From: Rémy Oudompheng <oudomphe@phare.normalesup.org>
Date: Fri, 15 Mar 2013 08:03:45 +0000 (+0100)
Subject: cmd/gc: fix escape analysis bug.
X-Git-Tag: go1.1rc2~488
X-Git-Url: http://www.git.cypherpunks.su/?a=commitdiff_plain;h=20c7e41555e2c2b393c239f581ef7e216c795db4;p=gostls13.git

cmd/gc: fix escape analysis bug.

It used to not mark parameters as escaping if only one of the
fields it points to leaks out of the function. This causes
problems when importing from another package.

Fixes #4964.

R=rsc, lvd, dvyukov, daniel.morsing
CC=golang-dev
https://golang.org/cl/7648045
---

diff --git a/src/cmd/gc/esc.c b/src/cmd/gc/esc.c
index 46c06d10e4..7be7b53413 100644
--- a/src/cmd/gc/esc.c
+++ b/src/cmd/gc/esc.c
@@ -1033,7 +1033,7 @@ escwalk(EscState *e, int level, Node *dst, Node *src)
 
 	switch(src->op) {
 	case ONAME:
-		if(src->class == PPARAM && leaks && src->esc != EscHeap) {
+		if(src->class == PPARAM && (leaks || dst->escloopdepth < 0) && src->esc != EscHeap) {
 			src->esc = EscScope;
 			if(debug['m'])
 				warnl(src->lineno, "leaking param: %hN", src);
diff --git a/test/escape2.go b/test/escape2.go
index 9481619338..3473e4fa45 100644
--- a/test/escape2.go
+++ b/test/escape2.go
@@ -80,7 +80,9 @@ func foo12(yyy **int) { // ERROR "leaking param: yyy"
 	xxx = yyy
 }
 
-func foo13(yyy **int) { // ERROR "yyy does not escape"
+// Must treat yyy as leaking because *yyy leaks, and the escape analysis 
+// summaries in exported metadata do not distinguish these two cases.
+func foo13(yyy **int) { // ERROR "leaking param: yyy"
 	*xxx = *yyy
 }
 
@@ -299,7 +301,8 @@ func (f *Foo) foo45() { // ERROR "f does not escape"
 	F.x = f.x
 }
 
-func (f *Foo) foo46() { // ERROR "f does not escape"
+// See foo13 above for explanation of why f leaks.
+func (f *Foo) foo46() { // ERROR "leaking param: f"
 	F.xx = f.xx
 }
 
diff --git a/test/fixedbugs/issue4964.dir/a.go b/test/fixedbugs/issue4964.dir/a.go
new file mode 100644
index 0000000000..2b9e44e351
--- /dev/null
+++ b/test/fixedbugs/issue4964.dir/a.go
@@ -0,0 +1,27 @@
+// Copyright 2013 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 a
+
+var global, global2 *int
+
+type T struct {
+	Pointer *int
+}
+
+func dontinline() {}
+
+func Store(t *T) {
+	global = t.Pointer
+	dontinline()
+}
+
+func Store2(t *T) {
+	global2 = t.Pointer
+	dontinline()
+}
+
+func Get() *int {
+	return global
+}
diff --git a/test/fixedbugs/issue4964.dir/b.go b/test/fixedbugs/issue4964.dir/b.go
new file mode 100644
index 0000000000..42a6f1d761
--- /dev/null
+++ b/test/fixedbugs/issue4964.dir/b.go
@@ -0,0 +1,34 @@
+// Copyright 2013 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 "./a"
+
+func F() {
+	// store 1 in a.global
+	x, y := 1, 2
+	t := a.T{Pointer: &x}
+	a.Store(&t)
+	_ = y
+}
+
+func G() {
+	// store 4 in a.global2
+	x, y := 3, 4
+	t := a.T{Pointer: &y}
+	a.Store2(&t)
+	_ = x
+}
+
+func main() {
+	F()
+	G()
+	p := a.Get()
+	n := *p
+	if n != 1 {
+		println(n, "!= 1")
+		panic("n != 1")
+	}
+}
diff --git a/test/fixedbugs/issue4964.go b/test/fixedbugs/issue4964.go
new file mode 100644
index 0000000000..8291d1bb97
--- /dev/null
+++ b/test/fixedbugs/issue4964.go
@@ -0,0 +1,10 @@
+// rundir
+
+// Copyright 2013 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.
+
+// Issue 4964: exported escape analysis result is not enough
+// for cross package analysis.
+
+package ignored