Revert "x86: sysret does not need REX prefix. this fixes issue keysto…

…ne-engine#94" This reverts commit f18b6e1.
echotyh · Jul 26, 2016 · faf9451 · faf9451
1 parent cac140b
commit faf9451
Showing 1 changed file with 3 additions and 4 deletions.
diff --git a/llvm/lib/Target/X86/MCTargetDesc/X86MCCodeEmitter.cpp b/llvm/lib/Target/X86/MCTargetDesc/X86MCCodeEmitter.cpp
@@ -1038,16 +1038,15 @@ bool X86MCCodeEmitter::EmitVEXOpcodePrefix(uint64_t TSFlags, unsigned &CurByte,
 /// REX prefix which specifies 1) 64-bit instructions, 2) non-default operand
 /// size, and 3) use of X86-64 extended registers.
 static unsigned DetermineREXPrefix(const MCInst &MI, uint64_t TSFlags,
-                                   const MCInstrDesc &Desc)
-{
+                                   const MCInstrDesc &Desc) {
   unsigned REX = 0;
   bool UsesHighByteReg = false;
 
-  if (MI.getNumOperands() == 0) return REX;
-
   if (TSFlags & X86II::REX_W)
     REX |= 1 << 3; // set REX.W
 
+  if (MI.getNumOperands() == 0) return REX;
+
   unsigned NumOps = MI.getNumOperands();
   // FIXME: MCInst should explicitize the two-addrness.
   bool isTwoAddr = NumOps > 1 &&