Tweak x86 -mcpu defaults.
 - Default to yonah on Darwin (to get SSE3).

 - Default to Pentium4 (32-bit) and x86-64 (64-bit) on
   non-Darwin. Welcome to the 21st century.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@71069 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Driver/Tools.cpp b/lib/Driver/Tools.cpp
index a52498d..ad4db49 100644
--- a/lib/Driver/Tools.cpp
+++ b/lib/Driver/Tools.cpp
@@ -341,6 +341,11 @@
       if (getToolChain().getArchName() == "x86_64")
         CmdArgs.push_back("--mcpu=core2");
       else if (getToolChain().getArchName() == "i386")
+        CmdArgs.push_back("--mcpu=yonah");
+    } else {
+      if (getToolChain().getArchName() == "x86_64")
+        CmdArgs.push_back("--mcpu=x86-64");
+      else if (getToolChain().getArchName() == "i386")
         CmdArgs.push_back("--mcpu=pentium4");
     }
   }