Compute feature bits at time of MCSubtargetInfo initialization.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@134606 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Target/X86/X86Subtarget.h b/lib/Target/X86/X86Subtarget.h
index d49b871..f6250b6 100644
--- a/lib/Target/X86/X86Subtarget.h
+++ b/lib/Target/X86/X86Subtarget.h
@@ -24,6 +24,7 @@
 
 namespace llvm {
 class GlobalValue;
+class StringRef;
 class TargetMachine;
 
 /// PICStyles - The X86 backend supports a number of different styles of PIC.
@@ -135,7 +136,7 @@
 
   /// ParseSubtargetFeatures - Parses features string setting specified
   /// subtarget options.  Definition of function is auto generated by tblgen.
-  void ParseSubtargetFeatures(const std::string &FS, const std::string &CPU);
+  void ParseSubtargetFeatures(StringRef CPU, StringRef FS);
 
   /// AutoDetectSubtargetFeatures - Auto-detect CPU features using CPUID
   /// instruction.