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[RISCV] For RV32C, disassembly of c.slli should fail when immediate > 31 #133713

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Merged
merged 1 commit into from
Mar 31, 2025
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[RISCV] For RV32C, disassembly of c.slli should fail when immediate > 31 #133713

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12 changes: 8 additions & 4 deletions llvm/lib/Target/RISCV/Disassembler/RISCVDisassembler.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -558,8 +558,12 @@ static DecodeStatus decodeRVCInstrRdRs1UImm(MCInst &Inst, uint32_t Insn,
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);

uint32_t UImm6 = fieldFromInstruction(Insn, 12, 1) << 5;
// On RV32C, uimm[5]=1 is reserved for custom extensions.
if (UImm6 != 0 && Decoder->getSubtargetInfo().hasFeature(RISCV::Feature32Bit))
return MCDisassembler::Fail;
UImm6 |= fieldFromInstruction(Insn, 2, 5);
[[maybe_unused]] DecodeStatus Result =
decodeUImmOperand<6>(Inst, UImm6, Address, Decoder);
assert(Result == MCDisassembler::Success && "Invalid immediate");
Expand Down Expand Up @@ -784,7 +788,7 @@ DecodeStatus RISCVDisassembler::getInstruction16(MCInst &MI, uint64_t &Size,
if (!Entry.haveContainedFeatures(STI.getFeatureBits()))
continue;

LLVM_DEBUG(dbgs() << "Trying " << Entry.Desc << "table:\n");
LLVM_DEBUG(dbgs() << "Trying " << Entry.Desc << " table:\n");
DecodeStatus Result =
decodeInstruction(Entry.Table, MI, Insn, Address, this, STI);
if (Result == MCDisassembler::Fail)
Expand Down Expand Up @@ -820,7 +824,7 @@ DecodeStatus RISCVDisassembler::getInstruction48(MCInst &MI, uint64_t &Size,
if (!Entry.haveContainedFeatures(STI.getFeatureBits()))
continue;

LLVM_DEBUG(dbgs() << "Trying " << Entry.Desc << "table:\n");
LLVM_DEBUG(dbgs() << "Trying " << Entry.Desc << " table:\n");
DecodeStatus Result =
decodeInstruction(Entry.Table, MI, Insn, Address, this, STI);
if (Result == MCDisassembler::Fail)
Expand Down
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