ffmpeg/libavutil/x86
Lynne bbe95f7353
x86: replace explicit REP_RETs with RETs
From x86inc:
> On AMD cpus <=K10, an ordinary ret is slow if it immediately follows either
> a branch or a branch target. So switch to a 2-byte form of ret in that case.
> We can automatically detect "follows a branch", but not a branch target.
> (SSSE3 is a sufficient condition to know that your cpu doesn't have this problem.)

x86inc can automatically determine whether to use REP_RET rather than
REP in most of these cases, so impact is minimal. Additionally, a few
REP_RETs were used unnecessary, despite the return being nowhere near a
branch.

The only CPUs affected were AMD K10s, made between 2007 and 2011, 16
years ago and 12 years ago, respectively.

In the future, everyone involved with x86inc should consider dropping
REP_RETs altogether.
2023-02-01 04:23:55 +01:00
..
Makefile
asm.h
bswap.h
cpu.c
cpu.h
cpuid.asm
emms.asm
emms.h
fixed_dsp.asm
fixed_dsp_init.c
float_dsp.asm x86: replace explicit REP_RETs with RETs 2023-02-01 04:23:55 +01:00
float_dsp_init.c
imgutils.asm
imgutils_init.c
intmath.h
intreadwrite.h
lls.asm x86: replace explicit REP_RETs with RETs 2023-02-01 04:23:55 +01:00
lls_init.c
pixelutils.asm
pixelutils.h
pixelutils_init.c
timer.h
tx_float.asm x86/tx_float: fix stray change in 15xM FFT and replace imul->lea 2022-11-28 16:58:12 +01:00
tx_float_init.c lavu/tx: refactor to explicitly track and convert lookup table order 2022-11-24 15:58:34 +01:00
w64xmmtest.h
x86inc.asm
x86util.asm