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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>
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@ -236,18 +236,14 @@ cgen(Node *n, Node *res)
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cgen(nl, &n1);
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nodconst(&n2, nl->type, -1);
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gins(a, &n2, &n1);
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gmove(&n1, res);
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regfree(&n1);
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goto ret;
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goto norm;
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case OMINUS:
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regalloc(&n1, nl->type, N);
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cgen(nl, &n1);
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nodconst(&n2, nl->type, 0);
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gins(optoas(OMINUS, nl->type), &n2, &n1);
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gmove(&n1, res);
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regfree(&n1);
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goto ret;
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goto norm;
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// symmetric binary
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case OAND:
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@ -483,12 +479,15 @@ abop: // asymmetric binary
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cgen(nl, &n1);
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}
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gins(a, &n2, &n1);
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norm:
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// Normalize result for types smaller than word.
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if(n->type->width < widthptr) {
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switch(n->op) {
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case OADD:
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case OSUB:
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case OMUL:
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case OCOM:
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case OMINUS:
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gins(optoas(OAS, n->type), &n1, &n1);
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break;
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}
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29
test/fixedbugs/issue9604.go
Normal file
29
test/fixedbugs/issue9604.go
Normal file
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@ -0,0 +1,29 @@
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// run
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// Copyright 2015 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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package main
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var x uint16 = 0xffff
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var y uint16 = 0xfffe
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var a uint16 = 0x7000
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var b uint16 = 0x9000
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func main() {
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// Make sure we truncate to smaller-width types after evaluating expressions.
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// This is a problem for arm where there is no 16-bit comparison op.
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if ^x != 0 {
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panic("^uint16(0xffff) != 0")
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}
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if ^y != 1 {
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panic("^uint16(0xfffe) != 1")
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}
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if -x != 1 {
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panic("-uint16(0xffff) != 1")
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}
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if a+b != 0 {
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panic("0x7000+0x9000 != 0")
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}
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}
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