runtime: make FuncForPC return the innermost inlined frame

Returning the innermost frame instead of the outermost
makes code that walks the results of runtime.Caller{,s}
still work correctly in the presence of mid-stack inlining.

Fixes #29582

Change-Id: I2392e3dd5636eb8c6f58620a61cef2194fe660a7
Reviewed-on: https://go-review.googlesource.com/c/156364
Run-TryBot: Keith Randall <khr@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>

1 files changed, 5 insertions, 5 deletions

diff --git a/test/inline_callers.go b/test/inline_callers.go
index f2c05622dd..ee7d647072 100644
--- a/test/inline_callers.go
+++ b/test/inline_callers.go
@@ -31,7 +31,7 @@ func testCallers(skp int) (frames []string) {
 	skip = skp
 	f()
 	for i := 0; i < npcs; i++ {
-		fn := runtime.FuncForPC(pcs[i])
+		fn := runtime.FuncForPC(pcs[i] - 1)
 		frames = append(frames, fn.Name())
 		if fn.Name() == "main.main" {
 			break
@@ -56,10 +56,10 @@ func testCallersFrames(skp int) (frames []string) {
 }
 
 var expectedFrames [][]string = [][]string{
-	0: {"runtime.Callers", "main.testCallers", "main.testCallers", "main.testCallers", "main.testCallers", "main.main"},
-	1: {"main.testCallers", "main.testCallers", "main.testCallers", "main.testCallers", "main.main"},
-	2: {"main.testCallers", "main.testCallers", "main.testCallers", "main.main"},
-	3: {"main.testCallers", "main.testCallers", "main.main"},
+	0: {"runtime.Callers", "main.h", "main.g", "main.f", "main.testCallers", "main.main"},
+	1: {"main.h", "main.g", "main.f", "main.testCallers", "main.main"},
+	2: {"main.g", "main.f", "main.testCallers", "main.main"},
+	3: {"main.f", "main.testCallers", "main.main"},
 	4: {"main.testCallers", "main.main"},
 	5: {"main.main"},
 }