With -march=native generate fma3 instruction by default for AMD processors which…

With -march=native generate fma3 instruction by default for AMD processors which support both fma and fma4

From-SVN: r187077

gcc/ChangeLog

+2012-05-03  Ganesh Gopalasubramanian  <Ganesh.Gopalasubramanian@amd.com>
+
+	* config/i386/driver-i386.c (host_detect_local_cpu): Reset
+	has_fma4 for AMD processors with both fma3 and fma4 support.
+
 2012-05-03  Kirill Yukhin  <kirill.yukhin@intel.com>
 
 	PR target/53201

gcc/config/i386/driver-i386.c

@@ -474,6 +474,8 @@ const char *host_detect_local_cpu (int argc, const char **argv)
       has_abm = ecx & bit_ABM;
       has_lwp = ecx & bit_LWP;
       has_fma4 = ecx & bit_FMA4;
+      if (vendor == SIG_AMD && has_fma4 && has_fma)
+	has_fma4 = 0;
       has_xop = ecx & bit_XOP;
       has_tbm = ecx & bit_TBM;
       has_lzcnt = ecx & bit_LZCNT;