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https://github.com/golang/go
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cmd/compile: refactor GOSSAHASH debugging to make it usable outside ssa package.
I've needed this more than once in the past, I hack it in, then throw it away, seems sensible to make the change and save it. Fixes #53937. Change-Id: I7fe886b1c93d73cbf553bed587f2c30f0f5d5a0b Reviewed-on: https://go-review.googlesource.com/c/go/+/418015 Reviewed-by: Keith Randall <khr@google.com> Reviewed-by: Keith Randall <khr@golang.org>
This commit is contained in:
David Chase
parent
f19f6c79e4
commit
522f0fc425
147
src/cmd/compile/internal/base/hashdebug.go
Normal file
147
src/cmd/compile/internal/base/hashdebug.go
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@ -0,0 +1,147 @@
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// Copyright 2022 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 base
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import (
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"cmd/internal/notsha256"
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"fmt"
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"io"
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"os"
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"strings"
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"sync"
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)
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const GOSSAHASH = "GOSSAHASH"
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type writeSyncer interface {
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io.Writer
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Sync() error
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}
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type HashDebug struct {
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mu sync.Mutex
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// what file (if any) receives the yes/no logging?
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// default is os.Stdout
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logfile writeSyncer
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}
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var hd HashDebug
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// DebugHashMatch reports whether environment variable GOSSAHASH
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//
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// 1. is empty (this is a special more-quickly implemented case of 3)
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// 2. is "y" or "Y"
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// 3. is a suffix of the sha1 hash of name
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// 4. OR
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// if evname(i) is a suffix of the sha1 hash of name
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// where evname(i)=fmt.Sprintf("GOSSAHASH%d", i),
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// for 0<=i<n such that for all i evname(i) != "" and evname(n) == ""
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//
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// That is, as long as they're not empty, try GOSSAHASH, GOSSAHASH0, GOSSAHASH1, etc,
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// but quit trying at the first empty environment variable substitution.
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//
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// Otherwise it returns false.
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// Clause 4 is not really intended for human use.
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//
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// Unless GOSSAHASH is empty, when DebugHashMatch returns true the message
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//
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// "%s triggered %s\n", evname, name
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//
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// is printed on the file named in environment variable GSHS_LOGFILE,
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// or standard out if that is empty.
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//
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// Typical use:
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//
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// 1. you make a change to the compiler, say, adding a new phase
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// 2. it is broken in some mystifying way, for example, make.bash builds a broken
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// compiler that almost works, but crashes compiling a test in run.bash.
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// 3. add this guard to the code, which by default leaves it broken, but
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// does not run the broken new code if GOSSAHASH is non-empty and non-matching:
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//
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// if !base.DebugHashMatch(ir.PkgFuncName(fn)) {
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// return nil // early exit, do nothing
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// }
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//
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// 4. rebuild w/o the bad code, GOSSAHASH=n ./all.bash to verify that you
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// put theguard in the right place with the right sense of the test.
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// 5. use github.com/dr2chase/gossahash to search for the error:
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//
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// go install github.com/dr2chase/gossahash@latest
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//
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// gossahash -- <the thing that fails>
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//
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// for example: GOMAXPROCS=1 gossahash -- ./all.bash
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// 6. gossahash should return a single function whose miscompilation
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// causes the problem, and you can focus on that.
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//
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func DebugHashMatch(pkgAndName string) bool {
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return hd.DebugHashMatch(pkgAndName)
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}
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func (d *HashDebug) DebugHashMatch(pkgAndName string) bool {
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evname := GOSSAHASH
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evhash := os.Getenv(evname)
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hstr := ""
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switch evhash {
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case "":
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return true // default behavior with no EV is "on"
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case "n", "N":
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return false
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}
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// Check the hash of the name against a partial input hash.
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// We use this feature to do a binary search to
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// find a function that is incorrectly compiled.
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for _, b := range notsha256.Sum256([]byte(pkgAndName)) {
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hstr += fmt.Sprintf("%08b", b)
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}
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if evhash == "y" || evhash == "Y" || strings.HasSuffix(hstr, evhash) {
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d.logDebugHashMatch(evname, pkgAndName, hstr)
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return true
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}
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// Iteratively try additional hashes to allow tests for multi-point
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// failure.
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for i := 0; true; i++ {
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ev := fmt.Sprintf("%s%d", evname, i)
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evv := os.Getenv(ev)
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if evv == "" {
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break
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}
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if strings.HasSuffix(hstr, evv) {
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d.logDebugHashMatch(ev, pkgAndName, hstr)
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return true
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}
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}
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return false
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}
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func (d *HashDebug) logDebugHashMatch(evname, name, hstr string) {
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d.mu.Lock()
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defer d.mu.Unlock()
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file := d.logfile
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if file == nil {
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if tmpfile := os.Getenv("GSHS_LOGFILE"); tmpfile != "" {
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var err error
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file, err = os.OpenFile(tmpfile, os.O_RDWR|os.O_CREATE|os.O_APPEND, 0666)
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if err != nil {
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Fatalf("could not open hash-testing logfile %s", tmpfile)
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return
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}
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}
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if file == nil {
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file = os.Stdout
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}
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d.logfile = file
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}
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if len(hstr) > 24 {
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hstr = hstr[len(hstr)-24:]
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}
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// External tools depend on this string
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fmt.Fprintf(file, "%s triggered %s %s\n", evname, name, hstr)
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file.Sync()
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}
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@ -268,13 +268,6 @@ func PkgFuncName(f *Func) string {
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s := f.Sym()
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pkg := s.Pkg
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// TODO(mdempsky): Remove after submitting CL 393715? This matches
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// how PkgFuncName has historically handled local functions, but
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// drchase points out it contradicts the documentation.
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if pkg == types.LocalPkg {
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return s.Name
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}
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return pkg.Path + "." + s.Name
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}
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@ -8,20 +8,13 @@ import (
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"cmd/compile/internal/abi"
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"cmd/compile/internal/base"
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"cmd/compile/internal/types"
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"cmd/internal/notsha256"
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"cmd/internal/src"
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"fmt"
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"io"
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"math"
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"os"
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"strings"
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)
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type writeSyncer interface {
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io.Writer
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Sync() error
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}
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// A Func represents a Go func declaration (or function literal) and its body.
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// This package compiles each Func independently.
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// Funcs are single-use; a new Func must be created for every compiled function.
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@ -38,11 +31,7 @@ type Func struct {
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bid idAlloc // block ID allocator
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vid idAlloc // value ID allocator
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// Given an environment variable used for debug hash match,
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// what file (if any) receives the yes/no logging?
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logfiles map[string]writeSyncer
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HTMLWriter *HTMLWriter // html writer, for debugging
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DebugTest bool // default true unless $GOSSAHASH != ""; as a debugging aid, make new code conditional on this and use GOSSAHASH to binary search for failing cases
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PrintOrHtmlSSA bool // true if GOSSAFUNC matches, true even if fe.Log() (spew phase results to stdout) is false. There's an odd dependence on this in debug.go for method logf.
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ruleMatches map[string]int // number of times countRule was called during compilation for any given string
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ABI0 *abi.ABIConfig // A copy, for no-sync access
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@ -819,88 +808,18 @@ func (f *Func) invalidateCFG() {
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f.cachedLoopnest = nil
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}
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// DebugHashMatch reports whether environment variable evname
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// 1. is empty (this is a special more-quickly implemented case of 3)
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// 2. is "y" or "Y"
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// 3. is a suffix of the sha1 hash of name
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// 4. is a suffix of the environment variable
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// fmt.Sprintf("%s%d", evname, n)
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// provided that all such variables are nonempty for 0 <= i <= n
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//
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// Otherwise it returns false.
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// When true is returned the message
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//
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// "%s triggered %s\n", evname, name
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//
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// is printed on the file named in environment variable
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//
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// GSHS_LOGFILE
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//
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// or standard out if that is empty or there is an error
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// opening the file.
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func (f *Func) DebugHashMatch(evname string) bool {
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// DebugHashMatch returns
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// base.DebugHashMatch(this function's package.name)
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// for use in bug isolation. The return value is true unless
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// environment variable GOSSAHASH is set, in which case "it depends".
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// See [base.DebugHashMatch] for more information.
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func (f *Func) DebugHashMatch() bool {
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evhash := os.Getenv(base.GOSSAHASH)
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if evhash == "" {
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return true
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}
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name := f.fe.MyImportPath() + "." + f.Name
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evhash := os.Getenv(evname)
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switch evhash {
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case "":
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return true // default behavior with no EV is "on"
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case "y", "Y":
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f.logDebugHashMatch(evname, name)
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return true
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case "n", "N":
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return false
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}
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// Check the hash of the name against a partial input hash.
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// We use this feature to do a binary search to
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// find a function that is incorrectly compiled.
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hstr := ""
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for _, b := range notsha256.Sum256([]byte(name)) {
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hstr += fmt.Sprintf("%08b", b)
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}
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if strings.HasSuffix(hstr, evhash) {
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f.logDebugHashMatch(evname, name)
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return true
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}
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// Iteratively try additional hashes to allow tests for multi-point
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// failure.
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for i := 0; true; i++ {
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ev := fmt.Sprintf("%s%d", evname, i)
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evv := os.Getenv(ev)
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if evv == "" {
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break
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}
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if strings.HasSuffix(hstr, evv) {
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f.logDebugHashMatch(ev, name)
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return true
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}
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}
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return false
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}
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func (f *Func) logDebugHashMatch(evname, name string) {
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if f.logfiles == nil {
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f.logfiles = make(map[string]writeSyncer)
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}
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file := f.logfiles[evname]
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if file == nil {
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file = os.Stdout
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if tmpfile := os.Getenv("GSHS_LOGFILE"); tmpfile != "" {
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var err error
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file, err = os.OpenFile(tmpfile, os.O_RDWR|os.O_CREATE|os.O_APPEND, 0666)
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if err != nil {
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f.Fatalf("could not open hash-testing logfile %s", tmpfile)
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}
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}
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f.logfiles[evname] = file
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}
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fmt.Fprintf(file, "%s triggered %s\n", evname, name)
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file.Sync()
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}
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func DebugNameMatch(evname, name string) bool {
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return os.Getenv(evname) == name
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return base.DebugHashMatch(name)
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}
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func (f *Func) spSb() (sp, sb *Value) {
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@ -357,7 +357,6 @@ func buildssa(fn *ir.Func, worker int) *ssa.Func {
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s.f.Cache = &ssaCaches[worker]
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s.f.Cache.Reset()
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s.f.Name = name
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s.f.DebugTest = s.f.DebugHashMatch("GOSSAHASH")
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s.f.PrintOrHtmlSSA = printssa
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if fn.Pragma&ir.Nosplit != 0 {
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s.f.NoSplit = true
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