Permalink
Fetching contributors…
Cannot retrieve contributors at this time
271 lines (241 sloc) 6.66 KB
// Copyright 2013 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 ssa
// This file implements the CREATE phase of SSA construction.
// See builder.go for explanation.
import (
"fmt"
"go/ast"
"go/token"
"go/types"
"os"
"sync"
"golang.org/x/tools/go/types/typeutil"
)
// NewProgram returns a new SSA Program.
//
// mode controls diagnostics and checking during SSA construction.
//
func NewProgram(fset *token.FileSet, mode BuilderMode) *Program {
prog := &Program{
Fset: fset,
imported: make(map[string]*Package),
packages: make(map[*types.Package]*Package),
thunks: make(map[selectionKey]*Function),
bounds: make(map[*types.Func]*Function),
mode: mode,
}
h := typeutil.MakeHasher() // protected by methodsMu, in effect
prog.methodSets.SetHasher(h)
prog.canon.SetHasher(h)
return prog
}
// memberFromObject populates package pkg with a member for the
// typechecker object obj.
//
// For objects from Go source code, syntax is the associated syntax
// tree (for funcs and vars only); it will be used during the build
// phase.
//
func memberFromObject(pkg *Package, obj types.Object, syntax ast.Node) {
name := obj.Name()
switch obj := obj.(type) {
case *types.Builtin:
if pkg.Pkg != types.Unsafe {
panic("unexpected builtin object: " + obj.String())
}
case *types.TypeName:
pkg.Members[name] = &Type{
object: obj,
pkg: pkg,
}
case *types.Const:
c := &NamedConst{
object: obj,
Value: NewConst(obj.Val(), obj.Type()),
pkg: pkg,
}
pkg.values[obj] = c.Value
pkg.Members[name] = c
case *types.Var:
g := &Global{
Pkg: pkg,
name: name,
object: obj,
typ: types.NewPointer(obj.Type()), // address
pos: obj.Pos(),
}
pkg.values[obj] = g
pkg.Members[name] = g
case *types.Func:
sig := obj.Type().(*types.Signature)
if sig.Recv() == nil && name == "init" {
pkg.ninit++
name = fmt.Sprintf("init#%d", pkg.ninit)
}
fn := &Function{
name: name,
object: obj,
Signature: sig,
syntax: syntax,
pos: obj.Pos(),
Pkg: pkg,
Prog: pkg.Prog,
}
if syntax == nil {
fn.Synthetic = "loaded from gc object file"
}
pkg.values[obj] = fn
if sig.Recv() == nil {
pkg.Members[name] = fn // package-level function
}
default: // (incl. *types.Package)
panic("unexpected Object type: " + obj.String())
}
}
// membersFromDecl populates package pkg with members for each
// typechecker object (var, func, const or type) associated with the
// specified decl.
//
func membersFromDecl(pkg *Package, decl ast.Decl) {
switch decl := decl.(type) {
case *ast.GenDecl: // import, const, type or var
switch decl.Tok {
case token.CONST:
for _, spec := range decl.Specs {
for _, id := range spec.(*ast.ValueSpec).Names {
if !isBlankIdent(id) {
memberFromObject(pkg, pkg.info.Defs[id], nil)
}
}
}
case token.VAR:
for _, spec := range decl.Specs {
for _, id := range spec.(*ast.ValueSpec).Names {
if !isBlankIdent(id) {
memberFromObject(pkg, pkg.info.Defs[id], spec)
}
}
}
case token.TYPE:
for _, spec := range decl.Specs {
id := spec.(*ast.TypeSpec).Name
if !isBlankIdent(id) {
memberFromObject(pkg, pkg.info.Defs[id], nil)
}
}
}
case *ast.FuncDecl:
id := decl.Name
if !isBlankIdent(id) {
memberFromObject(pkg, pkg.info.Defs[id], decl)
}
}
}
// CreatePackage constructs and returns an SSA Package from the
// specified type-checked, error-free file ASTs, and populates its
// Members mapping.
//
// importable determines whether this package should be returned by a
// subsequent call to ImportedPackage(pkg.Path()).
//
// The real work of building SSA form for each function is not done
// until a subsequent call to Package.Build().
//
func (prog *Program) CreatePackage(pkg *types.Package, files []*ast.File, info *types.Info, importable bool) *Package {
p := &Package{
Prog: prog,
Members: make(map[string]Member),
values: make(map[types.Object]Value),
Pkg: pkg,
info: info, // transient (CREATE and BUILD phases)
files: files, // transient (CREATE and BUILD phases)
}
// Add init() function.
p.init = &Function{
name: "init",
Signature: new(types.Signature),
Synthetic: "package initializer",
Pkg: p,
Prog: prog,
}
p.Members[p.init.name] = p.init
// CREATE phase.
// Allocate all package members: vars, funcs, consts and types.
if len(files) > 0 {
// Go source package.
for _, file := range files {
for _, decl := range file.Decls {
membersFromDecl(p, decl)
}
}
} else {
// GC-compiled binary package (or "unsafe")
// No code.
// No position information.
scope := p.Pkg.Scope()
for _, name := range scope.Names() {
obj := scope.Lookup(name)
memberFromObject(p, obj, nil)
if obj, ok := obj.(*types.TypeName); ok {
if named, ok := obj.Type().(*types.Named); ok {
for i, n := 0, named.NumMethods(); i < n; i++ {
memberFromObject(p, named.Method(i), nil)
}
}
}
}
}
if prog.mode&BareInits == 0 {
// Add initializer guard variable.
initguard := &Global{
Pkg: p,
name: "init$guard",
typ: types.NewPointer(tBool),
}
p.Members[initguard.Name()] = initguard
}
if prog.mode&GlobalDebug != 0 {
p.SetDebugMode(true)
}
if prog.mode&PrintPackages != 0 {
printMu.Lock()
p.WriteTo(os.Stdout)
printMu.Unlock()
}
if importable {
prog.imported[p.Pkg.Path()] = p
}
prog.packages[p.Pkg] = p
return p
}
// printMu serializes printing of Packages/Functions to stdout.
var printMu sync.Mutex
// AllPackages returns a new slice containing all packages in the
// program prog in unspecified order.
//
func (prog *Program) AllPackages() []*Package {
pkgs := make([]*Package, 0, len(prog.packages))
for _, pkg := range prog.packages {
pkgs = append(pkgs, pkg)
}
return pkgs
}
// ImportedPackage returns the importable Package whose PkgPath
// is path, or nil if no such Package has been created.
//
// A parameter to CreatePackage determines whether a package should be
// considered importable. For example, no import declaration can resolve
// to the ad-hoc main package created by 'go build foo.go'.
//
// TODO(adonovan): rethink this function and the "importable" concept;
// most packages are importable. This function assumes that all
// types.Package.Path values are unique within the ssa.Program, which is
// false---yet this function remains very convenient.
// Clients should use (*Program).Package instead where possible.
// SSA doesn't really need a string-keyed map of packages.
//
func (prog *Program) ImportedPackage(path string) *Package {
return prog.imported[path]
}