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[PATCH] Remove Fast_Copy_Backward from Intel Core processors
- From: "H.J. Lu" <hongjiu dot lu at intel dot com>
- To: GNU C Library <libc-alpha at sourceware dot org>
- Date: Fri, 1 Apr 2016 13:51:28 -0700
- Subject: [PATCH] Remove Fast_Copy_Backward from Intel Core processors
- Authentication-results: sourceware.org; auth=none
- Reply-to: "H.J. Lu" <hjl dot tools at gmail dot com>
Intel Core i3, i5 and i7 processors have fast unaligned copy and
copy backward is ignored. Remove Fast_Copy_Backward from Intel Core
processors to avoid confusion.
I will check it in shortly.
H.J.
---
* sysdeps/x86/cpu-features.c (init_cpu_features): Don't set
bit_arch_Fast_Copy_Backward.
---
sysdeps/x86/cpu-features.c | 6 +-----
1 file changed, 1 insertion(+), 5 deletions(-)
diff --git a/sysdeps/x86/cpu-features.c b/sysdeps/x86/cpu-features.c
index de75c79..963b845 100644
--- a/sysdeps/x86/cpu-features.c
+++ b/sysdeps/x86/cpu-features.c
@@ -176,11 +176,8 @@ init_cpu_features (struct cpu_features *cpu_features)
case 0x2c:
case 0x2e:
case 0x2f:
- /* Rep string instructions, copy backward, unaligned loads
+ /* Rep string instructions, unaligned load, unaligned copy,
and pminub are fast on Intel Core i3, i5 and i7. */
-#if index_arch_Fast_Rep_String != index_arch_Fast_Copy_Backward
-# error index_arch_Fast_Rep_String != index_arch_Fast_Copy_Backward
-#endif
#if index_arch_Fast_Rep_String != index_arch_Fast_Unaligned_Load
# error index_arch_Fast_Rep_String != index_arch_Fast_Unaligned_Load
#endif
@@ -192,7 +189,6 @@ init_cpu_features (struct cpu_features *cpu_features)
#endif
cpu_features->feature[index_arch_Fast_Rep_String]
|= (bit_arch_Fast_Rep_String
- | bit_arch_Fast_Copy_Backward
| bit_arch_Fast_Unaligned_Load
| bit_arch_Fast_Unaligned_Copy
| bit_arch_Prefer_PMINUB_for_stringop);
--
2.5.5