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[RISCV] Handle 'c.addi x0, $imm' alias for c.nop using PseudoC_ADDI_NOP. #150719

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Merged
merged 2 commits into from
Jul 26, 2025
Merged

[RISCV] Handle 'c.addi x0, $imm' alias for c.nop using PseudoC_ADDI_NOP. #150719

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49b40e6
[RISCV] Handle 'c.addi x0, $imm' alias for c.nop using PseudoC_ADDI_NOP.
topperc Jul 25, 2025
778e761
fixup! clang-format
topperc Jul 26, 2025
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9 changes: 7 additions & 2 deletions llvm/lib/Target/RISCV/AsmParser/RISCVAsmParser.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -3849,9 +3849,14 @@ bool RISCVAsmParser::processInstruction(MCInst &Inst, SMLoc IDLoc,
switch (Inst.getOpcode()) {
default:
break;
case RISCV::PseudoC_ADDI_NOP:
emitToStreamer(Out, MCInstBuilder(RISCV::C_NOP));
case RISCV::PseudoC_ADDI_NOP: {
if (Inst.getOperand(2).getImm() == 0)
emitToStreamer(Out, MCInstBuilder(RISCV::C_NOP));
else
emitToStreamer(
Out, MCInstBuilder(RISCV::C_NOP_HINT).addOperand(Inst.getOperand(2)));
return false;
}
case RISCV::PseudoLLAImm:
case RISCV::PseudoLAImm:
case RISCV::PseudoLI: {
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13 changes: 5 additions & 8 deletions llvm/lib/Target/RISCV/RISCVInstrInfoC.td
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Expand Up @@ -408,11 +408,13 @@ def C_ADDI : RVInst16CI<0b000, 0b01, (outs GPRNoX0:$rd_wb),
let Constraints = "$rd = $rd_wb";
}

// Alternate syntax for c.nop. Converted to C_NOP by the assembler.
// Alternate syntax for c.nop. Converted to C_NOP/C_NOP_HINT by the assembler.
let hasSideEffects = 0, mayLoad = 0, mayStore = 0, isCodeGenOnly = 0,
isAsmParserOnly = 1 in
def PseudoC_ADDI_NOP : Pseudo<(outs GPRX0:$rd), (ins GPRX0:$rs1, immzero:$imm),
[], "c.addi", "$rd, $imm">;
def PseudoC_ADDI_NOP : Pseudo<(outs GPRX0:$rd), (ins GPRX0:$rs1, simm6:$imm),
[], "c.addi", "$rd, $imm"> {
let Constraints = "$rs1 = $rd";
}

let hasSideEffects = 0, mayLoad = 0, mayStore = 0, isCall = 1,
DecoderNamespace = "RV32Only", Defs = [X1],
Expand Down Expand Up @@ -698,11 +700,6 @@ def C_SRAI64_HINT : RVInst16CB<0b100, 0b01, (outs GPRC:$rd),
// Assembler Pseudo Instructions
//===----------------------------------------------------------------------===//

let Predicates = [HasStdExtZca] in {
// Just a different syntax for the c.nop hint: c.addi x0, simm6 vs c.nop simm6.
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)>;
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2 changes: 1 addition & 1 deletion llvm/test/MC/RISCV/rvc-hints-invalid.s
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Expand Up @@ -5,7 +5,7 @@

c.nop 0 # CHECK: :[[@LINE]]:7: error: immediate must be non-zero in the range [-32, 31]

c.addi x0, 33 # CHECK: :[[@LINE]]:12: error: immediate must be non-zero in the range [-32, 31]
c.addi x0, 33 # CHECK: :[[@LINE]]:12: error: immediate must be an integer in the range [-32, 31]

c.li x0, 42 # CHECK: :[[@LINE]]:10: error: immediate must be an integer in the range [-32, 31]

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