Implement the data16 prefix.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@120224 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Target/X86/X86InstrInfo.td b/lib/Target/X86/X86InstrInfo.td
index d7a5505..560cafe 100644
--- a/lib/Target/X86/X86InstrInfo.td
+++ b/lib/Target/X86/X86InstrInfo.td
@@ -1147,6 +1147,9 @@
 // Rex64 instruction prefix
 def REX64_PREFIX : I<0x48, RawFrm, (outs),  (ins), "rex64", []>;
 
+// Data16 instruction prefix
+def DATA16_PREFIX : I<0x66, RawFrm, (outs),  (ins), "data16", []>;
+
 // Repeat string operation instruction prefixes
 // These uses the DF flag in the EFLAGS register to inc or dec ECX
 let Defs = [ECX], Uses = [ECX,EFLAGS] in {