+		}
+		sub := c.Type(dt.Type, pos)
+		t.Align = sub.Align
+		t.Go = &ast.ArrayType{
+			Len: c.intExpr(dt.Count),
+			Elt: sub.Go,
+		}
+		t.C.Set("__typeof__(%s[%d])", sub.C, dt.Count)
+
+	case *dwarf.BoolType:
+		t.Go = c.bool
+		t.Align = 1
+
+	case *dwarf.CharType:
+		if t.Size != 1 {
+			fatalf("%s: unexpected: %d-byte char type - %s", lineno(pos), t.Size, dtype)
+		}
+		t.Go = c.int8
+		t.Align = 1
+
+	case *dwarf.EnumType:
+		if t.Align = t.Size; t.Align >= c.ptrSize {
+			t.Align = c.ptrSize
+		}
+		t.C.Set("enum " + dt.EnumName)
+		signed := 0
+		t.EnumValues = make(map[string]int64)
+		for _, ev := range dt.Val {
+			t.EnumValues[ev.Name] = ev.Val
+			if ev.Val < 0 {
+				signed = signedDelta
+			}
+		}
+		switch t.Size + int64(signed) {
+		default:
+			fatalf("%s: unexpected: %d-byte enum type - %s", lineno(pos), t.Size, dtype)
+		case 1:
+			t.Go = c.uint8
+		case 2:
+			t.Go = c.uint16
+		case 4:
+			t.Go = c.uint32
+		case 8:
+			t.Go = c.uint64
+		case 1 + signedDelta:
+			t.Go = c.int8
+		case 2 + signedDelta:
+			t.Go = c.int16
+		case 4 + signedDelta:
+			t.Go = c.int32
+		case 8 + signedDelta:
+			t.Go = c.int64
+		}
+
+	case *dwarf.FloatType:
+		switch t.Size {
+		default:
+			fatalf("%s: unexpected: %d-byte float type - %s", lineno(pos), t.Size, dtype)
+		case 4:
+			t.Go = c.float32
+		case 8:
+			t.Go = c.float64
+		}
+		if t.Align = t.Size; t.Align >= c.ptrSize {
+			t.Align = c.ptrSize
+		}
+
+	case *dwarf.ComplexType:
+		switch t.Size {
+		default:
+			fatalf("%s: unexpected: %d-byte complex type - %s", lineno(pos), t.Size, dtype)
+		case 8:
+			t.Go = c.complex64
+		case 16:
+			t.Go = c.complex128
+		}
+		if t.Align = t.Size; t.Align >= c.ptrSize {
+			t.Align = c.ptrSize
+		}
+
+	case *dwarf.FuncType:
+		// No attempt at translation: would enable calls
+		// directly between worlds, but we need to moderate those.
+		t.Go = c.uintptr
+		t.Align = c.ptrSize
+
+	case *dwarf.IntType:
+		if dt.BitSize > 0 {
+			fatalf("%s: unexpected: %d-bit int type - %s", lineno(pos), dt.BitSize, dtype)
+		}
+		switch t.Size {
+		default:
+			fatalf("%s: unexpected: %d-byte int type - %s", lineno(pos), t.Size, dtype)
+		case 1:
+			t.Go = c.int8
+		case 2:
+			t.Go = c.int16
+		case 4:
+			t.Go = c.int32
+		case 8:
+			t.Go = c.int64
+		}
+		if t.Align = t.Size; t.Align >= c.ptrSize {
+			t.Align = c.ptrSize
+		}
+
+	case *dwarf.PtrType:
+		t.Align = c.ptrSize
+
+		// Translate void* as unsafe.Pointer
+		if _, ok := base(dt.Type).(*dwarf.VoidType); ok {
+			t.Go = c.unsafePointer
+			t.C.Set("void*")
+			break
+		}
+
+		// Placeholder initialization; completed in FinishType.
+		t.Go = &ast.StarExpr{}
+		t.C.Set("<incomplete>*")
+		c.ptrs[dt.Type] = append(c.ptrs[dt.Type], t)
+
+	case *dwarf.QualType:
+		// Ignore qualifier.
+		t = c.Type(dt.Type, pos)
+		c.m[dtype] = t
+		return t
+
+	case *dwarf.StructType:
+		// Convert to Go struct, being careful about alignment.
+		// Have to give it a name to simulate C "struct foo" references.
+		tag := dt.StructName
+		if dt.ByteSize < 0 && tag == "" { // opaque unnamed struct - should not be possible
+			break
+		}
+		if tag == "" {
+			tag = "__" + strconv.Itoa(tagGen)
+			tagGen++
+		} else if t.C.Empty() {
+			t.C.Set(dt.Kind + " " + tag)
+		}
+		name := c.Ident("_Ctype_" + dt.Kind + "_" + tag)
+		t.Go = name // publish before recursive calls
+		goIdent[name.Name] = name
+		if dt.ByteSize < 0 {
+			// Size calculation in c.Struct/c.Opaque will die with size=-1 (unknown),
+			// so execute the basic things that the struct case would do
+			// other than try to determine a Go representation.
+			tt := *t
+			tt.C = &TypeRepr{"%s %s", []interface{}{dt.Kind, tag}}
+			tt.Go = c.Ident("struct{}")
+			typedef[name.Name] = &tt
+			break
+		}
+		switch dt.Kind {
+		case "class", "union":
+			t.Go = c.Opaque(t.Size)
+			if t.C.Empty() {
+				t.C.Set("__typeof__(unsigned char[%d])", t.Size)
+			}
+			t.Align = 1 // TODO: should probably base this on field alignment.
+			typedef[name.Name] = t
+		case "struct":
+			g, csyntax, align := c.Struct(dt, pos)
+			if t.C.Empty() {
+				t.C.Set(csyntax)
+			}
+			t.Align = align
+			tt := *t
+			if tag != "" {
+				tt.C = &TypeRepr{"struct %s", []interface{}{tag}}
+			}
+			tt.Go = g
+			typedef[name.Name] = &tt
+		}
+
+	case *dwarf.TypedefType:
+		// Record typedef for printing.
+		if dt.Name == "_GoString_" {
+			// Special C name for Go string type.
+			// Knows string layout used by compilers: pointer plus length,
+			// which rounds up to 2 pointers after alignment.
+			t.Go = c.string
+			t.Size = c.ptrSize * 2
+			t.Align = c.ptrSize
+			break
+		}
+		if dt.Name == "_GoBytes_" {
+			// Special C name for Go []byte type.
+			// Knows slice layout used by compilers: pointer, length, cap.
+			t.Go = c.Ident("[]byte")
+			t.Size = c.ptrSize + 4 + 4
+			t.Align = c.ptrSize
+			break
+		}
+		name := c.Ident("_Ctype_" + dt.Name)
+		goIdent[name.Name] = name
+		sub := c.Type(dt.Type, pos)
+		t.Go = name
+		t.Size = sub.Size
+		t.Align = sub.Align
+		oldType := typedef[name.Name]
+		if oldType == nil {
+			tt := *t
+			tt.Go = sub.Go
+			typedef[name.Name] = &tt
+		}
+
+		// If sub.Go.Name is "_Ctype_struct_foo" or "_Ctype_union_foo" or "_Ctype_class_foo",
+		// use that as the Go form for this typedef too, so that the typedef will be interchangeable
+		// with the base type.
+		// In -godefs and -cdefs mode, do this for all typedefs.
+		if isStructUnionClass(sub.Go) || *godefs || *cdefs {
+			t.Go = sub.Go
+
+			if isStructUnionClass(sub.Go) {
+				// Use the typedef name for C code.
+				typedef[sub.Go.(*ast.Ident).Name].C = t.C
+			}
+
+			// If we've seen this typedef before, and it
+			// was an anonymous struct/union/class before
+			// too, use the old definition.
+			// TODO: it would be safer to only do this if
+			// we verify that the types are the same.
+			if oldType != nil && isStructUnionClass(oldType.Go) {
+				t.Go = oldType.Go
+			}
+		}
+
+	case *dwarf.UcharType:
+		if t.Size != 1 {
+			fatalf("%s: unexpected: %d-byte uchar type - %s", lineno(pos), t.Size, dtype)
+		}
+		t.Go = c.uint8
+		t.Align = 1
+
+	case *dwarf.UintType:
+		if dt.BitSize > 0 {
+			fatalf("%s: unexpected: %d-bit uint type - %s", lineno(pos), dt.BitSize, dtype)
+		}
+		switch t.Size {
+		default:
+			fatalf("%s: unexpected: %d-byte uint type - %s", lineno(pos), t.Size, dtype)
+		case 1:
+			t.Go = c.uint8
+		case 2:
+			t.Go = c.uint16
+		case 4:
+			t.Go = c.uint32
+		case 8:
+			t.Go = c.uint64
+		}
+		if t.Align = t.Size; t.Align >= c.ptrSize {
+			t.Align = c.ptrSize
+		}
+
+	case *dwarf.VoidType:
+		t.Go = c.goVoid
+		t.C.Set("void")
+		t.Align = 1
+	}
+
+	switch dtype.(type) {
+	case *dwarf.AddrType, *dwarf.BoolType, *dwarf.CharType, *dwarf.IntType, *dwarf.FloatType, *dwarf.UcharType, *dwarf.UintType:
+		s := dtype.Common().Name
+		if s != "" {
+			if ss, ok := dwarfToName[s]; ok {
+				s = ss
+			}
+			s = strings.Join(strings.Split(s, " "), "") // strip spaces
+			name := c.Ident("_Ctype_" + s)
+			tt := *t
+			typedef[name.Name] = &tt
+			if !*godefs && !*cdefs {
+				t.Go = name
+			}
+		}
+	}
+
+	if t.Size <= 0 {
+		// Clang does not record the size of a pointer in its DWARF entry,
+		// so if dtype is an array, the call to dtype.Size at the top of the function
+		// computed the size as the array length * 0 = 0.
+		// The type switch called Type (this function) recursively on the pointer
+		// entry, and the code near the top of the function updated the size to
+		// be correct, so calling dtype.Size again will produce the correct value.
+		t.Size = dtype.Size()
+		if t.Size < 0 {
+			// Unsized types are [0]byte, unless they're typedefs of other types
+			// or structs with tags.
+			// if so, use the name we've already defined.
+			t.Size = 0
+			switch dt := dtype.(type) {
+			case *dwarf.TypedefType:
+				// ok
+			case *dwarf.StructType:
+				if dt.StructName != "" {
+					break
+				}
+				t.Go = c.Opaque(0)
+			default:
+				t.Go = c.Opaque(0)
+			}
+			if t.C.Empty() {
+				t.C.Set("void")
+			}
+			return t
+		}
+	}
+
+	if t.C.Empty() {
+		fatalf("%s: internal error: did not create C name for %s", lineno(pos), dtype)
+	}
+
+	return t
+}
+
+// isStructUnionClass reports whether the type described by the Go syntax x
+// is a struct, union, or class with a tag.
+func isStructUnionClass(x ast.Expr) bool {
+	id, ok := x.(*ast.Ident)
+	if !ok {
+		return false
+	}
+	name := id.Name
+	return strings.HasPrefix(name, "_Ctype_struct_") ||
+		strings.HasPrefix(name, "_Ctype_union_") ||
+		strings.HasPrefix(name, "_Ctype_class_")
+}
+
+// FuncArg returns a Go type with the same memory layout as
+// dtype when used as the type of a C function argument.
+func (c *typeConv) FuncArg(dtype dwarf.Type, pos token.Pos) *Type {
+	t := c.Type(dtype, pos)
+	switch dt := dtype.(type) {
+	case *dwarf.ArrayType:
+		// Arrays are passed implicitly as pointers in C.
+		// In Go, we must be explicit.
+		tr := &TypeRepr{}
+		tr.Set("%s*", t.C)
+		return &Type{
+			Size:  c.ptrSize,
+			Align: c.ptrSize,
+			Go:    &ast.StarExpr{X: t.Go},
+			C:     tr,
+		}
+	case *dwarf.TypedefType:
+		// C has much more relaxed rules than Go for
+		// implicit type conversions.  When the parameter
+		// is type T defined as *X, simulate a little of the
+		// laxness of C by making the argument *X instead of T.
+		if ptr, ok := base(dt.Type).(*dwarf.PtrType); ok {
+			// Unless the typedef happens to point to void* since
+			// Go has special rules around using unsafe.Pointer.
+			if _, void := base(ptr.Type).(*dwarf.VoidType); void {
+				break
+			}
+
+			t = c.Type(ptr, pos)
+			if t == nil {
+				return nil
+			}
+
+			// Remember the C spelling, in case the struct
+			// has __attribute__((unavailable)) on it.  See issue 2888.
+			t.Typedef = dt.Name
+		}
+	}
+	return t
+}
+
+// FuncType returns the Go type analogous to dtype.
+// There is no guarantee about matching memory layout.
+func (c *typeConv) FuncType(dtype *dwarf.FuncType, pos token.Pos) *FuncType {
+	p := make([]*Type, len(dtype.ParamType))
+	gp := make([]*ast.Field, len(dtype.ParamType))
+	for i, f := range dtype.ParamType {
+		// gcc's DWARF generator outputs a single DotDotDotType parameter for
+		// function pointers that specify no parameters (e.g. void
+		// (*__cgo_0)()).  Treat this special case as void.  This case is
+		// invalid according to ISO C anyway (i.e. void (*__cgo_1)(...) is not
+		// legal).
+		if _, ok := f.(*dwarf.DotDotDotType); ok && i == 0 {
+			p, gp = nil, nil
+			break
+		}
+		p[i] = c.FuncArg(f, pos)
+		gp[i] = &ast.Field{Type: p[i].Go}
+	}
+	var r *Type
+	var gr []*ast.Field
+	if _, ok := dtype.ReturnType.(*dwarf.VoidType); ok {
+		gr = []*ast.Field{{Type: c.goVoid}}
+	} else if dtype.ReturnType != nil {
+		r = c.Type(dtype.ReturnType, pos)
+		gr = []*ast.Field{{Type: r.Go}}
+	}
+	return &FuncType{
+		Params: p,
+		Result: r,
+		Go: &ast.FuncType{
+			Params:  &ast.FieldList{List: gp},
+			Results: &ast.FieldList{List: gr},
+		},
+	}
+}
+
+// Identifier
+func (c *typeConv) Ident(s string) *ast.Ident {
+	return ast.NewIdent(s)
+}
+
+// Opaque type of n bytes.
+func (c *typeConv) Opaque(n int64) ast.Expr {
+	return &ast.ArrayType{
+		Len: c.intExpr(n),
+		Elt: c.byte,
+	}
+}
+
+// Expr for integer n.
+func (c *typeConv) intExpr(n int64) ast.Expr {
+	return &ast.BasicLit{
+		Kind:  token.INT,
+		Value: strconv.FormatInt(n, 10),
+	}
+}
+
+// Add padding of given size to fld.
+func (c *typeConv) pad(fld []*ast.Field, size int64) []*ast.Field {
+	n := len(fld)
+	fld = fld[0 : n+1]
+	fld[n] = &ast.Field{Names: []*ast.Ident{c.Ident("_")}, Type: c.Opaque(size)}
+	return fld
+}
+
+// Struct conversion: return Go and (6g) C syntax for type.
+func (c *typeConv) Struct(dt *dwarf.StructType, pos token.Pos) (expr *ast.StructType, csyntax string, align int64) {
+	var buf bytes.Buffer
+	buf.WriteString("struct {")
+	fld := make([]*ast.Field, 0, 2*len(dt.Field)+1) // enough for padding around every field
+	off := int64(0)
+
+	// Rename struct fields that happen to be named Go keywords into
+	// _{keyword}.  Create a map from C ident -> Go ident.  The Go ident will
+	// be mangled.  Any existing identifier that already has the same name on
+	// the C-side will cause the Go-mangled version to be prefixed with _.
+	// (e.g. in a struct with fields '_type' and 'type', the latter would be
+	// rendered as '__type' in Go).
+	ident := make(map[string]string)
+	used := make(map[string]bool)
+	for _, f := range dt.Field {
+		ident[f.Name] = f.Name
+		used[f.Name] = true
+	}
+
+	if !*godefs && !*cdefs {
+		for cid, goid := range ident {
+			if token.Lookup(goid).IsKeyword() {
+				// Avoid keyword
+				goid = "_" + goid
+
+				// Also avoid existing fields
+				for _, exist := used[goid]; exist; _, exist = used[goid] {
+					goid = "_" + goid
+				}
+
+				used[goid] = true
+				ident[cid] = goid
+			}
+		}
+	}
+
+	anon := 0
+	for _, f := range dt.Field {
+		if f.ByteOffset > off {
+			fld = c.pad(fld, f.ByteOffset-off)
+			off = f.ByteOffset
+		}
+		t := c.Type(f.Type, pos)
+		tgo := t.Go
+		size := t.Size
+		talign := t.Align
+		if f.BitSize > 0 {
+			if f.BitSize%8 != 0 {
+				continue
+			}
+			size = f.BitSize / 8
+			name := tgo.(*ast.Ident).String()
+			if strings.HasPrefix(name, "int") {
+				name = "int"
+			} else {
+				name = "uint"
+			}
+			tgo = ast.NewIdent(name + fmt.Sprint(f.BitSize))
+			talign = size
+		}
+
+		if talign > 0 && f.ByteOffset%talign != 0 {
+			// Drop misaligned fields, the same way we drop integer bit fields.
+			// The goal is to make available what can be made available.
+			// Otherwise one bad and unneeded field in an otherwise okay struct
+			// makes the whole program not compile. Much of the time these
+			// structs are in system headers that cannot be corrected.
+			continue
+		}
+		n := len(fld)
+		fld = fld[0 : n+1]
+		name := f.Name
+		if name == "" {
+			name = fmt.Sprintf("anon%d", anon)
+			anon++
+			ident[name] = name
+		}
+		fld[n] = &ast.Field{Names: []*ast.Ident{c.Ident(ident[name])}, Type: tgo}
+		off += size
+		buf.WriteString(t.C.String())
+		buf.WriteString(" ")
+		buf.WriteString(name)
+		buf.WriteString("; ")
+		if talign > align {
+			align = talign
+		}
+	}
+	if off < dt.ByteSize {
+		fld = c.pad(fld, dt.ByteSize-off)
+		off = dt.ByteSize
+	}
+	if off != dt.ByteSize {
+		fatalf("%s: struct size calculation error off=%d bytesize=%d", lineno(pos), off, dt.ByteSize)
+	}
+	buf.WriteString("}")
+	csyntax = buf.String()
+
+	if *godefs || *cdefs {
+		c.todoFlds = append(c.todoFlds, fld)
+	}
+	expr = &ast.StructType{Fields: &ast.FieldList{List: fld}}
+	return
+}
+
+func upper(s string) string {
+	if s == "" {
+		return ""
+	}
+	r, size := utf8.DecodeRuneInString(s)
+	if r == '_' {
+		return "X" + s
+	}
+	return string(unicode.ToUpper(r)) + s[size:]
+}
+
+// godefsFields rewrites field names for use in Go or C definitions.
+// It strips leading common prefixes (like tv_ in tv_sec, tv_usec)
+// converts names to upper case, and rewrites _ into Pad_godefs_n,
+// so that all fields are exported.
+func godefsFields(fld []*ast.Field) {
+	prefix := fieldPrefix(fld)
+	npad := 0
+	for _, f := range fld {
+		for _, n := range f.Names {
+			if n.Name != prefix {
+				n.Name = strings.TrimPrefix(n.Name, prefix)
+			}
+			if n.Name == "_" {
+				// Use exported name instead.
+				n.Name = "Pad_cgo_" + strconv.Itoa(npad)
+				npad++
+			}
+			if !*cdefs {
+				n.Name = upper(n.Name)
+			}
+		}
+		p := &f.Type
+		t := *p
+		if star, ok := t.(*ast.StarExpr); ok {
+			star = &ast.StarExpr{X: star.X}
+			*p = star
+			p = &star.X
+			t = *p
+		}
+		if id, ok := t.(*ast.Ident); ok {
+			if id.Name == "unsafe.Pointer" {
+				*p = ast.NewIdent("*byte")
+			}
+		}
+	}
+}
+
+// fieldPrefix returns the prefix that should be removed from all the
+// field names when generating the C or Go code.  For generated
+// C, we leave the names as is (tv_sec, tv_usec), since that's what
+// people are used to seeing in C.  For generated Go code, such as
+// package syscall's data structures, we drop a common prefix
+// (so sec, usec, which will get turned into Sec, Usec for exporting).
+func fieldPrefix(fld []*ast.Field) string {
+	if *cdefs {
+		return ""
+	}
+	prefix := ""
+	for _, f := range fld {
+		for _, n := range f.Names {
+			// Ignore field names that don't have the prefix we're
+			// looking for.  It is common in C headers to have fields
+			// named, say, _pad in an otherwise prefixed header.
+			// If the struct has 3 fields tv_sec, tv_usec, _pad1, then we
+			// still want to remove the tv_ prefix.
+			// The check for "orig_" here handles orig_eax in the
+			// x86 ptrace register sets, which otherwise have all fields
+			// with reg_ prefixes.
+			if strings.HasPrefix(n.Name, "orig_") || strings.HasPrefix(n.Name, "_") {
+				continue
+			}
+			i := strings.Index(n.Name, "_")
+			if i < 0 {
+				continue
+			}
+			if prefix == "" {
+				prefix = n.Name[:i+1]
+			} else if prefix != n.Name[:i+1] {
+				return ""
+			}
+		}
+	}
+	return prefix
+}
diff --git a/libgo/go/cmd/cgo/godefs.go b/libgo/go/cmd/cgo/godefs.go
new file mode 100644
index 0000000..ce5ac27
--- /dev/null
+++ b/libgo/go/cmd/cgo/godefs.go
@@ -0,0 +1,294 @@
+// Copyright 2011 The Go Authors.  All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package main
+
+import (
+	"bytes"
+	"fmt"
+	"go/ast"
+	"go/printer"
+	"go/token"
+	"os"
+	"strings"
+)
+
+// godefs returns the output for -godefs mode.
+func (p *Package) godefs(f *File, srcfile string) string {
+	var buf bytes.Buffer
+
+	fmt.Fprintf(&buf, "// Created by cgo -godefs - DO NOT EDIT\n")
+	fmt.Fprintf(&buf, "// %s\n", strings.Join(os.Args, " "))
+	fmt.Fprintf(&buf, "\n")
+
+	override := make(map[string]string)
+
+	// Allow source file to specify override mappings.
+	// For example, the socket data structures refer
+	// to in_addr and in_addr6 structs but we want to be
+	// able to treat them as byte arrays, so the godefs
+	// inputs in package syscall say
+	//
+	//	// +godefs map struct_in_addr [4]byte
+	//	// +godefs map struct_in_addr6 [16]byte
+	//
+	for _, g := range f.Comments {
+		for _, c := range g.List {
+			i := strings.Index(c.Text, "+godefs map")
+			if i < 0 {
+				continue
+			}
+			s := strings.TrimSpace(c.Text[i+len("+godefs map"):])
+			i = strings.Index(s, " ")
+			if i < 0 {
+				fmt.Fprintf(os.Stderr, "invalid +godefs map comment: %s\n", c.Text)
+				continue
+			}
+			override["_Ctype_"+strings.TrimSpace(s[:i])] = strings.TrimSpace(s[i:])
+		}
+	}
+	for _, n := range f.Name {
+		if s := override[n.Go]; s != "" {
+			override[n.Mangle] = s
+		}
+	}
+
+	// Otherwise, if the source file says type T C.whatever,
+	// use "T" as the mangling of C.whatever,
+	// except in the definition (handled at end of function).
+	refName := make(map[*ast.Expr]*Name)
+	for _, r := range f.Ref {
+		refName[r.Expr] = r.Name
+	}
+	for _, d := range f.AST.Decls {
+		d, ok := d.(*ast.GenDecl)
+		if !ok || d.Tok != token.TYPE {
+			continue
+		}
+		for _, s := range d.Specs {
+			s := s.(*ast.TypeSpec)
+			n := refName[&s.Type]
+			if n != nil && n.Mangle != "" {
+				override[n.Mangle] = s.Name.Name
+			}
+		}
+	}
+
+	// Extend overrides using typedefs:
+	// If we know that C.xxx should format as T
+	// and xxx is a typedef for yyy, make C.yyy format as T.
+	for typ, def := range typedef {
+		if new := override[typ]; new != "" {
+			if id, ok := def.Go.(*ast.Ident); ok {
+				override[id.Name] = new
+			}
+		}
+	}
+
+	// Apply overrides.
+	for old, new := range override {
+		if id := goIdent[old]; id != nil {
+			id.Name = new
+		}
+	}
+
+	// Any names still using the _C syntax are not going to compile,
+	// although in general we don't know whether they all made it
+	// into the file, so we can't warn here.
+	//
+	// The most common case is union types, which begin with
+	// _Ctype_union and for which typedef[name] is a Go byte
+	// array of the appropriate size (such as [4]byte).
+	// Substitute those union types with byte arrays.
+	for name, id := range goIdent {
+		if id.Name == name && strings.Contains(name, "_Ctype_union") {
+			if def := typedef[name]; def != nil {
+				id.Name = gofmt(def)
+			}
+		}
+	}
+
+	conf.Fprint(&buf, fset, f.AST)
+
+	return buf.String()
+}
+
+// cdefs returns the output for -cdefs mode.
+// The easiest way to do this is to translate the godefs Go to C.
+func (p *Package) cdefs(f *File, srcfile string) string {
+	godefsOutput := p.godefs(f, srcfile)
+
+	lines := strings.Split(godefsOutput, "\n")
+	lines[0] = "// Created by cgo -cdefs - DO NOT EDIT"
+
+	for i, line := range lines {
+		lines[i] = strings.TrimSpace(line)
+	}
+
+	var out bytes.Buffer
+	printf := func(format string, args ...interface{}) { fmt.Fprintf(&out, format, args...) }
+
+	didTypedef := false
+	for i := 0; i < len(lines); i++ {
+		line := lines[i]
+
+		// Delete
+		//	package x
+		if strings.HasPrefix(line, "package ") {
+			continue
+		}
+
+		// Convert
+		//	const (
+		//		A = 1
+		//		B = 2
+		//	)
+		//
+		// to
+		//
+		//	enum {
+		//		A = 1,
+		//		B = 2,
+		//	};
+		if line == "const (" {
+			printf("enum {\n")
+			for i++; i < len(lines) && lines[i] != ")"; i++ {
+				line = lines[i]
+				if line != "" {
+					printf("\t%s,", line)
+				}
+				printf("\n")
+			}
+			printf("};\n")
+			continue
+		}
+
+		// Convert
+		//	const A = 1
+		// to
+		//	enum { A = 1 };
+		if strings.HasPrefix(line, "const ") {
+			printf("enum { %s };\n", line[len("const "):])
+			continue
+		}
+
+		// On first type definition, typedef all the structs
+		// in case there are dependencies between them.
+		if !didTypedef && strings.HasPrefix(line, "type ") {
+			didTypedef = true
+			for _, line := range lines {
+				line = strings.TrimSpace(line)
+				if strings.HasPrefix(line, "type ") && strings.HasSuffix(line, " struct {") {
+					s := strings.TrimSuffix(strings.TrimPrefix(line, "type "), " struct {")
+					printf("typedef struct %s %s;\n", s, s)
+				}
+			}
+			printf("\n")
+			printf("#pragma pack on\n")
+			printf("\n")
+		}
+
+		// Convert
+		//	type T struct {
+		//		X int64
+		//		Y *int32
+		//		Z [4]byte
+		//	}
+		//
+		// to
+		//
+		//	struct T {
+		//		int64 X;
+		//		int32 *Y;
+		//		byte Z[4];
+		//	}
+		if strings.HasPrefix(line, "type ") && strings.HasSuffix(line, " struct {") {
+			if len(lines) > i+1 && lines[i+1] == "}" {
+				// do not output empty struct
+				i++
+				continue
+			}
+			s := line[len("type ") : len(line)-len(" struct {")]
+			printf("struct %s {\n", s)
+			for i++; i < len(lines) && lines[i] != "}"; i++ {
+				line := lines[i]
+				if line != "" {
+					f := strings.Fields(line)
+					if len(f) != 2 {
+						fmt.Fprintf(os.Stderr, "cgo: cannot parse struct field: %s\n", line)
+						nerrors++
+						continue
+					}
+					printf("\t%s;", cdecl(f[0], f[1]))
+				}
+				printf("\n")
+			}
+			printf("};\n")
+			continue
+		}
+
+		// Convert
+		//	type T int
+		// to
+		//	typedef int T;
+		if strings.HasPrefix(line, "type ") {
+			f := strings.Fields(line[len("type "):])
+			if len(f) != 2 {
+				fmt.Fprintf(os.Stderr, "cgo: cannot parse type definition: %s\n", line)
+				nerrors++
+				continue
+			}
+			printf("typedef\t%s;\n", cdecl(f[0], f[1]))
+			continue
+		}
+
+		printf("%s\n", line)
+	}
+
+	if didTypedef {
+		printf("\n")
+		printf("#pragma pack off\n")
+	}
+
+	return out.String()
+}
+
+// cdecl returns the C declaration for the given Go name and type.
+// It only handles the specific cases necessary for converting godefs output.
+func cdecl(name, typ string) string {
+	// X *[0]byte -> X *void
+	if strings.HasPrefix(typ, "*[0]") {
+		typ = "*void"
+	}
+	// X [4]byte -> X[4] byte
+	for strings.HasPrefix(typ, "[") {
+		i := strings.Index(typ, "]") + 1
+		name = name + typ[:i]
+		typ = typ[i:]
+	}
+	// X *byte -> *X byte
+	for strings.HasPrefix(typ, "*") {
+		name = "*" + name
+		typ = typ[1:]
+	}
+	// X T -> T X
+	// Handle the special case: 'unsafe.Pointer' is 'void *'
+	if typ == "unsafe.Pointer" {
+		typ = "void"
+		name = "*" + name
+	}
+	return typ + "\t" + name
+}
+
+var gofmtBuf bytes.Buffer
+
+// gofmt returns the gofmt-formatted string for an AST node.
+func gofmt(n interface{}) string {
+	gofmtBuf.Reset()
+	err := printer.Fprint(&gofmtBuf, fset, n)
+	if err != nil {
+		return "<" + err.Error() + ">"
+	}
+	return gofmtBuf.String()
+}
diff --git a/libgo/go/cmd/cgo/main.go b/libgo/go/cmd/cgo/main.go
new file mode 100644
index 0000000..ea4b9c2
--- /dev/null
+++ b/libgo/go/cmd/cgo/main.go
@@ -0,0 +1,360 @@
+// Copyright 2009 The Go Authors.  All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Cgo; see gmp.go for an overview.
+
+// TODO(rsc):
+//	Emit correct line number annotations.
+//	Make 6g understand the annotations.
+
+package main
+
+import (
+	"crypto/md5"
+	"flag"
+	"fmt"
+	"go/ast"
+	"go/printer"
+	"go/token"
+	"io"
+	"os"
+	"path/filepath"
+	"reflect"
+	"runtime"
+	"sort"
+	"strings"
+)
+
+// A Package collects information about the package we're going to write.
+type Package struct {
+	PackageName string // name of package
+	PackagePath string
+	PtrSize     int64
+	IntSize     int64
+	GccOptions  []string
+	CgoFlags    map[string][]string // #cgo flags (CFLAGS, LDFLAGS)
+	Written     map[string]bool
+	Name        map[string]*Name // accumulated Name from Files
+	ExpFunc     []*ExpFunc       // accumulated ExpFunc from Files
+	Decl        []ast.Decl
+	GoFiles     []string // list of Go files
+	GccFiles    []string // list of gcc output files
+	Preamble    string   // collected preamble for _cgo_export.h
+}
+
+// A File collects information about a single Go input file.
+type File struct {
+	AST      *ast.File           // parsed AST
+	Comments []*ast.CommentGroup // comments from file
+	Package  string              // Package name
+	Preamble string              // C preamble (doc comment on import "C")
+	Ref      []*Ref              // all references to C.xxx in AST
+	ExpFunc  []*ExpFunc          // exported functions for this file
+	Name     map[string]*Name    // map from Go name to Name
+}
+
+func nameKeys(m map[string]*Name) []string {
+	var ks []string
+	for k := range m {
+		ks = append(ks, k)
+	}
+	sort.Strings(ks)
+	return ks
+}
+
+// A Ref refers to an expression of the form C.xxx in the AST.
+type Ref struct {
+	Name    *Name
+	Expr    *ast.Expr
+	Context string // "type", "expr", "call", or "call2"
+}
+
+func (r *Ref) Pos() token.Pos {
+	return (*r.Expr).Pos()
+}
+
+// A Name collects information about C.xxx.
+type Name struct {
+	Go       string // name used in Go referring to package C
+	Mangle   string // name used in generated Go
+	C        string // name used in C
+	Define   string // #define expansion
+	Kind     string // "const", "type", "var", "fpvar", "func", "not-type"
+	Type     *Type  // the type of xxx
+	FuncType *FuncType
+	AddError bool
+	Const    string // constant definition
+}
+
+// IsVar returns true if Kind is either "var" or "fpvar"
+func (n *Name) IsVar() bool {
+	return n.Kind == "var" || n.Kind == "fpvar"
+}
+
+// A ExpFunc is an exported function, callable from C.
+// Such functions are identified in the Go input file
+// by doc comments containing the line //export ExpName
+type ExpFunc struct {
+	Func    *ast.FuncDecl
+	ExpName string // name to use from C
+}
+
+// A TypeRepr contains the string representation of a type.
+type TypeRepr struct {
+	Repr       string
+	FormatArgs []interface{}
+}
+
+// A Type collects information about a type in both the C and Go worlds.
+type Type struct {
+	Size       int64
+	Align      int64
+	C          *TypeRepr
+	Go         ast.Expr
+	EnumValues map[string]int64
+	Typedef    string
+}
+
+// A FuncType collects information about a function type in both the C and Go worlds.
+type FuncType struct {
+	Params []*Type
+	Result *Type
+	Go     *ast.FuncType
+}
+
+func usage() {
+	fmt.Fprint(os.Stderr, "usage: cgo -- [compiler options] file.go ...\n")
+	flag.PrintDefaults()
+	os.Exit(2)
+}
+
+var ptrSizeMap = map[string]int64{
+	"386":   4,
+	"amd64": 8,
+	"arm":   4,
+	"ppc64": 8,
+	"ppc64le": 8,
+	"s390x": 8,
+}
+
+var intSizeMap = map[string]int64{
+	"386":   4,
+	"amd64": 8,
+	"arm":   4,
+	"ppc64": 8,
+	"ppc64le": 8,
+	"s390x": 8,
+}
+
+var cPrefix string
+
+var fset = token.NewFileSet()
+
+var dynobj = flag.String("dynimport", "", "if non-empty, print dynamic import data for that file")
+var dynout = flag.String("dynout", "", "write -dynobj output to this file")
+var dynlinker = flag.Bool("dynlinker", false, "record dynamic linker information in dynimport mode")
+
+// These flags are for bootstrapping a new Go implementation,
+// to generate Go and C headers that match the data layout and
+// constant values used in the host's C libraries and system calls.
+var godefs = flag.Bool("godefs", false, "for bootstrap: write Go definitions for C file to standard output")
+var cdefs = flag.Bool("cdefs", false, "for bootstrap: write C definitions for C file to standard output")
+var objDir = flag.String("objdir", "", "object directory")
+
+var gccgo = flag.Bool("gccgo", false, "generate files for use with gccgo")
+var gccgoprefix = flag.String("gccgoprefix", "", "-fgo-prefix option used with gccgo")
+var gccgopkgpath = flag.String("gccgopkgpath", "", "-fgo-pkgpath option used with gccgo")
+var importRuntimeCgo = flag.Bool("import_runtime_cgo", true, "import runtime/cgo in generated code")
+var importSyscall = flag.Bool("import_syscall", true, "import syscall in generated code")
+var goarch, goos string
+
+func main() {
+	flag.Usage = usage
+	flag.Parse()
+
+	if *dynobj != "" {
+		// cgo -dynimport is essentially a separate helper command
+		// built into the cgo binary.  It scans a gcc-produced executable
+		// and dumps information about the imported symbols and the
+		// imported libraries.  The 'go build' rules for cgo prepare an
+		// appropriate executable and then use its import information
+		// instead of needing to make the linkers duplicate all the
+		// specialized knowledge gcc has about where to look for imported
+		// symbols and which ones to use.
+		dynimport(*dynobj)
+		return
+	}
+
+	if *godefs && *cdefs {
+		fmt.Fprintf(os.Stderr, "cgo: cannot use -cdefs and -godefs together\n")
+		os.Exit(2)
+	}
+
+	if *godefs || *cdefs {
+		// Generating definitions pulled from header files,
+		// to be checked into Go repositories.
+		// Line numbers are just noise.
+		conf.Mode &^= printer.SourcePos
+	}
+
+	args := flag.Args()
+	if len(args) < 1 {
+		usage()
+	}
+
+	// Find first arg that looks like a go file and assume everything before
+	// that are options to pass to gcc.
+	var i int
+	for i = len(args); i > 0; i-- {
+		if !strings.HasSuffix(args[i-1], ".go") {
+			break
+		}
+	}
+	if i == len(args) {
+		usage()
+	}
+
+	goFiles := args[i:]
+
+	p := newPackage(args[:i])
+
+	// Record CGO_LDFLAGS from the environment for external linking.
+	if ldflags := os.Getenv("CGO_LDFLAGS"); ldflags != "" {
+		args, err := splitQuoted(ldflags)
+		if err != nil {
+			fatalf("bad CGO_LDFLAGS: %q (%s)", ldflags, err)
+		}
+		p.addToFlag("LDFLAGS", args)
+	}
+
+	// Need a unique prefix for the global C symbols that
+	// we use to coordinate between gcc and ourselves.
+	// We already put _cgo_ at the beginning, so the main
+	// concern is other cgo wrappers for the same functions.
+	// Use the beginning of the md5 of the input to disambiguate.
+	h := md5.New()
+	for _, input := range goFiles {
+		f, err := os.Open(input)
+		if err != nil {
+			fatalf("%s", err)
+		}
+		io.Copy(h, f)
+		f.Close()
+	}
+	cPrefix = fmt.Sprintf("_%x", h.Sum(nil)[0:6])
+
+	fs := make([]*File, len(goFiles))
+	for i, input := range goFiles {
+		f := new(File)
+		f.ReadGo(input)
+		f.DiscardCgoDirectives()
+		fs[i] = f
+	}
+
+	if *objDir == "" {
+		// make sure that _obj directory exists, so that we can write
+		// all the output files there.
+		os.Mkdir("_obj", 0777)
+		*objDir = "_obj"
+	}
+	*objDir += string(filepath.Separator)
+
+	for i, input := range goFiles {
+		f := fs[i]
+		p.Translate(f)
+		for _, cref := range f.Ref {
+			switch cref.Context {
+			case "call", "call2":
+				if cref.Name.Kind != "type" {
+					break
+				}
+				*cref.Expr = cref.Name.Type.Go
+			}
+		}
+		if nerrors > 0 {
+			os.Exit(2)
+		}
+		pkg := f.Package
+		if dir := os.Getenv("CGOPKGPATH"); dir != "" {
+			pkg = filepath.Join(dir, pkg)
+		}
+		p.PackagePath = pkg
+		p.Record(f)
+		if *godefs {
+			os.Stdout.WriteString(p.godefs(f, input))
+		} else if *cdefs {
+			os.Stdout.WriteString(p.cdefs(f, input))
+		} else {
+			p.writeOutput(f, input)
+		}
+	}
+
+	if !*godefs && !*cdefs {
+		p.writeDefs()
+	}
+	if nerrors > 0 {
+		os.Exit(2)
+	}
+}
+
+// newPackage returns a new Package that will invoke
+// gcc with the additional arguments specified in args.
+func newPackage(args []string) *Package {
+	goarch = runtime.GOARCH
+	if s := os.Getenv("GOARCH"); s != "" {
+		goarch = s
+	}
+	goos = runtime.GOOS
+	if s := os.Getenv("GOOS"); s != "" {
+		goos = s
+	}
+	ptrSize := ptrSizeMap[goarch]
+	if ptrSize == 0 {
+		fatalf("unknown ptrSize for $GOARCH %q", goarch)
+	}
+	intSize := intSizeMap[goarch]
+	if intSize == 0 {
+		fatalf("unknown intSize for $GOARCH %q", goarch)
+	}
+
+	// Reset locale variables so gcc emits English errors [sic].
+	os.Setenv("LANG", "en_US.UTF-8")
+	os.Setenv("LC_ALL", "C")
+
+	p := &Package{
+		PtrSize:  ptrSize,
+		IntSize:  intSize,
+		CgoFlags: make(map[string][]string),
+		Written:  make(map[string]bool),
+	}
+	p.addToFlag("CFLAGS", args)
+	return p
+}
+
+// Record what needs to be recorded about f.
+func (p *Package) Record(f *File) {
+	if p.PackageName == "" {
+		p.PackageName = f.Package
+	} else if p.PackageName != f.Package {
+		error_(token.NoPos, "inconsistent package names: %s, %s", p.PackageName, f.Package)
+	}
+
+	if p.Name == nil {
+		p.Name = f.Name
+	} else {
+		for k, v := range f.Name {
+			if p.Name[k] == nil {
+				p.Name[k] = v
+			} else if !reflect.DeepEqual(p.Name[k], v) {
+				error_(token.NoPos, "inconsistent definitions for C.%s", fixGo(k))
+			}
+		}
+	}
+
+	if f.ExpFunc != nil {
+		p.ExpFunc = append(p.ExpFunc, f.ExpFunc...)
+		p.Preamble += "\n" + f.Preamble
+	}
+	p.Decl = append(p.Decl, f.AST.Decls...)
+}
diff --git a/libgo/go/cmd/cgo/out.go b/libgo/go/cmd/cgo/out.go
new file mode 100644
index 0000000..76c7247
--- /dev/null
+++ b/libgo/go/cmd/cgo/out.go
@@ -0,0 +1,1299 @@
+// Copyright 2009 The Go Authors.  All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package main
+
+import (
+	"bytes"
+	"debug/elf"
+	"debug/macho"
+	"debug/pe"
+	"fmt"
+	"go/ast"
+	"go/printer"
+	"go/token"
+	"os"
+	"sort"
+	"strings"
+)
+
+var conf = printer.Config{Mode: printer.SourcePos, Tabwidth: 8}
+
+// writeDefs creates output files to be compiled by 6g, 6c, and gcc.
+// (The comments here say 6g and 6c but the code applies to the 8 and 5 tools too.)
+func (p *Package) writeDefs() {
+	fgo2 := creat(*objDir + "_cgo_gotypes.go")
+	fc := creat(*objDir + "_cgo_defun.c")
+	fm := creat(*objDir + "_cgo_main.c")
+
+	var gccgoInit bytes.Buffer
+
+	fflg := creat(*objDir + "_cgo_flags")
+	for k, v := range p.CgoFlags {
+		fmt.Fprintf(fflg, "_CGO_%s=%s\n", k, strings.Join(v, " "))
+		if k == "LDFLAGS" && !*gccgo {
+			for _, arg := range v {
+				fmt.Fprintf(fc, "#pragma cgo_ldflag %q\n", arg)
+			}
+		}
+	}
+	fflg.Close()
+
+	// Write C main file for using gcc to resolve imports.
+	fmt.Fprintf(fm, "int main() { return 0; }\n")
+	if *importRuntimeCgo {
+		fmt.Fprintf(fm, "void crosscall2(void(*fn)(void*, int), void *a, int c) { }\n")
+	} else {
+		// If we're not importing runtime/cgo, we *are* runtime/cgo,
+		// which provides crosscall2.  We just need a prototype.
+		fmt.Fprintf(fm, "void crosscall2(void(*fn)(void*, int), void *a, int c);\n")
+	}
+	fmt.Fprintf(fm, "void _cgo_allocate(void *a, int c) { }\n")
+	fmt.Fprintf(fm, "void _cgo_panic(void *a, int c) { }\n")
+
+	// Write second Go output: definitions of _C_xxx.
+	// In a separate file so that the import of "unsafe" does not
+	// pollute the original file.
+	fmt.Fprintf(fgo2, "// Created by cgo - DO NOT EDIT\n\n")
+	fmt.Fprintf(fgo2, "package %s\n\n", p.PackageName)
+	fmt.Fprintf(fgo2, "import \"unsafe\"\n\n")
+	if *importSyscall {
+		fmt.Fprintf(fgo2, "import \"syscall\"\n\n")
+	}
+	if !*gccgo && *importRuntimeCgo {
+		fmt.Fprintf(fgo2, "import _ \"runtime/cgo\"\n\n")
+	}
+	fmt.Fprintf(fgo2, "type _ unsafe.Pointer\n\n")
+	if *importSyscall {
+		fmt.Fprintf(fgo2, "func _Cerrno(dst *error, x int32) { *dst = syscall.Errno(x) }\n")
+	}
+
+	typedefNames := make([]string, 0, len(typedef))
+	for name := range typedef {
+		typedefNames = append(typedefNames, name)
+	}
+	sort.Strings(typedefNames)
+	for _, name := range typedefNames {
+		def := typedef[name]
+		fmt.Fprintf(fgo2, "type %s ", name)
+		conf.Fprint(fgo2, fset, def.Go)
+		fmt.Fprintf(fgo2, "\n\n")
+	}
+	if *gccgo {
+		fmt.Fprintf(fgo2, "type _Ctype_void byte\n")
+	} else {
+		fmt.Fprintf(fgo2, "type _Ctype_void [0]byte\n")
+	}
+
+	if *gccgo {
+		fmt.Fprintf(fc, p.cPrologGccgo())
+	} else {
+		fmt.Fprintf(fc, cProlog)
+	}
+
+	gccgoSymbolPrefix := p.gccgoSymbolPrefix()
+
+	cVars := make(map[string]bool)
+	for _, key := range nameKeys(p.Name) {
+		n := p.Name[key]
+		if !n.IsVar() {
+			continue
+		}
+
+		if !cVars[n.C] {
+			fmt.Fprintf(fm, "extern char %s[];\n", n.C)
+			fmt.Fprintf(fm, "void *_cgohack_%s = %s;\n\n", n.C, n.C)
+
+			if !*gccgo {
+				fmt.Fprintf(fc, "#pragma cgo_import_static %s\n", n.C)
+			}
+
+			fmt.Fprintf(fc, "extern byte *%s;\n", n.C)
+
+			cVars[n.C] = true
+		}
+		var amp string
+		var node ast.Node
+		if n.Kind == "var" {
+			amp = "&"
+			node = &ast.StarExpr{X: n.Type.Go}
+		} else if n.Kind == "fpvar" {
+			node = n.Type.Go
+			if *gccgo {
+				amp = "&"
+			}
+		} else {
+			panic(fmt.Errorf("invalid var kind %q", n.Kind))
+		}
+		if *gccgo {
+			fmt.Fprintf(fc, `extern void *%s __asm__("%s.%s");`, n.Mangle, gccgoSymbolPrefix, n.Mangle)
+			fmt.Fprintf(&gccgoInit, "\t%s = %s%s;\n", n.Mangle, amp, n.C)
+		} else {
+			fmt.Fprintf(fc, "void *·%s = %s%s;\n", n.Mangle, amp, n.C)
+		}
+		fmt.Fprintf(fc, "\n")
+
+		fmt.Fprintf(fgo2, "var %s ", n.Mangle)
+		conf.Fprint(fgo2, fset, node)
+		fmt.Fprintf(fgo2, "\n")
+	}
+	fmt.Fprintf(fc, "\n")
+
+	for _, key := range nameKeys(p.Name) {
+		n := p.Name[key]
+		if n.Const != "" {
+			fmt.Fprintf(fgo2, "const _Cconst_%s = %s\n", n.Go, n.Const)
+		}
+	}
+	fmt.Fprintf(fgo2, "\n")
+
+	for _, key := range nameKeys(p.Name) {
+		n := p.Name[key]
+		if n.FuncType != nil {
+			p.writeDefsFunc(fc, fgo2, n)
+		}
+	}
+
+	if *gccgo {
+		p.writeGccgoExports(fgo2, fc, fm)
+	} else {
+		p.writeExports(fgo2, fc, fm)
+	}
+
+	init := gccgoInit.String()
+	if init != "" {
+		fmt.Fprintln(fc, "static void init(void) __attribute__ ((constructor));")
+		fmt.Fprintln(fc, "static void init(void) {")
+		fmt.Fprint(fc, init)
+		fmt.Fprintln(fc, "}")
+	}
+
+	fgo2.Close()
+	fc.Close()
+}
+
+func dynimport(obj string) {
+	stdout := os.Stdout
+	if *dynout != "" {
+		f, err := os.Create(*dynout)
+		if err != nil {
+			fatalf("%s", err)
+		}
+		stdout = f
+	}
+
+	if f, err := elf.Open(obj); err == nil {
+		if *dynlinker {
+			// Emit the cgo_dynamic_linker line.
+			if sec := f.Section(".interp"); sec != nil {
+				if data, err := sec.Data(); err == nil && len(data) > 1 {
+					// skip trailing \0 in data
+					fmt.Fprintf(stdout, "#pragma cgo_dynamic_linker %q\n", string(data[:len(data)-1]))
+				}
+			}
+		}
+		sym, err := f.ImportedSymbols()
+		if err != nil {
+			fatalf("cannot load imported symbols from ELF file %s: %v", obj, err)
+		}
+		for _, s := range sym {
+			targ := s.Name
+			if s.Version != "" {
+				targ += "#" + s.Version
+			}
+			fmt.Fprintf(stdout, "#pragma cgo_import_dynamic %s %s %q\n", s.Name, targ, s.Library)
+		}
+		lib, err := f.ImportedLibraries()
+		if err != nil {
+			fatalf("cannot load imported libraries from ELF file %s: %v", obj, err)
+		}
+		for _, l := range lib {
+			fmt.Fprintf(stdout, "#pragma cgo_import_dynamic _ _ %q\n", l)
+		}
+		return
+	}
+
+	if f, err := macho.Open(obj); err == nil {
+		sym, err := f.ImportedSymbols()
+		if err != nil {
+			fatalf("cannot load imported symbols from Mach-O file %s: %v", obj, err)
+		}
+		for _, s := range sym {
+			if len(s) > 0 && s[0] == '_' {
+				s = s[1:]
+			}
+			fmt.Fprintf(stdout, "#pragma cgo_import_dynamic %s %s %q\n", s, s, "")
+		}
+		lib, err := f.ImportedLibraries()
+		if err != nil {
+			fatalf("cannot load imported libraries from Mach-O file %s: %v", obj, err)
+		}
+		for _, l := range lib {
+			fmt.Fprintf(stdout, "#pragma cgo_import_dynamic _ _ %q\n", l)
+		}
+		return
+	}
+
+	if f, err := pe.Open(obj); err == nil {
+		sym, err := f.ImportedSymbols()
+		if err != nil {
+			fatalf("cannot load imported symbols from PE file %s: %v", obj, err)
+		}
+		for _, s := range sym {
+			ss := strings.Split(s, ":")
+			name := strings.Split(ss[0], "@")[0]
+			fmt.Fprintf(stdout, "#pragma cgo_import_dynamic %s %s %q\n", name, ss[0], strings.ToLower(ss[1]))
+		}
+		return
+	}
+
+	fatalf("cannot parse %s as ELF, Mach-O or PE", obj)
+}
+
+// Construct a gcc struct matching the 6c argument frame.
+// Assumes that in gcc, char is 1 byte, short 2 bytes, int 4 bytes, long long 8 bytes.
+// These assumptions are checked by the gccProlog.
+// Also assumes that 6c convention is to word-align the
+// input and output parameters.
+func (p *Package) structType(n *Name) (string, int64) {
+	var buf bytes.Buffer
+	fmt.Fprint(&buf, "struct {\n")
+	off := int64(0)
+	for i, t := range n.FuncType.Params {
+		if off%t.Align != 0 {
+			pad := t.Align - off%t.Align
+			fmt.Fprintf(&buf, "\t\tchar __pad%d[%d];\n", off, pad)
+			off += pad
+		}
+		c := t.Typedef
+		if c == "" {
+			c = t.C.String()
+		}
+		fmt.Fprintf(&buf, "\t\t%s p%d;\n", c, i)
+		off += t.Size
+	}
+	if off%p.PtrSize != 0 {
+		pad := p.PtrSize - off%p.PtrSize
+		fmt.Fprintf(&buf, "\t\tchar __pad%d[%d];\n", off, pad)
+		off += pad
+	}
+	if t := n.FuncType.Result; t != nil {
+		if off%t.Align != 0 {
+			pad := t.Align - off%t.Align
+			fmt.Fprintf(&buf, "\t\tchar __pad%d[%d];\n", off, pad)
+			off += pad
+		}
+		qual := ""
+		if c := t.C.String(); c[len(c)-1] == '*' {
+			qual = "const "
+		}
+		fmt.Fprintf(&buf, "\t\t%s%s r;\n", qual, t.C)
+		off += t.Size
+	}
+	if off%p.PtrSize != 0 {
+		pad := p.PtrSize - off%p.PtrSize
+		fmt.Fprintf(&buf, "\t\tchar __pad%d[%d];\n", off, pad)
+		off += pad
+	}
+	if n.AddError {
+		fmt.Fprint(&buf, "\t\tint e[2*sizeof(void *)/sizeof(int)]; /* error */\n")
+		off += 2 * p.PtrSize
+	}
+	if off == 0 {
+		fmt.Fprintf(&buf, "\t\tchar unused;\n") // avoid empty struct
+	}
+	fmt.Fprintf(&buf, "\t}")
+	return buf.String(), off
+}
+
+func (p *Package) writeDefsFunc(fc, fgo2 *os.File, n *Name) {
+	name := n.Go
+	gtype := n.FuncType.Go
+	void := gtype.Results == nil || len(gtype.Results.List) == 0
+	if n.AddError {
+		// Add "error" to return type list.
+		// Type list is known to be 0 or 1 element - it's a C function.
+		err := &ast.Field{Type: ast.NewIdent("error")}
+		l := gtype.Results.List
+		if len(l) == 0 {
+			l = []*ast.Field{err}
+		} else {
+			l = []*ast.Field{l[0], err}
+		}
+		t := new(ast.FuncType)
+		*t = *gtype
+		t.Results = &ast.FieldList{List: l}
+		gtype = t
+	}
+
+	// Go func declaration.
+	d := &ast.FuncDecl{
+		Name: ast.NewIdent(n.Mangle),
+		Type: gtype,
+	}
+
+	// Builtins defined in the C prolog.
+	inProlog := name == "CString" || name == "GoString" || name == "GoStringN" || name == "GoBytes" || name == "_CMalloc"
+
+	if *gccgo {
+		// Gccgo style hooks.
+		fmt.Fprint(fgo2, "\n")
+		cname := fmt.Sprintf("_cgo%s%s", cPrefix, n.Mangle)
+		paramnames := []string(nil)
+		for i, param := range d.Type.Params.List {
+			paramName := fmt.Sprintf("p%d", i)
+			param.Names = []*ast.Ident{ast.NewIdent(paramName)}
+			paramnames = append(paramnames, paramName)
+		}
+
+		conf.Fprint(fgo2, fset, d)
+		fmt.Fprint(fgo2, " {\n")
+		if !inProlog {
+			fmt.Fprint(fgo2, "\tdefer syscall.CgocallDone()\n")
+			fmt.Fprint(fgo2, "\tsyscall.Cgocall()\n")
+		}
+		if n.AddError {
+			fmt.Fprint(fgo2, "\tsyscall.SetErrno(0)\n")
+		}
+		fmt.Fprint(fgo2, "\t")
+		if !void {
+			fmt.Fprint(fgo2, "r := ")
+		}
+		fmt.Fprintf(fgo2, "%s(%s)\n", cname, strings.Join(paramnames, ", "))
+
+		if n.AddError {
+			fmt.Fprint(fgo2, "\te := syscall.GetErrno()\n")
+			fmt.Fprint(fgo2, "\tif e != 0 {\n")
+			fmt.Fprint(fgo2, "\t\treturn ")
+			if !void {
+				fmt.Fprint(fgo2, "r, ")
+			}
+			fmt.Fprint(fgo2, "e\n")
+			fmt.Fprint(fgo2, "\t}\n")
+			fmt.Fprint(fgo2, "\treturn ")
+			if !void {
+				fmt.Fprint(fgo2, "r, ")
+			}
+			fmt.Fprint(fgo2, "nil\n")
+		} else if !void {
+			fmt.Fprint(fgo2, "\treturn r\n")
+		}
+
+		fmt.Fprint(fgo2, "}\n")
+
+		// declare the C function.
+		fmt.Fprintf(fgo2, "//extern _cgo%s%s\n", cPrefix, n.Mangle)
+		d.Name = ast.NewIdent(cname)
+		if n.AddError {
+			l := d.Type.Results.List
+			d.Type.Results.List = l[:len(l)-1]
+		}
+		conf.Fprint(fgo2, fset, d)
+		fmt.Fprint(fgo2, "\n")
+
+		return
+	}
+	conf.Fprint(fgo2, fset, d)
+	fmt.Fprint(fgo2, "\n")
+
+	if inProlog {
+		return
+	}
+
+	var argSize int64
+	_, argSize = p.structType(n)
+
+	// C wrapper calls into gcc, passing a pointer to the argument frame.
+	fmt.Fprintf(fc, "#pragma cgo_import_static _cgo%s%s\n", cPrefix, n.Mangle)
+	fmt.Fprintf(fc, "void _cgo%s%s(void*);\n", cPrefix, n.Mangle)
+	fmt.Fprintf(fc, "\n")
+	fmt.Fprintf(fc, "void\n")
+	if argSize == 0 {
+		argSize++
+	}
+	// TODO(rsc): The struct here should declare pointers only where
+	// there are pointers in the actual argument frame.
+	// This is a workaround for golang.org/issue/6397.
+	fmt.Fprintf(fc, "·%s(struct{", n.Mangle)
+	if n := argSize / p.PtrSize; n > 0 {
+		fmt.Fprintf(fc, "void *y[%d];", n)
+	}
+	if n := argSize % p.PtrSize; n > 0 {
+		fmt.Fprintf(fc, "uint8 x[%d];", n)
+	}
+	fmt.Fprintf(fc, "}p)\n")
+	fmt.Fprintf(fc, "{\n")
+	fmt.Fprintf(fc, "\truntime·cgocall(_cgo%s%s, &p);\n", cPrefix, n.Mangle)
+	if n.AddError {
+		// gcc leaves errno in first word of interface at end of p.
+		// check whether it is zero; if so, turn interface into nil.
+		// if not, turn interface into errno.
+		// Go init function initializes ·_Cerrno with an os.Errno
+		// for us to copy.
+		fmt.Fprintln(fc, `	{
+			int32 e;
+			void **v;
+			v = (void**)(&p+1) - 2;	/* v = final two void* of p */
+			e = *(int32*)v;
+			v[0] = (void*)0xdeadbeef;
+			v[1] = (void*)0xdeadbeef;
+			if(e == 0) {
+				/* nil interface */
+				v[0] = 0;
+				v[1] = 0;
+			} else {
+				·_Cerrno(v, e);	/* fill in v as error for errno e */
+			}
+		}`)
+	}
+	fmt.Fprintf(fc, "}\n")
+	fmt.Fprintf(fc, "\n")
+}
+
+// writeOutput creates stubs for a specific source file to be compiled by 6g
+// (The comments here say 6g and 6c but the code applies to the 8 and 5 tools too.)
+func (p *Package) writeOutput(f *File, srcfile string) {
+	base := srcfile
+	if strings.HasSuffix(base, ".go") {
+		base = base[0 : len(base)-3]
+	}
+	base = strings.Map(slashToUnderscore, base)
+	fgo1 := creat(*objDir + base + ".cgo1.go")
+	fgcc := creat(*objDir + base + ".cgo2.c")
+
+	p.GoFiles = append(p.GoFiles, base+".cgo1.go")
+	p.GccFiles = append(p.GccFiles, base+".cgo2.c")
+
+	// Write Go output: Go input with rewrites of C.xxx to _C_xxx.
+	fmt.Fprintf(fgo1, "// Created by cgo - DO NOT EDIT\n\n")
+	conf.Fprint(fgo1, fset, f.AST)
+
+	// While we process the vars and funcs, also write 6c and gcc output.
+	// Gcc output starts with the preamble.
+	fmt.Fprintf(fgcc, "%s\n", f.Preamble)
+	fmt.Fprintf(fgcc, "%s\n", gccProlog)
+
+	for _, key := range nameKeys(f.Name) {
+		n := f.Name[key]
+		if n.FuncType != nil {
+			p.writeOutputFunc(fgcc, n)
+		}
+	}
+
+	fgo1.Close()
+	fgcc.Close()
+}
+
+// fixGo converts the internal Name.Go field into the name we should show
+// to users in error messages. There's only one for now: on input we rewrite
+// C.malloc into C._CMalloc, so change it back here.
+func fixGo(name string) string {
+	if name == "_CMalloc" {
+		return "malloc"
+	}
+	return name
+}
+
+var isBuiltin = map[string]bool{
+	"_Cfunc_CString":   true,
+	"_Cfunc_GoString":  true,
+	"_Cfunc_GoStringN": true,
+	"_Cfunc_GoBytes":   true,
+	"_Cfunc__CMalloc":  true,
+}
+
+func (p *Package) writeOutputFunc(fgcc *os.File, n *Name) {
+	name := n.Mangle
+	if isBuiltin[name] || p.Written[name] {
+		// The builtins are already defined in the C prolog, and we don't
+		// want to duplicate function definitions we've already done.
+		return
+	}
+	p.Written[name] = true
+
+	if *gccgo {
+		p.writeGccgoOutputFunc(fgcc, n)
+		return
+	}
+
+	ctype, _ := p.structType(n)
+
+	// Gcc wrapper unpacks the C argument struct
+	// and calls the actual C function.
+	fmt.Fprintf(fgcc, "void\n")
+	fmt.Fprintf(fgcc, "_cgo%s%s(void *v)\n", cPrefix, n.Mangle)
+	fmt.Fprintf(fgcc, "{\n")
+	if n.AddError {
+		fmt.Fprintf(fgcc, "\terrno = 0;\n")
+	}
+	// We're trying to write a gcc struct that matches 6c/8c/5c's layout.
+	// Use packed attribute to force no padding in this struct in case
+	// gcc has different packing requirements.
+	fmt.Fprintf(fgcc, "\t%s %v *a = v;\n", ctype, p.packedAttribute())
+	fmt.Fprintf(fgcc, "\t")
+	if t := n.FuncType.Result; t != nil {
+		fmt.Fprintf(fgcc, "a->r = ")
+		if c := t.C.String(); c[len(c)-1] == '*' {
+			fmt.Fprint(fgcc, "(__typeof__(a->r)) ")
+		}
+	}
+	fmt.Fprintf(fgcc, "%s(", n.C)
+	for i, t := range n.FuncType.Params {
+		if i > 0 {
+			fmt.Fprintf(fgcc, ", ")
+		}
+		// We know the type params are correct, because
+		// the Go equivalents had good type params.
+		// However, our version of the type omits the magic
+		// words const and volatile, which can provoke
+		// C compiler warnings.  Silence them by casting
+		// all pointers to void*.  (Eventually that will produce
+		// other warnings.)
+		if c := t.C.String(); c[len(c)-1] == '*' {
+			fmt.Fprintf(fgcc, "(void*)")
+		}
+		fmt.Fprintf(fgcc, "a->p%d", i)
+	}
+	fmt.Fprintf(fgcc, ");\n")
+	if n.AddError {
+		fmt.Fprintf(fgcc, "\t*(int*)(a->e) = errno;\n")
+	}
+	fmt.Fprintf(fgcc, "}\n")
+	fmt.Fprintf(fgcc, "\n")
+}
+
+// Write out a wrapper for a function when using gccgo.  This is a
+// simple wrapper that just calls the real function.  We only need a
+// wrapper to support static functions in the prologue--without a
+// wrapper, we can't refer to the function, since the reference is in
+// a different file.
+func (p *Package) writeGccgoOutputFunc(fgcc *os.File, n *Name) {
+	if t := n.FuncType.Result; t != nil {
+		fmt.Fprintf(fgcc, "%s\n", t.C.String())
+	} else {
+		fmt.Fprintf(fgcc, "void\n")
+	}
+	fmt.Fprintf(fgcc, "_cgo%s%s(", cPrefix, n.Mangle)
+	for i, t := range n.FuncType.Params {
+		if i > 0 {
+			fmt.Fprintf(fgcc, ", ")
+		}
+		c := t.Typedef
+		if c == "" {
+			c = t.C.String()
+		}
+		fmt.Fprintf(fgcc, "%s p%d", c, i)
+	}
+	fmt.Fprintf(fgcc, ")\n")
+	fmt.Fprintf(fgcc, "{\n")
+	fmt.Fprintf(fgcc, "\t")
+	if t := n.FuncType.Result; t != nil {
+		fmt.Fprintf(fgcc, "return ")
+		// Cast to void* to avoid warnings due to omitted qualifiers.
+		if c := t.C.String(); c[len(c)-1] == '*' {
+			fmt.Fprintf(fgcc, "(void*)")
+		}
+	}
+	fmt.Fprintf(fgcc, "%s(", n.C)
+	for i, t := range n.FuncType.Params {
+		if i > 0 {
+			fmt.Fprintf(fgcc, ", ")
+		}
+		// Cast to void* to avoid warnings due to omitted qualifiers.
+		if c := t.C.String(); c[len(c)-1] == '*' {
+			fmt.Fprintf(fgcc, "(void*)")
+		}
+		fmt.Fprintf(fgcc, "p%d", i)
+	}
+	fmt.Fprintf(fgcc, ");\n")
+	fmt.Fprintf(fgcc, "}\n")
+	fmt.Fprintf(fgcc, "\n")
+}
+
+// packedAttribute returns host compiler struct attribute that will be
+// used to match 6c/8c/5c's struct layout. For example, on 386 Windows,
+// gcc wants to 8-align int64s, but 8c does not.
+// Use __gcc_struct__ to work around http://gcc.gnu.org/PR52991 on x86,
+// and http://golang.org/issue/5603.
+func (p *Package) packedAttribute() string {
+	s := "__attribute__((__packed__"
+	if !strings.Contains(p.gccBaseCmd()[0], "clang") && (goarch == "amd64" || goarch == "386") {
+		s += ", __gcc_struct__"
+	}
+	return s + "))"
+}
+
+// Write out the various stubs we need to support functions exported
+// from Go so that they are callable from C.
+func (p *Package) writeExports(fgo2, fc, fm *os.File) {
+	fgcc := creat(*objDir + "_cgo_export.c")
+	fgcch := creat(*objDir + "_cgo_export.h")
+
+	fmt.Fprintf(fgcch, "/* Created by cgo - DO NOT EDIT. */\n")
+	fmt.Fprintf(fgcch, "%s\n", p.Preamble)
+	fmt.Fprintf(fgcch, "%s\n", p.gccExportHeaderProlog())
+
+	fmt.Fprintf(fgcc, "/* Created by cgo - DO NOT EDIT. */\n")
+	fmt.Fprintf(fgcc, "#include \"_cgo_export.h\"\n")
+
+	fmt.Fprintf(fgcc, "\nextern void crosscall2(void (*fn)(void *, int), void *, int);\n\n")
+
+	for _, exp := range p.ExpFunc {
+		fn := exp.Func
+
+		// Construct a gcc struct matching the 6c argument and
+		// result frame.  The gcc struct will be compiled with
+		// __attribute__((packed)) so all padding must be accounted
+		// for explicitly.
+		ctype := "struct {\n"
+		off := int64(0)
+		npad := 0
+		if fn.Recv != nil {
+			t := p.cgoType(fn.Recv.List[0].Type)
+			ctype += fmt.Sprintf("\t\t%s recv;\n", t.C)
+			off += t.Size
+		}
+		fntype := fn.Type
+		forFieldList(fntype.Params,
+			func(i int, atype ast.Expr) {
+				t := p.cgoType(atype)
+				if off%t.Align != 0 {
+					pad := t.Align - off%t.Align
+					ctype += fmt.Sprintf("\t\tchar __pad%d[%d];\n", npad, pad)
+					off += pad
+					npad++
+				}
+				ctype += fmt.Sprintf("\t\t%s p%d;\n", t.C, i)
+				off += t.Size
+			})
+		if off%p.PtrSize != 0 {
+			pad := p.PtrSize - off%p.PtrSize
+			ctype += fmt.Sprintf("\t\tchar __pad%d[%d];\n", npad, pad)
+			off += pad
+			npad++
+		}
+		forFieldList(fntype.Results,
+			func(i int, atype ast.Expr) {
+				t := p.cgoType(atype)
+				if off%t.Align != 0 {
+					pad := t.Align - off%t.Align
+					ctype += fmt.Sprintf("\t\tchar __pad%d[%d];\n", npad, pad)
+					off += pad
+					npad++
+				}
+				ctype += fmt.Sprintf("\t\t%s r%d;\n", t.C, i)
+				off += t.Size
+			})
+		if off%p.PtrSize != 0 {
+			pad := p.PtrSize - off%p.PtrSize
+			ctype += fmt.Sprintf("\t\tchar __pad%d[%d];\n", npad, pad)
+			off += pad
+			npad++
+		}
+		if ctype == "struct {\n" {
+			ctype += "\t\tchar unused;\n" // avoid empty struct
+		}
+		ctype += "\t}"
+
+		// Get the return type of the wrapper function
+		// compiled by gcc.
+		gccResult := ""
+		if fntype.Results == nil || len(fntype.Results.List) == 0 {
+			gccResult = "void"
+		} else if len(fntype.Results.List) == 1 && len(fntype.Results.List[0].Names) <= 1 {
+			gccResult = p.cgoType(fntype.Results.List[0].Type).C.String()
+		} else {
+			fmt.Fprintf(fgcch, "\n/* Return type for %s */\n", exp.ExpName)
+			fmt.Fprintf(fgcch, "struct %s_return {\n", exp.ExpName)
+			forFieldList(fntype.Results,
+				func(i int, atype ast.Expr) {
+					fmt.Fprintf(fgcch, "\t%s r%d;\n", p.cgoType(atype).C, i)
+				})
+			fmt.Fprintf(fgcch, "};\n")
+			gccResult = "struct " + exp.ExpName + "_return"
+		}
+
+		// Build the wrapper function compiled by gcc.
+		s := fmt.Sprintf("%s %s(", gccResult, exp.ExpName)
+		if fn.Recv != nil {
+			s += p.cgoType(fn.Recv.List[0].Type).C.String()
+			s += " recv"
+		}
+		forFieldList(fntype.Params,
+			func(i int, atype ast.Expr) {
+				if i > 0 || fn.Recv != nil {
+					s += ", "
+				}
+				s += fmt.Sprintf("%s p%d", p.cgoType(atype).C, i)
+			})
+		s += ")"
+		fmt.Fprintf(fgcch, "\nextern %s;\n", s)
+
+		fmt.Fprintf(fgcc, "extern void _cgoexp%s_%s(void *, int);\n", cPrefix, exp.ExpName)
+		fmt.Fprintf(fgcc, "\n%s\n", s)
+		fmt.Fprintf(fgcc, "{\n")
+		fmt.Fprintf(fgcc, "\t%s %v a;\n", ctype, p.packedAttribute())
+		if gccResult != "void" && (len(fntype.Results.List) > 1 || len(fntype.Results.List[0].Names) > 1) {
+			fmt.Fprintf(fgcc, "\t%s r;\n", gccResult)
+		}
+		if fn.Recv != nil {
+			fmt.Fprintf(fgcc, "\ta.recv = recv;\n")
+		}
+		forFieldList(fntype.Params,
+			func(i int, atype ast.Expr) {
+				fmt.Fprintf(fgcc, "\ta.p%d = p%d;\n", i, i)
+			})
+		fmt.Fprintf(fgcc, "\tcrosscall2(_cgoexp%s_%s, &a, %d);\n", cPrefix, exp.ExpName, off)
+		if gccResult != "void" {
+			if len(fntype.Results.List) == 1 && len(fntype.Results.List[0].Names) <= 1 {
+				fmt.Fprintf(fgcc, "\treturn a.r0;\n")
+			} else {
+				forFieldList(fntype.Results,
+					func(i int, atype ast.Expr) {
+						fmt.Fprintf(fgcc, "\tr.r%d = a.r%d;\n", i, i)
+					})
+				fmt.Fprintf(fgcc, "\treturn r;\n")
+			}
+		}
+		fmt.Fprintf(fgcc, "}\n")
+
+		// Build the wrapper function compiled by 6c/8c
+		goname := exp.Func.Name.Name
+		if fn.Recv != nil {
+			goname = "_cgoexpwrap" + cPrefix + "_" + fn.Recv.List[0].Names[0].Name + "_" + goname
+		}
+		fmt.Fprintf(fc, "#pragma cgo_export_dynamic %s\n", goname)
+		fmt.Fprintf(fc, "extern void ·%s();\n\n", goname)
+		fmt.Fprintf(fc, "#pragma cgo_export_static _cgoexp%s_%s\n", cPrefix, exp.ExpName)
+		fmt.Fprintf(fc, "#pragma textflag 7\n") // no split stack, so no use of m or g
+		fmt.Fprintf(fc, "void\n")
+		fmt.Fprintf(fc, "_cgoexp%s_%s(void *a, int32 n)\n", cPrefix, exp.ExpName)
+		fmt.Fprintf(fc, "{\n")
+		fmt.Fprintf(fc, "\truntime·cgocallback(·%s, a, n);\n", goname)
+		fmt.Fprintf(fc, "}\n")
+
+		fmt.Fprintf(fm, "int _cgoexp%s_%s;\n", cPrefix, exp.ExpName)
+
+		// Calling a function with a receiver from C requires
+		// a Go wrapper function.
+		if fn.Recv != nil {
+			fmt.Fprintf(fgo2, "func %s(recv ", goname)
+			conf.Fprint(fgo2, fset, fn.Recv.List[0].Type)
+			forFieldList(fntype.Params,
+				func(i int, atype ast.Expr) {
+					fmt.Fprintf(fgo2, ", p%d ", i)
+					conf.Fprint(fgo2, fset, atype)
+				})
+			fmt.Fprintf(fgo2, ")")
+			if gccResult != "void" {
+				fmt.Fprint(fgo2, " (")
+				forFieldList(fntype.Results,
+					func(i int, atype ast.Expr) {
+						if i > 0 {
+							fmt.Fprint(fgo2, ", ")
+						}
+						conf.Fprint(fgo2, fset, atype)
+					})
+				fmt.Fprint(fgo2, ")")
+			}
+			fmt.Fprint(fgo2, " {\n")
+			fmt.Fprint(fgo2, "\t")
+			if gccResult != "void" {
+				fmt.Fprint(fgo2, "return ")
+			}
+			fmt.Fprintf(fgo2, "recv.%s(", exp.Func.Name)
+			forFieldList(fntype.Params,
+				func(i int, atype ast.Expr) {
+					if i > 0 {
+						fmt.Fprint(fgo2, ", ")
+					}
+					fmt.Fprintf(fgo2, "p%d", i)
+				})
+			fmt.Fprint(fgo2, ")\n")
+			fmt.Fprint(fgo2, "}\n")
+		}
+	}
+}
+
+// Write out the C header allowing C code to call exported gccgo functions.
+func (p *Package) writeGccgoExports(fgo2, fc, fm *os.File) {
+	fgcc := creat(*objDir + "_cgo_export.c")
+	fgcch := creat(*objDir + "_cgo_export.h")
+
+	gccgoSymbolPrefix := p.gccgoSymbolPrefix()
+
+	fmt.Fprintf(fgcch, "/* Created by cgo - DO NOT EDIT. */\n")
+	fmt.Fprintf(fgcch, "%s\n", p.Preamble)
+	fmt.Fprintf(fgcch, "%s\n", p.gccExportHeaderProlog())
+
+	fmt.Fprintf(fgcc, "/* Created by cgo - DO NOT EDIT. */\n")
+	fmt.Fprintf(fgcc, "#include \"_cgo_export.h\"\n")
+
+	fmt.Fprintf(fm, "#include \"_cgo_export.h\"\n")
+
+	for _, exp := range p.ExpFunc {
+		fn := exp.Func
+		fntype := fn.Type
+
+		cdeclBuf := new(bytes.Buffer)
+		resultCount := 0
+		forFieldList(fntype.Results,
+			func(i int, atype ast.Expr) { resultCount++ })
+		switch resultCount {
+		case 0:
+			fmt.Fprintf(cdeclBuf, "void")
+		case 1:
+			forFieldList(fntype.Results,
+				func(i int, atype ast.Expr) {
+					t := p.cgoType(atype)
+					fmt.Fprintf(cdeclBuf, "%s", t.C)
+				})
+		default:
+			// Declare a result struct.
+			fmt.Fprintf(fgcch, "struct %s_result {\n", exp.ExpName)
+			forFieldList(fntype.Results,
+				func(i int, atype ast.Expr) {
+					t := p.cgoType(atype)
+					fmt.Fprintf(fgcch, "\t%s r%d;\n", t.C, i)
+				})
+			fmt.Fprintf(fgcch, "};\n")
+			fmt.Fprintf(cdeclBuf, "struct %s_result", exp.ExpName)
+		}
+
+		cRet := cdeclBuf.String()
+
+		cdeclBuf = new(bytes.Buffer)
+		fmt.Fprintf(cdeclBuf, "(")
+		if fn.Recv != nil {
+			fmt.Fprintf(cdeclBuf, "%s recv", p.cgoType(fn.Recv.List[0].Type).C.String())
+		}
+		// Function parameters.
+		forFieldList(fntype.Params,
+			func(i int, atype ast.Expr) {
+				if i > 0 || fn.Recv != nil {
+					fmt.Fprintf(cdeclBuf, ", ")
+				}
+				t := p.cgoType(atype)
+				fmt.Fprintf(cdeclBuf, "%s p%d", t.C, i)
+			})
+		fmt.Fprintf(cdeclBuf, ")")
+		cParams := cdeclBuf.String()
+
+		// We need to use a name that will be exported by the
+		// Go code; otherwise gccgo will make it static and we
+		// will not be able to link against it from the C
+		// code.
+		goName := "Cgoexp_" + exp.ExpName
+		fmt.Fprintf(fgcch, `extern %s %s %s __asm__("%s.%s");`, cRet, goName, cParams, gccgoSymbolPrefix, goName)
+		fmt.Fprint(fgcch, "\n")
+
+		// Use a #define so that the C code that includes
+		// cgo_export.h will be able to refer to the Go
+		// function using the expected name.
+		fmt.Fprintf(fgcch, "#define %s %s\n", exp.ExpName, goName)
+
+		// Use a #undef in _cgo_export.c so that we ignore the
+		// #define from cgo_export.h, since here we are
+		// defining the real function.
+		fmt.Fprintf(fgcc, "#undef %s\n", exp.ExpName)
+
+		fmt.Fprint(fgcc, "\n")
+		fmt.Fprintf(fgcc, "%s %s %s {\n", cRet, exp.ExpName, cParams)
+		fmt.Fprint(fgcc, "\t")
+		if resultCount > 0 {
+			fmt.Fprint(fgcc, "return ")
+		}
+		fmt.Fprintf(fgcc, "%s(", goName)
+		if fn.Recv != nil {
+			fmt.Fprint(fgcc, "recv")
+		}
+		forFieldList(fntype.Params,
+			func(i int, atype ast.Expr) {
+				if i > 0 || fn.Recv != nil {
+					fmt.Fprintf(fgcc, ", ")
+				}
+				fmt.Fprintf(fgcc, "p%d", i)
+			})
+		fmt.Fprint(fgcc, ");\n")
+		fmt.Fprint(fgcc, "}\n")
+
+		// Dummy declaration for _cgo_main.c
+		fmt.Fprintf(fm, "%s %s %s {}\n", cRet, goName, cParams)
+
+		// For gccgo we use a wrapper function in Go, in order
+		// to call CgocallBack and CgocallBackDone.
+
+		// This code uses printer.Fprint, not conf.Fprint,
+		// because we don't want //line comments in the middle
+		// of the function types.
+		fmt.Fprint(fgo2, "\n")
+		fmt.Fprintf(fgo2, "func %s(", goName)
+		if fn.Recv != nil {
+			fmt.Fprint(fgo2, "recv ")
+			printer.Fprint(fgo2, fset, fn.Recv.List[0].Type)
+		}
+		forFieldList(fntype.Params,
+			func(i int, atype ast.Expr) {
+				if i > 0 || fn.Recv != nil {
+					fmt.Fprintf(fgo2, ", ")
+				}
+				fmt.Fprintf(fgo2, "p%d ", i)
+				printer.Fprint(fgo2, fset, atype)
+			})
+		fmt.Fprintf(fgo2, ")")
+		if resultCount > 0 {
+			fmt.Fprintf(fgo2, " (")
+			forFieldList(fntype.Results,
+				func(i int, atype ast.Expr) {
+					if i > 0 {
+						fmt.Fprint(fgo2, ", ")
+					}
+					printer.Fprint(fgo2, fset, atype)
+				})
+			fmt.Fprint(fgo2, ")")
+		}
+		fmt.Fprint(fgo2, " {\n")
+		fmt.Fprint(fgo2, "\tsyscall.CgocallBack()\n")
+		fmt.Fprint(fgo2, "\tdefer syscall.CgocallBackDone()\n")
+		fmt.Fprint(fgo2, "\t")
+		if resultCount > 0 {
+			fmt.Fprint(fgo2, "return ")
+		}
+		if fn.Recv != nil {
+			fmt.Fprint(fgo2, "recv.")
+		}
+		fmt.Fprintf(fgo2, "%s(", exp.Func.Name)
+		forFieldList(fntype.Params,
+			func(i int, atype ast.Expr) {
+				if i > 0 {
+					fmt.Fprint(fgo2, ", ")
+				}
+				fmt.Fprintf(fgo2, "p%d", i)
+			})
+		fmt.Fprint(fgo2, ")\n")
+		fmt.Fprint(fgo2, "}\n")
+	}
+}
+
+// Return the package prefix when using gccgo.
+func (p *Package) gccgoSymbolPrefix() string {
+	if !*gccgo {
+		return ""
+	}
+
+	clean := func(r rune) rune {
+		switch {
+		case 'A' <= r && r <= 'Z', 'a' <= r && r <= 'z',
+			'0' <= r && r <= '9':
+			return r
+		}
+		return '_'
+	}
+
+	if *gccgopkgpath != "" {
+		return strings.Map(clean, *gccgopkgpath)
+	}
+	if *gccgoprefix == "" && p.PackageName == "main" {
+		return "main"
+	}
+	prefix := strings.Map(clean, *gccgoprefix)
+	if prefix == "" {
+		prefix = "go"
+	}
+	return prefix + "." + p.PackageName
+}
+
+// Call a function for each entry in an ast.FieldList, passing the
+// index into the list and the type.
+func forFieldList(fl *ast.FieldList, fn func(int, ast.Expr)) {
+	if fl == nil {
+		return
+	}
+	i := 0
+	for _, r := range fl.List {
+		if r.Names == nil {
+			fn(i, r.Type)
+			i++
+		} else {
+			for _ = range r.Names {
+				fn(i, r.Type)
+				i++
+			}
+		}
+	}
+}
+
+func c(repr string, args ...interface{}) *TypeRepr {
+	return &TypeRepr{repr, args}
+}
+
+// Map predeclared Go types to Type.
+var goTypes = map[string]*Type{
+	"bool":       {Size: 1, Align: 1, C: c("GoUint8")},
+	"byte":       {Size: 1, Align: 1, C: c("GoUint8")},
+	"int":        {Size: 0, Align: 0, C: c("GoInt")},
+	"uint":       {Size: 0, Align: 0, C: c("GoUint")},
+	"rune":       {Size: 4, Align: 4, C: c("GoInt32")},
+	"int8":       {Size: 1, Align: 1, C: c("GoInt8")},
+	"uint8":      {Size: 1, Align: 1, C: c("GoUint8")},
+	"int16":      {Size: 2, Align: 2, C: c("GoInt16")},
+	"uint16":     {Size: 2, Align: 2, C: c("GoUint16")},
+	"int32":      {Size: 4, Align: 4, C: c("GoInt32")},
+	"uint32":     {Size: 4, Align: 4, C: c("GoUint32")},
+	"int64":      {Size: 8, Align: 8, C: c("GoInt64")},
+	"uint64":     {Size: 8, Align: 8, C: c("GoUint64")},
+	"float32":    {Size: 4, Align: 4, C: c("GoFloat32")},
+	"float64":    {Size: 8, Align: 8, C: c("GoFloat64")},
+	"complex64":  {Size: 8, Align: 8, C: c("GoComplex64")},
+	"complex128": {Size: 16, Align: 16, C: c("GoComplex128")},
+}
+
+// Map an ast type to a Type.
+func (p *Package) cgoType(e ast.Expr) *Type {
+	switch t := e.(type) {
+	case *ast.StarExpr:
+		x := p.cgoType(t.X)
+		return &Type{Size: p.PtrSize, Align: p.PtrSize, C: c("%s*", x.C)}
+	case *ast.ArrayType:
+		if t.Len == nil {
+			// Slice: pointer, len, cap.
+			return &Type{Size: p.PtrSize * 3, Align: p.PtrSize, C: c("GoSlice")}
+		}
+	case *ast.StructType:
+		// TODO
+	case *ast.FuncType:
+		return &Type{Size: p.PtrSize, Align: p.PtrSize, C: c("void*")}
+	case *ast.InterfaceType:
+		return &Type{Size: 2 * p.PtrSize, Align: p.PtrSize, C: c("GoInterface")}
+	case *ast.MapType:
+		return &Type{Size: p.PtrSize, Align: p.PtrSize, C: c("GoMap")}
+	case *ast.ChanType:
+		return &Type{Size: p.PtrSize, Align: p.PtrSize, C: c("GoChan")}
+	case *ast.Ident:
+		// Look up the type in the top level declarations.
+		// TODO: Handle types defined within a function.
+		for _, d := range p.Decl {
+			gd, ok := d.(*ast.GenDecl)
+			if !ok || gd.Tok != token.TYPE {
+				continue
+			}
+			for _, spec := range gd.Specs {
+				ts, ok := spec.(*ast.TypeSpec)
+				if !ok {
+					continue
+				}
+				if ts.Name.Name == t.Name {
+					return p.cgoType(ts.Type)
+				}
+			}
+		}
+		if def := typedef[t.Name]; def != nil {
+			return def
+		}
+		if t.Name == "uintptr" {
+			return &Type{Size: p.PtrSize, Align: p.PtrSize, C: c("GoUintptr")}
+		}
+		if t.Name == "string" {
+			// The string data is 1 pointer + 1 (pointer-sized) int.
+			return &Type{Size: 2 * p.PtrSize, Align: p.PtrSize, C: c("GoString")}
+		}
+		if t.Name == "error" {
+			return &Type{Size: 2 * p.PtrSize, Align: p.PtrSize, C: c("GoInterface")}
+		}
+		if r, ok := goTypes[t.Name]; ok {
+			if r.Size == 0 { // int or uint
+				rr := new(Type)
+				*rr = *r
+				rr.Size = p.IntSize
+				rr.Align = p.IntSize
+				r = rr
+			}
+			if r.Align > p.PtrSize {
+				r.Align = p.PtrSize
+			}
+			return r
+		}
+		error_(e.Pos(), "unrecognized Go type %s", t.Name)
+		return &Type{Size: 4, Align: 4, C: c("int")}
+	case *ast.SelectorExpr:
+		id, ok := t.X.(*ast.Ident)
+		if ok && id.Name == "unsafe" && t.Sel.Name == "Pointer" {
+			return &Type{Size: p.PtrSize, Align: p.PtrSize, C: c("void*")}
+		}
+	}
+	error_(e.Pos(), "Go type not supported in export: %s", gofmt(e))
+	return &Type{Size: 4, Align: 4, C: c("int")}
+}
+
+const gccProlog = `
+// Usual nonsense: if x and y are not equal, the type will be invalid
+// (have a negative array count) and an inscrutable error will come
+// out of the compiler and hopefully mention "name".
+#define __cgo_compile_assert_eq(x, y, name) typedef char name[(x-y)*(x-y)*-2+1];
+
+// Check at compile time that the sizes we use match our expectations.
+#define __cgo_size_assert(t, n) __cgo_compile_assert_eq(sizeof(t), n, _cgo_sizeof_##t##_is_not_##n)
+
+__cgo_size_assert(char, 1)
+__cgo_size_assert(short, 2)
+__cgo_size_assert(int, 4)
+typedef long long __cgo_long_long;
+__cgo_size_assert(__cgo_long_long, 8)
+__cgo_size_assert(float, 4)
+__cgo_size_assert(double, 8)
+
+#include <errno.h>
+#include <string.h>
+`
+
+const builtinProlog = `
+#include <sys/types.h> /* for size_t below */
+
+/* Define intgo when compiling with GCC.  */
+#ifdef __PTRDIFF_TYPE__
+typedef __PTRDIFF_TYPE__ intgo;
+#elif defined(_LP64)
+typedef long long intgo;
+#else
+typedef int intgo;
+#endif
+
+typedef struct { char *p; intgo n; } _GoString_;
+typedef struct { char *p; intgo n; intgo c; } _GoBytes_;
+_GoString_ GoString(char *p);
+_GoString_ GoStringN(char *p, int l);
+_GoBytes_ GoBytes(void *p, int n);
+char *CString(_GoString_);
+void *_CMalloc(size_t);
+`
+
+const cProlog = `
+#include "runtime.h"
+#include "cgocall.h"
+
+void ·_Cerrno(void*, int32);
+
+void
+·_Cfunc_GoString(int8 *p, String s)
+{
+	s = runtime·gostring((byte*)p);
+	FLUSH(&s);
+}
+
+void
+·_Cfunc_GoStringN(int8 *p, int32 l, String s)
+{
+	s = runtime·gostringn((byte*)p, l);
+	FLUSH(&s);
+}
+
+void
+·_Cfunc_GoBytes(int8 *p, int32 l, Slice s)
+{
+	s = runtime·gobytes((byte*)p, l);
+	FLUSH(&s);
+}
+
+void
+·_Cfunc_CString(String s, int8 *p)
+{
+	p = runtime·cmalloc(s.len+1);
+	runtime·memmove((byte*)p, s.str, s.len);
+	p[s.len] = 0;
+	FLUSH(&p);
+}
+
+void
+·_Cfunc__CMalloc(uintptr n, int8 *p)
+{
+	p = runtime·cmalloc(n);
+	FLUSH(&p);
+}
+`
+
+func (p *Package) cPrologGccgo() string {
+	return strings.Replace(cPrologGccgo, "PREFIX", cPrefix, -1)
+}
+
+const cPrologGccgo = `
+#include <stdint.h>
+#include <stdlib.h>
+#include <string.h>
+
+typedef unsigned char byte;
+typedef intptr_t intgo;
+
+struct __go_string {
+	const unsigned char *__data;
+	intgo __length;
+};
+
+typedef struct __go_open_array {
+	void* __values;
+	intgo __count;
+	intgo __capacity;
+} Slice;
+
+struct __go_string __go_byte_array_to_string(const void* p, intgo len);
+struct __go_open_array __go_string_to_byte_array (struct __go_string str);
+
+const char *_cgoPREFIX_Cfunc_CString(struct __go_string s) {
+	char *p = malloc(s.__length+1);
+	memmove(p, s.__data, s.__length);
+	p[s.__length] = 0;
+	return p;
+}
+
+struct __go_string _cgoPREFIX_Cfunc_GoString(char *p) {
+	intgo len = (p != NULL) ? strlen(p) : 0;
+	return __go_byte_array_to_string(p, len);
+}
+
+struct __go_string _cgoPREFIX_Cfunc_GoStringN(char *p, int32_t n) {
+	return __go_byte_array_to_string(p, n);
+}
+
+Slice _cgoPREFIX_Cfunc_GoBytes(char *p, int32_t n) {
+	struct __go_string s = { (const unsigned char *)p, n };
+	return __go_string_to_byte_array(s);
+}
+
+extern void runtime_throw(const char *);
+void *_cgoPREFIX_Cfunc__CMalloc(size_t n) {
+        void *p = malloc(n);
+        if(p == NULL && n == 0)
+                p = malloc(1);
+        if(p == NULL)
+                runtime_throw("runtime: C malloc failed");
+        return p;
+}
+`
+
+func (p *Package) gccExportHeaderProlog() string {
+	return strings.Replace(gccExportHeaderProlog, "GOINTBITS", fmt.Sprint(8*p.IntSize), -1)
+}
+
+const gccExportHeaderProlog = `
+typedef signed char GoInt8;
+typedef unsigned char GoUint8;
+typedef short GoInt16;
+typedef unsigned short GoUint16;
+typedef int GoInt32;
+typedef unsigned int GoUint32;
+typedef long long GoInt64;
+typedef unsigned long long GoUint64;
+typedef GoIntGOINTBITS GoInt;
+typedef GoUintGOINTBITS GoUint;
+typedef __SIZE_TYPE__ GoUintptr;
+typedef float GoFloat32;
+typedef double GoFloat64;
+typedef __complex float GoComplex64;
+typedef __complex double GoComplex128;
+
+typedef struct { char *p; GoInt n; } GoString;
+typedef void *GoMap;
+typedef void *GoChan;
+typedef struct { void *t; void *v; } GoInterface;
+typedef struct { void *data; GoInt len; GoInt cap; } GoSlice;
+`
diff --git a/libgo/go/cmd/cgo/util.go b/libgo/go/cmd/cgo/util.go
new file mode 100644
index 0000000..4e7800d
--- /dev/null
+++ b/libgo/go/cmd/cgo/util.go
@@ -0,0 +1,84 @@
+// Copyright 2009 The Go Authors.  All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package main
+
+import (
+	"bytes"
+	"fmt"
+	"go/token"
+	"os"
+	"os/exec"
+)
+
+// run runs the command argv, feeding in stdin on standard input.
+// It returns the output to standard output and standard error.
+// ok indicates whether the command exited successfully.
+func run(stdin []byte, argv []string) (stdout, stderr []byte, ok bool) {
+	p := exec.Command(argv[0], argv[1:]...)
+	p.Stdin = bytes.NewReader(stdin)
+	var bout, berr bytes.Buffer
+	p.Stdout = &bout
+	p.Stderr = &berr
+	err := p.Run()
+	if _, ok := err.(*exec.ExitError); err != nil && !ok {
+		fatalf("%s", err)
+	}
+	ok = p.ProcessState.Success()
+	stdout, stderr = bout.Bytes(), berr.Bytes()
+	return
+}
+
+func lineno(pos token.Pos) string {
+	return fset.Position(pos).String()
+}
+
+// Die with an error message.
+func fatalf(msg string, args ...interface{}) {
+	// If we've already printed other errors, they might have
+	// caused the fatal condition.  Assume they're enough.
+	if nerrors == 0 {
+		fmt.Fprintf(os.Stderr, msg+"\n", args...)
+	}
+	os.Exit(2)
+}
+
+var nerrors int
+
+func error_(pos token.Pos, msg string, args ...interface{}) {
+	nerrors++
+	if pos.IsValid() {
+		fmt.Fprintf(os.Stderr, "%s: ", fset.Position(pos).String())
+	}
+	fmt.Fprintf(os.Stderr, msg, args...)
+	fmt.Fprintf(os.Stderr, "\n")
+}
+
+// isName returns true if s is a valid C identifier
+func isName(s string) bool {
+	for i, v := range s {
+		if v != '_' && (v < 'A' || v > 'Z') && (v < 'a' || v > 'z') && (v < '0' || v > '9') {
+			return false
+		}
+		if i == 0 && '0' <= v && v <= '9' {
+			return false
+		}
+	}
+	return s != ""
+}
+
+func creat(name string) *os.File {
+	f, err := os.Create(name)
+	if err != nil {
+		fatalf("%s", err)
+	}
+	return f
+}
+
+func slashToUnderscore(c rune) rune {
+	if c == '/' || c == '\\' || c == ':' {
+		c = '_'
+	}
+	return c
+}