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strength reduce constant integer multiplies

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CGH0S7
2026-06-30 00:42:27 +08:00
parent 6f943b395f
commit cb091a4b21
1 changed files with 27 additions and 0 deletions
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27
src/mir/Lowering.cpp
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@@ -368,6 +368,33 @@ void LowerInstruction(const ir::Instruction& inst, MachineFunction& function,
int dst_slot = function.CreateFrameIndex(4); int dst_slot = function.CreateFrameIndex(4);
slots.emplace(&inst, dst_slot); slots.emplace(&inst, dst_slot);
if (inst.GetOpcode() == ir::Opcode::Mul) {
const ir::Value* variable = nullptr;
int constant = 0;
if (auto* lhs_const = dynamic_cast<const ir::ConstantInt*>(bin.GetLhs())) {
variable = bin.GetRhs();
constant = lhs_const->GetValue();
} else if (auto* rhs_const = dynamic_cast<const ir::ConstantInt*>(bin.GetRhs())) {
variable = bin.GetLhs();
constant = rhs_const->GetValue();
}
if (variable && constant > 1) {
EmitValueToReg(variable, PhysReg::W8, slots, block);
if (IsPowerOfTwo(static_cast<uint32_t>(constant))) {
block.Append(Opcode::LslImm, {Operand::Reg(PhysReg::W8), Operand::Reg(PhysReg::W8), Operand::Imm(Log2(static_cast<uint32_t>(constant)))});
block.Append(Opcode::StoreStack, {Operand::Reg(PhysReg::W8), Operand::FrameIndex(dst_slot)});
return;
}
if (IsPowerOfTwo(static_cast<uint32_t>(constant - 1))) {
block.Append(Opcode::LslImm, {Operand::Reg(PhysReg::W9), Operand::Reg(PhysReg::W8), Operand::Imm(Log2(static_cast<uint32_t>(constant - 1)))});
block.Append(Opcode::AddRR, {Operand::Reg(PhysReg::W8), Operand::Reg(PhysReg::W9), Operand::Reg(PhysReg::W8)});
block.Append(Opcode::StoreStack, {Operand::Reg(PhysReg::W8), Operand::FrameIndex(dst_slot)});
return;
}
}
}
EmitValueToReg(bin.GetLhs(), PhysReg::W8, slots, block); EmitValueToReg(bin.GetLhs(), PhysReg::W8, slots, block);
EmitValueToReg(bin.GetRhs(), PhysReg::W9, slots, block); EmitValueToReg(bin.GetRhs(), PhysReg::W9, slots, block);