[X86][MC] Update condition about ExplicitVEXPrefix (#73312)

After #72835, ExplicitVEXPrefix has changed and it is not a bit now, but
in scope ExplicitOpPrefix, so the bitwise op of ExplicitVEXPrefix may
need to update.

Author: XinWang10

llvm/lib/Target/X86/AsmParser/X86AsmParser.cpp

@@ -3973,7 +3973,8 @@ unsigned X86AsmParser::checkTargetMatchPredicate(MCInst &Inst) {
       (MCID.TSFlags & X86II::EncodingMask) != X86II::VEX)
     return Match_Unsupported;
 
-  if (MCID.TSFlags & X86II::ExplicitVEXPrefix &&
+  if ((MCID.TSFlags & X86II::ExplicitOpPrefixMask) ==
+          X86II::ExplicitVEXPrefix &&
       (ForcedVEXEncoding != VEXEncoding_VEX &&
        ForcedVEXEncoding != VEXEncoding_VEX2 &&
        ForcedVEXEncoding != VEXEncoding_VEX3))

llvm/lib/Target/X86/MCTargetDesc/X86InstPrinterCommon.cpp

@@ -370,7 +370,8 @@ void X86InstPrinterCommon::printInstFlags(const MCInst *MI, raw_ostream &O,
     O << "\trep\t";
 
   // These all require a pseudo prefix
-  if ((Flags & X86::IP_USE_VEX) || (TSFlags & X86II::ExplicitVEXPrefix))
+  if ((Flags & X86::IP_USE_VEX) ||
+      (TSFlags & X86II::ExplicitOpPrefixMask) == X86II::ExplicitVEXPrefix)
     O << "\t{vex}";
   else if (Flags & X86::IP_USE_VEX2)
     O << "\t{vex2}";