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/* Copyright (C) 2018 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#include "instruction_simplifier_x86_shared.h"
#include "nodes_x86.h"
namespace art HIDDEN {
bool TryCombineAndNot(HAnd* instruction) {
DataType::Type type = instruction->GetType();
if (!DataType::IsIntOrLongType(type)) {
return false;
}
// Replace code looking like
// Not tmp, y
// And dst, x, tmp
// with
// AndNot dst, x, y
HInstruction* left = instruction->GetLeft();
HInstruction* right = instruction->GetRight();
// Perform simplication only when either left or right
// is Not. When both are Not, instruction should be simplified with
// DeMorgan's Laws.
if (left->IsNot() ^ right->IsNot()) {
bool left_is_not = left->IsNot();
HInstruction* other_ins = (left_is_not ? right : left);
HNot* not_ins = (left_is_not ? left : right)->AsNot();
// Only do the simplification if instruction has only one use
// and thus can be safely removed.
if (not_ins->HasOnlyOneNonEnvironmentUse()) {
ArenaAllocator* arena = instruction->GetBlock()->GetGraph()->GetAllocator();
HX86AndNot* and_not = new (arena) HX86AndNot(type,
not_ins->GetInput(),
other_ins,
instruction->GetDexPc());
instruction->GetBlock()->ReplaceAndRemoveInstructionWith(instruction, and_not);
DCHECK(!not_ins->HasUses());
not_ins->GetBlock()->RemoveInstruction(not_ins);
return true;
}
}
return false;
}
bool TryGenerateResetLeastSetBit(HAnd* instruction) {
DataType::Type type = instruction->GetType();
if (!DataType::IsIntOrLongType(type)) {
return false;
}
// Replace code looking like
// Add tmp, x, -1 or Sub tmp, x, 1
// And dest x, tmp
// with
// MaskOrResetLeastSetBit dest, x
HInstruction* candidate = nullptr;
HInstruction* other = nullptr;
HInstruction* left = instruction->GetLeft();
HInstruction* right = instruction->GetRight();
if (AreLeastSetBitInputs(left, right)) {
candidate = left;
other = right;
} else if (AreLeastSetBitInputs(right, left)) {
candidate = right;
other = left;
}
if (candidate != nullptr && candidate->HasOnlyOneNonEnvironmentUse()) {
ArenaAllocator* arena = instruction->GetBlock()->GetGraph()->GetAllocator();
HX86MaskOrResetLeastSetBit* lsb = new (arena) HX86MaskOrResetLeastSetBit(
type, HInstruction::kAnd, other, instruction->GetDexPc());
instruction->GetBlock()->ReplaceAndRemoveInstructionWith(instruction, lsb);
DCHECK(!candidate->HasUses());
candidate->GetBlock()->RemoveInstruction(candidate);
return true;
}
return false;
}
bool TryGenerateMaskUptoLeastSetBit(HXor* instruction) {
DataType::Type type = instruction->GetType();
if (!DataType::IsIntOrLongType(type)) {
return false;
}
// Replace code looking like
// Add tmp, x, -1 or Sub tmp, x, 1
// Xor dest x, tmp
// with
// MaskOrResetLeastSetBit dest, x
HInstruction* left = instruction->GetLeft();
HInstruction* right = instruction->GetRight();
HInstruction* other = nullptr;
HInstruction* candidate = nullptr;
if (AreLeastSetBitInputs(left, right)) {
candidate = left;
other = right;
} else if (AreLeastSetBitInputs(right, left)) {
candidate = right;
other = left;
}
if (candidate != nullptr && candidate->HasOnlyOneNonEnvironmentUse()) {
ArenaAllocator* arena = instruction->GetBlock()->GetGraph()->GetAllocator();
HX86MaskOrResetLeastSetBit* lsb = new (arena) HX86MaskOrResetLeastSetBit(
type, HInstruction::kXor, other, instruction->GetDexPc());
instruction->GetBlock()->ReplaceAndRemoveInstructionWith(instruction, lsb);
DCHECK(!candidate->HasUses());
candidate->GetBlock()->RemoveInstruction(candidate);
return true;
}
return false;
}
bool AreLeastSetBitInputs(HInstruction* to_test, HInstruction* other) {
if (to_test->IsAdd()) {
HAdd* add = to_test->AsAdd();
HConstant* cst = add->GetConstantRight();
return cst != nullptr && cst->IsMinusOne() && other == add->GetLeastConstantLeft();
}
if (to_test->IsSub()) {
HSub* sub = to_test->AsSub();
HConstant* cst = sub->GetConstantRight();
return cst != nullptr && cst->IsOne() && other == sub->GetLeastConstantLeft();
}
return false;
}
} // namespace art
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