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diff src/cpu/x86/vm/vm_version_x86.hpp @ 1914:ae065c367d93

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6987135: Performance regression on Intel platform with 32-bits edition between 6u13 and 6u14. Summary: Use hardware DIV instruction for long division by constant when it is faster than code with multiply. Reviewed-by: never
author kvn
date Tue, 02 Nov 2010 09:00:37 -0700
parents a83b0246bb77
children f95d63e2154a
line wrap: on
line diff
--- a/src/cpu/x86/vm/vm_version_x86.hpp	Sat Oct 30 13:08:23 2010 -0700
+++ b/src/cpu/x86/vm/vm_version_x86.hpp	Tue Nov 02 09:00:37 2010 -0700
@@ -446,6 +446,10 @@
   static bool supports_lzcnt()    { return (_cpuFeatures & CPU_LZCNT) != 0; }
   static bool supports_sse4a()    { return (_cpuFeatures & CPU_SSE4A) != 0; }
 
+  // Intel Core and newer cpus have fast IDIV instruction (excluding Atom).
+  static bool has_fast_idiv()     { return is_intel() && cpu_family() == 6 &&
+                                           supports_sse3() && _model != 0x1C; }
+
   static bool supports_compare_and_exchange() { return true; }
 
   static const char* cpu_features()           { return _features_str; }