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// 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.
// ssadump: a tool for displaying and interpreting the SSA form of Go programs.
package main // import "golang.org/x/tools/cmd/ssadump"
import (
"flag"
"fmt"
"go/build"
"go/types"
"os"
"runtime"
"runtime/pprof"
"golang.org/x/tools/go/buildutil"
"golang.org/x/tools/go/packages"
"golang.org/x/tools/go/ssa"
"golang.org/x/tools/go/ssa/interp"
"golang.org/x/tools/go/ssa/ssautil"
)
// flags
var (
mode = ssa.BuilderMode(0)
testFlag = flag.Bool("test", false, "include implicit test packages and executables")
runFlag = flag.Bool("run", false, "interpret the SSA program")
interpFlag = flag.String("interp", "", `Options controlling the SSA test interpreter.
The value is a sequence of zero or more more of these letters:
R disable [R]ecover() from panic; show interpreter crash instead.
T [T]race execution of the program. Best for single-threaded programs!
`)
cpuprofile = flag.String("cpuprofile", "", "write cpu profile to file")
args stringListValue
)
func init() {
flag.Var(&mode, "build", ssa.BuilderModeDoc)
flag.Var((*buildutil.TagsFlag)(&build.Default.BuildTags), "tags", buildutil.TagsFlagDoc)
flag.Var(&args, "arg", "add argument to interpreted program")
}
const usage = `SSA builder and interpreter.
Usage: ssadump [-build=[DBCSNFLG]] [-test] [-run] [-interp=[TR]] [-arg=...] package...
Use -help flag to display options.
Examples:
% ssadump -build=F hello.go # dump SSA form of a single package
% ssadump -build=F -test fmt # dump SSA form of a package and its tests
% ssadump -run -interp=T hello.go # interpret a program, with tracing
The -run flag causes ssadump to build the code in a runnable form and run the first
package named main.
Interpretation of the standard "testing" package is no longer supported.
`
func main() {
if err := doMain(); err != nil {
fmt.Fprintf(os.Stderr, "ssadump: %s\n", err)
os.Exit(1)
}
}
func doMain() error {
flag.Parse()
if len(flag.Args()) == 0 {
fmt.Fprint(os.Stderr, usage)
os.Exit(1)
}
cfg := &packages.Config{
Mode: packages.LoadSyntax,
Tests: *testFlag,
}
// Choose types.Sizes from conf.Build.
// TODO(adonovan): remove this when go/packages provides a better way.
var wordSize int64 = 8
switch build.Default.GOARCH {
case "386", "arm":
wordSize = 4
}
sizes := &types.StdSizes{
MaxAlign: 8,
WordSize: wordSize,
}
var interpMode interp.Mode
for _, c := range *interpFlag {
switch c {
case 'T':
interpMode |= interp.EnableTracing
case 'R':
interpMode |= interp.DisableRecover
default:
return fmt.Errorf("unknown -interp option: '%c'", c)
}
}
// Profiling support.
if *cpuprofile != "" {
f, err := os.Create(*cpuprofile)
if err != nil {
fmt.Fprintln(os.Stderr, err)
os.Exit(1)
}
pprof.StartCPUProfile(f)
defer pprof.StopCPUProfile()
}
// Load, parse and type-check the initial packages,
// and, if -run, their dependencies.
if *runFlag {
cfg.Mode = packages.LoadAllSyntax
}
initial, err := packages.Load(cfg, flag.Args()...)
if err != nil {
return err
}
if len(initial) == 0 {
return fmt.Errorf("no packages")
}
if packages.PrintErrors(initial) > 0 {
return fmt.Errorf("packages contain errors")
}
// Turn on instantiating generics during build if the program will be run.
if *runFlag {
mode |= ssa.InstantiateGenerics
}
// Create SSA-form program representation.
prog, pkgs := ssautil.AllPackages(initial, mode)
for i, p := range pkgs {
if p == nil {
return fmt.Errorf("cannot build SSA for package %s", initial[i])
}
}
if !*runFlag {
// Build and display only the initial packages
// (and synthetic wrappers).
for _, p := range pkgs {
p.Build()
}
} else {
// Run the interpreter.
// Build SSA for all packages.
prog.Build()
// Earlier versions of the interpreter needed the runtime
// package; however, interp cannot handle unsafe constructs
// used during runtime's package initialization at the moment.
// The key construct blocking support is:
// *((*T)(unsafe.Pointer(p)))
// Unfortunately, this means only trivial programs can be
// interpreted by ssadump.
if prog.ImportedPackage("runtime") != nil {
return fmt.Errorf("-run: program depends on runtime package (interpreter can run only trivial programs)")
}
if runtime.GOARCH != build.Default.GOARCH {
return fmt.Errorf("cross-interpretation is not supported (target has GOARCH %s, interpreter has %s)",
build.Default.GOARCH, runtime.GOARCH)
}
// Run first main package.
for _, main := range ssautil.MainPackages(pkgs) {
fmt.Fprintf(os.Stderr, "Running: %s\n", main.Pkg.Path())
os.Exit(interp.Interpret(main, interpMode, sizes, main.Pkg.Path(), args))
}
return fmt.Errorf("no main package")
}
return nil
}
// stringListValue is a flag.Value that accumulates strings.
// e.g. --flag=one --flag=two would produce []string{"one", "two"}.
type stringListValue []string
func newStringListValue(val []string, p *[]string) *stringListValue {
*p = val
return (*stringListValue)(p)
}
func (ss *stringListValue) Get() interface{} { return []string(*ss) }
func (ss *stringListValue) String() string { return fmt.Sprintf("%q", *ss) }
func (ss *stringListValue) Set(s string) error { *ss = append(*ss, s); return nil }
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