56 lines
2.3 KiB
Diff
56 lines
2.3 KiB
Diff
From d8bf4388df679fa5a3ae7889a649e573e3124530 Mon Sep 17 00:00:00 2001
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From: Aurelien Jarno <aurelien@aurel32.net>
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Date: Mon, 3 Oct 2022 23:46:11 +0200
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Subject: [PATCH 53/81] x86-64: Require BMI2 for AVX2 wcs(n)cmp implementations
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The AVX2 wcs(n)cmp implementations use the 'bzhi' instruction, which
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belongs to the BMI2 CPU feature.
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NB: It also uses the 'tzcnt' BMI1 instruction, but it is executed as BSF
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as BSF if the CPU doesn't support TZCNT, and produces the same result
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for non-zero input.
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Partially fixes: b77b06e0e296 ("x86: Optimize strcmp-avx2.S")
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Partially resolves: BZ #29611
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Reviewed-by: Noah Goldstein <goldstein.w.n@gmail.com>
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(cherry picked from commit f31a5a884ed84bd37032729d4d1eb9d06c9f3c29)
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---
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sysdeps/x86_64/multiarch/ifunc-impl-list.c | 8 ++++++--
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1 file changed, 6 insertions(+), 2 deletions(-)
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diff --git a/sysdeps/x86_64/multiarch/ifunc-impl-list.c b/sysdeps/x86_64/multiarch/ifunc-impl-list.c
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index aebef3daaf..fec8790c11 100644
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--- a/sysdeps/x86_64/multiarch/ifunc-impl-list.c
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+++ b/sysdeps/x86_64/multiarch/ifunc-impl-list.c
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@@ -810,10 +810,12 @@ __libc_ifunc_impl_list (const char *name, struct libc_ifunc_impl *array,
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&& CPU_FEATURE_USABLE (BMI2)),
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__wcscmp_evex)
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X86_IFUNC_IMPL_ADD_V3 (array, i, wcscmp,
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- CPU_FEATURE_USABLE (AVX2),
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+ (CPU_FEATURE_USABLE (AVX2)
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+ && CPU_FEATURE_USABLE (BMI2)),
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__wcscmp_avx2)
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X86_IFUNC_IMPL_ADD_V3 (array, i, wcscmp,
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(CPU_FEATURE_USABLE (AVX2)
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+ && CPU_FEATURE_USABLE (BMI2)
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&& CPU_FEATURE_USABLE (RTM)),
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__wcscmp_avx2_rtm)
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/* ISA V2 wrapper for SSE2 implementation because the SSE2
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@@ -830,10 +832,12 @@ __libc_ifunc_impl_list (const char *name, struct libc_ifunc_impl *array,
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&& CPU_FEATURE_USABLE (BMI2)),
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__wcsncmp_evex)
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X86_IFUNC_IMPL_ADD_V3 (array, i, wcsncmp,
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- CPU_FEATURE_USABLE (AVX2),
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+ (CPU_FEATURE_USABLE (AVX2)
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+ && CPU_FEATURE_USABLE (BMI2)),
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__wcsncmp_avx2)
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X86_IFUNC_IMPL_ADD_V3 (array, i, wcsncmp,
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(CPU_FEATURE_USABLE (AVX2)
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+ && CPU_FEATURE_USABLE (BMI2)
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&& CPU_FEATURE_USABLE (RTM)),
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__wcsncmp_avx2_rtm)
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/* ISA V2 wrapper for GENERIC implementation because the
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--
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2.19.1.6.gb485710b
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