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// Copyright 2015 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.
// +build go1.5
package ssautil
// This file defines utility functions for constructing programs in SSA form.
import (
// CreateProgram returns a new program in SSA form, given a program
// loaded from source. An SSA package is created for each transitively
// error-free package of lprog.
// Code for bodies of functions is not built until Build is called
// on the result.
// mode controls diagnostics and checking during SSA construction.
func CreateProgram(lprog *loader.Program, mode ssa.BuilderMode) *ssa.Program {
prog := ssa.NewProgram(lprog.Fset, mode)
for _, info := range lprog.AllPackages {
if info.TransitivelyErrorFree {
prog.CreatePackage(info.Pkg, info.Files, &info.Info, info.Importable)
return prog
// BuildPackage builds an SSA program with IR for a single package.
// It populates pkg by type-checking the specified file ASTs. All
// dependencies are loaded using the importer specified by tc, which
// typically loads compiler export data; SSA code cannot be built for
// those packages. BuildPackage then constructs an ssa.Program with all
// dependency packages created, and builds and returns the SSA package
// corresponding to pkg.
// The caller must have set pkg.Path() to the import path.
// The operation fails if there were any type-checking or import errors.
// See ../ssa/example_test.go for an example.
func BuildPackage(tc *types.Config, fset *token.FileSet, pkg *types.Package, files []*ast.File, mode ssa.BuilderMode) (*ssa.Package, *types.Info, error) {
if fset == nil {
panic("no token.FileSet")
if pkg.Path() == "" {
panic("package has no import path")
info := &types.Info{
Types: make(map[ast.Expr]types.TypeAndValue),
Defs: make(map[*ast.Ident]types.Object),
Uses: make(map[*ast.Ident]types.Object),
Implicits: make(map[ast.Node]types.Object),
Scopes: make(map[ast.Node]*types.Scope),
Selections: make(map[*ast.SelectorExpr]*types.Selection),
if err := types.NewChecker(tc, fset, pkg, info).Files(files); err != nil {
return nil, nil, err
prog := ssa.NewProgram(fset, mode)
// Create SSA packages for all imports.
// Order is not significant.
created := make(map[*types.Package]bool)
var createAll func(pkgs []*types.Package)
createAll = func(pkgs []*types.Package) {
for _, p := range pkgs {
if !created[p] {
created[p] = true
prog.CreatePackage(p, nil, nil, true)
// Create and build the primary package.
ssapkg := prog.CreatePackage(pkg, files, info, false)
return ssapkg, info, nil