cmd/gc: fix &^ code generation bug

Was not re-walking the new AND node, so that its ullman
count was wrong, so that the code generator attempted to
store values in registers across the call.

Fixes #4752.

R=ken2
CC=golang-dev
https://golang.org/cl/7288054

diff --git a/src/cmd/gc/walk.c b/src/cmd/gc/walk.c
index 911e0a4dd5e733d2bdcceb1a666ab2e245b12849..a781ed20c4279c510fda39ae87c5052754340702 100644 (file)
--- a/src/cmd/gc/walk.c
+++ b/src/cmd/gc/walk.c
@@ -926,10 +926,10 @@ walkexpr(Node **np, NodeList **init)
 
        case OANDNOT:
                walkexpr(&n->left, init);
-               walkexpr(&n->right, init);
                n->op = OAND;
                n->right = nod(OCOM, n->right, N);
                typecheck(&n->right, Erv);
+               walkexpr(&n->right, init);
                goto ret;
 
        case ODIV:

diff --git a/test/fixedbugs/issue4752.go b/test/fixedbugs/issue4752.go
new file mode 100644 (file)
index 0000000..d6781e3
--- /dev/null
+++ b/test/fixedbugs/issue4752.go
@@ -0,0 +1,26 @@
+// run
+
+// 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
+
+func F(xi, yi interface{}) uint64 {
+       x, y := xi.(uint64), yi.(uint64)
+       return x &^ y
+}
+
+func G(xi, yi interface{}) uint64 {
+       return xi.(uint64) &^ yi.(uint64) // generates incorrect code
+}
+
+func main() {
+       var x, y uint64 = 0, 1 << 63
+       f := F(x, y)
+       g := G(x, y)
+       if f != 0 || g != 0 {
+               println("F", f, "G", g)
+               panic("bad")
+       }
+}