compiler/optimizing/instruction_simplifier_arm.cc - platform/art - Git at Google

 /*
  * 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;
   }

   // TODO: Support intermediate address for object arrays on arm.
   if (type == DataType::Type::kReference) {
     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
	/*
	* 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;
	}

	// TODO: Support intermediate address for object arrays on arm.
	if (type == DataType::Type::kReference) {
	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