[RISCV] Merge some of the C_*_HINT instruction into the regular C_* instructions. (#150710)

Register classes and immediate predicates in a CompressPat no longer
need to match the compressed instruction. We can now merge most of the
C_*_HINT instructions into their non-HINT equivalents.

I've left c.slli64/srli64/srai6 out to avoid conflict with #150689.
C_NOP_HINT is left out because the spec refers to C_NOP as a separate
instruction from C_ADDI. C_NOP does not allow an immediate operand but
C_NOP_HINT does.

1 files changed, 6 insertions, 105 deletions

diff --git a/llvm/lib/Target/RISCV/Disassembler/RISCVDisassembler.cpp b/llvm/lib/Target/RISCV/Disassembler/RISCVDisassembler.cpp
index fa7bcfa..5e54b82 100644
--- a/llvm/lib/Target/RISCV/Disassembler/RISCVDisassembler.cpp
+++ b/llvm/lib/Target/RISCV/Disassembler/RISCVDisassembler.cpp
@@ -193,21 +193,19 @@ static DecodeStatus DecodeFPR128RegisterClass(MCInst &Inst, uint32_t RegNo,
 static DecodeStatus DecodeGPRNoX0RegisterClass(MCInst &Inst, uint32_t RegNo,
                                                uint64_t Address,
                                                const MCDisassembler *Decoder) {
-  if (RegNo == 0) {
+  if (RegNo == 0)
     return MCDisassembler::Fail;
-  }
 
   return DecodeGPRRegisterClass(Inst, RegNo, Address, Decoder);
 }
 
-static DecodeStatus
-DecodeGPRNoX0X2RegisterClass(MCInst &Inst, uint64_t RegNo, uint32_t Address,
-                             const MCDisassembler *Decoder) {
-  if (RegNo == 2) {
+static DecodeStatus DecodeGPRNoX2RegisterClass(MCInst &Inst, uint64_t RegNo,
+                                               uint32_t Address,
+                                               const MCDisassembler *Decoder) {
+  if (RegNo == 2)
     return MCDisassembler::Fail;
-  }
 
-  return DecodeGPRNoX0RegisterClass(Inst, RegNo, Address, Decoder);
+  return DecodeGPRRegisterClass(Inst, RegNo, Address, Decoder);
 }
 
 static DecodeStatus DecodeGPRNoX31RegisterClass(MCInst &Inst, uint32_t RegNo,
@@ -536,31 +534,6 @@ static DecodeStatus decodeRTZArg(MCInst &Inst, uint32_t Imm, int64_t Address,
   return MCDisassembler::Success;
 }
 
-static DecodeStatus decodeRVCInstrRdRs1ImmZero(MCInst &Inst, uint32_t Insn,
-                                               uint64_t Address,
-                                               const MCDisassembler *Decoder);
-
-static DecodeStatus decodeRVCInstrRdSImm6(MCInst &Inst, uint32_t Insn,
-                                          uint64_t Address,
-                                          const MCDisassembler *Decoder);
-
-static DecodeStatus decodeRVCInstrRdCLUIImm(MCInst &Inst, uint32_t Insn,
-                                            uint64_t Address,
-                                            const MCDisassembler *Decoder);
-
-static DecodeStatus
-decodeRVCInstrRdRs1UImmLog2XLenNonZero(MCInst &Inst, uint32_t Insn,
-                                       uint64_t Address,
-                                       const MCDisassembler *Decoder);
-
-static DecodeStatus decodeRVCInstrRdRs2(MCInst &Inst, uint32_t Insn,
-                                        uint64_t Address,
-                                        const MCDisassembler *Decoder);
-
-static DecodeStatus decodeRVCInstrRdRs1Rs2(MCInst &Inst, uint32_t Insn,
-                                           uint64_t Address,
-                                           const MCDisassembler *Decoder);
-
 static DecodeStatus decodeXTHeadMemPair(MCInst &Inst, uint32_t Insn,
                                         uint64_t Address,
                                         const MCDisassembler *Decoder);
@@ -579,18 +552,6 @@ static DecodeStatus decodeCSSPushPopchk(MCInst &Inst, uint32_t Insn,
 
 #include "RISCVGenDisassemblerTables.inc"
 
-static DecodeStatus decodeRVCInstrRdRs1ImmZero(MCInst &Inst, uint32_t Insn,
-                                               uint64_t Address,
-                                               const MCDisassembler *Decoder) {
-  DecodeStatus S = MCDisassembler::Success;
-  uint32_t Rd = fieldFromInstruction(Insn, 7, 5);
-  if (!Check(S, DecodeGPRNoX0RegisterClass(Inst, Rd, Address, Decoder)))
-    return MCDisassembler::Fail;
-  Inst.addOperand(Inst.getOperand(0));
-  Inst.addOperand(MCOperand::createImm(0));
-  return S;
-}
-
 static DecodeStatus decodeCSSPushPopchk(MCInst &Inst, uint32_t Insn,
                                         uint64_t Address,
                                         const MCDisassembler *Decoder) {
@@ -601,66 +562,6 @@ static DecodeStatus decodeCSSPushPopchk(MCInst &Inst, uint32_t Insn,
   return MCDisassembler::Success;
 }
 
-static DecodeStatus decodeRVCInstrRdSImm6(MCInst &Inst, uint32_t Insn,
-                                          uint64_t Address,
-                                          const MCDisassembler *Decoder) {
-  Inst.addOperand(MCOperand::createReg(RISCV::X0));
-  uint32_t Imm =
-      fieldFromInstruction(Insn, 12, 1) << 5 | fieldFromInstruction(Insn, 2, 5);
-  [[maybe_unused]] DecodeStatus Result =
-      decodeSImmOperand<6>(Inst, Imm, Address, Decoder);
-  assert(Result == MCDisassembler::Success && "Invalid immediate");
-  return MCDisassembler::Success;
-}
-
-static DecodeStatus decodeRVCInstrRdCLUIImm(MCInst &Inst, uint32_t Insn,
-                                            uint64_t Address,
-                                            const MCDisassembler *Decoder) {
-  Inst.addOperand(MCOperand::createReg(RISCV::X0));
-  uint32_t Imm =
-      fieldFromInstruction(Insn, 12, 1) << 5 | fieldFromInstruction(Insn, 2, 5);
-  return decodeCLUIImmOperand(Inst, Imm, Address, Decoder);
-}
-
-static DecodeStatus
-decodeRVCInstrRdRs1UImmLog2XLenNonZero(MCInst &Inst, uint32_t Insn,
-                                       uint64_t Address,
-                                       const MCDisassembler *Decoder) {
-  Inst.addOperand(MCOperand::createReg(RISCV::X0));
-  Inst.addOperand(Inst.getOperand(0));
-
-  uint32_t UImm6 =
-      fieldFromInstruction(Insn, 12, 1) << 5 | fieldFromInstruction(Insn, 2, 5);
-  return decodeUImmLog2XLenNonZeroOperand(Inst, UImm6, Address, Decoder);
-}
-
-static DecodeStatus decodeRVCInstrRdRs2(MCInst &Inst, uint32_t Insn,
-                                        uint64_t Address,
-                                        const MCDisassembler *Decoder) {
-  DecodeStatus S = MCDisassembler::Success;
-  uint32_t Rd = fieldFromInstruction(Insn, 7, 5);
-  uint32_t Rs2 = fieldFromInstruction(Insn, 2, 5);
-  if (!Check(S, DecodeGPRRegisterClass(Inst, Rd, Address, Decoder)))
-    return MCDisassembler::Fail;
-  if (!Check(S, DecodeGPRRegisterClass(Inst, Rs2, Address, Decoder)))
-    return MCDisassembler::Fail;
-  return S;
-}
-
-static DecodeStatus decodeRVCInstrRdRs1Rs2(MCInst &Inst, uint32_t Insn,
-                                           uint64_t Address,
-                                           const MCDisassembler *Decoder) {
-  DecodeStatus S = MCDisassembler::Success;
-  uint32_t Rd = fieldFromInstruction(Insn, 7, 5);
-  uint32_t Rs2 = fieldFromInstruction(Insn, 2, 5);
-  if (!Check(S, DecodeGPRRegisterClass(Inst, Rd, Address, Decoder)))
-    return MCDisassembler::Fail;
-  Inst.addOperand(Inst.getOperand(0));
-  if (!Check(S, DecodeGPRRegisterClass(Inst, Rs2, Address, Decoder)))
-    return MCDisassembler::Fail;
-  return S;
-}
-
 static DecodeStatus decodeXTHeadMemPair(MCInst &Inst, uint32_t Insn,
                                         uint64_t Address,
                                         const MCDisassembler *Decoder) {