Added LargestRead type for x86. I might have picked the wrong type.

--HG--
extra : convert_revision : 5570a595b9adbe9c35f9b4f8dd3b50533b5beb97

src/arch/x86/types.hh

@@ -68,6 +68,8 @@ namespace X86ISA
     typedef uint64_t ExtMachInst;
 
     typedef uint64_t IntReg;
+    //XXX Should this be a 128 bit structure for XMM memory ops?
+    typedef uint64_t LargestRead;
     typedef uint64_t MiscReg;
 
     //These floating point types are correct for mmx, but not