[llvm] [X86][MC] Support encoding of EGPR for APX (PR #71909)

[Shengchen Kan via llvm-commits]

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@@ -1329,6 +1412,10 @@ PrefixKind X86MCCodeEmitter::emitOpcodePrefix(int MemOperand, const MCInst &MI,
   // 0x0F escape code must be emitted just before the opcode.
   switch (TSFlags & X86II::OpMapMask) {
   case X86II::TB:        // Two-byte opcode map
+    // Encoded by M bit in REX2
+    if (Kind == REX2)
+      break;
+    LLVM_FALLTHROUGH;
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KanRobert wrote:

Done

https://github.com/llvm/llvm-project/pull/71909