Fix a cast that was casting away 'const' unnecessarily 

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@161726 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Target/X86/X86FastISel.cpp b/lib/Target/X86/X86FastISel.cpp
index 72ff4e8..9ba7a1f 100644
--- a/lib/Target/X86/X86FastISel.cpp
+++ b/lib/Target/X86/X86FastISel.cpp
@@ -2182,7 +2182,7 @@
   if (!X86SelectAddress(LI->getOperand(0), AM))
     return false;
 
-  X86InstrInfo &XII = (X86InstrInfo&)TII;
+  const X86InstrInfo &XII = (const X86InstrInfo&)TII;
 
   unsigned Size = TD.getTypeAllocSize(LI->getType());
   unsigned Alignment = LI->getAlignment();