a32452a544
Simply memcpy and memset inline strategies to avoid branches for
Skylake family CPUs:
1. With MOVE_RATIO and CLEAR_RATIO == 17, GCC will use integer/vector
load and store for up to 16 * 16 (256) bytes when the data size is
fixed and known.
2. Inline only if data size is known to be <= 256.
a. Use "rep movsb/stosb" with simple code sequence if the data size
is a constant.
b. Use loop if data size is not a constant.
3. Use memcpy/memset libray function if data size is unknown or > 256.
On Cascadelake processor with -march=native -Ofast -flto,
1. Performance impacts of SPEC CPU 2017 rate are:
500.perlbench_r 0.17%
502.gcc_r -0.36%
505.mcf_r 0.00%
520.omnetpp_r 0.08%
523.xalancbmk_r -0.62%
525.x264_r 1.04%
531.deepsjeng_r 0.11%
541.leela_r -1.09%
548.exchange2_r -0.25%
557.xz_r 0.17%
Geomean -0.08%
503.bwaves_r 0.00%
507.cactuBSSN_r 0.69%
508.namd_r -0.07%
510.parest_r 1.12%
511.povray_r 1.82%
519.lbm_r 0.00%
521.wrf_r -1.32%
526.blender_r -0.47%
527.cam4_r 0.23%
538.imagick_r -1.72%
544.nab_r -0.56%
549.fotonik3d_r 0.12%
554.roms_r 0.43%
Geomean 0.02%
2. Significant impacts on eembc benchmarks are:
eembc/idctrn01 9.23%
eembc/nnet_test 29.26%
gcc/
* config/i386/x86-tune-costs.h (skylake_memcpy): Updated.
(skylake_memset): Likewise.
(skylake_cost): Change CLEAR_RATIO to 17.
* config/i386/x86-tune.def (X86_TUNE_PREFER_KNOWN_REP_MOVSB_STOSB):
Replace m_CANNONLAKE, m_ICELAKE_CLIENT, m_ICELAKE_SERVER,
m_TIGERLAKE and m_SAPPHIRERAPIDS with m_SKYLAKE and m_CORE_AVX512.
gcc/testsuite/
* gcc.target/i386/memcpy-strategy-9.c: New test.
* gcc.target/i386/memcpy-strategy-10.c: Likewise.
* gcc.target/i386/memcpy-strategy-11.c: Likewise.
* gcc.target/i386/memset-strategy-7.c: Likewise.
* gcc.target/i386/memset-strategy-8.c: Likewise.
* gcc.target/i386/memset-strategy-9.c: Likewise.
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| c++tools | ||
| config | ||
| contrib | ||
| fixincludes | ||
| gcc | ||
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| include | ||
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| libffi | ||
| libgcc | ||
| libgfortran | ||
| libgo | ||
| libgomp | ||
| libhsail-rt | ||
| libiberty | ||
| libitm | ||
| libobjc | ||
| liboffloadmic | ||
| libphobos | ||
| libquadmath | ||
| libsanitizer | ||
| libssp | ||
| libstdc++-v3 | ||
| libvtv | ||
| lto-plugin | ||
| maintainer-scripts | ||
| zlib | ||
| .dir-locals.el | ||
| .gitattributes | ||
| .gitignore | ||
| ABOUT-NLS | ||
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| COPYING | ||
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| COPYING3.LIB | ||
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| COPYING.RUNTIME | ||
| depcomp | ||
| install-sh | ||
| libtool-ldflags | ||
| libtool.m4 | ||
| lt~obsolete.m4 | ||
| ltgcc.m4 | ||
| ltmain.sh | ||
| ltoptions.m4 | ||
| ltsugar.m4 | ||
| ltversion.m4 | ||
| MAINTAINERS | ||
| Makefile.def | ||
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| missing | ||
| mkdep | ||
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| README | ||
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| test-driver | ||
| ylwrap | ||
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