[X86][NFC] Remove unused encoding string: VK[1/2/4/8/16]PAIR

[LiuChen3]

Summary

This is also a bug. The VK[1/2/4/8/16]PAIR here should be VK[1/2/4/8/16]Pair which has its
custom PrintMethod and ParserMatchClass. However we don't have any instructions using vvvv
and ModR/M.REG field so this issue is not exposed.

[craig.topper]

LGTM

[xiangzhangllvm]

Change VK1PAIR to VK1Pair may be reasonable. (keep same with other xxRegisterEncodingFromString for future ISA.)

lib/Target/X86/X86RegisterInfo.td:629:def VK1PAIR : RegisterClass<"X86", [untyped], 16, (add KPAIRS)> {let Size = 32;}
lib/Target/X86/X86InstrInfo.td:817:def VK1Pair : RegisterOperand<VK1PAIR, "printVKPair"> {

[craig.topper]

In D109564#2993400, @xiangzhangllvm wrote:

Change VK1PAIR to VK1Pair may be reasonable. (keep same with other xxRegisterEncodingFromString for future ISA.)

lib/Target/X86/X86RegisterInfo.td:629:def VK1PAIR : RegisterClass<"X86", [untyped], 16, (add KPAIRS)> {let Size = 32;}
lib/Target/X86/X86InstrInfo.td:817:def VK1Pair : RegisterOperand<VK1PAIR, "printVKPair"> {

I think it is fine to remove it. Tablegen will issue an error if a new instruction is added. At that point its easy to add back.

[xiangzhangllvm]

Yes, make sense

[LiuChen3]

Thanks for reviewing this patch!

llvm/utils/TableGen/X86RecognizableInstr.cpp

RecognizableInstr::rmRegisterEncodingFromString(const std::string &s,
   ENCODING("VR512",           ENCODING_RM)
   ENCODING("VK1",             ENCODING_RM)
   ENCODING("VK2",             ENCODING_RM)
   ENCODING("VK4",             ENCODING_RM)
   ENCODING("VK8",             ENCODING_RM)
   ENCODING("VK16",            ENCODING_RM)
   ENCODING("VK32",            ENCODING_RM)
   ENCODING("VK64",            ENCODING_RM)
-  ENCODING("VK1PAIR",         ENCODING_RM)
-  ENCODING("VK2PAIR",         ENCODING_RM)
-  ENCODING("VK4PAIR",         ENCODING_RM)
-  ENCODING("VK8PAIR",         ENCODING_RM)
-  ENCODING("VK16PAIR",        ENCODING_RM)
   ENCODING("BNDR",            ENCODING_RM)
   ENCODING("TILE",            ENCODING_RM)
   errs() << "Unhandled R/M register encoding " << s << "\n";
   llvm_unreachable("Unhandled R/M register encoding");
 }
 
 OperandEncoding
 RecognizableInstr::roRegisterEncodingFromString(const std::string &s,
RecognizableInstr::vvvvRegisterEncodingFromString(const std::string &s,
   ENCODING("VR512",           ENCODING_VVVV)
   ENCODING("VK1",             ENCODING_VVVV)
   ENCODING("VK2",             ENCODING_VVVV)
   ENCODING("VK4",             ENCODING_VVVV)
   ENCODING("VK8",             ENCODING_VVVV)
   ENCODING("VK16",            ENCODING_VVVV)
   ENCODING("VK32",            ENCODING_VVVV)
   ENCODING("VK64",            ENCODING_VVVV)
-  ENCODING("VK1PAIR",         ENCODING_VVVV)
-  ENCODING("VK2PAIR",         ENCODING_VVVV)
-  ENCODING("VK4PAIR",         ENCODING_VVVV)
-  ENCODING("VK8PAIR",         ENCODING_VVVV)
-  ENCODING("VK16PAIR",        ENCODING_VVVV)
   ENCODING("TILE",            ENCODING_VVVV)
   errs() << "Unhandled VEX.vvvv register encoding " << s << "\n";
   llvm_unreachable("Unhandled VEX.vvvv register encoding");
 }
 
 OperandEncoding
 RecognizableInstr::writemaskRegisterEncodingFromString(const std::string &s,
                                                        uint8_t OpSize) {