compiler/optimizing/builder.cc - SHIFTPHONES/android_art - Gitiles

 /*
  *
  * Copyright (C) 2014 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 "dex_file.h"
 #include "dex_file-inl.h"
 #include "dex_instruction.h"
 #include "dex_instruction-inl.h"
 #include "builder.h"
 #include "nodes.h"
 #include "primitive.h"

 namespace art {

 void HGraphBuilder::InitializeLocals(int count) {
   locals_.SetSize(count);
   for (int i = 0; i < count; i++) {
     HLocal* local = new (arena_) HLocal(i);
     entry_block_->AddInstruction(local);
     locals_.Put(i, local);
   }
 }

 static bool CanHandleCodeItem(const DexFile::CodeItem& code_item) {
   if (code_item.tries_size_ > 0) {
     return false;
   } else if (code_item.outs_size_ > 0) {
     return false;
   } else if (code_item.ins_size_ > 0) {
     return false;
   }
   return true;
 }

 HGraph* HGraphBuilder::BuildGraph(const DexFile::CodeItem& code_item) {
   if (!CanHandleCodeItem(code_item)) {
     return nullptr;
   }

   const uint16_t* code_ptr = code_item.insns_;
   const uint16_t* code_end = code_item.insns_ + code_item.insns_size_in_code_units_;

   // Setup the graph with the entry block and exit block.
   graph_ = new (arena_) HGraph(arena_);
   entry_block_ = new (arena_) HBasicBlock(graph_);
   graph_->AddBlock(entry_block_);
   exit_block_ = new (arena_) HBasicBlock(graph_);
   graph_->SetEntryBlock(entry_block_);
   graph_->SetExitBlock(exit_block_);

   InitializeLocals(code_item.registers_size_);

   // To avoid splitting blocks, we compute ahead of time the instructions that
   // start a new block, and create these blocks.
   ComputeBranchTargets(code_ptr, code_end);

   size_t dex_offset = 0;
   while (code_ptr < code_end) {
     // Update the current block if dex_offset starts a new block.
     MaybeUpdateCurrentBlock(dex_offset);
     const Instruction& instruction = *Instruction::At(code_ptr);
     if (!AnalyzeDexInstruction(instruction, dex_offset)) return nullptr;
     dex_offset += instruction.SizeInCodeUnits();
     code_ptr += instruction.SizeInCodeUnits();
   }

   // Add the exit block at the end to give it the highest id.
   graph_->AddBlock(exit_block_);
   exit_block_->AddInstruction(new (arena_) HExit());
   entry_block_->AddInstruction(new (arena_) HGoto());
   return graph_;
 }

 void HGraphBuilder::MaybeUpdateCurrentBlock(size_t index) {
   HBasicBlock* block = FindBlockStartingAt(index);
   if (block == nullptr) {
     return;
   }

   if (current_block_ != nullptr) {
     // Branching instructions clear current_block, so we know
     // the last instruction of the current block is not a branching
     // instruction. We add an unconditional goto to the found block.
     current_block_->AddInstruction(new (arena_) HGoto());
     current_block_->AddSuccessor(block);
   }
   graph_->AddBlock(block);
   current_block_ = block;
 }

 void HGraphBuilder::ComputeBranchTargets(const uint16_t* code_ptr, const uint16_t* code_end) {
   // TODO: Support switch instructions.
   branch_targets_.SetSize(code_end - code_ptr);

   // Create the first block for the dex instructions, single successor of the entry block.
   HBasicBlock* block = new (arena_) HBasicBlock(graph_);
   branch_targets_.Put(0, block);
   entry_block_->AddSuccessor(block);

   // Iterate over all instructions and find branching instructions. Create blocks for
   // the locations these instructions branch to.
   size_t dex_offset = 0;
   while (code_ptr < code_end) {
     const Instruction& instruction = *Instruction::At(code_ptr);
     if (instruction.IsBranch()) {
       int32_t target = instruction.GetTargetOffset() + dex_offset;
       // Create a block for the target instruction.
       if (FindBlockStartingAt(target) == nullptr) {
         block = new (arena_) HBasicBlock(graph_);
         branch_targets_.Put(target, block);
       }
       dex_offset += instruction.SizeInCodeUnits();
       code_ptr += instruction.SizeInCodeUnits();
       if ((code_ptr < code_end) && (FindBlockStartingAt(dex_offset) == nullptr)) {
         block = new (arena_) HBasicBlock(graph_);
         branch_targets_.Put(dex_offset, block);
       }
     } else {
       code_ptr += instruction.SizeInCodeUnits();
       dex_offset += instruction.SizeInCodeUnits();
     }
   }
 }

 HBasicBlock* HGraphBuilder::FindBlockStartingAt(int32_t index) const {
   DCHECK_GE(index, 0);
   return branch_targets_.Get(index);
 }

 bool HGraphBuilder::AnalyzeDexInstruction(const Instruction& instruction, int32_t dex_offset) {
   if (current_block_ == nullptr) {
     return true;  // Dead code
   }

   switch (instruction.Opcode()) {
     case Instruction::CONST_4: {
       int32_t register_index = instruction.VRegA();
       HIntConstant* constant = GetConstant(instruction.VRegB_11n());
       UpdateLocal(register_index, constant);
       break;
     }

     case Instruction::RETURN_VOID: {
       current_block_->AddInstruction(new (arena_) HReturnVoid());
       current_block_->AddSuccessor(exit_block_);
       current_block_ = nullptr;
       break;
     }

     case Instruction::IF_EQ: {
       HInstruction* first = LoadLocal(instruction.VRegA());
       HInstruction* second = LoadLocal(instruction.VRegB());
       current_block_->AddInstruction(new (arena_) HEqual(first, second));
       current_block_->AddInstruction(new (arena_) HIf(current_block_->GetLastInstruction()));
       HBasicBlock* target = FindBlockStartingAt(instruction.GetTargetOffset() + dex_offset);
       DCHECK(target != nullptr);
       current_block_->AddSuccessor(target);
       target = FindBlockStartingAt(dex_offset + instruction.SizeInCodeUnits());
       DCHECK(target != nullptr);
       current_block_->AddSuccessor(target);
       current_block_ = nullptr;
       break;
     }

     case Instruction::GOTO:
     case Instruction::GOTO_16:
     case Instruction::GOTO_32: {
       HBasicBlock* target = FindBlockStartingAt(instruction.GetTargetOffset() + dex_offset);
       DCHECK(target != nullptr);
       current_block_->AddInstruction(new (arena_) HGoto());
       current_block_->AddSuccessor(target);
       current_block_ = nullptr;
       break;
     }

     case Instruction::RETURN: {
       HInstruction* value = LoadLocal(instruction.VRegA());
       current_block_->AddInstruction(new (arena_) HReturn(value));
       current_block_->AddSuccessor(exit_block_);
       current_block_ = nullptr;
       break;
     }

     case Instruction::INVOKE_STATIC: {
       uint32_t method_idx = instruction.VRegB_35c();
       const DexFile::MethodId& method_id = dex_file_->GetMethodId(method_idx);
       uint32_t return_type_idx = dex_file_->GetProtoId(method_id.proto_idx_).return_type_idx_;
       const char* descriptor = dex_file_->StringByTypeIdx(return_type_idx);
       const size_t number_of_arguments = instruction.VRegA_35c();
       if (number_of_arguments != 0) {
         return false;
       }
       if (Primitive::GetType(descriptor[0]) != Primitive::kPrimVoid) {
         return false;
       }
       current_block_->AddInstruction(new (arena_) HInvokeStatic(
           arena_, number_of_arguments, dex_offset, method_idx));
       break;
     }

     case Instruction::NOP:
       break;

     default:
       return false;
   }
   return true;
 }

 HIntConstant* HGraphBuilder::GetConstant0() {
   if (constant0_ != nullptr) {
     return constant0_;
   }
   constant0_ = new(arena_) HIntConstant(0);
   entry_block_->AddInstruction(constant0_);
   return constant0_;
 }

 HIntConstant* HGraphBuilder::GetConstant1() {
   if (constant1_ != nullptr) {
     return constant1_;
   }
   constant1_ = new(arena_) HIntConstant(1);
   entry_block_->AddInstruction(constant1_);
   return constant1_;
 }

 HIntConstant* HGraphBuilder::GetConstant(int constant) {
   switch (constant) {
     case 0: return GetConstant0();
     case 1: return GetConstant1();
     default: {
       HIntConstant* instruction = new (arena_) HIntConstant(constant);
       entry_block_->AddInstruction(instruction);
       return instruction;
     }
   }
 }

 HLocal* HGraphBuilder::GetLocalAt(int register_index) const {
   return locals_.Get(register_index);
 }

 void HGraphBuilder::UpdateLocal(int register_index, HInstruction* instruction) const {
   HLocal* local = GetLocalAt(register_index);
   current_block_->AddInstruction(new (arena_) HStoreLocal(local, instruction));
 }

 HInstruction* HGraphBuilder::LoadLocal(int register_index) const {
   HLocal* local = GetLocalAt(register_index);
   current_block_->AddInstruction(new (arena_) HLoadLocal(local));
   return current_block_->GetLastInstruction();
 }

 }  // namespace art
	/*
	*
	* Copyright (C) 2014 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 "dex_file.h"
	#include "dex_file-inl.h"
	#include "dex_instruction.h"
	#include "dex_instruction-inl.h"
	#include "builder.h"
	#include "nodes.h"
	#include "primitive.h"

	namespace art {

	void HGraphBuilder::InitializeLocals(int count) {
	locals_.SetSize(count);
	for (int i = 0; i < count; i++) {
	HLocal* local = new (arena_) HLocal(i);
	entry_block_->AddInstruction(local);
	locals_.Put(i, local);
	}
	}

	static bool CanHandleCodeItem(const DexFile::CodeItem& code_item) {
	if (code_item.tries_size_ > 0) {
	return false;
	} else if (code_item.outs_size_ > 0) {
	return false;
	} else if (code_item.ins_size_ > 0) {
	return false;
	}
	return true;
	}

	HGraph* HGraphBuilder::BuildGraph(const DexFile::CodeItem& code_item) {
	if (!CanHandleCodeItem(code_item)) {
	return nullptr;
	}

	const uint16_t* code_ptr = code_item.insns_;
	const uint16_t* code_end = code_item.insns_ + code_item.insns_size_in_code_units_;

	// Setup the graph with the entry block and exit block.
	graph_ = new (arena_) HGraph(arena_);
	entry_block_ = new (arena_) HBasicBlock(graph_);
	graph_->AddBlock(entry_block_);
	exit_block_ = new (arena_) HBasicBlock(graph_);
	graph_->SetEntryBlock(entry_block_);
	graph_->SetExitBlock(exit_block_);

	InitializeLocals(code_item.registers_size_);

	// To avoid splitting blocks, we compute ahead of time the instructions that
	// start a new block, and create these blocks.
	ComputeBranchTargets(code_ptr, code_end);

	size_t dex_offset = 0;
	while (code_ptr < code_end) {
	// Update the current block if dex_offset starts a new block.
	MaybeUpdateCurrentBlock(dex_offset);
	const Instruction& instruction = *Instruction::At(code_ptr);
	if (!AnalyzeDexInstruction(instruction, dex_offset)) return nullptr;
	dex_offset += instruction.SizeInCodeUnits();
	code_ptr += instruction.SizeInCodeUnits();
	}

	// Add the exit block at the end to give it the highest id.
	graph_->AddBlock(exit_block_);
	exit_block_->AddInstruction(new (arena_) HExit());
	entry_block_->AddInstruction(new (arena_) HGoto());
	return graph_;
	}

	void HGraphBuilder::MaybeUpdateCurrentBlock(size_t index) {
	HBasicBlock* block = FindBlockStartingAt(index);
	if (block == nullptr) {
	return;
	}

	if (current_block_ != nullptr) {
	// Branching instructions clear current_block, so we know
	// the last instruction of the current block is not a branching
	// instruction. We add an unconditional goto to the found block.
	current_block_->AddInstruction(new (arena_) HGoto());
	current_block_->AddSuccessor(block);
	}
	graph_->AddBlock(block);
	current_block_ = block;
	}

	void HGraphBuilder::ComputeBranchTargets(const uint16_t* code_ptr, const uint16_t* code_end) {
	// TODO: Support switch instructions.
	branch_targets_.SetSize(code_end - code_ptr);

	// Create the first block for the dex instructions, single successor of the entry block.
	HBasicBlock* block = new (arena_) HBasicBlock(graph_);
	branch_targets_.Put(0, block);
	entry_block_->AddSuccessor(block);

	// Iterate over all instructions and find branching instructions. Create blocks for
	// the locations these instructions branch to.
	size_t dex_offset = 0;
	while (code_ptr < code_end) {
	const Instruction& instruction = *Instruction::At(code_ptr);
	if (instruction.IsBranch()) {
	int32_t target = instruction.GetTargetOffset() + dex_offset;
	// Create a block for the target instruction.
	if (FindBlockStartingAt(target) == nullptr) {
	block = new (arena_) HBasicBlock(graph_);
	branch_targets_.Put(target, block);
	}
	dex_offset += instruction.SizeInCodeUnits();
	code_ptr += instruction.SizeInCodeUnits();
	if ((code_ptr < code_end) && (FindBlockStartingAt(dex_offset) == nullptr)) {
	block = new (arena_) HBasicBlock(graph_);
	branch_targets_.Put(dex_offset, block);
	}
	} else {
	code_ptr += instruction.SizeInCodeUnits();
	dex_offset += instruction.SizeInCodeUnits();
	}
	}
	}

	HBasicBlock* HGraphBuilder::FindBlockStartingAt(int32_t index) const {
	DCHECK_GE(index, 0);
	return branch_targets_.Get(index);
	}

	bool HGraphBuilder::AnalyzeDexInstruction(const Instruction& instruction, int32_t dex_offset) {
	if (current_block_ == nullptr) {
	return true; // Dead code
	}

	switch (instruction.Opcode()) {
	case Instruction::CONST_4: {
	int32_t register_index = instruction.VRegA();
	HIntConstant* constant = GetConstant(instruction.VRegB_11n());
	UpdateLocal(register_index, constant);
	break;
	}

	case Instruction::RETURN_VOID: {
	current_block_->AddInstruction(new (arena_) HReturnVoid());
	current_block_->AddSuccessor(exit_block_);
	current_block_ = nullptr;
	break;
	}

	case Instruction::IF_EQ: {
	HInstruction* first = LoadLocal(instruction.VRegA());
	HInstruction* second = LoadLocal(instruction.VRegB());
	current_block_->AddInstruction(new (arena_) HEqual(first, second));
	current_block_->AddInstruction(new (arena_) HIf(current_block_->GetLastInstruction()));
	HBasicBlock* target = FindBlockStartingAt(instruction.GetTargetOffset() + dex_offset);
	DCHECK(target != nullptr);
	current_block_->AddSuccessor(target);
	target = FindBlockStartingAt(dex_offset + instruction.SizeInCodeUnits());
	DCHECK(target != nullptr);
	current_block_->AddSuccessor(target);
	current_block_ = nullptr;
	break;
	}

	case Instruction::GOTO:
	case Instruction::GOTO_16:
	case Instruction::GOTO_32: {
	HBasicBlock* target = FindBlockStartingAt(instruction.GetTargetOffset() + dex_offset);
	DCHECK(target != nullptr);
	current_block_->AddInstruction(new (arena_) HGoto());
	current_block_->AddSuccessor(target);
	current_block_ = nullptr;
	break;
	}

	case Instruction::RETURN: {
	HInstruction* value = LoadLocal(instruction.VRegA());
	current_block_->AddInstruction(new (arena_) HReturn(value));
	current_block_->AddSuccessor(exit_block_);
	current_block_ = nullptr;
	break;
	}

	case Instruction::INVOKE_STATIC: {
	uint32_t method_idx = instruction.VRegB_35c();
	const DexFile::MethodId& method_id = dex_file_->GetMethodId(method_idx);
	uint32_t return_type_idx = dex_file_->GetProtoId(method_id.proto_idx_).return_type_idx_;
	const char* descriptor = dex_file_->StringByTypeIdx(return_type_idx);
	const size_t number_of_arguments = instruction.VRegA_35c();
	if (number_of_arguments != 0) {
	return false;
	}
	if (Primitive::GetType(descriptor[0]) != Primitive::kPrimVoid) {
	return false;
	}
	current_block_->AddInstruction(new (arena_) HInvokeStatic(
	arena_, number_of_arguments, dex_offset, method_idx));
	break;
	}

	case Instruction::NOP:
	break;

	default:
	return false;
	}
	return true;
	}

	HIntConstant* HGraphBuilder::GetConstant0() {
	if (constant0_ != nullptr) {
	return constant0_;
	}
	constant0_ = new(arena_) HIntConstant(0);
	entry_block_->AddInstruction(constant0_);
	return constant0_;
	}

	HIntConstant* HGraphBuilder::GetConstant1() {
	if (constant1_ != nullptr) {
	return constant1_;
	}
	constant1_ = new(arena_) HIntConstant(1);
	entry_block_->AddInstruction(constant1_);
	return constant1_;
	}

	HIntConstant* HGraphBuilder::GetConstant(int constant) {
	switch (constant) {
	case 0: return GetConstant0();
	case 1: return GetConstant1();
	default: {
	HIntConstant* instruction = new (arena_) HIntConstant(constant);
	entry_block_->AddInstruction(instruction);
	return instruction;
	}
	}
	}

	HLocal* HGraphBuilder::GetLocalAt(int register_index) const {
	return locals_.Get(register_index);
	}

	void HGraphBuilder::UpdateLocal(int register_index, HInstruction* instruction) const {
	HLocal* local = GetLocalAt(register_index);
	current_block_->AddInstruction(new (arena_) HStoreLocal(local, instruction));
	}

	HInstruction* HGraphBuilder::LoadLocal(int register_index) const {
	HLocal* local = GetLocalAt(register_index);
	current_block_->AddInstruction(new (arena_) HLoadLocal(local));
	return current_block_->GetLastInstruction();
	}

	} // namespace art