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constant_propagation_pass: Handle folding for Least/MostSignificant{Bit, Byte, Half, Word} opcodes

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These are quite trivial to fold.
This commit is contained in:
Lioncash 2018-11-23 23:06:29 -05:00 committed by MerryMage
parent 7c8fcaef26
commit d302d9bd0c
1 changed files with 60 additions and 0 deletions
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60
src/ir_opt/constant_propagation_pass.cpp
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@ -98,6 +98,51 @@ void FoldEOR(IR::Inst& inst, bool is_32_bit) {
} }
} }
void FoldLeastSignificantByte(IR::Inst& inst) {
if (!inst.AreAllArgsImmediates()) {
return;
}
const auto operand = inst.GetArg(0);
inst.ReplaceUsesWith(IR::Value{static_cast<u8>(operand.GetImmediateAsU64())});
}
void FoldLeastSignificantHalf(IR::Inst& inst) {
if (!inst.AreAllArgsImmediates()) {
return;
}
const auto operand = inst.GetArg(0);
inst.ReplaceUsesWith(IR::Value{static_cast<u16>(operand.GetImmediateAsU64())});
}
void FoldLeastSignificantWord(IR::Inst& inst) {
if (!inst.AreAllArgsImmediates()) {
return;
}
const auto operand = inst.GetArg(0);
inst.ReplaceUsesWith(IR::Value{static_cast<u32>(operand.GetImmediateAsU64())});
}
void FoldMostSignificantBit(IR::Inst& inst) {
if (!inst.AreAllArgsImmediates()) {
return;
}
const auto operand = inst.GetArg(0);
inst.ReplaceUsesWith(IR::Value{(operand.GetImmediateAsU64() >> 31) != 0});
}
void FoldMostSignificantWord(IR::Inst& inst) {
if (!inst.AreAllArgsImmediates()) {
return;
}
const auto operand = inst.GetArg(0);
inst.ReplaceUsesWith(IR::Value{static_cast<u32>(operand.GetImmediateAsU64() >> 32)});
}
// Folds multiplication operations based on the following: // Folds multiplication operations based on the following:
// //
// 1. imm_x * imm_y -> result // 1. imm_x * imm_y -> result
@ -216,6 +261,21 @@ void ConstantPropagation(IR::Block& block) {
const auto opcode = inst.GetOpcode(); const auto opcode = inst.GetOpcode();
switch (opcode) { switch (opcode) {
case IR::Opcode::LeastSignificantWord:
FoldLeastSignificantWord(inst);
break;
case IR::Opcode::MostSignificantWord:
FoldMostSignificantWord(inst);
break;
case IR::Opcode::LeastSignificantHalf:
FoldLeastSignificantHalf(inst);
break;
case IR::Opcode::LeastSignificantByte:
FoldLeastSignificantByte(inst);
break;
case IR::Opcode::MostSignificantBit:
FoldMostSignificantBit(inst);
break;
case IR::Opcode::LogicalShiftLeft32: case IR::Opcode::LogicalShiftLeft32:
case IR::Opcode::LogicalShiftLeft64: case IR::Opcode::LogicalShiftLeft64:
case IR::Opcode::LogicalShiftRight32: case IR::Opcode::LogicalShiftRight32: