5g: fix -f()

R=ken2
CC=golang-dev
https://golang.org/cl/5161041

diff --git a/src/cmd/5g/cgen.c b/src/cmd/5g/cgen.c
index 0ea8695a024cfb9ea5e04a1edfe70e1511154071..15defaf111eef5f423c5fcc0b91cbd51c8e73180 100644 (file)
--- a/src/cmd/5g/cgen.c
+++ b/src/cmd/5g/cgen.c
@@ -213,11 +213,11 @@ cgen(Node *n, Node *res)
                goto ret;
 
        case OMINUS:
+               regalloc(&n1, nl->type, N);
+               cgen(nl, &n1);
                nodconst(&n3, nl->type, 0);
                regalloc(&n2, nl->type, res);
-               regalloc(&n1, nl->type, N);
                gmove(&n3, &n2);
-               cgen(nl, &n1);
                gins(optoas(OSUB, nl->type), &n1, &n2);
                gmove(&n2, res);
                regfree(&n1);

diff --git a/test/fixedbugs/bug368.go b/test/fixedbugs/bug368.go
new file mode 100644 (file)
index 0000000..8d94f53
--- /dev/null
+++ b/test/fixedbugs/bug368.go
@@ -0,0 +1,26 @@
+// $G $D/$F.go && $L $F.$A && ./$A.out
+
+// Copyright 2011 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
+
+// 5g bug used to set up the 0 for -f() before calling f,
+// and the call to f smashed the register.
+
+func f(n int) int {
+       s := 0
+       for i := 0; i < n; i++ {
+               s += i>>1
+       }
+       return s
+}
+
+func main() {
+       x := -f(100)
+       if x != -2450 {
+               println(x)
+               panic("broken")
+       }
+}