x86: Tune Skylake, Cannonlake and Icelake as Haswell

Programming / Compilers / GCC - hjl [138bc75d-0d04-0410-961f-82ee72b054a4] - 13 July 2018 20:25 EDT

r259399, which added PROCESSOR_SKYLAKE, disabled many x86 optimizations which are enabled by PROCESSOR_HASWELL. As the result, -mtune=skylake generates slower codes on Skylake than before. The same also applies to Cannonlake and Icelak tuning.

This patch changes -mtune={skylake|cannonlake|icelake} to tune like-mtune=haswell for until their tuning is properly adjusted. It also enables -mprefer-vector-width=256 for -mtune=haswell, which has no impact on codegen when AVX512 isn't enabled.

Performance impacts on SPEC CPU 2017 rate with 1 copy using

-march=native -mfpmath=sse -O2 -m64

are

1. On Broadwell server:

500.perlbench_r -0.56% 502.gcc_r -0.18% 505.mcf_r 0.24% 520.omnetpp_r 0.00% 523.xalancbmk_r -0.32% 525.x264_r -0.17% 531.deepsjeng_r 0.00% 541.leela_r 0.00% 548.exchange2_r 0.12% 557.xz_r 0.00% Geomean 0.00%

503.bwaves_r 0.00% 507.cactuBSSN_r 0.21% 508.namd_r 0.00% 510.parest_r 0.19% 511.povray_r -0.48% 519.lbm_r 0.00% 521.wrf_r 0.28% 526.blender_r 0.19% 527.cam4_r 0.39% 538.imagick_r 0.00% 544.nab_r -0.36% 549.fotonik3d_r 0.51% 554.roms_r 0.00% Geomean 0.17%

On Skylake client:

500.perlbench_r 0.96% 502.gcc_r 0.13% 505.mcf_r -1.03% 520.omnetpp_r -1.11% 523.xalancbmk_r 1.02% 525.x264_r 0.50% 531.deepsjeng_r 2.97% 541.leela_r 0.50% 548.exchange2_r -0.95% 557.xz_r 2.41% Geomean 0.56%

503.bwaves_r 0.49% 507.cactuBSSN_r 3.17% 508.namd_r 4.05% 510.parest_r 0.15% 511.povray_r 0.80% 519.lbm_r 3.15% 521.wrf_r 10.56% 526.blender_r 2.97% 527.cam4_r 2.36% 538.imagick_r 46.40% 544.nab_r 2.04% 549.fotonik3d_r 0.00% 554.roms_r 1.27% Geomean 5.49%

On Skylake server:

500.perlbench_r 0.71% 502.gcc_r -0.51% 505.mcf_r -1.06% 520.omnetpp_r -0.33% 523.xalancbmk_r -0.22% 525.x264_r 1.72% 531.deepsjeng_r -0.26% 541.leela_r 0.57% 548.exchange2_r -0.75% 557.xz_r -1.28% Geomean -0.21%

503.bwaves_r 0.00% 507.cactuBSSN_r 2.66% 508.namd_r 3.67% 510.parest_r 1.25% 511.povray_r 2.26% 519.lbm_r 1.69% 521.wrf_r 11.03% 526.blender_r 3.39% 527.cam4_r 1.69% 538.imagick_r 64.59% 544.nab_r -0.54% 549.fotonik3d_r 2.68% 554.roms_r 0.00% Geomean 6.19%

This patch improves -march=native performance on Skylake up to 60% and leaves -march=native performance unchanged on Haswell.

gcc/

2018-07-13 H.J. Lu Sunil K Pandey

PR target/84413
- config/i386/i386.c (m_CORE_AVX512): New. (m_CORE_AVX2): Likewise. (m_CORE_ALL): Add m_CORE_AVX2.
- config/i386/x86-tune.def: Replace m_HASWELL with m_CORE_AVX2. Replace m_SKYLAKE_AVX512 with m_CORE_AVX512 on avx256_optimal and remove the rest of m_SKYLAKE_AVX512.

gcc/testsuite/

2018-07-13 H.J. Lu Sunil K Pandey

PR target/84413
- gcc.target/i386/pr84413-1.c: New test.
- gcc.target/i386/pr84413-2.c: Likewise.
- gcc.target/i386/pr84413-3.c: Likewise.

890efbebbdb x86: Tune Skylake, Cannonlake and Icelake as Haswell
ChangeLog | 11 +++++++++++
gcc/config/i386/i386.c | 5 ++++-
gcc/config/i386/x86-tune.def | 26 +++++++++++++-------------
gcc/testsuite/ChangeLog | 8 ++++++++
gcc/testsuite/gcc.target/i386/pr84413-1.c | 17 +++++++++++++++++
gcc/testsuite/gcc.target/i386/pr84413-2.c | 17 +++++++++++++++++
gcc/testsuite/gcc.target/i386/pr84413-3.c | 17 +++++++++++++++++
7 files changed, 87 insertions(+), 14 deletions(-)

Upstream: gcc.gnu.org


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