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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 11:33:05 -0800 |
| commit | 3bb13e91495c763c1ce7759e3b0d2cb32d4095b6 (patch) | |
| tree | e5310296b94b9258bb9242867c7a96cc2161815a | |
| parent | 40eebb02ccbc2d621e796795d5994fe7483b679f (diff) | |
| download | glibc-3bb13e91495c763c1ce7759e3b0d2cb32d4095b6.tar.gz glibc-3bb13e91495c763c1ce7759e3b0d2cb32d4095b6.tar.xz glibc-3bb13e91495c763c1ce7759e3b0d2cb32d4095b6.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 | 2 |
3 files changed, 22 insertions, 2 deletions
diff --git a/sysdeps/x86/cpu-features.c b/sysdeps/x86/cpu-features.c index 4c24ba7c31..eb554b6d14 100644 --- a/sysdeps/x86/cpu-features.c +++ b/sysdeps/x86/cpu-features.c @@ -546,8 +546,24 @@ init_cpu_features (struct cpu_features *cpu_features) cpu_features->preferred[index_arch_Prefer_No_VZEROUPPER] |= bit_arch_Prefer_No_VZEROUPPER; else - cpu_features->preferred[index_arch_Prefer_No_AVX512] - |= bit_arch_Prefer_No_AVX512; + { + cpu_features->preferred[index_arch_Prefer_No_AVX512] + |= bit_arch_Prefer_No_AVX512; + + /* Avoid RTM abort triggered by VZEROUPPER inside a + transactionally executing RTM region. */ + if (CPU_FEATURE_USABLE_P (cpu_features, RTM)) + cpu_features->preferred[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_FEATURE_USABLE_P (cpu_features, AVX2)) + cpu_features->preferred[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 a0b9b9177c..72ea74d083 100644 --- a/sysdeps/x86/cpu-features.h +++ b/sysdeps/x86/cpu-features.h @@ -804,6 +804,7 @@ 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 PREFERRED_FEATURE_INDEX_1 #define index_arch_Fast_Copy_Backward PREFERRED_FEATURE_INDEX_1 @@ -821,6 +822,7 @@ extern const struct cpu_features *__get_cpu_features (void) #define index_arch_Prefer_No_AVX512 PREFERRED_FEATURE_INDEX_1 #define index_arch_MathVec_Prefer_No_AVX512 PREFERRED_FEATURE_INDEX_1 #define index_arch_Prefer_FSRM PREFERRED_FEATURE_INDEX_1 +#define index_arch_Prefer_AVX2_STRCMP PREFERRED_FEATURE_INDEX_1 /* XCR0 Feature flags. */ #define bit_XMM_state (1u << 1) diff --git a/sysdeps/x86/cpu-tunables.c b/sysdeps/x86/cpu-tunables.c index 588bbf9448..b251a91af3 100644 --- a/sysdeps/x86/cpu-tunables.c +++ b/sysdeps/x86/cpu-tunables.c @@ -238,6 +238,8 @@ TUNABLE_CALLBACK (set_hwcaps) (tunable_val_t *valp) CHECK_GLIBC_IFUNC_PREFERRED_BOTH (n, cpu_features, Fast_Copy_Backward, disable, 18); + CHECK_GLIBC_IFUNC_PREFERRED_NEED_BOTH + (n, cpu_features, Prefer_AVX2_STRCMP, AVX2, disable, 18); } break; case 19: |