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constant_propagation_pass: Fold add and sub

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This commit is contained in:
MerryMage 2020-04-29 14:16:17 +01:00
parent dca983803a
commit e7166e8ba7
1 changed files with 51 additions and 0 deletions
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51
src/ir_opt/constant_propagation_pass.cpp
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@ -73,6 +73,36 @@ bool FoldCommutative(IR::Inst& inst, bool is_32_bit, ImmFn imm_fn) {
return true; return true;
} }
void FoldAdd(IR::Inst& inst, bool is_32_bit) {
const auto lhs = inst.GetArg(0);
const auto rhs = inst.GetArg(1);
const auto carry = inst.GetArg(2);
if (lhs.IsImmediate() && !rhs.IsImmediate()) {
// Normalize
inst.SetArg(0, rhs);
inst.SetArg(1, lhs);
FoldAdd(inst, is_32_bit);
return;
}
if (!lhs.IsImmediate() && rhs.IsImmediate()) {
const IR::Inst* lhs_inst = lhs.GetInstRecursive();
if (lhs_inst->GetOpcode() == inst.GetOpcode() && lhs_inst->GetArg(1).IsImmediate() && lhs_inst->GetArg(2).IsImmediate()) {
const u64 combined = rhs.GetImmediateAsU64() + lhs_inst->GetArg(1).GetImmediateAsU64() + lhs_inst->GetArg(2).GetU1();
inst.SetArg(0, lhs_inst->GetArg(0));
inst.SetArg(1, Value(is_32_bit, combined));
return;
}
}
if (inst.AreAllArgsImmediates() && !inst.HasAssociatedPseudoOperation()) {
const u64 result = lhs.GetImmediateAsU64() + rhs.GetImmediateAsU64() + carry.GetU1();
ReplaceUsesWith(inst, is_32_bit, result);
return;
}
}
// Folds AND operations based on the following: // Folds AND operations based on the following:
// //
// 1. imm_x & imm_y -> result // 1. imm_x & imm_y -> result
@ -297,6 +327,19 @@ void FoldSignExtendXToLong(IR::Inst& inst) {
inst.ReplaceUsesWith(IR::Value{static_cast<u64>(value)}); inst.ReplaceUsesWith(IR::Value{static_cast<u64>(value)});
} }
void FoldSub(IR::Inst& inst, bool is_32_bit) {
if (!inst.AreAllArgsImmediates() || inst.HasAssociatedPseudoOperation()) {
return;
}
const auto lhs = inst.GetArg(0);
const auto rhs = inst.GetArg(1);
const auto carry = inst.GetArg(2);
const u64 result = lhs.GetImmediateAsU64() + (~rhs.GetImmediateAsU64()) + carry.GetU1();
ReplaceUsesWith(inst, is_32_bit, result);
}
void FoldZeroExtendXToWord(IR::Inst& inst) { void FoldZeroExtendXToWord(IR::Inst& inst) {
if (!inst.AreAllArgsImmediates()) { if (!inst.AreAllArgsImmediates()) {
return; return;
@ -426,6 +469,14 @@ void ConstantPropagation(IR::Block& block) {
ReplaceUsesWith(inst, false, Common::RotateRight<u64>(inst.GetArg(0).GetU64(), inst.GetArg(1).GetU64())); ReplaceUsesWith(inst, false, Common::RotateRight<u64>(inst.GetArg(0).GetU64(), inst.GetArg(1).GetU64()));
} }
break; break;
case Op::Add32:
case Op::Add64:
FoldAdd(inst, opcode == Op::Add32);
break;
case Op::Sub32:
case Op::Sub64:
FoldSub(inst, opcode == Op::Sub32);
break;
case Op::Mul32: case Op::Mul32:
case Op::Mul64: case Op::Mul64:
FoldMultiply(inst, opcode == Op::Mul32); FoldMultiply(inst, opcode == Op::Mul32);