8000 [release-branch.go1.3] cmd/6g, cmd/8g: fix, test byte-sized magic mul… · golang/go@3fa4a78 · GitHub
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[release-branch.go1.3] cmd/6g, cmd/8g: fix, test byte-sized magic multiply
««« CL 124950043 / 8e5ec6948793 cmd/6g, cmd/8g: fix, test byte-sized magic multiply Credit to Rémy for finding and writing test case. Fixes #8325. LGTM=r R=golang-codereviews, r CC=dave, golang-codereviews, iant, remyoudompheng https://golang.org/cl/124950043 »»» TBR=rsc CC=golang-codereviews https://golang.org/cl/126000043
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lines changed

5 files changed

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lines changed

‎src/cmd/6g/ggen.c‎

Lines changed: 1 addition & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -943,7 +943,7 @@ cgen_hmul(Node *nl, Node *nr, Node *res)
943943
if(t->width == 1) {
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// byte multiply behaves differently.
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nodreg(&ax, t, D_AH);
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nodreg(&dx, t, D_DL);
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nodreg(&dx, t, D_DX);
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gmove(&ax, &dx);
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}
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nodreg(&dx, t, D_DX);

‎src/cmd/6g/peep.c‎

Lines changed: 5 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -838,6 +838,11 @@ copyu(Prog *p, Adr *v, Adr *s)
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static int
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copyas(Adr *a, Adr *v)
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{
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if(D_AL <= a->type && a->type <= D_R15B)
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fatal("use of byte register");
843+
if(D_AL <= v->type && v->type <= D_R15B)
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fatal("use of byte register");
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841846
if(a->type != v->type)
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return 0;
843848
if(regtyp(v))

‎src/cmd/8g/ggen.c‎

Lines changed: 1 addition & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -991,7 +991,7 @@ cgen_hmul(Node *nl, Node *nr, Node *res)
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if(t->width == 1) {
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// byte multiply behaves differently.
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nodreg(&ax, t, D_AH);
994-
nodreg(&dx, t, D_DL);
994+
nodreg(&dx, t, D_DX);
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gmove(&ax, &dx);
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}
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nodreg(&dx, t, D_DX);

‎src/cmd/8g/peep.c‎

Lines changed: 5 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -634,6 +634,11 @@ copyu(Prog *p, Adr *v, Adr *s)
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static int
635635
copyas(Adr *a, Adr *v)
636636
{
637+
if(D_AL <= a->type && a->type <= D_R15B)
638+
fatal("use of byte register");
639+
if(D_AL <= v->type && v->type <= D_R15B)
640+
fatal("use of byte register");
641+
637642
if(a->type != v->type)
638643
return 0;
639644
if(regtyp(v))

‎test/fixedbugs/issue8325.go‎

Lines changed: 31 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,31 @@
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// run
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// Copyright 2014 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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// Issue 8325: corrupted byte operations during optimization
8+
// pass.
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package main
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const alphanum = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ"
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func main() {
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var bytes = []byte{10, 20, 30, 40, 50}
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for i, b := range bytes {
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bytes[i] = alphanum[b%byte(len(alphanum))]
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}
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for _, b := range bytes {
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switch {
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case '0' <= b && b <= '9',
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'A' <= b && b <= 'Z':
25+
default:
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println("found a bad character", string(b))
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panic("BUG")
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}
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}
31+
}

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