[x86] Add a feature bit: Fast_Unaligned_Copy
On AMD processors, memcpy optimized with unaligned SSE load is slower than emcpy optimized with aligned SSSE3 while other string functions are faster with unaligned SSE load. A feature bit, Fast_Unaligned_Copy, is added to select memcpy optimized with unaligned SSE load. [BZ #19583] * sysdeps/x86/cpu-features.c (init_cpu_features): Set Fast_Unaligned_Copy with Fast_Unaligned_Load for Intel processors. Set Fast_Copy_Backward for AMD Excavator processors. * sysdeps/x86/cpu-features.h (bit_arch_Fast_Unaligned_Copy): New. (index_arch_Fast_Unaligned_Copy): Likewise. * sysdeps/x86_64/multiarch/memcpy.S (__new_memcpy): Check Fast_Unaligned_Copy instead of Fast_Unaligned_Load.
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ChangeLog
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ChangeLog
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@ -1,3 +1,17 @@
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2016-03-28 H.J. Lu <hongjiu.lu@intel.com>
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Amit Pawar <Amit.Pawar@amd.com>
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[BZ #19583]
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* sysdeps/x86/cpu-features.c (init_cpu_features): Set
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Fast_Unaligned_Copy with Fast_Unaligned_Load for Intel
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processors. Set Fast_Copy_Backward for AMD Excavator
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processors.
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* sysdeps/x86/cpu-features.h (bit_arch_Fast_Unaligned_Copy):
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New.
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(index_arch_Fast_Unaligned_Copy): Likewise.
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* sysdeps/x86_64/multiarch/memcpy.S (__new_memcpy): Check
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Fast_Unaligned_Copy instead of Fast_Unaligned_Load.
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2016-03-25 Florian Weimer <fweimer@redhat.com>
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[BZ #19791]
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@ -152,9 +152,13 @@ init_cpu_features (struct cpu_features *cpu_features)
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#endif
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#if index_arch_Fast_Unaligned_Load != index_arch_Slow_SSE4_2
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# error index_arch_Fast_Unaligned_Load != index_arch_Slow_SSE4_2
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#endif
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#if index_arch_Fast_Unaligned_Load != index_arch_Fast_Unaligned_Copy
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# error index_arch_Fast_Unaligned_Load != index_arch_Fast_Unaligned_Copy
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#endif
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cpu_features->feature[index_arch_Fast_Unaligned_Load]
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|= (bit_arch_Fast_Unaligned_Load
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| bit_arch_Fast_Unaligned_Copy
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| bit_arch_Prefer_PMINUB_for_stringop
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| bit_arch_Slow_SSE4_2);
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break;
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@ -182,11 +186,15 @@ init_cpu_features (struct cpu_features *cpu_features)
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#endif
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#if index_arch_Fast_Rep_String != index_arch_Prefer_PMINUB_for_stringop
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# error index_arch_Fast_Rep_String != index_arch_Prefer_PMINUB_for_stringop
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#endif
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#if index_arch_Fast_Rep_String != index_arch_Fast_Unaligned_Copy
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# error index_arch_Fast_Rep_String != index_arch_Fast_Unaligned_Copy
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#endif
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cpu_features->feature[index_arch_Fast_Rep_String]
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|= (bit_arch_Fast_Rep_String
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| bit_arch_Fast_Copy_Backward
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| bit_arch_Fast_Unaligned_Load
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| bit_arch_Fast_Unaligned_Copy
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| bit_arch_Prefer_PMINUB_for_stringop);
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break;
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}
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@ -220,10 +228,14 @@ init_cpu_features (struct cpu_features *cpu_features)
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if (family == 0x15)
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{
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#if index_arch_Fast_Unaligned_Load != index_arch_Fast_Copy_Backward
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# error index_arch_Fast_Unaligned_Load != index_arch_Fast_Copy_Backward
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#endif
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/* "Excavator" */
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if (model >= 0x60 && model <= 0x7f)
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cpu_features->feature[index_arch_Fast_Unaligned_Load]
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|= bit_arch_Fast_Unaligned_Load;
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|= (bit_arch_Fast_Unaligned_Load
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| bit_arch_Fast_Copy_Backward);
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}
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}
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else
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@ -35,6 +35,7 @@
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#define bit_arch_I686 (1 << 15)
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#define bit_arch_Prefer_MAP_32BIT_EXEC (1 << 16)
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#define bit_arch_Prefer_No_VZEROUPPER (1 << 17)
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#define bit_arch_Fast_Unaligned_Copy (1 << 18)
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/* CPUID Feature flags. */
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@ -101,6 +102,7 @@
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# define index_arch_I686 FEATURE_INDEX_1*FEATURE_SIZE
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# define index_arch_Prefer_MAP_32BIT_EXEC FEATURE_INDEX_1*FEATURE_SIZE
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# define index_arch_Prefer_No_VZEROUPPER FEATURE_INDEX_1*FEATURE_SIZE
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# define index_arch_Fast_Unaligned_Copy FEATURE_INDEX_1*FEATURE_SIZE
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# if defined (_LIBC) && !IS_IN (nonlib)
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@ -265,6 +267,7 @@ extern const struct cpu_features *__get_cpu_features (void)
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# define index_arch_I686 FEATURE_INDEX_1
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# define index_arch_Prefer_MAP_32BIT_EXEC FEATURE_INDEX_1
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# define index_arch_Prefer_No_VZEROUPPER FEATURE_INDEX_1
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# define index_arch_Fast_Unaligned_Copy FEATURE_INDEX_1
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#endif /* !__ASSEMBLER__ */
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@ -42,7 +42,7 @@ ENTRY(__new_memcpy)
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HAS_ARCH_FEATURE (AVX_Fast_Unaligned_Load)
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jnz 2f
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lea __memcpy_sse2_unaligned(%rip), %RAX_LP
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HAS_ARCH_FEATURE (Fast_Unaligned_Load)
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HAS_ARCH_FEATURE (Fast_Unaligned_Copy)
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jnz 2f
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lea __memcpy_sse2(%rip), %RAX_LP
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HAS_CPU_FEATURE (SSSE3)
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