cmd/5g: make sure we normalize after unary ops on small types
We were failing ^uint16(0xffff) == 0, as we computed 0xffff0000 instead.
I could only trigger a failure for the above case, the other two tests
^uint16(0xfffe) == 1 and -uint16(0xffff) == 1 didn't seem to fail
previously. Somehow they get MOVHUs inserted for other reasons (used
by CMP instead of TST?). I fixed OMINUS anyway, better safe than
sorry.
Fixes #9604
Change-Id: I4c2d5bdc667742873ac029fdbe3db0cf12893c27
Reviewed-on: https://go-review.googlesource.com/2940
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Reviewed-by: Minux Ma <minux@golang.org>
diff --git a/src/cmd/5g/cgen.c b/src/cmd/5g/cgen.c
index c535cfb..87c64f6 100644
--- a/src/cmd/5g/cgen.c
+++ b/src/cmd/5g/cgen.c
@@ -236,18 +236,14 @@
cgen(nl, &n1);
nodconst(&n2, nl->type, -1);
gins(a, &n2, &n1);
- gmove(&n1, res);
- regfree(&n1);
- goto ret;
+ goto norm;
case OMINUS:
regalloc(&n1, nl->type, N);
cgen(nl, &n1);
nodconst(&n2, nl->type, 0);
gins(optoas(OMINUS, nl->type), &n2, &n1);
- gmove(&n1, res);
- regfree(&n1);
- goto ret;
+ goto norm;
// symmetric binary
case OAND:
@@ -483,12 +479,15 @@
cgen(nl, &n1);
}
gins(a, &n2, &n1);
+norm:
// Normalize result for types smaller than word.
if(n->type->width < widthptr) {
switch(n->op) {
case OADD:
case OSUB:
case OMUL:
+ case OCOM:
+ case OMINUS:
gins(optoas(OAS, n->type), &n1, &n1);
break;
}
diff --git a/test/fixedbugs/issue9604.go b/test/fixedbugs/issue9604.go
new file mode 100644
index 0000000..cd9e9e4
--- /dev/null
+++ b/test/fixedbugs/issue9604.go
@@ -0,0 +1,29 @@
+// run
+
+// Copyright 2015 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
+
+var x uint16 = 0xffff
+var y uint16 = 0xfffe
+var a uint16 = 0x7000
+var b uint16 = 0x9000
+
+func main() {
+ // Make sure we truncate to smaller-width types after evaluating expressions.
+ // This is a problem for arm where there is no 16-bit comparison op.
+ if ^x != 0 {
+ panic("^uint16(0xffff) != 0")
+ }
+ if ^y != 1 {
+ panic("^uint16(0xfffe) != 1")
+ }
+ if -x != 1 {
+ panic("-uint16(0xffff) != 1")
+ }
+ if a+b != 0 {
+ panic("0x7000+0x9000 != 0")
+ }
+}
