[X86][NFC] Use mnemonic tables in validateInstruction 4/4

Group switch cases by opcode:
- VGATHERDPD
- VGATHERDPS
- VGATHERQPD
- VGATHERQPS
- VPGATHERDD
- VPGATHERDQ
- VPGATHERQD
- VPGATHERQQ

Distinguish masked vs non-masked forms by EVEX encoding.

Reviewed By: skan, craig.topper

Differential Revision: https://reviews.llvm.org/D127719

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

@@ -3836,6 +3836,7 @@ bool X86AsmParser::validateInstruction(MCInst &Inst, const OperandVector &Ops) {
   using namespace X86;
   const MCRegisterInfo *MRI = getContext().getRegisterInfo();
   unsigned Opcode = Inst.getOpcode();
+  uint64_t TSFlags = MII.get(Opcode).TSFlags;
   if (isVFCMADDCPH(Opcode) || isVFCMADDCSH(Opcode) || isVFMADDCPH(Opcode) ||
       isVFMADDCSH(Opcode)) {
     unsigned Dest = Inst.getOperand(0).getReg();
@@ -3866,74 +3867,34 @@ bool X86AsmParser::validateInstruction(MCInst &Inst, const OperandVector &Ops) {
                      RegName.take_front(3) + Twine(GroupEnd) +
                      "' source group");
     }
-  }
+  } else if (isVGATHERDPD(Opcode) || isVGATHERDPS(Opcode) ||
-
+             isVGATHERQPD(Opcode) || isVGATHERQPS(Opcode) ||
-  switch (Inst.getOpcode()) {
+             isVPGATHERDD(Opcode) || isVPGATHERDQ(Opcode) ||
-  case X86::VGATHERDPDYrm:
+             isVPGATHERQD(Opcode) || isVPGATHERQQ(Opcode)) {
-  case X86::VGATHERDPDrm:
+    bool HasEVEX = (TSFlags & X86II::EncodingMask) == X86II::EVEX;
-  case X86::VGATHERDPSYrm:
+    if (HasEVEX) {
-  case X86::VGATHERDPSrm:
-  case X86::VGATHERQPDYrm:
-  case X86::VGATHERQPDrm:
-  case X86::VGATHERQPSYrm:
-  case X86::VGATHERQPSrm:
-  case X86::VPGATHERDDYrm:
-  case X86::VPGATHERDDrm:
-  case X86::VPGATHERDQYrm:
-  case X86::VPGATHERDQrm:
-  case X86::VPGATHERQDYrm:
-  case X86::VPGATHERQDrm:
-  case X86::VPGATHERQQYrm:
-  case X86::VPGATHERQQrm: {
       unsigned Dest = MRI->getEncodingValue(Inst.getOperand(0).getReg());
-    unsigned Mask = MRI->getEncodingValue(Inst.getOperand(1).getReg());
+      unsigned Index = MRI->getEncodingValue(
-    unsigned Index =
+          Inst.getOperand(4 + X86::AddrIndexReg).getReg());
-      MRI->getEncodingValue(Inst.getOperand(3 + X86::AddrIndexReg).getReg());
-    if (Dest == Mask || Dest == Index || Mask == Index)
-      return Warning(Ops[0]->getStartLoc(), "mask, index, and destination "
-                                            "registers should be distinct");
-    break;
-  }
-  case X86::VGATHERDPDZ128rm:
-  case X86::VGATHERDPDZ256rm:
-  case X86::VGATHERDPDZrm:
-  case X86::VGATHERDPSZ128rm:
-  case X86::VGATHERDPSZ256rm:
-  case X86::VGATHERDPSZrm:
-  case X86::VGATHERQPDZ128rm:
-  case X86::VGATHERQPDZ256rm:
-  case X86::VGATHERQPDZrm:
-  case X86::VGATHERQPSZ128rm:
-  case X86::VGATHERQPSZ256rm:
-  case X86::VGATHERQPSZrm:
-  case X86::VPGATHERDDZ128rm:
-  case X86::VPGATHERDDZ256rm:
-  case X86::VPGATHERDDZrm:
-  case X86::VPGATHERDQZ128rm:
-  case X86::VPGATHERDQZ256rm:
-  case X86::VPGATHERDQZrm:
-  case X86::VPGATHERQDZ128rm:
-  case X86::VPGATHERQDZ256rm:
-  case X86::VPGATHERQDZrm:
-  case X86::VPGATHERQQZ128rm:
-  case X86::VPGATHERQQZ256rm:
-  case X86::VPGATHERQQZrm: {
-    unsigned Dest = MRI->getEncodingValue(Inst.getOperand(0).getReg());
-    unsigned Index =
-      MRI->getEncodingValue(Inst.getOperand(4 + X86::AddrIndexReg).getReg());
       if (Dest == Index)
         return Warning(Ops[0]->getStartLoc(), "index and destination registers "
                                               "should be distinct");
-    break;
+    } else {
+      unsigned Dest = MRI->getEncodingValue(Inst.getOperand(0).getReg());
+      unsigned Mask = MRI->getEncodingValue(Inst.getOperand(1).getReg());
+      unsigned Index = MRI->getEncodingValue(
+          Inst.getOperand(3 + X86::AddrIndexReg).getReg());
+      if (Dest == Mask || Dest == Index || Mask == Index)
+        return Warning(Ops[0]->getStartLoc(), "mask, index, and destination "
+                                              "registers should be distinct");
     }
   }
 
-  const MCInstrDesc &MCID = MII.get(Inst.getOpcode());
   // Check that we aren't mixing AH/BH/CH/DH with REX prefix. We only need to
   // check this with the legacy encoding, VEX/EVEX/XOP don't use REX.
-  if ((MCID.TSFlags & X86II::EncodingMask) == 0) {
+  if ((TSFlags & X86II::EncodingMask) == 0) {
     MCPhysReg HReg = X86::NoRegister;
-    bool UsesRex = MCID.TSFlags & X86II::REX_W;
+    bool UsesRex = TSFlags & X86II::REX_W;
     unsigned NumOps = Inst.getNumOperands();
     for (unsigned i = 0; i != NumOps; ++i) {
       const MCOperand &MO = Inst.getOperand(i);