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perf(evm): optimize signextend lowering #438

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Merged
zoowii merged 2 commits into from
Apr 8, 2026
Merged

perf(evm): optimize signextend lowering #438

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88ba944
perf(evm): optimize signextend lowering
ZR74 Mar 24, 2026
d3671ee
style: remove unused Const8 variable in handleSignextend
ZR74 Apr 3, 2026
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119 changes: 51 additions & 68 deletions src/compiler/evm_frontend/evm_mir_compiler.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -2819,92 +2819,75 @@ EVMMirBuilder::handleSignextend(Operand IndexOp, Operand ValueOp) {

MType *MirI64Type =
EVMFrontendContext::getMIRTypeFromEVMType(EVMType::UINT64);
MType *MirI8Type = EVMFrontendContext::getMIRTypeFromEVMType(EVMType::UINT8);

// Calculate sign bit position: index * 8 + 7
MInstruction *Const8 = createIntConstInstruction(MirI64Type, 8);
MInstruction *ByteBitPos = createInstruction<BinaryInstruction>(
false, OP_mul, MirI64Type, IndexComponents[0], Const8);
MInstruction *Const7 = createIntConstInstruction(MirI64Type, 7);
MInstruction *SignBitPos = createInstruction<BinaryInstruction>(
false, OP_add, MirI64Type, ByteBitPos, Const7);

// ComponentIndex = (index * 8 + 7) / 64
MInstruction *Const64 = createIntConstInstruction(MirI64Type, 64);
MInstruction *ComponentIndex = createInstruction<BinaryInstruction>(
false, OP_udiv, MirI64Type, SignBitPos, Const64);
// BitOffset = (index * 8 + 7) % 64
MInstruction *BitOffset = createInstruction<BinaryInstruction>(
false, OP_urem, MirI64Type, SignBitPos, Const64);

// Calculate sign extension mask
// FullMask = (1 << (BitOffset + 1)) - 1
// InvMask = ~FullMask = FullMask ^ AllOnes
// Note: When BitOffset == 63, MaskBits == 64, and (1 << 64) causes undefined
// behavior on x86-64 (SHL masks shift amount to 6 bits, so 1 << 64 becomes
// 1 << 0 = 1). We need to handle this case specially.
MInstruction *One = createIntConstInstruction(MirI64Type, 1);
MInstruction *Const3 = createIntConstInstruction(MirI64Type, 3);
MInstruction *Const63 = createIntConstInstruction(MirI64Type, 63);
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MInstruction *AllOnes = createIntConstInstruction(MirI64Type, ~0ULL);
MInstruction *MaskBits = createInstruction<BinaryInstruction>(
false, OP_add, MirI64Type, BitOffset, One);
MInstruction *Is64 = createInstruction<CmpInstruction>(
false, CmpInstruction::Predicate::ICMP_EQ, &Ctx.I64Type, MaskBits,
Const64);
MInstruction *Mask = createInstruction<BinaryInstruction>(
false, OP_shl, MirI64Type, One, MaskBits);
MInstruction *FullMaskNormal = createInstruction<BinaryInstruction>(
false, OP_sub, MirI64Type, Mask, One);
// When MaskBits == 64, FullMask should be AllOnes (0xFFFFFFFFFFFFFFFF)
MInstruction *FullMask = createInstruction<SelectInstruction>(
false, MirI64Type, Is64, AllOnes, FullMaskNormal);
MInstruction *InvMask = createInstruction<BinaryInstruction>(
false, OP_xor, MirI64Type, FullMask, AllOnes);

// Extract sign bit
MInstruction *Zero = createIntConstInstruction(MirI64Type, 0);
MInstruction *SignBit = Zero;
for (int I = 0; I < 4; I++) {
MInstruction *IsComp = createInstruction<CmpInstruction>(
false, CmpInstruction::Predicate::ICMP_EQ, &Ctx.I64Type, ComponentIndex,

// Match the interpreter strategy:
// sign_word_index = index / 8
// sign_byte_index = index % 8
// sign_word = value[sign_word_index]
// sign_word' = sext(int8(sign_word >> (sign_byte_index * 8)))
// upper words = sign fill
MInstruction *SignWordIndex = createInstruction<BinaryInstruction>(
false, OP_ushr, MirI64Type, IndexComponents[0], Const3);
MInstruction *SignByteIndex = createInstruction<BinaryInstruction>(
false, OP_and, MirI64Type, IndexComponents[0], Const7);
MInstruction *SignByteOffset = createInstruction<BinaryInstruction>(
false, OP_shl, MirI64Type, SignByteIndex, Const3);

MInstruction *SelectedWord = ValueComponents[0];
for (size_t I = 1; I < EVM_ELEMENTS_COUNT; ++I) {
MInstruction *IsThisWord = createInstruction<CmpInstruction>(
false, CmpInstruction::Predicate::ICMP_EQ, &Ctx.I64Type, SignWordIndex,
createIntConstInstruction(MirI64Type, I));
// Shifted = ValueComponents[I] >> BitOffset
MInstruction *Shifted = createInstruction<BinaryInstruction>(
false, OP_ushr, MirI64Type, ValueComponents[I], BitOffset);
// Bit = Shifted & 1
MInstruction *Bit = createInstruction<BinaryInstruction>(
false, OP_and, MirI64Type, Shifted, One);
// SignBit = IsComp ? Bit : SignBit
SignBit = createInstruction<SelectInstruction>(false, MirI64Type, IsComp,
Bit, SignBit);
SelectedWord = createInstruction<SelectInstruction>(
false, MirI64Type, IsThisWord, ValueComponents[I], SelectedWord);
}

MInstruction *ShiftedWord = createInstruction<BinaryInstruction>(
false, OP_ushr, MirI64Type, SelectedWord, SignByteOffset);
MInstruction *ConstFF = createIntConstInstruction(MirI64Type, 0xFF);
MInstruction *SignByte = createInstruction<BinaryInstruction>(
false, OP_and, MirI64Type, ShiftedWord, ConstFF);
MInstruction *SignByteI8 = createInstruction<ConversionInstruction>(
false, OP_trunc, MirI8Type, SignByte);
MInstruction *SextByte = createInstruction<ConversionInstruction>(
false, OP_sext, MirI64Type, SignByteI8);

MInstruction *SignMask = createInstruction<BinaryInstruction>(
false, OP_shl, MirI64Type, AllOnes, SignByteOffset);
MInstruction *LowerMask = createInstruction<BinaryInstruction>(
false, OP_xor, MirI64Type, SignMask, AllOnes);
MInstruction *LowerBits = createInstruction<BinaryInstruction>(
false, OP_and, MirI64Type, SelectedWord, LowerMask);
MInstruction *SextWord = createInstruction<BinaryInstruction>(
false, OP_shl, MirI64Type, SextByte, SignByteOffset);
MInstruction *ExtendedSelectedWord = createInstruction<BinaryInstruction>(
false, OP_or, MirI64Type, SextWord, LowerBits);
MInstruction *HighValue = createInstruction<BinaryInstruction>(
false, OP_sshr, MirI64Type, SextByte, Const63);

// Create sign extension for each component
U256Inst ResultComponents = {};
for (int I = 0; I < 4; I++) {
MInstruction *CompIdx = createIntConstInstruction(MirI64Type, I);
MInstruction *IsAbove = createInstruction<CmpInstruction>(
false, CmpInstruction::Predicate::ICMP_UGT, &Ctx.I64Type, CompIdx,
ComponentIndex);
SignWordIndex);
MInstruction *IsEqual = createInstruction<CmpInstruction>(
false, CmpInstruction::Predicate::ICMP_EQ, &Ctx.I64Type, CompIdx,
ComponentIndex);

// For components above sign bit: all 1s if negative, all 0s if positive
MInstruction *HighValue = createInstruction<SelectInstruction>(
false, MirI64Type, SignBit, AllOnes, Zero);

// For sign component: apply mask and sign extension
MInstruction *SignCompValue = createInstruction<BinaryInstruction>(
false, OP_and, MirI64Type, ValueComponents[I], FullMask);
MInstruction *SignExtBits = createInstruction<BinaryInstruction>(
false, OP_and, MirI64Type, InvMask, HighValue);
MInstruction *ExtendedSignComp = createInstruction<BinaryInstruction>(
false, OP_or, MirI64Type, SignCompValue, SignExtBits);
SignWordIndex);

// Select appropriate value based on position relative to sign bit
MInstruction *SameOrBelow = createInstruction<SelectInstruction>(
false, MirI64Type, IsEqual, ExtendedSelectedWord, ValueComponents[I]);
MInstruction *ComponentResult = createInstruction<SelectInstruction>(
false, MirI64Type, IsAbove, HighValue,
createInstruction<SelectInstruction>(
false, MirI64Type, IsEqual, ExtendedSignComp, ValueComponents[I]));
false, MirI64Type, IsAbove, HighValue, SameOrBelow);

// If index >= 31, use original value; otherwise use sign-extended value
ResultComponents[I] =
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