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Add optimization of a-0 and a+(-0)

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This can sometimes be helpful after all.
This commit is contained in:
Arseny Kapoulkine 2024-11-27 10:01:29 +09:00
parent 301b06c152
commit d83ff5a8bd
1 changed files with 18 additions and 1 deletions
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19
CodeGen/src/OptimizeConstProp.cpp
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@ -1194,9 +1194,26 @@ static void constPropInInst(ConstPropState& state, IrBuilder& build, IrFunction&
break; break;
case IrCmd::ADD_INT: case IrCmd::ADD_INT:
case IrCmd::SUB_INT: case IrCmd::SUB_INT:
state.substituteOrRecord(inst, index);
break;
case IrCmd::ADD_NUM: case IrCmd::ADD_NUM:
case IrCmd::SUB_NUM: case IrCmd::SUB_NUM:
state.substituteOrRecord(inst, index); if (FFlag::LuauCodeGenArithOpt)
{
if (std::optional<double> k = function.asDoubleOp(inst.b.kind == IrOpKind::Constant ? inst.b : state.tryGetValue(inst.b)))
{
// a + 0.0 and a - (-0.0) can't be folded since the behavior is different for negative zero
// however, a - 0.0 and a + (-0.0) can be folded into a
if (*k == 0.0 && bool(signbit(*k)) == (inst.cmd == IrCmd::ADD_NUM))
substitute(function, inst, inst.a);
else
state.substituteOrRecord(inst, index);
}
else
state.substituteOrRecord(inst, index);
}
else
state.substituteOrRecord(inst, index);
break; break;
case IrCmd::MUL_NUM: case IrCmd::MUL_NUM:
if (FFlag::LuauCodeGenArithOpt) if (FFlag::LuauCodeGenArithOpt)