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go/oracle/callgraph.go
Alan Donovan 25a0cc4bfd go.tools/oracle: refactor Oracle API to allow repeated queries on same scope.
The existing standalone Query function builds an importer, ssa.Program, oracle,
and query position, executes the query and returns the result.
For clients (such as Frederik Zipp's web-based github.com/fzipp/pythia tool)
that wish to load the program once and make several queries, we now expose
these as separate operations too.  Here's a client, in pseudocode:

        o := oracle.New(...)
        for ... {
                qpos := o.ParseQueryPos(...)
                res := o.Query(mode, qpos)
                print result
        }

NB: this is a slight deoptimisation in the one-shot case since we have to
build the entire SSA program with debug info, not just the query package,
since we now don't know the query package at that time.

The 'exact' param to ParseQueryPos needs more thought since its
ideal value is a function of the query mode.  This will do for now.

Details:
- expose Oracle type, New() func and Query() method.
- expose QueryPos type and ParseQueryPos func.
- improved package doc comment.
- un-exposed the "needs" bits.
- added test.

R=crawshaw
CC=frederik.zipp, golang-dev
https://golang.org/cl/13810043
2013-09-23 15:02:18 -04:00

106 lines
3.0 KiB
Go

// 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 oracle
import (
"go/token"
"strings"
"code.google.com/p/go.tools/oracle/json"
"code.google.com/p/go.tools/pointer"
)
// callgraph displays the entire callgraph of the current program.
//
// Nodes may be seem to appear multiple times due to (limited)
// context sensitivity.
//
// TODO(adonovan): add options for restricting the display to a region
// of interest: function, package, subgraph, dirtree, goroutine, etc.
//
// TODO(adonovan): add an option to project away context sensitivity.
// The callgraph API should provide this feature.
//
// TODO(adonovan): elide nodes for synthetic functions?
//
func callgraph(o *Oracle, _ *QueryPos) (queryResult, error) {
buildSSA(o)
// Run the pointer analysis and build the complete callgraph.
callgraph := make(pointer.CallGraph)
o.config.Call = callgraph.AddEdge
root := ptrAnalysis(o)
// Assign (preorder) numbers to all the callgraph nodes.
// TODO(adonovan): the callgraph API should do this for us.
// (Actually, it does have unique numbers under the hood.)
numbering := make(map[pointer.CallGraphNode]int)
var number func(cgn pointer.CallGraphNode)
number = func(cgn pointer.CallGraphNode) {
if _, ok := numbering[cgn]; !ok {
numbering[cgn] = len(numbering)
for callee := range callgraph[cgn] {
number(callee)
}
}
}
number(root)
return &callgraphResult{
root: root,
callgraph: callgraph,
numbering: numbering,
}, nil
}
type callgraphResult struct {
root pointer.CallGraphNode
callgraph pointer.CallGraph
numbering map[pointer.CallGraphNode]int
}
func (r *callgraphResult) display(printf printfFunc) {
printf(nil, `
Below is a call graph of the entire program.
The numbered nodes form a spanning tree.
Non-numbered nodes indicate back- or cross-edges to the node whose
number follows in parentheses.
Some nodes may appear multiple times due to context-sensitive
treatment of some calls.
`)
// TODO(adonovan): compute the numbers as we print; right now
// it depends on map iteration so it's arbitrary,which is ugly.
seen := make(map[pointer.CallGraphNode]bool)
var print func(cgn pointer.CallGraphNode, indent int)
print = func(cgn pointer.CallGraphNode, indent int) {
n := r.numbering[cgn]
if !seen[cgn] {
seen[cgn] = true
printf(cgn.Func(), "%d\t%s%s", n, strings.Repeat(" ", indent), cgn.Func())
for callee := range r.callgraph[cgn] {
print(callee, indent+1)
}
} else {
printf(cgn.Func(), "\t%s%s (%d)", strings.Repeat(" ", indent), cgn.Func(), n)
}
}
print(r.root, 0)
}
func (r *callgraphResult) toJSON(res *json.Result, fset *token.FileSet) {
cg := make([]json.CallGraph, len(r.numbering))
for n, i := range r.numbering {
j := &cg[i]
fn := n.Func()
j.Name = fn.String()
j.Pos = fset.Position(fn.Pos()).String()
for callee := range r.callgraph[n] {
j.Children = append(j.Children, r.numbering[callee])
}
}
res.Callgraph = cg
}