[llvm] d374546 - [X86][NFC] Assert MRMr0 format from emitREXPrefix

[Shengchen Kan via llvm-commits]

Author: Shengchen Kan
Date: 2023-02-18T14:15:31+08:00
New Revision: d3745461dacbf2e158a9e5fb47c0a518d64a936b

URL: https://github.com/llvm/llvm-project/commit/d3745461dacbf2e158a9e5fb47c0a518d64a936b
DIFF: https://github.com/llvm/llvm-project/commit/d3745461dacbf2e158a9e5fb47c0a518d64a936b.diff

LOG: [X86][NFC] Assert MRMr0 format from emitREXPrefix

The only instruction of this format is VEX encoding

Added: 
    

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

Removed: 
    


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diff  --git a/llvm/lib/Target/X86/MCTargetDesc/X86MCCodeEmitter.cpp b/llvm/lib/Target/X86/MCTargetDesc/X86MCCodeEmitter.cpp
index cbdcba12f86d..5e9aaeff8b48 100644
--- a/llvm/lib/Target/X86/MCTargetDesc/X86MCCodeEmitter.cpp
+++ b/llvm/lib/Target/X86/MCTargetDesc/X86MCCodeEmitter.cpp
@@ -1247,8 +1247,7 @@ PrefixKind X86MCCodeEmitter::emitREXPrefix(int MemOperand, const MCInst &MI,
     Prefix.setB(MI, CurOp++);
     break;
   case X86II::MRMr0:
-    Prefix.setR(MI, CurOp++);
-    break;
+    llvm_unreachable("MRMr0 format never need REX prefix!");
   case X86II::MRMDestMemFSIB:
     llvm_unreachable("FSIB format never need REX prefix!");
   }