Remove Fast_Copy_Backward from Intel Core processors

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.

	* sysdeps/x86/cpu-features.c (init_cpu_features): Don't set
	bit_arch_Fast_Copy_Backward for Intel Core proessors.

diff --git a/ChangeLog b/ChangeLog
index c181042349e2a34a4b173402c8eb603c4d28c50f..d22231b95d5ddc3770987e1960ea86f47077abaa 100644 (file)
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+2016-04-01   H.J. Lu  <hongjiu.lu@intel.com>
+
+       * sysdeps/x86/cpu-features.c (init_cpu_features): Don't set
+       bit_arch_Fast_Copy_Backward for Intel Core proessors.
+
 2016-04-01  Adhemerval Zanella  <adhemerval.zanella@linaro.org>
 
        * string/strcspn.c (strcspn): Use PTR_ALIGN_DOWN.

diff --git a/sysdeps/x86/cpu-features.c b/sysdeps/x86/cpu-features.c
index de75c79cf987ce109580bfe22c8d10ed9d9f4de3..963b84591687e08bea6917077c6bd99954d344a0 100644 (file)
--- 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);