cmd/compile: add more information to the bisect-verbose report

running on cmd/compile/internal/testdata/inlines now shows:
```
--- change set #1 (enabling changes causes failure)
b/b.go:16:6: loop variable i now per-iteration (loop inlined into b/b.go:10)
b/b.go:16:6: loop variable i now per-iteration
./b/b.go:16:6: loop variable b.i now per-iteration (loop inlined into a/a.go:18)
./b/b.go:16:6: loop variable b.i now per-iteration (loop inlined into ./main.go:37)
./b/b.go:16:6: loop variable b.i now per-iteration (loop inlined into ./main.go:38)
---
```
and
```
--- change set #2 (enabling changes causes failure)
./main.go:27:6: loop variable i now per-iteration
./main.go:27:6: loop variable i now per-iteration (loop inlined into ./main.go:35)
---
```

Still unsure about the utility of mentioning the inlined occurrence, but better
than mysteriously repeating the line over and over again.

Change-Id: I357f5d419ab4928fa316f4612eec3b75e7f8ac34
Reviewed-on: https://go-review.googlesource.com/c/go/+/494296
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
Run-TryBot: David Chase <drchase@google.com>

diff --git a/src/cmd/compile/internal/loopvar/loopvar.go b/src/cmd/compile/internal/loopvar/loopvar.go
index a015672c2d4e65c886302d38dab9f3757ef2c79e..e5fedd2fceaf0ace1ad27aadc1acd2275206c273 100644 (file)
--- a/src/cmd/compile/internal/loopvar/loopvar.go
+++ b/src/cmd/compile/internal/loopvar/loopvar.go
@@ -48,6 +48,16 @@ func ForCapture(fn *ir.Func) []VarAndLoop {
        // if a loop variable is transformed it is appended to this slice for later logging
        var transformed []VarAndLoop
 
+       describe := func(n *ir.Name) string {
+               pos := n.Pos()
+               inner := base.Ctxt.InnermostPos(pos)
+               outer := base.Ctxt.OutermostPos(pos)
+               if inner == outer {
+                       return fmt.Sprintf("loop variable %v now per-iteration", n)
+               }
+               return fmt.Sprintf("loop variable %v now per-iteration (loop inlined into %s:%d)", n, outer.Filename(), outer.Line())
+       }
+
        forCapture := func() {
                seq := 1
 
@@ -91,7 +101,10 @@ 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(), nil) {
+                               desc := func() string {
+                                       return describe(n)
+                               }
+                               if base.LoopVarHash.MatchPos(n.Pos(), desc) {
                                        // Rename the loop key, prefix body with assignment from loop key
                                        transformed = append(transformed, VarAndLoop{n, x, lastPos})
                                        tk := typecheck.Temp(n.Type())
@@ -198,8 +211,11 @@ func ForCapture(fn *ir.Func) []VarAndLoop {
                                // Collect the leaking variables for the much-more-complex transformation.
                                forAllDefInInit(x, func(z ir.Node) {
                                        if n, ok := z.(*ir.Name); ok && possiblyLeaked[n] {
+                                               desc := func() string {
+                                                       return describe(n)
+                                               }
                                                // Hash on n.Pos() for most precise failure location.
-                                               if base.LoopVarHash.MatchPos(n.Pos(), nil) {
+                                               if base.LoopVarHash.MatchPos(n.Pos(), desc) {
                                                        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 d48b5ada7f99a560ea123cf93931771a544675f5..03e6eec4373654e75c55fb11a090b19ccf1d6732 100644 (file)
--- a/src/cmd/compile/internal/loopvar/loopvar_test.go
+++ b/src/cmd/compile/internal/loopvar/loopvar_test.go
@@ -8,6 +8,7 @@ import (
        "internal/testenv"
        "os/exec"
        "path/filepath"
+       "regexp"
        "runtime"
        "strings"
        "testing"
@@ -159,6 +160,11 @@ func TestLoopVarInlines(t *testing.T) {
        }
 }
 
+func countMatches(s, re string) int {
+       slice := regexp.MustCompile(re).FindAllString(s, -1)
+       return len(slice)
+}
+
 func TestLoopVarHashes(t *testing.T) {
        switch runtime.GOOS {
        case "linux", "darwin":
@@ -195,7 +201,7 @@ func TestLoopVarHashes(t *testing.T) {
                m := f(arg)
                t.Logf(m)
 
-               mCount := strings.Count(m, "loopvarhash triggered cmd/compile/internal/loopvar/testdata/inlines/main.go:27:6 001100110110110010100100")
+               mCount := countMatches(m, "loopvarhash triggered cmd/compile/internal/loopvar/testdata/inlines/main.go:27:6: .* 001100110110110010100100")
                otherCount := strings.Count(m, "loopvarhash")
                if mCount < 1 {
                        t.Errorf("%s: did not see triggered main.go:27:6", arg)
@@ -203,8 +209,7 @@ func TestLoopVarHashes(t *testing.T) {
                if mCount != otherCount {
                        t.Errorf("%s: too many matches", arg)
                }
-
-               mCount = strings.Count(m, "cmd/compile/internal/loopvar/testdata/inlines/main.go:27:6 [bisect-match 0x7802e115b9336ca4]")
+               mCount = countMatches(m, "cmd/compile/internal/loopvar/testdata/inlines/main.go:27:6: .* \\[bisect-match 0x7802e115b9336ca4\\]")
                otherCount = strings.Count(m, "[bisect-match ")
                if mCount < 1 {
                        t.Errorf("%s: did not see bisect-match for main.go:27:6", arg)