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bug in shift of longer operand

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by a shorter operand. the bits
in the difference were not cheared.

R=r
OCL=27705
CL=27705
This commit is contained in:
Ken Thompson 2009-04-21 19:38:58 -07:00
parent dc08ad4f37
commit c18db5aa18
1 changed files with 11 additions and 8 deletions
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19
src/cmd/6g/gen.c
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@ -549,7 +549,7 @@ void
cgen_shift(int op, Node *nl, Node *nr, Node *res)
{
Node n1, n2, n3;
int a, rcl;
int a;
Prog *p1;
a = optoas(op, nl->type);
@ -569,23 +569,26 @@ cgen_shift(int op, Node *nl, Node *nr, Node *res)
goto ret;
}
rcl = reg[D_CX];
nodreg(&n1, types[TINT64], D_CX);
regalloc(&n1, nr->type, &n1);
nodreg(&n1, types[TUINT32], D_CX);
regalloc(&n1, nr->type, &n1); // to hold the shift type in CX
regalloc(&n3, types[TUINT64], &n1); // to clear high bits of CX
regalloc(&n2, nl->type, res);
if(nl->ullman >= nr->ullman) {
cgen(nl, &n2);
cgen(nr, &n1);
gmove(&n1, &n3);
} else {
cgen(nr, &n1);
gmove(&n1, &n3);
cgen(nl, &n2);
}
regfree(&n3);
// test and fix up large shifts
nodconst(&n3, types[TUINT32], nl->type->width*8);
gins(optoas(OCMP, types[TUINT32]), &n1, &n3);
p1 = gbranch(optoas(OLT, types[TUINT32]), T);
nodconst(&n3, types[TUINT64], nl->type->width*8);
gins(optoas(OCMP, types[TUINT64]), &n1, &n3);
p1 = gbranch(optoas(OLT, types[TUINT64]), T);
if(op == ORSH && issigned[nl->type->etype]) {
nodconst(&n3, types[TUINT32], nl->type->width*8-1);
gins(a, &n3, &n2);