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asm/assemble.c: change the overflow handling for signed byte immediates

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For byte immediates that are sign-extended to a wider operand size,
simplify the code and make the warning code behave as what is
expected.

Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
This commit is contained in:
H. Peter Anvin 2017-03-01 13:25:08 -08:00
parent 55e06dead1
commit fbb07d6843
1 changed files with 17 additions and 23 deletions
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40
asm/assemble.c
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@ -1748,34 +1748,28 @@ static void gencode(struct out_data *data, insn *ins)
case4(0274):
{
uint64_t uv, um;
int64_t uv;
int s;
if (ins->rex & REX_W)
s = 64;
else if (ins->prefixes[PPS_OSIZE] == P_O16)
s = 16;
else if (ins->prefixes[PPS_OSIZE] == P_O32)
s = 32;
else
s = bits;
if (absolute_op(opx)) {
if (ins->rex & REX_W)
s = 64;
else if (ins->prefixes[PPS_OSIZE] == P_O16)
s = 16;
else if (ins->prefixes[PPS_OSIZE] == P_O32)
s = 32;
else
s = bits;
um = (uint64_t)2 << (s-1);
uv = opx->offset;
if (uv > 127 && uv < (uint64_t)-128 &&
(uv < um-128 || uv > um-1)) {
/* If this wasn't explicitly byte-sized, warn as though we
* had fallen through to the imm16/32/64 case.
/*
* Forcibly discard bits irrelevant for our needs, to
* prevent bogus warnings.
*/
nasm_error(ERR_WARNING | ERR_PASS2 | ERR_WARN_NOV,
"%s value exceeds bounds",
(opx->type & BITS8) ? "signed byte" :
s == 16 ? "word" :
s == 32 ? "dword" :
"signed dword");
uv = opx->offset;
uv = (uv << (64-s)) >> (64-s);
opx->offset = uv;
}
out_imm(data, opx, 1, OUT_WRAP); /* XXX: OUT_SIGNED? */
out_imm(data, opx, 1, OUT_SIGNED);
break;
}