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cmd/5g: make sure we normalize after unary ops on small types

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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>
This commit is contained in:
Keith Randall 2015-01-15 14:39:58 -08:00
parent fdb855420b
commit daa64ddfe6
2 changed files with 34 additions and 6 deletions
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11
src/cmd/5g/cgen.c
View file

@ -236,18 +236,14 @@ cgen(Node *n, Node *res)
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 @@ abop: // asymmetric binary
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;
}

29
test/fixedbugs/issue9604.go Normal file
View file

@ -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")
}
}