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constant_propagation_pass: Fold AND operations

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Lioncash 2018-09-29 03:24:35 -04:00 committed by MerryMage
parent f40fcda1f6
commit 898d096e39
1 changed files with 41 additions and 1 deletions
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42
src/ir_opt/constant_propagation_pass.cpp
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@ -13,7 +13,43 @@
namespace Dynarmic::Optimization {
namespace {
// Folds EOR operations based on:
// Folds AND operations based on the following:
//
// 1. imm_x & imm_y -> result
// 2. x & 0 -> 0
// 3. 0 & y -> 0
// 4. x & y -> y (where x has all bits set to 1)
// 5. x & y -> x (where y has all bits set to 1)
//
void FoldAND(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) || (is_rhs_immediate && rhs.GetImmediateAsU64() == 0)) {
if (is_32_bit) {
inst.ReplaceUsesWith(IR::Value{u32{0}});
} else {
inst.ReplaceUsesWith(IR::Value{u64{0}});
}
} else if (is_lhs_immediate && lhs.HasAllBitsSet()) {
inst.ReplaceUsesWith(rhs);
} else if (is_rhs_immediate && rhs.HasAllBitsSet()) {
inst.ReplaceUsesWith(lhs);
}
}
// Folds EOR operations based on the following:
//
// 1. imm_x ^ imm_y -> result
// 2. x ^ 0 -> x
@ -65,6 +101,10 @@ void ConstantPropagation(IR::Block& block) {
}
break;
}
case IR::Opcode::And32:
case IR::Opcode::And64:
FoldAND(inst, opcode == IR::Opcode::And32);
break;
case IR::Opcode::Eor32:
case IR::Opcode::Eor64:
FoldEOR(inst, opcode == IR::Opcode::Eor32);