| 1 | // Copyright 2018 The Go Authors. All rights reserved. |
|---|---|
| 2 | // Use of this source code is governed by a BSD-style |
| 3 | // license that can be found in the LICENSE file. |
| 4 | |
| 5 | // Package buildssa defines an Analyzer that constructs the SSA |
| 6 | // representation of an error-free package and returns the set of all |
| 7 | // functions within it. It does not report any diagnostics itself but |
| 8 | // may be used as an input to other analyzers. |
| 9 | // |
| 10 | // THIS INTERFACE IS EXPERIMENTAL AND MAY BE SUBJECT TO INCOMPATIBLE CHANGE. |
| 11 | package buildssa |
| 12 | |
| 13 | import ( |
| 14 | "go/ast" |
| 15 | "go/types" |
| 16 | "reflect" |
| 17 | |
| 18 | "golang.org/x/tools/go/analysis" |
| 19 | "golang.org/x/tools/go/ssa" |
| 20 | ) |
| 21 | |
| 22 | var Analyzer = &analysis.Analyzer{ |
| 23 | Name: "buildssa", |
| 24 | Doc: "build SSA-form IR for later passes", |
| 25 | Run: run, |
| 26 | ResultType: reflect.TypeOf(new(SSA)), |
| 27 | } |
| 28 | |
| 29 | // SSA provides SSA-form intermediate representation for all the |
| 30 | // non-blank source functions in the current package. |
| 31 | type SSA struct { |
| 32 | Pkg *ssa.Package |
| 33 | SrcFuncs []*ssa.Function |
| 34 | } |
| 35 | |
| 36 | func run(pass *analysis.Pass) (interface{}, error) { |
| 37 | // Plundered from ssautil.BuildPackage. |
| 38 | |
| 39 | // We must create a new Program for each Package because the |
| 40 | // analysis API provides no place to hang a Program shared by |
| 41 | // all Packages. Consequently, SSA Packages and Functions do not |
| 42 | // have a canonical representation across an analysis session of |
| 43 | // multiple packages. This is unlikely to be a problem in |
| 44 | // practice because the analysis API essentially forces all |
| 45 | // packages to be analysed independently, so any given call to |
| 46 | // Analysis.Run on a package will see only SSA objects belonging |
| 47 | // to a single Program. |
| 48 | |
| 49 | // Some Analyzers may need GlobalDebug, in which case we'll have |
| 50 | // to set it globally, but let's wait till we need it. |
| 51 | mode := ssa.BuilderMode(0) |
| 52 | |
| 53 | prog := ssa.NewProgram(pass.Fset, mode) |
| 54 | |
| 55 | // Create SSA packages for all imports. |
| 56 | // Order is not significant. |
| 57 | created := make(map[*types.Package]bool) |
| 58 | var createAll func(pkgs []*types.Package) |
| 59 | createAll = func(pkgs []*types.Package) { |
| 60 | for _, p := range pkgs { |
| 61 | if !created[p] { |
| 62 | created[p] = true |
| 63 | prog.CreatePackage(p, nil, nil, true) |
| 64 | createAll(p.Imports()) |
| 65 | } |
| 66 | } |
| 67 | } |
| 68 | createAll(pass.Pkg.Imports()) |
| 69 | |
| 70 | // Create and build the primary package. |
| 71 | ssapkg := prog.CreatePackage(pass.Pkg, pass.Files, pass.TypesInfo, false) |
| 72 | ssapkg.Build() |
| 73 | |
| 74 | // Compute list of source functions, including literals, |
| 75 | // in source order. |
| 76 | var funcs []*ssa.Function |
| 77 | for _, f := range pass.Files { |
| 78 | for _, decl := range f.Decls { |
| 79 | if fdecl, ok := decl.(*ast.FuncDecl); ok { |
| 80 | |
| 81 | // SSA will not build a Function |
| 82 | // for a FuncDecl named blank. |
| 83 | // That's arguably too strict but |
| 84 | // relaxing it would break uniqueness of |
| 85 | // names of package members. |
| 86 | if fdecl.Name.Name == "_" { |
| 87 | continue |
| 88 | } |
| 89 | |
| 90 | // (init functions have distinct Func |
| 91 | // objects named "init" and distinct |
| 92 | // ssa.Functions named "init#1", ...) |
| 93 | |
| 94 | fn := pass.TypesInfo.Defs[fdecl.Name].(*types.Func) |
| 95 | if fn == nil { |
| 96 | panic(fn) |
| 97 | } |
| 98 | |
| 99 | f := ssapkg.Prog.FuncValue(fn) |
| 100 | if f == nil { |
| 101 | panic(fn) |
| 102 | } |
| 103 | |
| 104 | var addAnons func(f *ssa.Function) |
| 105 | addAnons = func(f *ssa.Function) { |
| 106 | funcs = append(funcs, f) |
| 107 | for _, anon := range f.AnonFuncs { |
| 108 | addAnons(anon) |
| 109 | } |
| 110 | } |
| 111 | addAnons(f) |
| 112 | } |
| 113 | } |
| 114 | } |
| 115 | |
| 116 | return &SSA{Pkg: ssapkg, SrcFuncs: funcs}, nil |
| 117 | } |
| 118 |
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