[llvm] r320898 - [X86] Add back the assert from r320830 that was reverted in r320850

[Craig Topper via llvm-commits]

Author: ctopper
Date: Fri Dec 15 16:33:16 2017
New Revision: 320898

URL: http://llvm.org/viewvc/llvm-project?rev=320898&view=rev
Log:
[X86] Add back the assert from r320830 that was reverted in r320850

Hopefully r320864 has fixed the offending case that failed the assert.

Modified:
    llvm/trunk/lib/Target/X86/MCTargetDesc/X86MCCodeEmitter.cpp

Modified: llvm/trunk/lib/Target/X86/MCTargetDesc/X86MCCodeEmitter.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/X86/MCTargetDesc/X86MCCodeEmitter.cpp?rev=320898&r1=320897&r2=320898&view=diff
==============================================================================
--- llvm/trunk/lib/Target/X86/MCTargetDesc/X86MCCodeEmitter.cpp (original)
+++ llvm/trunk/lib/Target/X86/MCTargetDesc/X86MCCodeEmitter.cpp Fri Dec 15 16:33:16 2017
@@ -1130,6 +1130,8 @@ bool X86MCCodeEmitter::emitOpcodePrefix(
       EmitByte(0x40 | REX, CurByte, OS);
       Ret = true;
     }
+  } else {
+    assert(!(TSFlags & X86II::REX_W) && "REX.W requires 64bit mode.");
   }
 
   // 0x0F escape code must be emitted just before the opcode.