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decode: Group all EVEX-handling for ModRM operands

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Most instructions aren't EVEX-encoded, so hide all uncommon paths behind
a single branch.
This commit is contained in:
Alexis Engelke
2023-04-23 11:29:34 +02:00
parent bbc1b0b648
commit 1290e9f094
1 changed files with 19 additions and 16 deletions
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35
decode.c
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@@ -479,25 +479,28 @@ direct:
else
{
bool vsib = UNLIKELY(DESC_VSIB(desc));
// EVEX.z for memory destination operand is UD.
if (UNLIKELY(prefix_evex & 0x80) && DESC_MODRM_IDX(desc) == 0)
return FD_ERR_UD;
// EVEX.b for memory-operand without broadcast support is UD.
unsigned dispscale = 0;
if (UNLIKELY(prefix_evex & 0x10)) {
if (UNLIKELY(!DESC_EVEX_BCST(desc)))
if (UNLIKELY(prefix_evex)) {
// EVEX.z for memory destination operand is UD.
if (UNLIKELY(prefix_evex & 0x80) && DESC_MODRM_IDX(desc) == 0)
return FD_ERR_UD;
if (UNLIKELY(DESC_EVEX_BCST16(desc)))
dispscale = 1;
else
dispscale = prefix_rex & PREFIX_REXW ? 3 : 2;
instr->segment |= dispscale << 6; // Store broadcast size
op_modrm->type = FD_OT_MEMBCST;
} else {
if (UNLIKELY(prefix_evex))
// EVEX.b for memory-operand without broadcast support is UD.
if (UNLIKELY(prefix_evex & 0x10)) {
if (UNLIKELY(!DESC_EVEX_BCST(desc)))
return FD_ERR_UD;
if (UNLIKELY(DESC_EVEX_BCST16(desc)))
dispscale = 1;
else
dispscale = prefix_rex & PREFIX_REXW ? 3 : 2;
instr->segment |= dispscale << 6; // Store broadcast size
op_modrm->type = FD_OT_MEMBCST;
} else {
dispscale = op_modrm->size - 1;
op_modrm->type = FD_OT_MEM;
}
} else {
op_modrm->type = FD_OT_MEM;
}