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-rw-r--r--sysdeps/x86/cacheinfo.h9
1 files changed, 9 insertions, 0 deletions
diff --git a/sysdeps/x86/cacheinfo.h b/sysdeps/x86/cacheinfo.h
index eba8dbc4a6..41d2c81369 100644
--- a/sysdeps/x86/cacheinfo.h
+++ b/sysdeps/x86/cacheinfo.h
@@ -49,6 +49,11 @@ long int __x86_rep_stosb_threshold attribute_hidden = 2048;
 /* Threshold to stop using Enhanced REP MOVSB.  */
 long int __x86_rep_movsb_stop_threshold attribute_hidden;
 
+/* A bit-wise OR of string/memory requirements for optimal performance
+   e.g. X86_STRING_CONTROL_AVOID_SHORT_DISTANCE_REP_MOVSB.  These bits
+   are used at runtime to tune implementation behavior.  */
+int __x86_string_control attribute_hidden;
+
 static void
 init_cacheinfo (void)
 {
@@ -71,5 +76,9 @@ init_cacheinfo (void)
   __x86_rep_movsb_threshold = cpu_features->rep_movsb_threshold;
   __x86_rep_stosb_threshold = cpu_features->rep_stosb_threshold;
   __x86_rep_movsb_stop_threshold =  cpu_features->rep_movsb_stop_threshold;
+
+  if (CPU_FEATURES_ARCH_P (cpu_features, Avoid_Short_Distance_REP_MOVSB))
+    __x86_string_control
+      |= X86_STRING_CONTROL_AVOID_SHORT_DISTANCE_REP_MOVSB;
 }
 #endif