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constant_propagation_pass: Fold NOT operations

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Lioncash 2018-09-29 04:07:32 -04:00 committed by MerryMage
parent 8013548bbb
commit c09f4cf28e
1 changed files with 19 additions and 0 deletions
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19
src/ir_opt/constant_propagation_pass.cpp
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@ -77,6 +77,21 @@ void FoldEOR(IR::Inst& inst, bool is_32_bit) {
}
}
// Folds NOT operations if the contained value is an immediate.
void FoldNOT(IR::Inst& inst, bool is_32_bit) {
const auto operand = inst.GetArg(0);
if (operand.IsImmediate()) {
const u64 result = ~operand.GetImmediateAsU64();
if (is_32_bit) {
inst.ReplaceUsesWith(IR::Value{static_cast<u32>(result)});
} else {
inst.ReplaceUsesWith(IR::Value{result});
}
}
}
// Folds OR operations based on the following:
//
// 1. imm_x | imm_y -> result
@ -141,6 +156,10 @@ void ConstantPropagation(IR::Block& block) {
case IR::Opcode::Or64:
FoldOR(inst, opcode == IR::Opcode::Or32);
break;
case IR::Opcode::Not32:
case IR::Opcode::Not64:
FoldNOT(inst, opcode == IR::Opcode::Not32);
break;
case IR::Opcode::ZeroExtendByteToWord: {
if (!inst.AreAllArgsImmediates())
break;