cmd/compile: disable inlining for functions using runtime.deferrangefunc

The rangefunc rewrite pass implements defer using deferrangefunc and
deferproccat. The loop body is rewritten into a closure, it cannot be
inlined due to defer call. But the outer function may still be inlined
in certain scenarios (e.g., with PGO), leading to the defer executing
at the wrong time.

Fixes #77033

Change-Id: I4649fad5cd1b65891832523522002d9352711123
Reviewed-on: https://go-review.googlesource.com/c/go/+/732140
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: David Chase <drchase@google.com>
Reviewed-by: Cherry Mui <cherryyz@google.com>

2 files changed, 43 insertions, 0 deletions

diff --git a/src/cmd/compile/internal/inline/inl.go b/src/cmd/compile/internal/inline/inl.go
index 33f9c325c3..4fa9cf07fb 100644
--- a/src/cmd/compile/internal/inline/inl.go
+++ b/src/cmd/compile/internal/inline/inl.go
@@ -516,6 +516,9 @@ opSwitch:
 						break opSwitch
 					case "panicrangestate":
 						cheap = true
+					case "deferrangefunc":
+						v.reason = "defer call in range func"
+						return true
 					}
 				}
 			}
diff --git a/src/cmd/compile/testdata/script/issue77033.txt b/src/cmd/compile/testdata/script/issue77033.txt
new file mode 100644
index 0000000000..3b977e5440
--- /dev/null
+++ b/src/cmd/compile/testdata/script/issue77033.txt
@@ -0,0 +1,40 @@
+go test -bench=Foo -cpuprofile=default.pgo
+go test -bench=Foo -pgo=default.pgo
+! stdout 'FAIL'
+
+-- main_test.go --
+package main
+
+import (
+	"testing"
+)
+
+var a int
+
+func save(x int) {
+	a = x
+}
+
+func foo() {
+	for i := range yield1 {
+		defer save(i)
+	}
+}
+
+func yield1(yield func(int) bool) {
+	yield(1)
+}
+
+func BenchmarkFoo(b *testing.B) {
+	for i := 0; i < b.N; i++ {
+		foo()
+	}
+	if a != 1 {
+		b.Fatalf("a = %d; want 1", a)
+	}
+}
+
+-- go.mod --
+module demo
+
+go 1.24