x86or.h
LBT intrinsic · group: x86 Logical
Synopsis
Instruction: x86or.h rj, rk
CPU Flags: LBT
Description
x86-style bitwise OR: compute 16-bit OR of values in rj and rk. Clear CF, OF, AF. Update PF, ZF, SF according to the result. Only EFLAGS (LBT4) is updated; the GPR is not modified.
Operation
uint16_t lhs = (uint16_t)a;
uint16_t rhs = (uint16_t)b;
uint16_t result = lhs | rhs;
EFLAGS.CF = 0;
EFLAGS.OF = 0;
EFLAGS.AF = 0;
EFLAGS.PF = parity_even((uint8_t)result);
EFLAGS.ZF = result == 0;
EFLAGS.SF = (int16_t)result < 0;
Tested on real machine.
Latency and Throughput
| CPU | µarch | Latency | Throughput (IPC) |
|---|---|---|---|
| 3C5000 | LA464 | 2 | 0.5(1/2) |
| 3C6000 | LA664 | 2 | 0.5(1/2) |