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// Copyright 2018 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 buildssa defines an Analyzer that constructs the SSA
// representation of an error-free package and returns the set of all
// functions within it. It does not report any diagnostics itself but
// may be used as an input to other analyzers.
//
// THIS INTERFACE IS EXPERIMENTAL AND MAY BE SUBJECT TO INCOMPATIBLE CHANGE.
package buildssa
import (
"go/ast"
"go/types"
"reflect"
"golang.org/x/tools/go/analysis"
"honnef.co/go/tools/ssa"
)
var Analyzer = &analysis.Analyzer{
Name: "buildssa",
Doc: "build SSA-form IR for later passes",
Run: run,
ResultType: reflect.TypeOf(new(SSA)),
}
// SSA provides SSA-form intermediate representation for all the
// non-blank source functions in the current package.
type SSA struct {
Pkg *ssa.Package
SrcFuncs []*ssa.Function
}
func run(pass *analysis.Pass) (interface{}, error) {
// Plundered from ssautil.BuildPackage.
// We must create a new Program for each Package because the
// analysis API provides no place to hang a Program shared by
// all Packages. Consequently, SSA Packages and Functions do not
// have a canonical representation across an analysis session of
// multiple packages. This is unlikely to be a problem in
// practice because the analysis API essentially forces all
// packages to be analysed independently, so any given call to
// Analysis.Run on a package will see only SSA objects belonging
// to a single Program.
mode := ssa.GlobalDebug
prog := ssa.NewProgram(pass.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)
createAll(p.Imports())
}
}
}
createAll(pass.Pkg.Imports())
// Create and build the primary package.
ssapkg := prog.CreatePackage(pass.Pkg, pass.Files, pass.TypesInfo, false)
ssapkg.Build()
// Compute list of source functions, including literals,
// in source order.
var funcs []*ssa.Function
var addAnons func(f *ssa.Function)
addAnons = func(f *ssa.Function) {
funcs = append(funcs, f)
for _, anon := range f.AnonFuncs {
addAnons(anon)
}
}
addAnons(ssapkg.Members["init"].(*ssa.Function))
for _, f := range pass.Files {
for _, decl := range f.Decls {
if fdecl, ok := decl.(*ast.FuncDecl); ok {
// SSA will not build a Function
// for a FuncDecl named blank.
// That's arguably too strict but
// relaxing it would break uniqueness of
// names of package members.
if fdecl.Name.Name == "_" {
continue
}
// (init functions have distinct Func
// objects named "init" and distinct
// ssa.Functions named "init#1", ...)
fn := pass.TypesInfo.Defs[fdecl.Name].(*types.Func)
if fn == nil {
panic(fn)
}
f := ssapkg.Prog.FuncValue(fn)
if f == nil {
panic(fn)
}
addAnons(f)
}
}
}
return &SSA{Pkg: ssapkg, SrcFuncs: funcs}, nil
}
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