+++ /dev/null
-// Copyright 2014 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 cha computes the call graph of a Go program using the Class
-// Hierarchy Analysis (CHA) algorithm.
-//
-// CHA was first described in "Optimization of Object-Oriented Programs
-// Using Static Class Hierarchy Analysis", Jeffrey Dean, David Grove,
-// and Craig Chambers, ECOOP'95.
-//
-// CHA is related to RTA (see go/callgraph/rta); the difference is that
-// CHA conservatively computes the entire "implements" relation between
-// interfaces and concrete types ahead of time, whereas RTA uses dynamic
-// programming to construct it on the fly as it encounters new functions
-// reachable from main. CHA may thus include spurious call edges for
-// types that haven't been instantiated yet, or types that are never
-// instantiated.
-//
-// Since CHA conservatively assumes that all functions are address-taken
-// and all concrete types are put into interfaces, it is sound to run on
-// partial programs, such as libraries without a main or test function.
-//
-package cha // import "honnef.co/go/tools/callgraph/cha"
-
-import (
- "go/types"
-
- "golang.org/x/tools/go/types/typeutil"
- "honnef.co/go/tools/callgraph"
- "honnef.co/go/tools/ir"
- "honnef.co/go/tools/ir/irutil"
-)
-
-// CallGraph computes the call graph of the specified program using the
-// Class Hierarchy Analysis algorithm.
-//
-func CallGraph(prog *ir.Program) *callgraph.Graph {
- cg := callgraph.New(nil) // TODO(adonovan) eliminate concept of rooted callgraph
-
- allFuncs := irutil.AllFunctions(prog)
-
- // funcsBySig contains all functions, keyed by signature. It is
- // the effective set of address-taken functions used to resolve
- // a dynamic call of a particular signature.
- var funcsBySig typeutil.Map // value is []*ir.Function
-
- // methodsByName contains all methods,
- // grouped by name for efficient lookup.
- methodsByName := make(map[string][]*ir.Function)
-
- // methodsMemo records, for every abstract method call call I.f on
- // interface type I, the set of concrete methods C.f of all
- // types C that satisfy interface I.
- methodsMemo := make(map[*types.Func][]*ir.Function)
- lookupMethods := func(m *types.Func) []*ir.Function {
- methods, ok := methodsMemo[m]
- if !ok {
- I := m.Type().(*types.Signature).Recv().Type().Underlying().(*types.Interface)
- for _, f := range methodsByName[m.Name()] {
- C := f.Signature.Recv().Type() // named or *named
- if types.Implements(C, I) {
- methods = append(methods, f)
- }
- }
- methodsMemo[m] = methods
- }
- return methods
- }
-
- for f := range allFuncs {
- if f.Signature.Recv() == nil {
- // Package initializers can never be address-taken.
- if f.Name() == "init" && f.Synthetic == "package initializer" {
- continue
- }
- funcs, _ := funcsBySig.At(f.Signature).([]*ir.Function)
- funcs = append(funcs, f)
- funcsBySig.Set(f.Signature, funcs)
- } else {
- methodsByName[f.Name()] = append(methodsByName[f.Name()], f)
- }
- }
-
- addEdge := func(fnode *callgraph.Node, site ir.CallInstruction, g *ir.Function) {
- gnode := cg.CreateNode(g)
- callgraph.AddEdge(fnode, site, gnode)
- }
-
- addEdges := func(fnode *callgraph.Node, site ir.CallInstruction, callees []*ir.Function) {
- // Because every call to a highly polymorphic and
- // frequently used abstract method such as
- // (io.Writer).Write is assumed to call every concrete
- // Write method in the program, the call graph can
- // contain a lot of duplication.
- //
- // TODO(adonovan): opt: consider factoring the callgraph
- // API so that the Callers component of each edge is a
- // slice of nodes, not a singleton.
- for _, g := range callees {
- addEdge(fnode, site, g)
- }
- }
-
- for f := range allFuncs {
- fnode := cg.CreateNode(f)
- for _, b := range f.Blocks {
- for _, instr := range b.Instrs {
- if site, ok := instr.(ir.CallInstruction); ok {
- call := site.Common()
- if call.IsInvoke() {
- addEdges(fnode, site, lookupMethods(call.Method))
- } else if g := call.StaticCallee(); g != nil {
- addEdge(fnode, site, g)
- } else if _, ok := call.Value.(*ir.Builtin); !ok {
- callees, _ := funcsBySig.At(call.Signature()).([]*ir.Function)
- addEdges(fnode, site, callees)
- }
- }
- }
- }
- }
-
- return cg
-}
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