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constant_propagation_pass: Fold OR operations

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Lioncash 2018-09-29 03:57:16 -04:00 committed by MerryMage
parent 898d096e39
commit 8013548bbb
1 changed files with 32 additions and 0 deletions
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32
src/ir_opt/constant_propagation_pass.cpp
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@ -76,6 +76,34 @@ void FoldEOR(IR::Inst& inst, bool is_32_bit) {
inst.ReplaceUsesWith(lhs);
}
}
// Folds OR operations based on the following:
//
// 1. imm_x | imm_y -> result
// 2. x | 0 -> x
// 3. 0 | y -> y
//
void FoldOR(IR::Inst& inst, bool is_32_bit) {
const auto lhs = inst.GetArg(0);
const auto rhs = inst.GetArg(1);
const bool is_lhs_immediate = lhs.IsImmediate();
const bool is_rhs_immediate = rhs.IsImmediate();
if (is_lhs_immediate && is_rhs_immediate) {
const u64 result = lhs.GetImmediateAsU64() | rhs.GetImmediateAsU64();
if (is_32_bit) {
inst.ReplaceUsesWith(IR::Value{static_cast<u32>(result)});
} else {
inst.ReplaceUsesWith(IR::Value{result});
}
} else if (is_lhs_immediate && lhs.GetImmediateAsU64() == 0) {
inst.ReplaceUsesWith(rhs);
} else if (is_rhs_immediate && rhs.GetImmediateAsU64() == 0) {
inst.ReplaceUsesWith(lhs);
}
}
} // Anonymous namespace
void ConstantPropagation(IR::Block& block) {
@ -109,6 +137,10 @@ void ConstantPropagation(IR::Block& block) {
case IR::Opcode::Eor64:
FoldEOR(inst, opcode == IR::Opcode::Eor32);
break;
case IR::Opcode::Or32:
case IR::Opcode::Or64:
FoldOR(inst, opcode == IR::Opcode::Or32);
break;
case IR::Opcode::ZeroExtendByteToWord: {
if (!inst.AreAllArgsImmediates())
break;