mirror of
https://github.com/golang/go
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72 lines
1.7 KiB
Go
72 lines
1.7 KiB
Go
// Copyright 2013 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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package pointer
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import (
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"fmt"
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"go/token"
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"strings"
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"code.google.com/p/go.tools/ssa"
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)
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// A Label is an abstract location or an instruction that allocates memory.
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// A points-to set is (conceptually) a set of labels.
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//
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// (This is basically a pair of a Value that allocates an object and a
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// subelement indicator within that object.)
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//
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// TODO(adonovan): local labels should include their context (CallGraphNode).
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//
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type Label struct {
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Value ssa.Value
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subelement *fieldInfo // e.g. ".a.b[*].c"
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}
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func (l *Label) Pos() token.Pos {
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if l.Value != nil {
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return l.Value.Pos()
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}
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return token.NoPos
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}
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func (l *Label) String() string {
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var s string
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switch v := l.Value.(type) {
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case *ssa.Function, *ssa.Global:
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s = v.String()
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case *ssa.Const:
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s = v.Name()
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case *ssa.Alloc:
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s = v.Comment
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if s == "" {
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s = "alloc"
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}
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case *ssa.Call:
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// Currently only calls to append can allocate objects.
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if v.Call.Value.(*ssa.Builtin).Object().Name() != "append" {
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panic("unhandled *ssa.Call label: " + v.Name())
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}
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s = "append"
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case *ssa.MakeMap, *ssa.MakeChan, *ssa.MakeSlice, *ssa.Convert:
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s = strings.ToLower(strings.TrimPrefix(fmt.Sprintf("%T", v), "*ssa."))
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case *ssa.MakeInterface:
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// MakeInterface is usually implicit in Go source (so
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// Pos()==0), and interfaces objects may be allocated
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// synthetically (so no *MakeInterface data).
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s = "makeinterface:" + v.X.Type().String()
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default:
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panic(fmt.Sprintf("unhandled Label.Value type: %T", v))
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}
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return s + l.subelement.path()
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}
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