[llvm] [RISCV] Merge some of the C_*_HINT instruction into the regular C_* instructions. (PR #150710)
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Fri Jul 25 15:11:51 PDT 2025
llvmbot wrote:
<!--LLVM PR SUMMARY COMMENT-->
@llvm/pr-subscribers-backend-risc-v
Author: Craig Topper (topperc)
<details>
<summary>Changes</summary>
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.
---
Full diff: https://github.com/llvm/llvm-project/pull/150710.diff
5 Files Affected:
- (modified) llvm/lib/Target/RISCV/Disassembler/RISCVDisassembler.cpp (+6-104)
- (modified) llvm/lib/Target/RISCV/RISCVAsmPrinter.cpp (+1-1)
- (modified) llvm/lib/Target/RISCV/RISCVInstrInfoC.td (+11-59)
- (modified) llvm/lib/Target/RISCV/RISCVRegisterInfo.td (+5)
- (modified) llvm/test/MC/RISCV/rv32c-invalid.s (+2-2)
``````````diff
diff --git a/llvm/lib/Target/RISCV/Disassembler/RISCVDisassembler.cpp b/llvm/lib/Target/RISCV/Disassembler/RISCVDisassembler.cpp
index fa7bcfa0e8132..07aa6a32c84c7 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,
@@ -536,30 +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,
@@ -579,18 +553,6 @@ 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 +563,6 @@ 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) {
diff --git a/llvm/lib/Target/RISCV/RISCVAsmPrinter.cpp b/llvm/lib/Target/RISCV/RISCVAsmPrinter.cpp
index d4f5d8fcad6bc..2f32e2ac3eba3 100644
--- a/llvm/lib/Target/RISCV/RISCVAsmPrinter.cpp
+++ b/llvm/lib/Target/RISCV/RISCVAsmPrinter.cpp
@@ -293,7 +293,7 @@ void RISCVAsmPrinter::emitNTLHint(const MachineInstr *MI) {
MCInst Hint;
if (STI->hasStdExtZca())
- Hint.setOpcode(RISCV::C_ADD_HINT);
+ Hint.setOpcode(RISCV::C_ADD);
else
Hint.setOpcode(RISCV::ADD);
diff --git a/llvm/lib/Target/RISCV/RISCVInstrInfoC.td b/llvm/lib/Target/RISCV/RISCVInstrInfoC.td
index 8252a9b170eb3..1fa812edd0622 100644
--- a/llvm/lib/Target/RISCV/RISCVInstrInfoC.td
+++ b/llvm/lib/Target/RISCV/RISCVInstrInfoC.td
@@ -402,7 +402,7 @@ def C_NOP : RVInst16CI<0b000, 0b01, (outs), (ins), "c.nop", "">,
let hasSideEffects = 0, mayLoad = 0, mayStore = 0 in
def C_ADDI : RVInst16CI<0b000, 0b01, (outs GPRNoX0:$rd_wb),
- (ins GPRNoX0:$rd, simm6nonzero:$imm),
+ (ins GPRNoX0:$rd, simm6:$imm),
"c.addi", "$rd, $imm">,
Sched<[WriteIALU, ReadIALU]> {
let Constraints = "$rd = $rd_wb";
@@ -430,7 +430,7 @@ def C_ADDIW : RVInst16CI<0b001, 0b01, (outs GPRNoX0:$rd_wb),
}
let hasSideEffects = 0, mayLoad = 0, mayStore = 0 in
-def C_LI : RVInst16CI<0b010, 0b01, (outs GPRNoX0:$rd), (ins simm6:$imm),
+def C_LI : RVInst16CI<0b010, 0b01, (outs GPR:$rd), (ins simm6:$imm),
"c.li", "$rd, $imm">,
Sched<[WriteIALU]>;
@@ -449,7 +449,7 @@ def C_ADDI16SP : RVInst16CI<0b011, 0b01, (outs SP:$rd_wb),
}
let hasSideEffects = 0, mayLoad = 0, mayStore = 0 in
-def C_LUI : RVInst16CI<0b011, 0b01, (outs GPRNoX0X2:$rd),
+def C_LUI : RVInst16CI<0b011, 0b01, (outs GPRNoX2:$rd),
(ins c_lui_imm:$imm),
"c.lui", "$rd, $imm">,
Sched<[WriteIALU]>;
@@ -497,7 +497,7 @@ def C_BEQZ : Bcz<0b110, "c.beqz">, Sched<[WriteJmp, ReadJmp]>;
def C_BNEZ : Bcz<0b111, "c.bnez">, Sched<[WriteJmp, ReadJmp]>;
let hasSideEffects = 0, mayLoad = 0, mayStore = 0 in
-def C_SLLI : RVInst16CI<0b000, 0b10, (outs GPRNoX0:$rd_wb),
+def C_SLLI : RVInst16CI<0b000, 0b10, (outs GPR:$rd_wb),
(ins GPRNoX0:$rd, uimmlog2xlennonzero:$imm),
"c.slli", "$rd, $imm">,
Sched<[WriteShiftImm, ReadShiftImm]> {
@@ -544,7 +544,7 @@ def C_JR : RVInst16CR<0b1000, 0b10, (outs), (ins GPRNoX0:$rs1),
let hasSideEffects = 0, mayLoad = 0, mayStore = 0, isMoveReg = 1,
isAsCheapAsAMove = 1 in
-def C_MV : RVInst16CR<0b1000, 0b10, (outs GPRNoX0:$rs1), (ins GPRNoX0:$rs2),
+def C_MV : RVInst16CR<0b1000, 0b10, (outs GPR:$rs1), (ins GPRNoX0:$rs2),
"c.mv", "$rs1, $rs2">,
Sched<[WriteIALU, ReadIALU]>;
@@ -557,8 +557,8 @@ def C_JALR : RVInst16CR<0b1001, 0b10, (outs), (ins GPRNoX0:$rs1),
"c.jalr", "$rs1">, Sched<[WriteJalr, ReadJalr]>;
let hasSideEffects = 0, mayLoad = 0, mayStore = 0 in
-def C_ADD : RVInst16CR<0b1001, 0b10, (outs GPRNoX0:$rd),
- (ins GPRNoX0:$rs1, GPRNoX0:$rs2),
+def C_ADD : RVInst16CR<0b1001, 0b10, (outs GPR:$rd),
+ (ins GPR:$rs1, GPRNoX0:$rs2),
"c.add", "$rs1, $rs2">,
Sched<[WriteIALU, ReadIALU, ReadIALU]> {
let Constraints = "$rs1 = $rd";
@@ -616,54 +616,6 @@ def C_NOP_HINT : RVInst16CI<0b000, 0b01, (outs), (ins simm6nonzero:$imm),
let rd = 0;
}
-def C_ADDI_HINT_IMM_ZERO : RVInst16CI<0b000, 0b01, (outs GPRNoX0:$rd_wb),
- (ins GPRNoX0:$rd, immzero:$imm),
- "c.addi", "$rd, $imm">,
- Sched<[WriteIALU, ReadIALU]> {
- let Constraints = "$rd = $rd_wb";
- let imm = 0;
- let DecoderMethod = "decodeRVCInstrRdRs1ImmZero";
-}
-
-def C_LI_HINT : RVInst16CI<0b010, 0b01, (outs GPRX0:$rd), (ins simm6:$imm),
- "c.li", "$rd, $imm">,
- Sched<[WriteIALU]> {
- let Inst{11-7} = 0;
- let DecoderMethod = "decodeRVCInstrRdSImm6";
-}
-
-def C_LUI_HINT : RVInst16CI<0b011, 0b01, (outs GPRX0:$rd),
- (ins c_lui_imm:$imm),
- "c.lui", "$rd, $imm">,
- Sched<[WriteIALU]> {
- let Inst{11-7} = 0;
- let DecoderMethod = "decodeRVCInstrRdCLUIImm";
-}
-
-def C_MV_HINT : RVInst16CR<0b1000, 0b10, (outs GPRX0:$rs1), (ins GPRNoX0:$rs2),
- "c.mv", "$rs1, $rs2">, Sched<[WriteIALU, ReadIALU]> {
- let Inst{11-7} = 0;
- let DecoderMethod = "decodeRVCInstrRdRs2";
-}
-
-def C_ADD_HINT : RVInst16CR<0b1001, 0b10, (outs GPRX0:$rd),
- (ins GPRX0:$rs1, GPRNoX0:$rs2),
- "c.add", "$rs1, $rs2">,
- Sched<[WriteIALU, ReadIALU, ReadIALU]> {
- let Constraints = "$rs1 = $rd";
- let Inst{11-7} = 0;
- let DecoderMethod = "decodeRVCInstrRdRs1Rs2";
-}
-
-def C_SLLI_HINT : RVInst16CI<0b000, 0b10, (outs GPRX0:$rd_wb),
- (ins GPRX0:$rd, uimmlog2xlennonzero:$imm),
- "c.slli", "$rd, $imm">,
- Sched<[WriteShiftImm, ReadShiftImm]> {
- let Constraints = "$rd = $rd_wb";
- let Inst{11-7} = 0;
- let DecoderMethod = "decodeRVCInstrRdRs1UImmLog2XLenNonZero";
-}
-
def C_SLLI64_HINT : RVInst16CI<0b000, 0b10, (outs GPR:$rd_wb), (ins GPR:$rd),
"c.slli64", "$rd">,
Sched<[WriteShiftImm, ReadShiftImm]> {
@@ -704,10 +656,10 @@ def : InstAlias<"c.addi x0, $imm", (C_NOP_HINT simm6nonzero:$imm), 0>;
}
let Predicates = [HasStdExtC, HasStdExtZihintntl] in {
-def : InstAlias<"c.ntl.p1", (C_ADD_HINT X0, X2)>;
-def : InstAlias<"c.ntl.pall", (C_ADD_HINT X0, X3)>;
-def : InstAlias<"c.ntl.s1", (C_ADD_HINT X0, X4)>;
-def : InstAlias<"c.ntl.all", (C_ADD_HINT X0, X5)>;
+def : InstAlias<"c.ntl.p1", (C_ADD X0, X2)>;
+def : InstAlias<"c.ntl.pall", (C_ADD X0, X3)>;
+def : InstAlias<"c.ntl.s1", (C_ADD X0, X4)>;
+def : InstAlias<"c.ntl.all", (C_ADD X0, X5)>;
} // Predicates = [HasStdExtC, HasStdExtZihintntl]
let EmitPriority = 0 in {
diff --git a/llvm/lib/Target/RISCV/RISCVRegisterInfo.td b/llvm/lib/Target/RISCV/RISCVRegisterInfo.td
index e87f4523a84f9..ccb39e8f42916 100644
--- a/llvm/lib/Target/RISCV/RISCVRegisterInfo.td
+++ b/llvm/lib/Target/RISCV/RISCVRegisterInfo.td
@@ -268,6 +268,11 @@ def GPRNoX0 : GPRRegisterClass<(sub GPR, X0)> {
let DiagnosticString = "register must be a GPR excluding zero (x0)";
}
+def GPRNoX2 : GPRRegisterClass<(sub GPR, X2)> {
+ let DiagnosticType = "InvalidRegClassGPRNoX2";
+ let DiagnosticString = "register must be a GPR excluding sp (x2)";
+}
+
def GPRNoX0X2 : GPRRegisterClass<(sub GPR, X0, X2)> {
let DiagnosticType = "InvalidRegClassGPRNoX0X2";
let DiagnosticString = "register must be a GPR excluding zero (x0) and sp (x2)";
diff --git a/llvm/test/MC/RISCV/rv32c-invalid.s b/llvm/test/MC/RISCV/rv32c-invalid.s
index 413573af1c5e6..c22820fcf4f95 100644
--- a/llvm/test/MC/RISCV/rv32c-invalid.s
+++ b/llvm/test/MC/RISCV/rv32c-invalid.s
@@ -26,8 +26,8 @@ c.jalr zero # CHECK: :[[@LINE]]:9: error: register must be a GPR excluding zero
c.mv ra, x0 # CHECK: :[[@LINE]]:11: error: register must be a GPR excluding zero (x0)
c.add ra, ra, x0 # CHECK: :[[@LINE]]:16: error: invalid operand for instruction
-## GPRNoX0X2
-c.lui x2, 4 # CHECK: :[[@LINE]]:7: error: register must be a GPR excluding zero (x0) and sp (x2){{$}}
+## GPRNoX2
+c.lui x2, 4 # CHECK: :[[@LINE]]:7: error: register must be a GPR excluding sp (x2){{$}}
## SP
c.addi4spn a0, a0, 12 # CHECK: :[[@LINE]]:17: error: register must be sp (x2)
``````````
</details>
https://github.com/llvm/llvm-project/pull/150710
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