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decode: Optimize decoding of shift operands

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This commit is contained in:
Alexis Engelke
2023-03-19 21:14:32 +01:00
parent 3de8490e0c
commit 957537651e
1 changed files with 21 additions and 14 deletions
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11
decode.c
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@@ -552,16 +552,22 @@ fd_decode(const uint8_t* buffer, size_t len_sz, int mode_int, uintptr_t address,
if (UNLIKELY(DESC_HAS_VEXREG(desc))) if (UNLIKELY(DESC_HAS_VEXREG(desc)))
{ {
// Without VEX prefix, this encodes an implicit register
FdOp* operand = &instr->operands[DESC_VEXREG_IDX(desc)]; FdOp* operand = &instr->operands[DESC_VEXREG_IDX(desc)];
if (DESC_ZEROREG_VAL(desc)) {
operand->type = FD_OT_REG; operand->type = FD_OT_REG;
operand->size = 1;
operand->reg = FD_REG_CL;
operand->misc = FD_RT_GPL;
} else {
operand->type = FD_OT_REG;
// Without VEX prefix, this encodes an implicit register
operand->size = operand_sizes[(desc->operand_sizes >> 4) & 3]; operand->size = operand_sizes[(desc->operand_sizes >> 4) & 3];
if (mode == DECODE_32) if (mode == DECODE_32)
vex_operand &= 0x7; vex_operand &= 0x7;
// Note: 32-bit will never UD here. EVEX.V' is caught above already. // Note: 32-bit will never UD here. EVEX.V' is caught above already.
// Note: UD if > 16 for non-VEC. No EVEX-encoded instruction uses // Note: UD if > 16 for non-VEC. No EVEX-encoded instruction uses
// EVEX.vvvv to refer to non-vector registers. Verified in parseinstrs. // EVEX.vvvv to refer to non-vector registers. Verified in parseinstrs.
operand->reg = vex_operand | DESC_ZEROREG_VAL(desc); operand->reg = vex_operand;
unsigned reg_ty = DESC_REGTY_VEXREG(desc); // VEC GPL MSK FPU unsigned reg_ty = DESC_REGTY_VEXREG(desc); // VEC GPL MSK FPU
// In 64-bit mode: UD if FD_RT_MASK and vex_operand&8 != 0 // In 64-bit mode: UD if FD_RT_MASK and vex_operand&8 != 0
@@ -569,6 +575,7 @@ fd_decode(const uint8_t* buffer, size_t len_sz, int mode_int, uintptr_t address,
return FD_ERR_UD; return FD_ERR_UD;
operand->misc = (04710 >> (3 * reg_ty)) & 0x7; operand->misc = (04710 >> (3 * reg_ty)) & 0x7;
} }
}
else if (vex_operand != 0) else if (vex_operand != 0)
{ {
// TODO: bit 3 ignored in 32-bit mode? unverified // TODO: bit 3 ignored in 32-bit mode? unverified