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| author |   H.J. Lu <hjl.tools@gmail.com> | 2021-02-26 05:36:59 -0800 |
|---|---|---|
| committer |   Andreas K. Hüttel <dilfridge@gentoo.org> | 2022-01-31 22:06:25 +0100 |
| commit | 7e2386584bf88ae5c93ef2dbf0057672a3a99851 (patch) | |
| tree | 05e1b5e21ace9f2f6289c4397feecd1404d3f5c7 | |
| parent | test-strnlen.c: Check that strnlen won't go beyond the maximum length (diff) | |
| download | glibc-7e2386584bf88ae5c93ef2dbf0057672a3a99851.tar.gz glibc-7e2386584bf88ae5c93ef2dbf0057672a3a99851.tar.bz2 glibc-7e2386584bf88ae5c93ef2dbf0057672a3a99851.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)
(cherry picked from commit f0a2b671471bf1fe943feb4a2d00409625e05ba4)
| -rw-r--r-- | sysdeps/x86/cpu-features.c | 20 | ||||
| -rw-r--r-- | sysdeps/x86/cpu-tunables.c | 2 | ||||
| -rw-r--r-- | sysdeps/x86/include/cpu-features-preferred_feature_index_1.def | 1 |
3 files changed, 21 insertions, 2 deletions
diff --git a/sysdeps/x86/cpu-features.c b/sysdeps/x86/cpu-features.c index 73b0a4dc9a..dfad82f14c 100644 --- a/sysdeps/x86/cpu-features.c +++ b/sysdeps/x86/cpu-features.c @@ -520,8 +520,24 @@ 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-tunables.c b/sysdeps/x86/cpu-tunables.c index 126896f41b..a90df39b78 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: diff --git a/sysdeps/x86/include/cpu-features-preferred_feature_index_1.def b/sysdeps/x86/include/cpu-features-preferred_feature_index_1.def index 06af1a8dd5..133aab19f1 100644 --- a/sysdeps/x86/include/cpu-features-preferred_feature_index_1.def +++ b/sysdeps/x86/include/cpu-features-preferred_feature_index_1.def @@ -32,3 +32,4 @@ BIT (Prefer_ERMS) BIT (Prefer_No_AVX512) BIT (MathVec_Prefer_No_AVX512) BIT (Prefer_FSRM) +BIT (Prefer_AVX2_STRCMP) |