Appendix C Instruction Latencies 309
Software Optimization Guide for AMD64 Processors
25112 Rev. 3.06 September 2005
FDIVRP ST(i), ST DEh 11-110-xxx DirectPath FMUL 16/20
/24
1, 6
FFREE ST(i) DDh 11-000-xxx DirectPath FADD/FMUL/
FSTORE
21, 2
FIADD [mem32int] DAh mm-000-xxx Double - 11
FIADD [mem16int] DEh mm-000-xxx Double - 11
FICOM [mem32int] DAh mm-010-xxx Double - 9
FICOM [mem16int] DEh mm-010-xxx Double - 9
FICOMP [mem32int] DAh mm-011-xxx Double - 9
FICOMP [mem16int] DEh mm-011-xxx Double - 9
FIDIV [mem32int] DAh mm-110-xxx Double - 18
FIDIV [mem16int] DEh mm-110-xxx Double - 18
FIDIVR [mem32int] DAh mm-111-xxx Double - 18
FIDIVR [mem16int] DEh mm-111-xxx Double - 18
FILD [mem16int] DFh mm-000-xxx DirectPath FSTORE 6
FILD [mem32int] DBh mm-000-xxx DirectPath FSTORE 6
FILD [mem64int] DFh mm-101-xxx DirectPath FSTORE 6
FIMUL [mem32int] DAh mm-001-xxx Double - 11
FIMUL [mem16int] DEh mm-001-xxx Double - 11
FINCSTP D9h 11-110-111 DirectPath FADD/FMUL/
FSTORE
22
FINIT DBh 11-100-011 VectorPath - ~
FIST [mem16int] DFh mm-010-xxx DirectPath FSTORE 4
FIST [mem32int] DBh mm-010-xxx DirectPath FSTORE 4
FISTP [mem16int] DFh mm-011-xxx DirectPath FSTORE 4
FISTP [mem32int] DBh mm-011-xxx DirectPath FSTORE 4
Table 15. x87 Floating-Point Instructions (Continued)
Syntax
Encoding
Decode
type
FPU
pipe(s)
Latency Note
First
byte
Second
byte
ModRM byte
Notes:
1. The last three bits of the ModRM byte select the stack entry ST(i).
2. These instructions have an effective latency as shown. However, these instructions generate an internal NOP
with a latency of two cycles but no related dependencies. These internal NOPs can be executed at a rate of
three per cycle and can use any of the three execution resources.
3. This is a VectorPath decoded operation that uses one execution pipe (one ROP).
4. There is additional latency associated with this instruction. “e” represents the difference between the exponents
of the divisor and the dividend. If “s” is the number of normalization shifts performed on the result, then
n = (s+1)/2 where (0 <= n <= 32).
5. The latency provided for this operation is the best-case latency.
6. The three latency numbers represent the latency values for precision control settings of single precision, double
precision, and extended precision, respectively.
