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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@95445 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Target/X86/X86MCCodeEmitter.cpp

@@ -293,6 +293,8 @@ static unsigned DetermineREXPrefix(const MCInst &MI, unsigned TSFlags,
     if (!MO.isReg()) continue;
     unsigned Reg = MO.getReg();
     if (!X86InstrInfo::isX86_64NonExtLowByteReg(Reg)) continue;
+    // FIXME: The caller of DetermineREXPrefix slaps this prefix onto anything
+    // that returns non-zero.
     REX |= 0x40;
     break;
   }