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.
x64 always has MMX, MMXEXT, SSE and SSE2 and this means
that some functions for MMX, MMXEXT and 3dnow are always
overridden by other functions (unless one e.g. explicitly
disables SSE2) for x64. So given that the only systems that
benefit from these functions are truely ancient 32bit x86s
they are removed.
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
* commit '6860b4081d046558c44b1b42f22022ea341a2a73':
x86: include x86inc.asm in x86util.asm
cng: Reindent some incorrectly indented lines
cngdec: Allow flushing the decoder
cngdec: Make the dbov variable have the right unit
cngdec: Fix the memset size to cover the full array
cngdec: Update the LPC coefficients after averaging the reflection coefficients
configure: fix print_config() with broke awks
Conflicts:
libavcodec/x86/ac3dsp.asm
libavcodec/x86/dct32.asm
libavcodec/x86/deinterlace.asm
libavcodec/x86/dsputil.asm
libavcodec/x86/dsputilenc.asm
libavcodec/x86/fft.asm
libavcodec/x86/fmtconvert.asm
libavcodec/x86/h264_chromamc.asm
libavcodec/x86/h264_deblock.asm
libavcodec/x86/h264_deblock_10bit.asm
libavcodec/x86/h264_idct.asm
libavcodec/x86/h264_idct_10bit.asm
libavcodec/x86/h264_intrapred.asm
libavcodec/x86/h264_intrapred_10bit.asm
libavcodec/x86/h264_weight.asm
libavcodec/x86/vc1dsp.asm
libavcodec/x86/vp3dsp.asm
libavcodec/x86/vp56dsp.asm
libavcodec/x86/vp8dsp.asm
Merged-by: Michael Niedermayer <michaelni@gmx.at>
Lynne
Andreas Rheinhardt
James Almer
Ronald S. Bultje
Michael Niedermayer
Carl Eugen Hoyos