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[DecoderEmitter] Eliminate DecodeComplete parameter to decodeToMCInst #159130

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[DecoderEmitter] Eliminate DecodeComplete parameter to decodeToMCInst #159130

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10 changes: 5 additions & 5 deletions llvm/include/llvm/MC/MCDisassembler/MCDisassembler.h
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Expand Up @@ -98,11 +98,11 @@ class LLVM_ABI MCDisassembler {
/// from Success->SoftFail ->Fail can be done with a simple
/// bitwise-AND:
///
/// LEFT & TOP = | Success Unpredictable Fail
/// --------------+-----------------------------------
/// Success | Success Unpredictable Fail
/// Unpredictable | Unpredictable Unpredictable Fail
/// Fail | Fail Fail Fail
/// LEFT & TOP = | Success SoftFail Fail
/// --------------+-----------------------------
/// Success | Success SoftFail Fail
/// SoftFail | SoftFail SoftFail Fail
/// Fail | Fail Fail Fail
///
/// An easy way of encoding this is as 0b11, 0b01, 0b00 for
/// Success, SoftFail, Fail respectively.
Expand Down
12 changes: 6 additions & 6 deletions llvm/test/TableGen/DecoderEmitter/DecoderEmitterFnTable.td
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Expand Up @@ -71,14 +71,14 @@ def Inst3 : TestInstruction {
let AsmString = "Inst3";
}

// CHECK-LABEL: DecodeStatus decodeFn_0(DecodeStatus S, InsnType insn, MCInst &MI, uint64_t Address, const MCDisassembler *Decoder, bool &DecodeComplete)
// CHECK-LABEL: DecodeStatus decodeFn_1(DecodeStatus S, InsnType insn, MCInst &MI, uint64_t Address, const MCDisassembler *Decoder, bool &DecodeComplete)
// CHECK-LABEL: DecodeStatus decodeFn_2(DecodeStatus S, InsnType insn, MCInst &MI, uint64_t Address, const MCDisassembler *Decoder, bool &DecodeComplete)
// CHECK-LABEL: DecodeStatus decodeFn_3(DecodeStatus S, InsnType insn, MCInst &MI, uint64_t Address, const MCDisassembler *Decoder, bool &DecodeComplete)
// CHECK-LABEL: decodeToMCInst(unsigned Idx, DecodeStatus S, InsnType insn, MCInst &MI, uint64_t Address, const MCDisassembler *Decoder, bool &DecodeComplete)
// CHECK-LABEL: DecodeStatus decodeFn_0(DecodeStatus S, InsnType insn, MCInst &MI, uint64_t Address, const MCDisassembler *Decoder)
// CHECK-LABEL: DecodeStatus decodeFn_1(DecodeStatus S, InsnType insn, MCInst &MI, uint64_t Address, const MCDisassembler *Decoder)
// CHECK-LABEL: DecodeStatus decodeFn_2(DecodeStatus S, InsnType insn, MCInst &MI, uint64_t Address, const MCDisassembler *Decoder)
// CHECK-LABEL: DecodeStatus decodeFn_3(DecodeStatus S, InsnType insn, MCInst &MI, uint64_t Address, const MCDisassembler *Decoder)
// CHECK-LABEL: decodeToMCInst(unsigned Idx, DecodeStatus S, InsnType insn, MCInst &MI, uint64_t Address, const MCDisassembler *Decoder)
// CHECK: static constexpr DecodeFnTy decodeFnTable[]
// CHECK-NEXT: decodeFn_0,
// CHECK-NEXT: decodeFn_1,
// CHECK-NEXT: decodeFn_2,
// CHECK-NEXT: decodeFn_3,
// CHECK: return decodeFnTable[Idx](S, insn, MI, Address, Decoder, DecodeComplete)
// CHECK: return decodeFnTable[Idx](S, insn, MI, Address, Decoder)
4 changes: 2 additions & 2 deletions llvm/test/TableGen/DecoderEmitter/trydecode-emission.td
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Expand Up @@ -41,7 +41,7 @@ def InstB : TestInstruction {
// CHECK-NEXT: /* 15 */ OPC_Decode, {{[0-9]+}}, {{[0-9]+}}, 1, // Opcode: InstA, DecodeIdx: 1
// CHECK-NEXT: };

// CHECK: if (!Check(S, DecodeInstB(MI, insn, Address, Decoder))) { DecodeComplete = false; return MCDisassembler::Fail; }
// CHECK: if (!Check(S, DecodeInstB(MI, insn, Address, Decoder))) { return MCDisassembler::Fail; }

// CHECK: unsigned NumToSkip = *Ptr++;
// CHECK-NEXT: NumToSkip |= (*Ptr++) << 8;
Expand All @@ -54,7 +54,7 @@ def InstB : TestInstruction {
// CHECK-LARGE-NEXT: /* 16 */ OPC_Decode, {{[0-9]+}}, {{[0-9]+}}, 1, // Opcode: InstA, DecodeIdx: 1
// CHECK-LARGE-NEXT: };

// CHECK-LARGE: if (!Check(S, DecodeInstB(MI, insn, Address, Decoder))) { DecodeComplete = false; return MCDisassembler::Fail; }
// CHECK-LARGE: if (!Check(S, DecodeInstB(MI, insn, Address, Decoder))) { return MCDisassembler::Fail; }

// CHECK-LARGE: unsigned NumToSkip = *Ptr++;
// CHECK-LARGE-NEXT: NumToSkip |= (*Ptr++) << 8;
Expand Down
8 changes: 4 additions & 4 deletions llvm/test/TableGen/DecoderEmitter/trydecode-emission2.td
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Expand Up @@ -39,8 +39,8 @@ def InstB : TestInstruction {
// CHECK-NEXT: /* 19 */ OPC_CheckField, 3, 2, 0,
// CHECK-NEXT: /* 23 */ OPC_TryDecode, {{[0-9]+}}, {{[0-9]+}}, 1,

// CHECK: if (!Check(S, DecodeInstB(MI, insn, Address, Decoder))) { DecodeComplete = false; return MCDisassembler::Fail; }
// CHECK: if (!Check(S, DecodeInstA(MI, insn, Address, Decoder))) { DecodeComplete = false; return MCDisassembler::Fail; }
// CHECK: if (!Check(S, DecodeInstB(MI, insn, Address, Decoder))) { return MCDisassembler::Fail; }
// CHECK: if (!Check(S, DecodeInstA(MI, insn, Address, Decoder))) { return MCDisassembler::Fail; }

// CHECK-LARGE: /* 0 */ OPC_CheckField, 2, 1, 0,
// CHECK-LARGE-NEXT: /* 4 */ OPC_CheckField, 5, 3, 0,
Expand All @@ -51,5 +51,5 @@ def InstB : TestInstruction {
// CHECK-LARGE-NEXT: /* 24 */ OPC_TryDecode, {{[0-9]+}}, {{[0-9]+}}, 1,
// CHECK-LARGE-NEXT: };

// CHECK-LARGE: if (!Check(S, DecodeInstB(MI, insn, Address, Decoder))) { DecodeComplete = false; return MCDisassembler::Fail; }
// CHECK-LARGE: if (!Check(S, DecodeInstA(MI, insn, Address, Decoder))) { DecodeComplete = false; return MCDisassembler::Fail; }
// CHECK-LARGE: if (!Check(S, DecodeInstB(MI, insn, Address, Decoder))) { return MCDisassembler::Fail; }
// CHECK-LARGE: if (!Check(S, DecodeInstA(MI, insn, Address, Decoder))) { return MCDisassembler::Fail; }
4 changes: 2 additions & 2 deletions llvm/test/TableGen/DecoderEmitter/trydecode-emission3.td
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Expand Up @@ -42,7 +42,7 @@ def InstB : TestInstruction {
// CHECK-NEXT: /* 15 */ OPC_Decode, {{[0-9]+}}, {{[0-9]+}}, 1, // Opcode: InstA, DecodeIdx: 1
// CHECK-NEXT: };

// CHECK: if (!Check(S, DecodeInstBOp(MI, tmp, Address, Decoder))) { DecodeComplete = false; return MCDisassembler::Fail; }
// CHECK: if (!Check(S, DecodeInstBOp(MI, tmp, Address, Decoder))) { return MCDisassembler::Fail; }

// CHECK-LARGE: /* 0 */ OPC_CheckField, 4, 4, 0,
// CHECK-LARGE-NEXT: /* 4 */ OPC_Scope, 8, 0, 0, // end scope at 16
Expand All @@ -51,4 +51,4 @@ def InstB : TestInstruction {
// CHECK-LARGE-NEXT: /* 16 */ OPC_Decode, {{[0-9]+}}, {{[0-9]+}}, 1, // Opcode: InstA, DecodeIdx: 1
// CHECK-LARGE-NEXT: };

// CHECK-LARGE: if (!Check(S, DecodeInstBOp(MI, tmp, Address, Decoder))) { DecodeComplete = false; return MCDisassembler::Fail; }
// CHECK-LARGE: if (!Check(S, DecodeInstBOp(MI, tmp, Address, Decoder))) { return MCDisassembler::Fail; }
4 changes: 2 additions & 2 deletions llvm/test/TableGen/DecoderEmitter/trydecode-emission4.td
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Expand Up @@ -40,7 +40,7 @@ def InstB : TestInstruction {
// CHECK-NEXT: /* 17 */ OPC_Decode, {{[0-9]+}}, {{[0-9]+}}, 1, // Opcode: InstA, DecodeIdx: 1
// CHECK-NEXT: };

// CHECK: if (!Check(S, DecodeInstB(MI, insn, Address, Decoder))) { DecodeComplete = false; return MCDisassembler::Fail; }
// CHECK: if (!Check(S, DecodeInstB(MI, insn, Address, Decoder))) { return MCDisassembler::Fail; }


// CHECK-LARGE: /* 0 */ OPC_CheckField, 250, 3, 4, 0,
Expand All @@ -50,4 +50,4 @@ def InstB : TestInstruction {
// CHECK-LARGE-NEXT: /* 18 */ OPC_Decode, {{[0-9]+}}, {{[0-9]+}}, 1, // Opcode: InstA, DecodeIdx: 1
// CHECK-LARGE-NEXT: };

// CHECK-LARGE: if (!Check(S, DecodeInstB(MI, insn, Address, Decoder))) { DecodeComplete = false; return MCDisassembler::Fail; }
// CHECK-LARGE: if (!Check(S, DecodeInstB(MI, insn, Address, Decoder))) { return MCDisassembler::Fail; }
29 changes: 9 additions & 20 deletions llvm/utils/TableGen/DecoderEmitter.cpp
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Expand Up @@ -865,7 +865,7 @@ void DecoderEmitter::emitDecoderFunction(formatted_raw_ostream &OS,
"InsnType, uint64_t>;\n";
StringRef DecodeParams =
"DecodeStatus S, InsnType insn, MCInst &MI, uint64_t Address, const "
"MCDisassembler *Decoder, bool &DecodeComplete";
"MCDisassembler *Decoder";

// Print the name of the decode function to OS.
auto PrintDecodeFnName = [&OS, BucketBitWidth](unsigned DecodeIdx) {
Expand Down Expand Up @@ -904,7 +904,6 @@ void DecoderEmitter::emitDecoderFunction(formatted_raw_ostream &OS,
OS << "// Handling " << Decoders.size() << " cases.\n";
PrintTemplate();
OS << "decodeToMCInst(unsigned Idx, " << DecodeParams << ") {\n";
OS << " DecodeComplete = true;\n";

if (UseFnTableInDecodeToMCInst) {
// Build a table of function pointers
Expand All @@ -918,8 +917,7 @@ void DecoderEmitter::emitDecoderFunction(formatted_raw_ostream &OS,
OS << " };\n";
OS << " if (Idx >= " << Decoders.size() << ")\n";
OS << " llvm_unreachable(\"Invalid decoder index!\");\n";
OS << " return decodeFnTable[Idx](S, insn, MI, Address, Decoder, "
"DecodeComplete);\n";
OS << " return decodeFnTable[Idx](S, insn, MI, Address, Decoder);\n";
} else {
OS << " " << TmpTypeDecl;
OS << " TmpType tmp;\n";
Expand Down Expand Up @@ -1052,9 +1050,7 @@ static void emitBinaryParser(raw_ostream &OS, indent Indent,
StringRef Decoder = OpInfo.Decoder;
if (!Decoder.empty()) {
OS << Indent << "if (!Check(S, " << Decoder
<< "(MI, tmp, Address, Decoder))) { "
<< (OpInfo.HasCompleteDecoder ? "" : "DecodeComplete = false; ")
<< "return MCDisassembler::Fail; }\n";
<< "(MI, tmp, Address, Decoder))) { return MCDisassembler::Fail; }\n";
} else {
OS << Indent << "MI.addOperand(MCOperand::createImm(tmp));\n";
}
Expand All @@ -1069,9 +1065,7 @@ static std::string getDecoderString(const InstructionEncoding &Encoding) {
StringRef DecoderMethod = Encoding.getDecoderMethod();
if (!DecoderMethod.empty()) {
OS << Indent << "if (!Check(S, " << DecoderMethod
<< "(MI, insn, Address, Decoder))) { "
<< (Encoding.hasCompleteDecoder() ? "" : "DecodeComplete = false; ")
<< "return MCDisassembler::Fail; }\n";
<< "(MI, insn, Address, Decoder))) { return MCDisassembler::Fail; }\n";
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@s-barannikov s-barannikov Sep 16, 2025

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Drop the braces? They were needed before because there could be two statements inside them.
Same above.

} else {
for (const OperandInfo &Op : Encoding.getOperands())
emitBinaryParser(OS, Indent, Encoding, Op);
Expand Down Expand Up @@ -1682,15 +1676,13 @@ static DecodeStatus decodeInstruction(const uint8_t DecodeTable[], MCInst &MI,
unsigned DecodeIdx = decodeULEB128AndIncUnsafe(Ptr);

MI.clear();
MI.setOpcode(Opc);
bool DecodeComplete;)";
MI.setOpcode(Opc);)";
if (IsVarLenInst) {
OS << "\n unsigned Len = InstrLenTable[Opc];\n"
<< " makeUp(insn, Len);";
}
OS << R"(
S = decodeToMCInst(DecodeIdx, S, insn, MI, Address, DisAsm, DecodeComplete);
assert(DecodeComplete);
S = decodeToMCInst(DecodeIdx, S, insn, MI, Address, DisAsm);

LLVM_DEBUG(dbgs() << Loc << ": OPC_Decode: opcode " << Opc
<< ", using decoder " << DecodeIdx << ": "
Expand All @@ -1707,18 +1699,15 @@ static DecodeStatus decodeInstruction(const uint8_t DecodeTable[], MCInst &MI,
// Perform the decode operation.
MCInst TmpMI;
TmpMI.setOpcode(Opc);
bool DecodeComplete;
S = decodeToMCInst(DecodeIdx, S, insn, TmpMI, Address, DisAsm, DecodeComplete);
S = decodeToMCInst(DecodeIdx, S, insn, TmpMI, Address, DisAsm);
LLVM_DEBUG(dbgs() << Loc << ": OPC_TryDecode: opcode " << Opc
<< ", using decoder " << DecodeIdx << ": ");

if (DecodeComplete) {
// Decoding complete.
LLVM_DEBUG(dbgs() << (S != MCDisassembler::Fail ? "PASS\n" : "FAIL\n"));
if (S != MCDisassembler::Fail) {
LLVM_DEBUG(dbgs() << (S != MCDisassembler::Success ? "Success\n" : "SoftFail\n"));
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@s-barannikov s-barannikov Sep 16, 2025 •
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The condition is reversed.
Also, PASS/FAIL is printed by most other opcodes, I think we should stick to it. Or change them all to print Success/SoftFail/Fail (in a separate PR).

MI = TmpMI;
return S;
}
assert(S == MCDisassembler::Fail);
if (ScopeStack.empty()) {
LLVM_DEBUG(dbgs() << "FAIL, returning FAIL\n");
return MCDisassembler::Fail;
Expand Down