irgen/compiler.go - llvm-project/llgo - Git at Google

 //===- compiler.go - IR generator entry point -----------------------------===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
 //
 // This file implements the main IR generator entry point, (*Compiler).Compile.
 //
 //===----------------------------------------------------------------------===//

 package irgen

 import (
 	"bytes"
 	"go/ast"
 	"go/token"
 	"log"
 	"sort"
 	"strconv"

 	llgobuild "llvm.org/llgo/build"
 	"llvm.org/llgo/debug"
 	"llvm.org/llvm/bindings/go/llvm"

 	"llvm.org/llgo/third_party/gotools/go/gccgoimporter"
 	"llvm.org/llgo/third_party/gotools/go/importer"
 	"llvm.org/llgo/third_party/gotools/go/loader"
 	"llvm.org/llgo/third_party/gotools/go/ssa"
 	"llvm.org/llgo/third_party/gotools/go/types"
 )

 type Module struct {
 	llvm.Module
 	Path       string
 	ExportData []byte
 	Package    *types.Package
 	disposed   bool
 }

 func (m *Module) Dispose() {
 	if m.disposed {
 		return
 	}
 	m.Module.Dispose()
 	m.disposed = true
 }

 ///////////////////////////////////////////////////////////////////////////////

 type CompilerOptions struct {
 	// TargetTriple is the LLVM triple for the target.
 	TargetTriple string

 	// GenerateDebug decides whether debug data is
 	// generated in the output module.
 	GenerateDebug bool

 	// DebugPrefixMaps is a list of mappings from source prefixes to
 	// replacement prefixes, to be applied in debug info.
 	DebugPrefixMaps []debug.PrefixMap

 	// Logger is a logger used for tracing compilation.
 	Logger *log.Logger

 	// DumpSSA is a debugging option that dumps each SSA function
 	// to stderr before generating code for it.
 	DumpSSA bool

 	// GccgoPath is the path to the gccgo binary whose libgo we read import
 	// data from. If blank, the caller is expected to supply an import
 	// path in ImportPaths.
 	GccgoPath string

 	// Whether to use the gccgo ABI.
 	GccgoABI bool

 	// ImportPaths is the list of additional import paths
 	ImportPaths []string

 	// SanitizerAttribute is an attribute to apply to functions to enable
 	// dynamic instrumentation using a sanitizer.
 	SanitizerAttribute llvm.Attribute

 	// Importer is the importer. If nil, the compiler will set this field
 	// automatically using MakeImporter().
 	Importer types.Importer

 	// InitMap is the init map used by Importer. If Importer is nil, the
 	// compiler will set this field automatically using MakeImporter().
 	// If Importer is non-nil, InitMap must be non-nil also.
 	InitMap map[*types.Package]gccgoimporter.InitData

 	// PackageCreated is a hook passed to the go/loader package via
 	// loader.Config, see the documentation for that package for more
 	// information.
 	PackageCreated func(*types.Package)

 	// DisableUnusedImportCheck disables the unused import check performed
 	// by go/types if set to true.
 	DisableUnusedImportCheck bool

 	// Packages is used by go/types as the imported package map if non-nil.
 	Packages map[string]*types.Package
 }

 type Compiler struct {
 	opts       CompilerOptions
 	dataLayout string
 }

 func NewCompiler(opts CompilerOptions) (*Compiler, error) {
 	compiler := &Compiler{opts: opts}
 	dataLayout, err := llvmDataLayout(compiler.opts.TargetTriple)
 	if err != nil {
 		return nil, err
 	}
 	compiler.dataLayout = dataLayout
 	return compiler, nil
 }

 func (c *Compiler) Compile(fset *token.FileSet, astFiles []*ast.File, importpath string) (m *Module, err error) {
 	target := llvm.NewTargetData(c.dataLayout)
 	compiler := &compiler{
 		CompilerOptions: c.opts,
 		dataLayout:      c.dataLayout,
 		target:          target,
 		llvmtypes:       NewLLVMTypeMap(llvm.GlobalContext(), target),
 	}
 	return compiler.compile(fset, astFiles, importpath)
 }

 type compiler struct {
 	CompilerOptions

 	module     *Module
 	dataLayout string
 	target     llvm.TargetData
 	fileset    *token.FileSet

 	runtime   *runtimeInterface
 	llvmtypes *llvmTypeMap
 	types     *TypeMap

 	debug *debug.DIBuilder
 }

 func (c *compiler) logf(format string, v ...interface{}) {
 	if c.Logger != nil {
 		c.Logger.Printf(format, v...)
 	}
 }

 func (c *compiler) addCommonFunctionAttrs(fn llvm.Value) {
 	fn.AddTargetDependentFunctionAttr("disable-tail-calls", "true")
 	fn.AddTargetDependentFunctionAttr("split-stack", "")
 	if c.SanitizerAttribute.GetEnumKind() != 0 {
 		fn.AddFunctionAttr(c.SanitizerAttribute)
 	}
 }

 // MakeImporter sets CompilerOptions.Importer to an appropriate importer
 // for the search paths given in CompilerOptions.ImportPaths, and sets
 // CompilerOptions.InitMap to an init map belonging to that importer.
 // If CompilerOptions.GccgoPath is non-empty, the importer will also use
 // the search paths for that gccgo installation.
 func (opts *CompilerOptions) MakeImporter() error {
 	opts.InitMap = make(map[*types.Package]gccgoimporter.InitData)
 	if opts.GccgoPath == "" {
 		paths := append(append([]string{}, opts.ImportPaths...), ".")
 		opts.Importer = gccgoimporter.GetImporter(paths, opts.InitMap)
 	} else {
 		var inst gccgoimporter.GccgoInstallation
 		err := inst.InitFromDriver(opts.GccgoPath)
 		if err != nil {
 			return err
 		}
 		opts.Importer = inst.GetImporter(opts.ImportPaths, opts.InitMap)
 	}
 	return nil
 }

 func (compiler *compiler) compile(fset *token.FileSet, astFiles []*ast.File, importpath string) (m *Module, err error) {
 	buildctx, err := llgobuild.ContextFromTriple(compiler.TargetTriple)
 	if err != nil {
 		return nil, err
 	}

 	if compiler.Importer == nil {
 		err = compiler.MakeImporter()
 		if err != nil {
 			return nil, err
 		}
 	}

 	impcfg := &loader.Config{
 		Fset: fset,
 		TypeChecker: types.Config{
 			Packages: compiler.Packages,
 			Import:   compiler.Importer,
 			Sizes:    compiler.llvmtypes,
 			DisableUnusedImportCheck: compiler.DisableUnusedImportCheck,
 		},
 		ImportFromBinary: true,
 		Build:            &buildctx.Context,
 		PackageCreated:   compiler.PackageCreated,
 	}
 	// If no import path is specified, then set the import
 	// path to be the same as the package's name.
 	if importpath == "" {
 		importpath = astFiles[0].Name.String()
 	}
 	impcfg.CreateFromFiles(importpath, astFiles...)
 	iprog, err := impcfg.Load()
 	if err != nil {
 		return nil, err
 	}
 	program := ssa.Create(iprog, ssa.BareInits)
 	mainPkginfo := iprog.InitialPackages()[0]
 	mainPkg := program.CreatePackage(mainPkginfo)

 	// Create a Module, which contains the LLVM module.
 	modulename := importpath
 	compiler.module = &Module{Module: llvm.NewModule(modulename), Path: modulename, Package: mainPkg.Object}
 	compiler.module.SetTarget(compiler.TargetTriple)
 	compiler.module.SetDataLayout(compiler.dataLayout)

 	// Create a new translation unit.
 	unit := newUnit(compiler, mainPkg)

 	// Create the runtime interface.
 	compiler.runtime, err = newRuntimeInterface(compiler.module.Module, compiler.llvmtypes)
 	if err != nil {
 		return nil, err
 	}

 	mainPkg.Build()

 	// Create a struct responsible for mapping static types to LLVM types,
 	// and to runtime/dynamic type values.
 	compiler.types = NewTypeMap(
 		mainPkg,
 		compiler.llvmtypes,
 		compiler.module.Module,
 		compiler.runtime,
 		MethodResolver(unit),
 	)

 	if compiler.GenerateDebug {
 		compiler.debug = debug.NewDIBuilder(
 			types.Sizes(compiler.llvmtypes),
 			compiler.module.Module,
 			impcfg.Fset,
 			compiler.DebugPrefixMaps,
 		)
 		defer compiler.debug.Destroy()
 		defer compiler.debug.Finalize()
 	}

 	unit.translatePackage(mainPkg)
 	compiler.processAnnotations(unit, mainPkginfo)

 	if importpath == "main" {
 		compiler.createInitMainFunction(mainPkg)
 	} else {
 		compiler.module.ExportData = compiler.buildExportData(mainPkg)
 	}

 	return compiler.module, nil
 }

 type byPriorityThenFunc []gccgoimporter.PackageInit

 func (a byPriorityThenFunc) Len() int      { return len(a) }
 func (a byPriorityThenFunc) Swap(i, j int) { a[i], a[j] = a[j], a[i] }
 func (a byPriorityThenFunc) Less(i, j int) bool {
 	switch {
 	case a[i].Priority < a[j].Priority:
 		return true
 	case a[i].Priority > a[j].Priority:
 		return false
 	case a[i].InitFunc < a[j].InitFunc:
 		return true
 	default:
 		return false
 	}
 }

 func (c *compiler) buildPackageInitData(mainPkg *ssa.Package) gccgoimporter.InitData {
 	var inits []gccgoimporter.PackageInit
 	for _, imp := range mainPkg.Object.Imports() {
 		inits = append(inits, c.InitMap[imp].Inits...)
 	}
 	sort.Sort(byPriorityThenFunc(inits))

 	// Deduplicate init entries. We want to preserve the entry with the highest priority.
 	// Normally a package's priorities will be consistent among its dependencies, but it is
 	// possible for them to be different. For example, if a standard library test augments a
 	// package which is a dependency of 'regexp' (which is imported by every test main package)
 	// with additional dependencies, those dependencies may cause the package under test to
 	// receive a higher priority than indicated by its init clause in 'regexp'.
 	uniqinits := make([]gccgoimporter.PackageInit, len(inits))
 	uniqinitpos := len(inits)
 	uniqinitnames := make(map[string]struct{})
 	for i, _ := range inits {
 		init := inits[len(inits)-1-i]
 		if _, ok := uniqinitnames[init.InitFunc]; !ok {
 			uniqinitnames[init.InitFunc] = struct{}{}
 			uniqinitpos--
 			uniqinits[uniqinitpos] = init
 		}
 	}
 	uniqinits = uniqinits[uniqinitpos:]

 	ourprio := 1
 	if len(uniqinits) != 0 {
 		ourprio = uniqinits[len(uniqinits)-1].Priority + 1
 	}

 	if imp := mainPkg.Func("init"); imp != nil {
 		impname := c.types.mc.mangleFunctionName(imp)
 		uniqinits = append(uniqinits, gccgoimporter.PackageInit{mainPkg.Object.Name(), impname, ourprio})
 	}

 	return gccgoimporter.InitData{ourprio, uniqinits}
 }

 func (c *compiler) createInitMainFunction(mainPkg *ssa.Package) {
 	int8ptr := llvm.PointerType(c.types.ctx.Int8Type(), 0)
 	ftyp := llvm.FunctionType(llvm.VoidType(), []llvm.Type{int8ptr}, false)
 	initMain := llvm.AddFunction(c.module.Module, "__go_init_main", ftyp)
 	c.addCommonFunctionAttrs(initMain)
 	entry := llvm.AddBasicBlock(initMain, "entry")

 	builder := llvm.GlobalContext().NewBuilder()
 	defer builder.Dispose()
 	builder.SetInsertPointAtEnd(entry)

 	args := []llvm.Value{llvm.Undef(int8ptr)}

 	if !c.GccgoABI {
 		initfn := c.module.Module.NamedFunction("main..import")
 		if !initfn.IsNil() {
 			builder.CreateCall(initfn, args, "")
 		}
 		builder.CreateRetVoid()
 		return
 	}

 	initdata := c.buildPackageInitData(mainPkg)

 	for _, init := range initdata.Inits {
 		initfn := c.module.Module.NamedFunction(init.InitFunc)
 		if initfn.IsNil() {
 			initfn = llvm.AddFunction(c.module.Module, init.InitFunc, ftyp)
 		}
 		builder.CreateCall(initfn, args, "")
 	}

 	builder.CreateRetVoid()
 }

 func (c *compiler) buildExportData(mainPkg *ssa.Package) []byte {
 	exportData := importer.ExportData(mainPkg.Object)
 	b := bytes.NewBuffer(exportData)

 	b.WriteString("v1;\n")
 	if !c.GccgoABI {
 		return b.Bytes()
 	}

 	initdata := c.buildPackageInitData(mainPkg)
 	b.WriteString("priority ")
 	b.WriteString(strconv.Itoa(initdata.Priority))
 	b.WriteString(";\n")

 	if len(initdata.Inits) != 0 {
 		b.WriteString("init")
 		for _, init := range initdata.Inits {
 			b.WriteRune(' ')
 			b.WriteString(init.Name)
 			b.WriteRune(' ')
 			b.WriteString(init.InitFunc)
 			b.WriteRune(' ')
 			b.WriteString(strconv.Itoa(init.Priority))
 		}
 		b.WriteString(";\n")
 	}

 	return b.Bytes()
 }

 // vim: set ft=go :
	//===- compiler.go - IR generator entry point -----------------------------===//
	//
	// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
	// See https://llvm.org/LICENSE.txt for license information.
	// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
	//
	//===----------------------------------------------------------------------===//
	//
	// This file implements the main IR generator entry point, (*Compiler).Compile.
	//
	//===----------------------------------------------------------------------===//

	package irgen

	import (
	"bytes"
	"go/ast"
	"go/token"
	"log"
	"sort"
	"strconv"

	llgobuild "llvm.org/llgo/build"
	"llvm.org/llgo/debug"
	"llvm.org/llvm/bindings/go/llvm"

	"llvm.org/llgo/third_party/gotools/go/gccgoimporter"
	"llvm.org/llgo/third_party/gotools/go/importer"
	"llvm.org/llgo/third_party/gotools/go/loader"
	"llvm.org/llgo/third_party/gotools/go/ssa"
	"llvm.org/llgo/third_party/gotools/go/types"
	)

	type Module struct {
	llvm.Module
	Path string
	ExportData []byte
	Package *types.Package
	disposed bool
	}

	func (m *Module) Dispose() {
	if m.disposed {
	return
	}
	m.Module.Dispose()
	m.disposed = true
	}

	///////////////////////////////////////////////////////////////////////////////

	type CompilerOptions struct {
	// TargetTriple is the LLVM triple for the target.
	TargetTriple string

	// GenerateDebug decides whether debug data is
	// generated in the output module.
	GenerateDebug bool

	// DebugPrefixMaps is a list of mappings from source prefixes to
	// replacement prefixes, to be applied in debug info.
	DebugPrefixMaps []debug.PrefixMap

	// Logger is a logger used for tracing compilation.
	Logger *log.Logger

	// DumpSSA is a debugging option that dumps each SSA function
	// to stderr before generating code for it.
	DumpSSA bool

	// GccgoPath is the path to the gccgo binary whose libgo we read import
	// data from. If blank, the caller is expected to supply an import
	// path in ImportPaths.
	GccgoPath string

	// Whether to use the gccgo ABI.
	GccgoABI bool

	// ImportPaths is the list of additional import paths
	ImportPaths []string

	// SanitizerAttribute is an attribute to apply to functions to enable
	// dynamic instrumentation using a sanitizer.
	SanitizerAttribute llvm.Attribute

	// Importer is the importer. If nil, the compiler will set this field
	// automatically using MakeImporter().
	Importer types.Importer

	// InitMap is the init map used by Importer. If Importer is nil, the
	// compiler will set this field automatically using MakeImporter().
	// If Importer is non-nil, InitMap must be non-nil also.
	InitMap map[*types.Package]gccgoimporter.InitData

	// PackageCreated is a hook passed to the go/loader package via
	// loader.Config, see the documentation for that package for more
	// information.
	PackageCreated func(*types.Package)

	// DisableUnusedImportCheck disables the unused import check performed
	// by go/types if set to true.
	DisableUnusedImportCheck bool

	// Packages is used by go/types as the imported package map if non-nil.
	Packages map[string]*types.Package
	}

	type Compiler struct {
	opts CompilerOptions
	dataLayout string
	}

	func NewCompiler(opts CompilerOptions) (*Compiler, error) {
	compiler := &Compiler{opts: opts}
	dataLayout, err := llvmDataLayout(compiler.opts.TargetTriple)
	if err != nil {
	return nil, err
	}
	compiler.dataLayout = dataLayout
	return compiler, nil
	}

	func (c Compiler) Compile(fset token.FileSet, astFiles []ast.File, importpath string) (m Module, err error) {
	target := llvm.NewTargetData(c.dataLayout)
	compiler := &compiler{
	CompilerOptions: c.opts,
	dataLayout: c.dataLayout,
	target: target,
	llvmtypes: NewLLVMTypeMap(llvm.GlobalContext(), target),
	}
	return compiler.compile(fset, astFiles, importpath)
	}

	type compiler struct {
	CompilerOptions

	module *Module
	dataLayout string
	target llvm.TargetData
	fileset *token.FileSet

	runtime *runtimeInterface
	llvmtypes *llvmTypeMap
	types *TypeMap

	debug *debug.DIBuilder
	}

	func (c *compiler) logf(format string, v ...interface{}) {
	if c.Logger != nil {
	c.Logger.Printf(format, v...)
	}
	}

	func (c *compiler) addCommonFunctionAttrs(fn llvm.Value) {
	fn.AddTargetDependentFunctionAttr("disable-tail-calls", "true")
	fn.AddTargetDependentFunctionAttr("split-stack", "")
	if c.SanitizerAttribute.GetEnumKind() != 0 {
	fn.AddFunctionAttr(c.SanitizerAttribute)
	}
	}

	// MakeImporter sets CompilerOptions.Importer to an appropriate importer
	// for the search paths given in CompilerOptions.ImportPaths, and sets
	// CompilerOptions.InitMap to an init map belonging to that importer.
	// If CompilerOptions.GccgoPath is non-empty, the importer will also use
	// the search paths for that gccgo installation.
	func (opts *CompilerOptions) MakeImporter() error {
	opts.InitMap = make(map[*types.Package]gccgoimporter.InitData)
	if opts.GccgoPath == "" {
	paths := append(append([]string{}, opts.ImportPaths...), ".")
	opts.Importer = gccgoimporter.GetImporter(paths, opts.InitMap)
	} else {
	var inst gccgoimporter.GccgoInstallation
	err := inst.InitFromDriver(opts.GccgoPath)
	if err != nil {
	return err
	}
	opts.Importer = inst.GetImporter(opts.ImportPaths, opts.InitMap)
	}
	return nil
	}

	func (compiler compiler) compile(fset token.FileSet, astFiles []ast.File, importpath string) (m Module, err error) {
	buildctx, err := llgobuild.ContextFromTriple(compiler.TargetTriple)
	if err != nil {
	return nil, err
	}

	if compiler.Importer == nil {
	err = compiler.MakeImporter()
	if err != nil {
	return nil, err
	}
	}

	impcfg := &loader.Config{
	Fset: fset,
	TypeChecker: types.Config{
	Packages: compiler.Packages,
	Import: compiler.Importer,
	Sizes: compiler.llvmtypes,
	DisableUnusedImportCheck: compiler.DisableUnusedImportCheck,
	},
	ImportFromBinary: true,
	Build: &buildctx.Context,
	PackageCreated: compiler.PackageCreated,
	}
	// If no import path is specified, then set the import
	// path to be the same as the package's name.
	if importpath == "" {
	importpath = astFiles[0].Name.String()
	}
	impcfg.CreateFromFiles(importpath, astFiles...)
	iprog, err := impcfg.Load()
	if err != nil {
	return nil, err
	}
	program := ssa.Create(iprog, ssa.BareInits)
	mainPkginfo := iprog.InitialPackages()[0]
	mainPkg := program.CreatePackage(mainPkginfo)

	// Create a Module, which contains the LLVM module.
	modulename := importpath
	compiler.module = &Module{Module: llvm.NewModule(modulename), Path: modulename, Package: mainPkg.Object}
	compiler.module.SetTarget(compiler.TargetTriple)
	compiler.module.SetDataLayout(compiler.dataLayout)

	// Create a new translation unit.
	unit := newUnit(compiler, mainPkg)

	// Create the runtime interface.
	compiler.runtime, err = newRuntimeInterface(compiler.module.Module, compiler.llvmtypes)
	if err != nil {
	return nil, err
	}

	mainPkg.Build()

	// Create a struct responsible for mapping static types to LLVM types,
	// and to runtime/dynamic type values.
	compiler.types = NewTypeMap(
	mainPkg,
	compiler.llvmtypes,
	compiler.module.Module,
	compiler.runtime,
	MethodResolver(unit),
	)

	if compiler.GenerateDebug {
	compiler.debug = debug.NewDIBuilder(
	types.Sizes(compiler.llvmtypes),
	compiler.module.Module,
	impcfg.Fset,
	compiler.DebugPrefixMaps,
	)
	defer compiler.debug.Destroy()
	defer compiler.debug.Finalize()
	}

	unit.translatePackage(mainPkg)
	compiler.processAnnotations(unit, mainPkginfo)

	if importpath == "main" {
	compiler.createInitMainFunction(mainPkg)
	} else {
	compiler.module.ExportData = compiler.buildExportData(mainPkg)
	}

	return compiler.module, nil
	}

	type byPriorityThenFunc []gccgoimporter.PackageInit

	func (a byPriorityThenFunc) Len() int { return len(a) }
	func (a byPriorityThenFunc) Swap(i, j int) { a[i], a[j] = a[j], a[i] }
	func (a byPriorityThenFunc) Less(i, j int) bool {
	switch {
	case a[i].Priority < a[j].Priority:
	return true
	case a[i].Priority > a[j].Priority:
	return false
	case a[i].InitFunc < a[j].InitFunc:
	return true
	default:
	return false
	}
	}

	func (c compiler) buildPackageInitData(mainPkg ssa.Package) gccgoimporter.InitData {
	var inits []gccgoimporter.PackageInit
	for _, imp := range mainPkg.Object.Imports() {
	inits = append(inits, c.InitMap[imp].Inits...)
	}
	sort.Sort(byPriorityThenFunc(inits))

	// Deduplicate init entries. We want to preserve the entry with the highest priority.
	// Normally a package's priorities will be consistent among its dependencies, but it is
	// possible for them to be different. For example, if a standard library test augments a
	// package which is a dependency of 'regexp' (which is imported by every test main package)
	// with additional dependencies, those dependencies may cause the package under test to
	// receive a higher priority than indicated by its init clause in 'regexp'.
	uniqinits := make([]gccgoimporter.PackageInit, len(inits))
	uniqinitpos := len(inits)
	uniqinitnames := make(map[string]struct{})
	for i, _ := range inits {
	init := inits[len(inits)-1-i]
	if _, ok := uniqinitnames[init.InitFunc]; !ok {
	uniqinitnames[init.InitFunc] = struct{}{}
	uniqinitpos--
	uniqinits[uniqinitpos] = init
	}
	}
	uniqinits = uniqinits[uniqinitpos:]

	ourprio := 1
	if len(uniqinits) != 0 {
	ourprio = uniqinits[len(uniqinits)-1].Priority + 1
	}

	if imp := mainPkg.Func("init"); imp != nil {
	impname := c.types.mc.mangleFunctionName(imp)
	uniqinits = append(uniqinits, gccgoimporter.PackageInit{mainPkg.Object.Name(), impname, ourprio})
	}

	return gccgoimporter.InitData{ourprio, uniqinits}
	}

	func (c compiler) createInitMainFunction(mainPkg ssa.Package) {
	int8ptr := llvm.PointerType(c.types.ctx.Int8Type(), 0)
	ftyp := llvm.FunctionType(llvm.VoidType(), []llvm.Type{int8ptr}, false)
	initMain := llvm.AddFunction(c.module.Module, "__go_init_main", ftyp)
	c.addCommonFunctionAttrs(initMain)
	entry := llvm.AddBasicBlock(initMain, "entry")

	builder := llvm.GlobalContext().NewBuilder()
	defer builder.Dispose()
	builder.SetInsertPointAtEnd(entry)

	args := []llvm.Value{llvm.Undef(int8ptr)}

	if !c.GccgoABI {
	initfn := c.module.Module.NamedFunction("main..import")
	if !initfn.IsNil() {
	builder.CreateCall(initfn, args, "")
	}
	builder.CreateRetVoid()
	return
	}

	initdata := c.buildPackageInitData(mainPkg)

	for _, init := range initdata.Inits {
	initfn := c.module.Module.NamedFunction(init.InitFunc)
	if initfn.IsNil() {
	initfn = llvm.AddFunction(c.module.Module, init.InitFunc, ftyp)
	}
	builder.CreateCall(initfn, args, "")
	}

	builder.CreateRetVoid()
	}

	func (c compiler) buildExportData(mainPkg ssa.Package) []byte {
	exportData := importer.ExportData(mainPkg.Object)
	b := bytes.NewBuffer(exportData)

	b.WriteString("v1;\n")
	if !c.GccgoABI {
	return b.Bytes()
	}

	initdata := c.buildPackageInitData(mainPkg)
	b.WriteString("priority ")
	b.WriteString(strconv.Itoa(initdata.Priority))
	b.WriteString(";\n")

	if len(initdata.Inits) != 0 {
	b.WriteString("init")
	for _, init := range initdata.Inits {
	b.WriteRune(' ')
	b.WriteString(init.Name)
	b.WriteRune(' ')
	b.WriteString(init.InitFunc)
	b.WriteRune(' ')
	b.WriteString(strconv.Itoa(init.Priority))
	}
	b.WriteString(";\n")
	}

	return b.Bytes()
	}

	// vim: set ft=go :