> > We have also noticed that benchmarks on skylake are not good compared to
> > haswell, this nicely explains it. I think this is -march=native regression
> > compared to GCC versions that did not suppored better CPUs than Haswell.
> > So it
> > would be nice to backport it.
>
> Yes, we should. Here is the patch to backport to GCC 8. OK for GCC 8 after
> it has been checked into trunk?
OK,
Honza
>
> Thanks.
>
> --
> H.J.
> From 40a1050b330b421a1f445cb2a40b5a002da2e6d6 Mon Sep 17 00:00:00 2001
> From: "H.J. Lu" <hjl.to...@gmail.com>
> Date: Mon, 4 Jun 2018 19:16:06 -0700
> Subject: [PATCH] x86: Tune Skylake, Cannonlake and Icelake as Haswell
>
> 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/
>
> Backport from mainline
> 2018-07-12 H.J. Lu <hongjiu...@intel.com>
> Sunil K Pandey <sunil.k.pan...@intel.com>
>
> 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/
>
> Backport from mainline
> 2018-07-12 H.J. Lu <hongjiu...@intel.com>
> Sunil K Pandey <sunil.k.pan...@intel.com>
>
> 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.
> * gcc.target/i386/pr84413-4.c: Likewise.
> ---
> gcc/config/i386/i386.c | 5 ++++-
> gcc/config/i386/x86-tune.def | 26 +++++++++++------------
> 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 +++++++++++++++
> gcc/testsuite/gcc.target/i386/pr84413-4.c | 17 +++++++++++++++
> 6 files changed, 85 insertions(+), 14 deletions(-)
> create mode 100644 gcc/testsuite/gcc.target/i386/pr84413-1.c
> create mode 100644 gcc/testsuite/gcc.target/i386/pr84413-2.c
> create mode 100644 gcc/testsuite/gcc.target/i386/pr84413-3.c
> create mode 100644 gcc/testsuite/gcc.target/i386/pr84413-4.c
>
> diff --git a/gcc/config/i386/i386.c b/gcc/config/i386/i386.c
> index d7dad81786a..8a032371e7f 100644
> --- a/gcc/config/i386/i386.c
> +++ b/gcc/config/i386/i386.c
> @@ -139,7 +139,6 @@ const struct processor_costs *ix86_cost = NULL;
> #define m_NEHALEM (HOST_WIDE_INT_1U<<PROCESSOR_NEHALEM)
> #define m_SANDYBRIDGE (HOST_WIDE_INT_1U<<PROCESSOR_SANDYBRIDGE)
> #define m_HASWELL (HOST_WIDE_INT_1U<<PROCESSOR_HASWELL)
> -#define m_CORE_ALL (m_CORE2 | m_NEHALEM | m_SANDYBRIDGE | m_HASWELL)
> #define m_BONNELL (HOST_WIDE_INT_1U<<PROCESSOR_BONNELL)
> #define m_SILVERMONT (HOST_WIDE_INT_1U<<PROCESSOR_SILVERMONT)
> #define m_KNL (HOST_WIDE_INT_1U<<PROCESSOR_KNL)
> @@ -149,6 +148,10 @@ const struct processor_costs *ix86_cost = NULL;
> #define m_CANNONLAKE (HOST_WIDE_INT_1U<<PROCESSOR_CANNONLAKE)
> #define m_ICELAKE_CLIENT (HOST_WIDE_INT_1U<<PROCESSOR_ICELAKE_CLIENT)
> #define m_ICELAKE_SERVER (HOST_WIDE_INT_1U<<PROCESSOR_ICELAKE_SERVER)
> +#define m_CORE_AVX512 (m_SKYLAKE_AVX512 | m_CANNONLAKE \
> + | m_ICELAKE_CLIENT | m_ICELAKE_SERVER)
> +#define m_CORE_AVX2 (m_HASWELL | m_SKYLAKE | m_CORE_AVX512)
> +#define m_CORE_ALL (m_CORE2 | m_NEHALEM | m_SANDYBRIDGE | m_CORE_AVX2)
> #define m_INTEL (HOST_WIDE_INT_1U<<PROCESSOR_INTEL)
>
> #define m_GEODE (HOST_WIDE_INT_1U<<PROCESSOR_GEODE)
> diff --git a/gcc/config/i386/x86-tune.def b/gcc/config/i386/x86-tune.def
> index 60625668236..c99e45cba58 100644
> --- a/gcc/config/i386/x86-tune.def
> +++ b/gcc/config/i386/x86-tune.def
> @@ -48,9 +48,9 @@ DEF_TUNE (X86_TUNE_SCHEDULE, "schedule",
> over partial stores. For example preffer MOVZBL or MOVQ to load 8bit
> value over movb. */
> DEF_TUNE (X86_TUNE_PARTIAL_REG_DEPENDENCY, "partial_reg_dependency",
> - m_P4_NOCONA | m_CORE2 | m_NEHALEM | m_SANDYBRIDGE | m_HASWELL
> + m_P4_NOCONA | m_CORE2 | m_NEHALEM | m_SANDYBRIDGE | m_CORE_AVX2
> | m_BONNELL | m_SILVERMONT | m_INTEL
> - | m_KNL | m_KNM | m_AMD_MULTIPLE | m_SKYLAKE_AVX512 | m_GENERIC)
> + | m_KNL | m_KNM | m_AMD_MULTIPLE | m_GENERIC)
>
> /* X86_TUNE_SSE_PARTIAL_REG_DEPENDENCY: This knob promotes all store
> destinations to be 128bit to allow register renaming on 128bit SSE units,
> @@ -84,8 +84,8 @@ DEF_TUNE (X86_TUNE_PARTIAL_FLAG_REG_STALL,
> "partial_flag_reg_stall",
> partial dependencies. */
> DEF_TUNE (X86_TUNE_MOVX, "movx",
> m_PPRO | m_P4_NOCONA | m_CORE2 | m_NEHALEM | m_SANDYBRIDGE
> - | m_BONNELL | m_SILVERMONT | m_KNL | m_KNM | m_INTEL | m_HASWELL
> - | m_GEODE | m_AMD_MULTIPLE | m_SKYLAKE_AVX512 | m_GENERIC)
> + | m_BONNELL | m_SILVERMONT | m_KNL | m_KNM | m_INTEL | m_CORE_AVX2
> + | m_GEODE | m_AMD_MULTIPLE | m_GENERIC)
>
> /* X86_TUNE_MEMORY_MISMATCH_STALL: Avoid partial stores that are followed by
> full sized loads. */
> @@ -101,19 +101,19 @@ DEF_TUNE (X86_TUNE_FUSE_CMP_AND_BRANCH_32,
> "fuse_cmp_and_branch_32",
> /* X86_TUNE_FUSE_CMP_AND_BRANCH_64: Fuse compare with a subsequent
> conditional jump instruction for TARGET_64BIT. */
> DEF_TUNE (X86_TUNE_FUSE_CMP_AND_BRANCH_64, "fuse_cmp_and_branch_64",
> - m_NEHALEM | m_SANDYBRIDGE | m_HASWELL | m_BDVER | m_ZNVER1 |
> m_GENERIC)
> + m_NEHALEM | m_SANDYBRIDGE | m_CORE_AVX2 | m_BDVER | m_ZNVER1 |
> m_GENERIC)
>
> /* X86_TUNE_FUSE_CMP_AND_BRANCH_SOFLAGS: Fuse compare with a
> subsequent conditional jump instruction when the condition jump
> check sign flag (SF) or overflow flag (OF). */
> DEF_TUNE (X86_TUNE_FUSE_CMP_AND_BRANCH_SOFLAGS,
> "fuse_cmp_and_branch_soflags",
> - m_NEHALEM | m_SANDYBRIDGE | m_HASWELL | m_BDVER | m_ZNVER1 |
> m_GENERIC)
> + m_NEHALEM | m_SANDYBRIDGE | m_CORE_AVX2 | m_BDVER | m_ZNVER1 |
> m_GENERIC)
>
> /* X86_TUNE_FUSE_ALU_AND_BRANCH: Fuse alu with a subsequent conditional
> jump instruction when the alu instruction produces the CCFLAG consumed by
> the conditional jump instruction. */
> DEF_TUNE (X86_TUNE_FUSE_ALU_AND_BRANCH, "fuse_alu_and_branch",
> - m_SANDYBRIDGE | m_HASWELL | m_GENERIC)
> + m_SANDYBRIDGE | m_CORE_AVX2 | m_GENERIC)
>
>
>
> /*****************************************************************************/
> @@ -286,7 +286,7 @@ DEF_TUNE (X86_TUNE_USE_BT, "use_bt",
> /* X86_TUNE_AVOID_FALSE_DEP_FOR_BMI: Avoid false dependency
> for bit-manipulation instructions. */
> DEF_TUNE (X86_TUNE_AVOID_FALSE_DEP_FOR_BMI, "avoid_false_dep_for_bmi",
> - m_SANDYBRIDGE | m_HASWELL | m_GENERIC)
> + m_SANDYBRIDGE | m_CORE_AVX2 | m_GENERIC)
>
> /* X86_TUNE_ADJUST_UNROLL: This enables adjusting the unroll factor based
> on hardware capabilities. Bdver3 hardware has a loop buffer which makes
> @@ -335,15 +335,15 @@ DEF_TUNE (X86_TUNE_GENERAL_REGS_SSE_SPILL,
> "general_regs_sse_spill",
> /* X86_TUNE_SSE_UNALIGNED_LOAD_OPTIMAL: Use movups for misaligned loads
> instead
> of a sequence loading registers by parts. */
> DEF_TUNE (X86_TUNE_SSE_UNALIGNED_LOAD_OPTIMAL, "sse_unaligned_load_optimal",
> - m_NEHALEM | m_SANDYBRIDGE | m_HASWELL | m_SILVERMONT | m_KNL | m_KNM
> - | m_INTEL | m_SKYLAKE_AVX512 | m_AMDFAM10 | m_BDVER | m_BTVER
> + m_NEHALEM | m_SANDYBRIDGE | m_CORE_AVX2 | m_SILVERMONT | m_KNL | m_KNM
> + | m_INTEL | m_AMDFAM10 | m_BDVER | m_BTVER
> | m_ZNVER1 | m_GENERIC)
>
> /* X86_TUNE_SSE_UNALIGNED_STORE_OPTIMAL: Use movups for misaligned stores
> instead
> of a sequence loading registers by parts. */
> DEF_TUNE (X86_TUNE_SSE_UNALIGNED_STORE_OPTIMAL,
> "sse_unaligned_store_optimal",
> - m_NEHALEM | m_SANDYBRIDGE | m_HASWELL | m_SILVERMONT | m_KNL | m_KNM
> - | m_INTEL | m_SKYLAKE_AVX512 | m_BDVER | m_ZNVER1 | m_GENERIC)
> + m_NEHALEM | m_SANDYBRIDGE | m_CORE_AVX2 | m_SILVERMONT | m_KNL | m_KNM
> + | m_INTEL | m_BDVER | m_ZNVER1 | m_GENERIC)
>
> /* Use packed single precision instructions where posisble. I.e. movups
> instead
> of movupd. */
> @@ -429,7 +429,7 @@ DEF_TUNE (X86_TUNE_AVX128_OPTIMAL, "avx128_optimal",
> m_BDVER | m_BTVER2
>
> /* X86_TUNE_AVX256_OPTIMAL: Use 256-bit AVX instructions instead of 512-bit
> AVX
> instructions in the auto-vectorizer. */
> -DEF_TUNE (X86_TUNE_AVX256_OPTIMAL, "avx256_optimal", m_SKYLAKE_AVX512)
> +DEF_TUNE (X86_TUNE_AVX256_OPTIMAL, "avx256_optimal", m_CORE_AVX512)
>
>
> /*****************************************************************************/
> /* Historical relics: tuning flags that helps a specific old CPU designs
> */
> diff --git a/gcc/testsuite/gcc.target/i386/pr84413-1.c
> b/gcc/testsuite/gcc.target/i386/pr84413-1.c
> new file mode 100644
> index 00000000000..1c94d7715cf
> --- /dev/null
> +++ b/gcc/testsuite/gcc.target/i386/pr84413-1.c
> @@ -0,0 +1,17 @@
> +/* { dg-do compile } */
> +/* { dg-options "-O3 -march=skylake-avx512" } */
> +/* { dg-final { scan-assembler-not "%zmm\[0-9\]+" } } */
> +/* { dg-final { scan-assembler "vmulpd\[ \\t\]+\[^\n\]*%ymm\[0-9\]+" } } */
> +
> +#define N 1024
> +
> +double a[N], b[N], c[N];
> +
> +void
> +avx512f_test (void)
> +{
> + int i;
> +
> + for (i = 0; i < N; i++)
> + c[i] = a[i] * b[i];
> +}
> diff --git a/gcc/testsuite/gcc.target/i386/pr84413-2.c
> b/gcc/testsuite/gcc.target/i386/pr84413-2.c
> new file mode 100644
> index 00000000000..adf9b527cd6
> --- /dev/null
> +++ b/gcc/testsuite/gcc.target/i386/pr84413-2.c
> @@ -0,0 +1,17 @@
> +/* { dg-do compile } */
> +/* { dg-options "-O3 -march=cannonlake" } */
> +/* { dg-final { scan-assembler-not "%zmm\[0-9\]+" } } */
> +/* { dg-final { scan-assembler "vmulpd\[ \\t\]+\[^\n\]*%ymm\[0-9\]+" } } */
> +
> +#define N 1024
> +
> +double a[N], b[N], c[N];
> +
> +void
> +avx512f_test (void)
> +{
> + int i;
> +
> + for (i = 0; i < N; i++)
> + c[i] = a[i] * b[i];
> +}
> diff --git a/gcc/testsuite/gcc.target/i386/pr84413-3.c
> b/gcc/testsuite/gcc.target/i386/pr84413-3.c
> new file mode 100644
> index 00000000000..76bf25fc56b
> --- /dev/null
> +++ b/gcc/testsuite/gcc.target/i386/pr84413-3.c
> @@ -0,0 +1,17 @@
> +/* { dg-do compile } */
> +/* { dg-options "-O3 -march=icelake-server" } */
> +/* { dg-final { scan-assembler-not "%zmm\[0-9\]+" } } */
> +/* { dg-final { scan-assembler "vmulpd\[ \\t\]+\[^\n\]*%ymm\[0-9\]+" } } */
> +
> +#define N 1024
> +
> +double a[N], b[N], c[N];
> +
> +void
> +avx512f_test (void)
> +{
> + int i;
> +
> + for (i = 0; i < N; i++)
> + c[i] = a[i] * b[i];
> +}
> diff --git a/gcc/testsuite/gcc.target/i386/pr84413-4.c
> b/gcc/testsuite/gcc.target/i386/pr84413-4.c
> new file mode 100644
> index 00000000000..031ef0c8916
> --- /dev/null
> +++ b/gcc/testsuite/gcc.target/i386/pr84413-4.c
> @@ -0,0 +1,17 @@
> +/* { dg-do compile } */
> +/* { dg-options "-O3 -march=haswell -mavx512f" } */
> +/* { dg-final { scan-assembler-not "%zmm\[0-9\]+" } } */
> +/* { dg-final { scan-assembler "vmulpd\[ \\t\]+\[^\n\]*%ymm\[0-9\]+" } } */
> +
> +#define N 1024
> +
> +double a[N], b[N], c[N];
> +
> +void
> +avx512f_test (void)
> +{
> + int i;
> +
> + for (i = 0; i < N; i++)
> + c[i] = a[i] * b[i];
> +}
> --
> 2.17.1
>
