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| author | H.J. Lu <hjl.tools@gmail.com> | 2021-02-26 05:36:59 -0800 |
|---|---|---|
| committer | H.J. Lu <hjl.tools@gmail.com> | 2022-01-27 12:07:11 -0800 |
| commit | be07b3e059d337aadbdcbcc20a407fa474c802dc (patch) | |
| tree | 589b5098e26dbd91fb7ad603cf86f788e4c9d87e | |
| parent | 2f3fb944b311b67e609ed79478cc1737f6066af9 (diff) | |
| download | glibc-be07b3e059d337aadbdcbcc20a407fa474c802dc.tar glibc-be07b3e059d337aadbdcbcc20a407fa474c802dc.tar.gz glibc-be07b3e059d337aadbdcbcc20a407fa474c802dc.tar.bz2 glibc-be07b3e059d337aadbdcbcc20a407fa474c802dc.zip | |
x86: Set Prefer_No_VZEROUPPER and add Prefer_AVX2_STRCMP
1. Set Prefer_No_VZEROUPPER if RTM is usable to avoid RTM abort triggered
by VZEROUPPER inside a transactionally executing RTM region.
2. Since to compare 2 32-byte strings, 256-bit EVEX strcmp requires 2
loads, 3 VPCMPs and 2 KORDs while AVX2 strcmp requires 1 load, 2 VPCMPEQs,
1 VPMINU and 1 VPMOVMSKB, AVX2 strcmp is faster than EVEX strcmp. Add
Prefer_AVX2_STRCMP to prefer AVX2 strcmp family functions.
(cherry picked from commit 1da50d4bda07f04135dca39f40e79fc9eabed1f8)
| -rw-r--r-- | sysdeps/x86/cpu-features.c | 20 | ||||
| -rw-r--r-- | sysdeps/x86/cpu-features.h | 2 | ||||
| -rw-r--r-- | sysdeps/x86/cpu-tunables.c | 3 |
3 files changed, 23 insertions, 2 deletions
diff --git a/sysdeps/x86/cpu-features.c b/sysdeps/x86/cpu-features.c index 121f706402..3db490aa8f 100644 --- a/sysdeps/x86/cpu-features.c +++ b/sysdeps/x86/cpu-features.c @@ -422,8 +422,24 @@ init_cpu_features (struct cpu_features *cpu_features) cpu_features->feature[index_arch_Prefer_No_VZEROUPPER] |= bit_arch_Prefer_No_VZEROUPPER; else - cpu_features->feature[index_arch_Prefer_No_AVX512] - |= bit_arch_Prefer_No_AVX512; + { + cpu_features->feature[index_arch_Prefer_No_AVX512] + |= bit_arch_Prefer_No_AVX512; + + /* Avoid RTM abort triggered by VZEROUPPER inside a + transactionally executing RTM region. */ + if (CPU_FEATURES_CPU_P (cpu_features, RTM)) + cpu_features->feature[index_arch_Prefer_No_VZEROUPPER] + |= bit_arch_Prefer_No_VZEROUPPER; + + /* Since to compare 2 32-byte strings, 256-bit EVEX strcmp + requires 2 loads, 3 VPCMPs and 2 KORDs while AVX2 strcmp + requires 1 load, 2 VPCMPEQs, 1 VPMINU and 1 VPMOVMSKB, + AVX2 strcmp is faster than EVEX strcmp. */ + if (CPU_FEATURES_ARCH_P (cpu_features, AVX2_Usable)) + cpu_features->feature[index_arch_Prefer_AVX2_STRCMP] + |= bit_arch_Prefer_AVX2_STRCMP; + } } /* This spells out "AuthenticAMD" or "HygonGenuine". */ else if ((ebx == 0x68747541 && ecx == 0x444d4163 && edx == 0x69746e65) diff --git a/sysdeps/x86/cpu-features.h b/sysdeps/x86/cpu-features.h index 03a9b2a5e9..ca2924bd95 100644 --- a/sysdeps/x86/cpu-features.h +++ b/sysdeps/x86/cpu-features.h @@ -897,6 +897,7 @@ extern const struct cpu_features *__get_cpu_features (void) #define bit_arch_Prefer_FSRM (1u << 13) #define bit_arch_Prefer_No_AVX512 (1u << 14) #define bit_arch_MathVec_Prefer_No_AVX512 (1u << 15) +#define bit_arch_Prefer_AVX2_STRCMP (1u << 16) #define index_arch_Fast_Rep_String FEATURE_INDEX_2 #define index_arch_Fast_Copy_Backward FEATURE_INDEX_2 @@ -914,6 +915,7 @@ extern const struct cpu_features *__get_cpu_features (void) #define index_arch_Prefer_No_AVX512 FEATURE_INDEX_2 #define index_arch_MathVec_Prefer_No_AVX512 FEATURE_INDEX_2 #define index_arch_Prefer_FSRM FEATURE_INDEX_2 +#define index_arch_Prefer_AVX2_STRCMP FEATURE_INDEX_2 /* XCR0 Feature flags. */ #define bit_XMM_state (1u << 1) diff --git a/sysdeps/x86/cpu-tunables.c b/sysdeps/x86/cpu-tunables.c index 2cb315111b..d4d5e450a6 100644 --- a/sysdeps/x86/cpu-tunables.c +++ b/sysdeps/x86/cpu-tunables.c @@ -282,6 +282,9 @@ TUNABLE_CALLBACK (set_hwcaps) (tunable_val_t *valp) CHECK_GLIBC_IFUNC_ARCH_BOTH (n, cpu_features, Fast_Copy_Backward, disable, 18); + CHECK_GLIBC_IFUNC_ARCH_NEED_ARCH_BOTH + (n, cpu_features, Prefer_AVX2_STRCMP, AVX2_Usable, + disable, 18); } break; case 19: |