[release-branch.go1.3] cmd/gc: fix liveness for address-taken variables in inlined functions

««« CL 96670046 / 1bec455e95f1
cmd/gc: fix liveness for address-taken variables in inlined functions

The 'address taken' bit in a function variable was not
propagating into the inlined copies, causing incorrect
liveness information.

LGTM=dsymonds, bradfitz
R=golang-codereviews, bradfitz
CC=dsymonds, golang-codereviews, iant, khr, r
https://golang.org/cl/96670046
»»»

TBR=adg
R=adg
CC=golang-codereviews
https://golang.org/cl/103810046

src/cmd/gc/inl.c

@@ -802,6 +802,7 @@ inlvar(Node *var)
 	n->class = PAUTO;
 	n->used = 1;
 	n->curfn = curfn;   // the calling function, not the called one
+	n->addrtaken = var->addrtaken;
 
 	// esc pass wont run if we're inlining into a iface wrapper
 	// luckily, we can steal the results from the target func

test/live.go

@@ -4,6 +4,9 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+// liveness tests with inlining disabled.
+// see also live2.go.
+
 package main
 
 func f1() {
@@ -590,3 +593,32 @@ func f39c() (x [10]*int) {
 	println() // ERROR "live at call to printnl: x"
 	return
 }
+
+// issue 8142: lost 'addrtaken' bit on inlined variables.
+// no inlining in this test, so just checking that non-inlined works.
+
+type T40 struct {
+	m map[int]int
+}
+
+func newT40() *T40 {
+	ret := T40{ // ERROR "live at call to makemap: &ret"
+		make(map[int]int), 
+	}
+	return &ret
+}
+
+func bad40() {
+	t := newT40()
+	println()
+	_ = t
+}
+
+func good40() {
+	ret := T40{ // ERROR "live at call to makemap: ret"
+		make(map[int]int),
+	}
+	t := &ret
+	println() // ERROR "live at call to printnl: ret"
+	_ = t
+}

test/live2.go

+// errorcheck -0 -live
+
+// Copyright 2014 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.
+
+// liveness tests with inlining ENABLED
+// see also live.go.
+
+package main
+
+// issue 8142: lost 'addrtaken' bit on inlined variables.
+// no inlining in this test, so just checking that non-inlined works.
+
+type T40 struct {
+	m map[int]int
+}
+
+func newT40() *T40 {
+	ret := T40{ // ERROR "live at call to makemap: &ret"
+		make(map[int]int),
+	}
+	return &ret
+}
+
+func bad40() {
+	t := newT40() // ERROR "live at call to makemap: ret"
+	println()     // ERROR "live at call to printnl: ret"
+	_ = t
+}
+
+func good40() {
+	ret := T40{ // ERROR "live at call to makemap: ret"
+		make(map[int]int),
+	}
+	t := &ret
+	println() // ERROR "live at call to printnl: ret"
+	_ = t
+}