cmd/compile: add ability to print extra information in bisect output

Change-Id: I619c21ab9754f67b69215cfed238a3e489c7fbcf
Reviewed-on: https://go-review.googlesource.com/c/go/+/493955
Reviewed-by: David Chase <drchase@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Run-TryBot: Russ Cox <rsc@golang.org>

5 files changed, 45 insertions, 41 deletions

diff --git a/src/cmd/compile/internal/base/hashdebug.go b/src/cmd/compile/internal/base/hashdebug.go
index c99695642c..11b9dcbb1d 100644
--- a/src/cmd/compile/internal/base/hashdebug.go
+++ b/src/cmd/compile/internal/base/hashdebug.go
@@ -122,11 +122,11 @@ var LoopVarHash *HashDebug // for debugging shared/private loop variable changes
 //  6. gossahash should return a single function whose miscompilation
 //     causes the problem, and you can focus on that.
 func DebugHashMatchPkgFunc(pkg, fn string) bool {
-	return hashDebug.MatchPkgFunc(pkg, fn)
+	return hashDebug.MatchPkgFunc(pkg, fn, nil)
 }
 
 func DebugHashMatchPos(pos src.XPos) bool {
-	return hashDebug.MatchPos(pos)
+	return hashDebug.MatchPos(pos, nil)
 }
 
 // HasDebugHash returns true if Flags.Gossahash is non-empty, which
@@ -247,29 +247,17 @@ func (d *HashDebug) match(hash uint64) *hashAndMask {
 // representation of the hash of pkg and fn.  If the variable is not nil,
 // then a true result is accompanied by stylized output to d.logfile, which
 // is used for automated bug search.
-func (d *HashDebug) MatchPkgFunc(pkg, fn string) bool {
+func (d *HashDebug) MatchPkgFunc(pkg, fn string, note func() string) bool {
 	if d == nil {
 		return true
 	}
 	// Written this way to make inlining likely.
-	return d.matchPkgFunc(pkg, fn)
+	return d.matchPkgFunc(pkg, fn, note)
 }
 
-func (d *HashDebug) matchPkgFunc(pkg, fn string) bool {
+func (d *HashDebug) matchPkgFunc(pkg, fn string, note func() string) bool {
 	hash := bisect.Hash(pkg, fn)
-	if d.bisect != nil {
-		if d.bisect.ShouldPrint(hash) {
-			d.log(d.name, hash, pkg+"."+fn)
-		}
-		return d.bisect.ShouldEnable(hash)
-	}
-
-	// TODO: Delete rest of function body when we switch to bisect-only.
-	if m := d.match(hash); m != nil {
-		d.log(m.name, hash, pkg+"."+fn)
-		return true
-	}
-	return false
+	return d.matchAndLog(hash, func() string { return pkg + "." + fn }, note)
 }
 
 // MatchPos is similar to MatchPkgFunc, but for hash computation
@@ -277,32 +265,48 @@ func (d *HashDebug) matchPkgFunc(pkg, fn string) bool {
 // package name and path.
 // Note that the default answer for no environment variable (d == nil)
 // is "yes", do the thing.
-func (d *HashDebug) MatchPos(pos src.XPos) bool {
+func (d *HashDebug) MatchPos(pos src.XPos, desc func() string) bool {
 	if d == nil {
 		return true
 	}
 	// Written this way to make inlining likely.
-	return d.matchPos(Ctxt, pos)
+	return d.matchPos(Ctxt, pos, desc)
 }
 
-func (d *HashDebug) matchPos(ctxt *obj.Link, pos src.XPos) bool {
+func (d *HashDebug) matchPos(ctxt *obj.Link, pos src.XPos, note func() string) bool {
 	hash := d.hashPos(ctxt, pos)
+	return d.matchAndLog(hash, func() string { return d.fmtPos(ctxt, pos) }, note)
+}
 
+// matchAndLog is the core matcher. It reports whether the hash matches the pattern.
+// If a report needs to be printed, match prints that report to the log file.
+// The text func must be non-nil and should return a user-readable
+// representation of what was hashed. The note func may be nil; if non-nil,
+// it should return additional information to display to the user when this
+// change is selected.
+func (d *HashDebug) matchAndLog(hash uint64, text, note func() string) bool {
 	if d.bisect != nil {
 		if d.bisect.ShouldPrint(hash) {
-			d.log(d.name, hash, d.fmtPos(ctxt, pos))
+			var t string
+			if !d.bisect.MarkerOnly() {
+				t = text()
+				if note != nil {
+					if n := note(); n != "" {
+						t += ": " + n
+					}
+				}
+			}
+			d.log(d.name, hash, t)
 		}
 		return d.bisect.ShouldEnable(hash)
 	}
 
 	// TODO: Delete rest of function body when we switch to bisect-only.
-
-	// Return false for explicitly excluded hashes
 	if d.excluded(hash) {
 		return false
 	}
 	if m := d.match(hash); m != nil {
-		d.log(m.name, hash, d.fmtPos(ctxt, pos))
+		d.log(m.name, hash, text())
 		return true
 	}
 	return false
diff --git a/src/cmd/compile/internal/base/hashdebug_test.go b/src/cmd/compile/internal/base/hashdebug_test.go
index e6ced4d148..086801a2f0 100644
--- a/src/cmd/compile/internal/base/hashdebug_test.go
+++ b/src/cmd/compile/internal/base/hashdebug_test.go
@@ -16,7 +16,7 @@ func TestHashDebugGossahashY(t *testing.T) {
 	if hd == nil {
 		t.Errorf("NewHashDebug should not return nil for GOSSASHASH=y")
 	}
-	if !hd.MatchPkgFunc("anything", "anyfunc") {
+	if !hd.MatchPkgFunc("anything", "anyfunc", nil) {
 		t.Errorf("NewHashDebug should return yes for everything for GOSSASHASH=y")
 	}
 }
@@ -26,7 +26,7 @@ func TestHashDebugGossahashN(t *testing.T) {
 	if hd == nil {
 		t.Errorf("NewHashDebug should not return nil for GOSSASHASH=n")
 	}
-	if hd.MatchPkgFunc("anything", "anyfunc") {
+	if hd.MatchPkgFunc("anything", "anyfunc", nil) {
 		t.Errorf("NewHashDebug should return no for everything for GOSSASHASH=n")
 	}
 }
@@ -60,21 +60,21 @@ func TestHash(t *testing.T) {
 
 func TestHashMatch(t *testing.T) {
 	b := new(bytes.Buffer)
-	hd := NewHashDebug("GOSSAHASH", "1110", b)
-	check := hd.MatchPkgFunc("bar", "0")
+	hd := NewHashDebug("GOSSAHASH", "v1110", b)
+	check := hd.MatchPkgFunc("bar", "0", func() string { return "note" })
 	msg := b.String()
 	t.Logf("message was '%s'", msg)
 	if !check {
 		t.Errorf("GOSSAHASH=1110 should have matched for 'bar', '0'")
 	}
-	wantPrefix(t, msg, "bar.0 [bisect-match ")
-	wantContains(t, msg, "\nGOSSAHASH triggered bar.0 ")
+	wantPrefix(t, msg, "bar.0: note [bisect-match ")
+	wantContains(t, msg, "\nGOSSAHASH triggered bar.0: note ")
 }
 
 func TestYMatch(t *testing.T) {
 	b := new(bytes.Buffer)
-	hd := NewHashDebug("GOSSAHASH", "y", b)
-	check := hd.MatchPkgFunc("bar", "0")
+	hd := NewHashDebug("GOSSAHASH", "vy", b)
+	check := hd.MatchPkgFunc("bar", "0", nil)
 	msg := b.String()
 	t.Logf("message was '%s'", msg)
 	if !check {
@@ -86,8 +86,8 @@ func TestYMatch(t *testing.T) {
 
 func TestNMatch(t *testing.T) {
 	b := new(bytes.Buffer)
-	hd := NewHashDebug("GOSSAHASH", "n", b)
-	check := hd.MatchPkgFunc("bar", "0")
+	hd := NewHashDebug("GOSSAHASH", "vn", b)
+	check := hd.MatchPkgFunc("bar", "0", nil)
 	msg := b.String()
 	t.Logf("message was '%s'", msg)
 	if check {
@@ -100,7 +100,7 @@ func TestNMatch(t *testing.T) {
 func TestHashNoMatch(t *testing.T) {
 	b := new(bytes.Buffer)
 	hd := NewHashDebug("GOSSAHASH", "01110", b)
-	check := hd.MatchPkgFunc("bar", "0")
+	check := hd.MatchPkgFunc("bar", "0", nil)
 	msg := b.String()
 	t.Logf("message was '%s'", msg)
 	if check {
@@ -116,7 +116,7 @@ func TestHashSecondMatch(t *testing.T) {
 	b := new(bytes.Buffer)
 	hd := NewHashDebug("GOSSAHASH", "01110/11110", b)
 
-	check := hd.MatchPkgFunc("bar", "0")
+	check := hd.MatchPkgFunc("bar", "0", nil)
 	msg := b.String()
 	t.Logf("message was '%s'", msg)
 	if !check {
diff --git a/src/cmd/compile/internal/loopvar/loopvar.go b/src/cmd/compile/internal/loopvar/loopvar.go
index ccb14df80b..a015672c2d 100644
--- a/src/cmd/compile/internal/loopvar/loopvar.go
+++ b/src/cmd/compile/internal/loopvar/loopvar.go
@@ -91,7 +91,7 @@ func ForCapture(fn *ir.Func) []VarAndLoop {
 		// subject to hash-variable debugging.
 		maybeReplaceVar := func(k ir.Node, x *ir.RangeStmt) ir.Node {
 			if n, ok := k.(*ir.Name); ok && possiblyLeaked[n] {
-				if base.LoopVarHash.MatchPos(n.Pos()) {
+				if base.LoopVarHash.MatchPos(n.Pos(), nil) {
 					// Rename the loop key, prefix body with assignment from loop key
 					transformed = append(transformed, VarAndLoop{n, x, lastPos})
 					tk := typecheck.Temp(n.Type())
@@ -199,7 +199,7 @@ func ForCapture(fn *ir.Func) []VarAndLoop {
 				forAllDefInInit(x, func(z ir.Node) {
 					if n, ok := z.(*ir.Name); ok && possiblyLeaked[n] {
 						// Hash on n.Pos() for most precise failure location.
-						if base.LoopVarHash.MatchPos(n.Pos()) {
+						if base.LoopVarHash.MatchPos(n.Pos(), nil) {
 							leaked = append(leaked, n)
 						}
 					}
diff --git a/src/cmd/compile/internal/loopvar/loopvar_test.go b/src/cmd/compile/internal/loopvar/loopvar_test.go
index b94f69709d..3bfc802eb2 100644
--- a/src/cmd/compile/internal/loopvar/loopvar_test.go
+++ b/src/cmd/compile/internal/loopvar/loopvar_test.go
@@ -191,7 +191,7 @@ func TestLoopVarHashes(t *testing.T) {
 		return string(b)
 	}
 
-	m := f("001100110110110010100100")
+	m := f("v001100110110110010100100")
 	t.Logf(m)
 
 	mCount := strings.Count(m, "loopvarhash triggered cmd/compile/internal/loopvar/testdata/inlines/main.go:27:6 001100110110110010100100")
diff --git a/src/cmd/compile/internal/ssa/func.go b/src/cmd/compile/internal/ssa/func.go
index f2f548e9ba..2d203e583b 100644
--- a/src/cmd/compile/internal/ssa/func.go
+++ b/src/cmd/compile/internal/ssa/func.go
@@ -807,5 +807,5 @@ func (f *Func) useFMA(v *Value) bool {
 	if base.FmaHash == nil {
 		return true
 	}
-	return base.FmaHash.MatchPos(v.Pos)
+	return base.FmaHash.MatchPos(v.Pos, nil)
 }