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/*
* Copyright (C) 2015 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_arm.h"
#include "code_generator.h"
#include "common_arm.h"
#include "instruction_simplifier_shared.h"
#include "mirror/array-inl.h"
#include "mirror/string.h"
#include "nodes.h"
namespace art {
using helpers::CanFitInShifterOperand;
using helpers::HasShifterOperand;
namespace arm {
class InstructionSimplifierArmVisitor : public HGraphVisitor {
public:
InstructionSimplifierArmVisitor(HGraph* graph, OptimizingCompilerStats* stats)
: HGraphVisitor(graph), stats_(stats) {}
private:
void RecordSimplification() {
MaybeRecordStat(stats_, MethodCompilationStat::kInstructionSimplificationsArch);
}
bool TryMergeIntoUsersShifterOperand(HInstruction* instruction);
bool TryMergeIntoShifterOperand(HInstruction* use, HInstruction* bitfield_op, bool do_merge);
bool CanMergeIntoShifterOperand(HInstruction* use, HInstruction* bitfield_op) {
return TryMergeIntoShifterOperand(use, bitfield_op, /* do_merge */ false);
}
bool MergeIntoShifterOperand(HInstruction* use, HInstruction* bitfield_op) {
DCHECK(CanMergeIntoShifterOperand(use, bitfield_op));
return TryMergeIntoShifterOperand(use, bitfield_op, /* do_merge */ true);
}
/**
* This simplifier uses a special-purpose BB visitor.
* (1) No need to visit Phi nodes.
* (2) Since statements can be removed in a "forward" fashion,
* the visitor should test if each statement is still there.
*/
void VisitBasicBlock(HBasicBlock* block) override {
// TODO: fragile iteration, provide more robust iterators?
for (HInstructionIterator it(block->GetInstructions()); !it.Done(); it.Advance()) {
HInstruction* instruction = it.Current();
if (instruction->IsInBlock()) {
instruction->Accept(this);
}
}
}
void VisitAnd(HAnd* instruction) override;
void VisitArrayGet(HArrayGet* instruction) override;
void VisitArraySet(HArraySet* instruction) override;
void VisitMul(HMul* instruction) override;
void VisitOr(HOr* instruction) override;
void VisitShl(HShl* instruction) override;
void VisitShr(HShr* instruction) override;
void VisitTypeConversion(HTypeConversion* instruction) override;
void VisitUShr(HUShr* instruction) override;
OptimizingCompilerStats* stats_;
};
bool InstructionSimplifierArmVisitor::TryMergeIntoShifterOperand(HInstruction* use,
HInstruction* bitfield_op,
bool do_merge) {
DCHECK(HasShifterOperand(use, InstructionSet::kArm));
DCHECK(use->IsBinaryOperation());
DCHECK(CanFitInShifterOperand(bitfield_op));
DCHECK(!bitfield_op->HasEnvironmentUses());
DataType::Type type = use->GetType();
if (type != DataType::Type::kInt32 && type != DataType::Type::kInt64) {
return false;
}
HInstruction* left = use->InputAt(0);
HInstruction* right = use->InputAt(1);
DCHECK(left == bitfield_op || right == bitfield_op);
if (left == right) {
// TODO: Handle special transformations in this situation?
// For example should we transform `(x << 1) + (x << 1)` into `(x << 2)`?
// Or should this be part of a separate transformation logic?
return false;
}
bool is_commutative = use->AsBinaryOperation()->IsCommutative();
HInstruction* other_input;
if (bitfield_op == right) {
other_input = left;
} else {
if (is_commutative) {
other_input = right;
} else {
return false;
}
}
HDataProcWithShifterOp::OpKind op_kind;
int shift_amount = 0;
HDataProcWithShifterOp::GetOpInfoFromInstruction(bitfield_op, &op_kind, &shift_amount);
shift_amount &= use->GetType() == DataType::Type::kInt32
? kMaxIntShiftDistance
: kMaxLongShiftDistance;
if (HDataProcWithShifterOp::IsExtensionOp(op_kind)) {
if (!use->IsAdd() && (!use->IsSub() || use->GetType() != DataType::Type::kInt64)) {
return false;
}
// Shift by 1 is a special case that results in the same number and type of instructions
// as this simplification, but potentially shorter code.
} else if (type == DataType::Type::kInt64 && shift_amount == 1) {
return false;
}
if (do_merge) {
HDataProcWithShifterOp* alu_with_op =
new (GetGraph()->GetAllocator()) HDataProcWithShifterOp(use,
other_input,
bitfield_op->InputAt(0),
op_kind,
shift_amount,
use->GetDexPc());
use->GetBlock()->ReplaceAndRemoveInstructionWith(use, alu_with_op);
if (bitfield_op->GetUses().empty()) {
bitfield_op->GetBlock()->RemoveInstruction(bitfield_op);
}
RecordSimplification();
}
return true;
}
// Merge a bitfield move instruction into its uses if it can be merged in all of them.
bool InstructionSimplifierArmVisitor::TryMergeIntoUsersShifterOperand(HInstruction* bitfield_op) {
DCHECK(CanFitInShifterOperand(bitfield_op));
if (bitfield_op->HasEnvironmentUses()) {
return false;
}
const HUseList<HInstruction*>& uses = bitfield_op->GetUses();
// Check whether we can merge the instruction in all its users' shifter operand.
for (const HUseListNode<HInstruction*>& use : uses) {
HInstruction* user = use.GetUser();
if (!HasShifterOperand(user, InstructionSet::kArm)) {
return false;
}
if (!CanMergeIntoShifterOperand(user, bitfield_op)) {
return false;
}
}
// Merge the instruction into its uses.
for (auto it = uses.begin(), end = uses.end(); it != end; /* ++it below */) {
HInstruction* user = it->GetUser();
// Increment `it` now because `*it` will disappear thanks to MergeIntoShifterOperand().
++it;
bool merged = MergeIntoShifterOperand(user, bitfield_op);
DCHECK(merged);
}
return true;
}
void InstructionSimplifierArmVisitor::VisitAnd(HAnd* instruction) {
if (TryMergeNegatedInput(instruction)) {
RecordSimplification();
}
}
void InstructionSimplifierArmVisitor::VisitArrayGet(HArrayGet* instruction) {
size_t data_offset = CodeGenerator::GetArrayDataOffset(instruction);
DataType::Type type = instruction->GetType();
// TODO: Implement reading (length + compression) for String compression feature from
// negative offset (count_offset - data_offset). Thumb2Assembler (now removed) did
// not support T4 encoding of "LDR (immediate)", but ArmVIXLMacroAssembler might.
// Don't move array pointer if it is charAt because we need to take the count first.
if (mirror::kUseStringCompression && instruction->IsStringCharAt()) {
return;
}
if (type == DataType::Type::kInt64
|| type == DataType::Type::kFloat32
|| type == DataType::Type::kFloat64) {
// T32 doesn't support ShiftedRegOffset mem address mode for these types
// to enable optimization.
return;
}
if (TryExtractArrayAccessAddress(instruction,
instruction->GetArray(),
instruction->GetIndex(),
data_offset)) {
RecordSimplification();
}
}
void InstructionSimplifierArmVisitor::VisitArraySet(HArraySet* instruction) {
size_t access_size = DataType::Size(instruction->GetComponentType());
size_t data_offset = mirror::Array::DataOffset(access_size).Uint32Value();
DataType::Type type = instruction->GetComponentType();
if (type == DataType::Type::kInt64
|| type == DataType::Type::kFloat32
|| type == DataType::Type::kFloat64) {
// T32 doesn't support ShiftedRegOffset mem address mode for these types
// to enable optimization.
return;
}
if (TryExtractArrayAccessAddress(instruction,
instruction->GetArray(),
instruction->GetIndex(),
data_offset)) {
RecordSimplification();
}
}
void InstructionSimplifierArmVisitor::VisitMul(HMul* instruction) {
if (TryCombineMultiplyAccumulate(instruction, InstructionSet::kArm)) {
RecordSimplification();
}
}
void InstructionSimplifierArmVisitor::VisitOr(HOr* instruction) {
if (TryMergeNegatedInput(instruction)) {
RecordSimplification();
}
}
void InstructionSimplifierArmVisitor::VisitShl(HShl* instruction) {
if (instruction->InputAt(1)->IsConstant()) {
TryMergeIntoUsersShifterOperand(instruction);
}
}
void InstructionSimplifierArmVisitor::VisitShr(HShr* instruction) {
if (instruction->InputAt(1)->IsConstant()) {
TryMergeIntoUsersShifterOperand(instruction);
}
}
void InstructionSimplifierArmVisitor::VisitTypeConversion(HTypeConversion* instruction) {
DataType::Type result_type = instruction->GetResultType();
DataType::Type input_type = instruction->GetInputType();
if (input_type == result_type) {
// We let the arch-independent code handle this.
return;
}
if (DataType::IsIntegralType(result_type) && DataType::IsIntegralType(input_type)) {
TryMergeIntoUsersShifterOperand(instruction);
}
}
void InstructionSimplifierArmVisitor::VisitUShr(HUShr* instruction) {
if (instruction->InputAt(1)->IsConstant()) {
TryMergeIntoUsersShifterOperand(instruction);
}
}
bool InstructionSimplifierArm::Run() {
InstructionSimplifierArmVisitor visitor(graph_, stats_);
visitor.VisitReversePostOrder();
return true;
}
} // namespace arm
} // namespace art