From cbb9cd03f80c0487cee0adcfef9a2a5de9fe2cc1 Mon Sep 17 00:00:00 2001
From: Keith Randall <khr@golang.org>
Date: Mon, 13 Feb 2023 23:27:51 -0800
Subject: [PATCH] cmd/compile: ensure FuncForPC works on closures that start
 with NOPs

A 0-sized no-op shouldn't prevent us from detecting that the first
instruction is from an inlined callee.

Update #58300

Change-Id: Ic5f6ed108c54a32c05e9b2264b516f2cc17e4619
Reviewed-on: https://go-review.googlesource.com/c/go/+/467977
Run-TryBot: Keith Randall <khr@golang.org>
Reviewed-by: Keith Randall <khr@google.com>
Reviewed-by: David Chase <drchase@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
---
 src/cmd/compile/internal/ssagen/ssa.go |  2 +-
 test/fixedbugs/issue58300b.go          | 35 ++++++++++++++++++++++++++
 test/fixedbugs/issue58300b.out         |  2 ++
 3 files changed, 38 insertions(+), 1 deletion(-)
 create mode 100644 test/fixedbugs/issue58300b.go
 create mode 100644 test/fixedbugs/issue58300b.out

diff --git a/src/cmd/compile/internal/ssagen/ssa.go b/src/cmd/compile/internal/ssagen/ssa.go
index 004806b029..6831da6908 100644
--- a/src/cmd/compile/internal/ssagen/ssa.go
+++ b/src/cmd/compile/internal/ssagen/ssa.go
@@ -7171,7 +7171,7 @@ func genssa(f *ssa.Func, pp *objw.Progs) {
 			// This ensures that runtime.FuncForPC(uintptr(reflect.ValueOf(fn).Pointer())).Name()
 			// returns the right answer. See issue 58300.
 			for p := pp.Text; p != nil; p = p.Link {
-				if p.As == obj.AFUNCDATA || p.As == obj.APCDATA || p.As == obj.ATEXT {
+				if p.As == obj.AFUNCDATA || p.As == obj.APCDATA || p.As == obj.ATEXT || p.As == obj.ANOP {
 					continue
 				}
 				if base.Ctxt.PosTable.Pos(p.Pos).Base().InliningIndex() >= 0 {
diff --git a/test/fixedbugs/issue58300b.go b/test/fixedbugs/issue58300b.go
new file mode 100644
index 0000000000..5192b3f0f4
--- /dev/null
+++ b/test/fixedbugs/issue58300b.go
@@ -0,0 +1,35 @@
+// run
+
+// Copyright 2023 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.
+
+package main
+
+import (
+	"reflect"
+	"runtime"
+)
+
+type T struct {
+	a, b int
+}
+
+func f(t *T) int {
+	if t != nil {
+		return t.b
+	}
+	return 0
+}
+
+func g(t *T) int {
+	return f(t) + 5
+}
+
+func main() {
+	x(f)
+	x(g)
+}
+func x(v any) {
+	println(runtime.FuncForPC(reflect.ValueOf(v).Pointer()).Name())
+}
diff --git a/test/fixedbugs/issue58300b.out b/test/fixedbugs/issue58300b.out
new file mode 100644
index 0000000000..f347287480
--- /dev/null
+++ b/test/fixedbugs/issue58300b.out
@@ -0,0 +1,2 @@
+main.f
+main.g