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/*
* 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 "graph_checker.h"
#include <string>
#include <map>
#include <sstream>
namespace art {
void GraphChecker::VisitBasicBlock(HBasicBlock* block) {
current_block_ = block;
// Check consistency with respect to predecessors of `block`.
const GrowableArray<HBasicBlock*>& predecessors = block->GetPredecessors();
std::map<HBasicBlock*, size_t> predecessors_count;
for (size_t i = 0, e = predecessors.Size(); i < e; ++i) {
HBasicBlock* p = predecessors.Get(i);
++predecessors_count[p];
}
for (auto& pc : predecessors_count) {
HBasicBlock* p = pc.first;
size_t p_count_in_block_predecessors = pc.second;
const GrowableArray<HBasicBlock*>& p_successors = p->GetSuccessors();
size_t block_count_in_p_successors = 0;
for (size_t j = 0, f = p_successors.Size(); j < f; ++j) {
if (p_successors.Get(j) == block) {
++block_count_in_p_successors;
}
}
if (p_count_in_block_predecessors != block_count_in_p_successors) {
std::stringstream error;
error << "Block " << block->GetBlockId()
<< " lists " << p_count_in_block_predecessors
<< " occurrences of block " << p->GetBlockId()
<< " in its predecessors, whereas block " << p->GetBlockId()
<< " lists " << block_count_in_p_successors
<< " occurrences of block " << block->GetBlockId()
<< " in its successors.";
errors_.Insert(error.str());
}
}
// Check consistency with respect to successors of `block`.
const GrowableArray<HBasicBlock*>& successors = block->GetSuccessors();
std::map<HBasicBlock*, size_t> successors_count;
for (size_t i = 0, e = successors.Size(); i < e; ++i) {
HBasicBlock* s = successors.Get(i);
++successors_count[s];
}
for (auto& sc : successors_count) {
HBasicBlock* s = sc.first;
size_t s_count_in_block_successors = sc.second;
const GrowableArray<HBasicBlock*>& s_predecessors = s->GetPredecessors();
size_t block_count_in_s_predecessors = 0;
for (size_t j = 0, f = s_predecessors.Size(); j < f; ++j) {
if (s_predecessors.Get(j) == block) {
++block_count_in_s_predecessors;
}
}
if (s_count_in_block_successors != block_count_in_s_predecessors) {
std::stringstream error;
error << "Block " << block->GetBlockId()
<< " lists " << s_count_in_block_successors
<< " occurrences of block " << s->GetBlockId()
<< " in its successors, whereas block " << s->GetBlockId()
<< " lists " << block_count_in_s_predecessors
<< " occurrences of block " << block->GetBlockId()
<< " in its predecessors.";
errors_.Insert(error.str());
}
}
// Ensure `block` ends with a branch instruction.
HInstruction* last_inst = block->GetLastInstruction();
if (last_inst == nullptr || !last_inst->IsControlFlow()) {
std::stringstream error;
error << "Block " << block->GetBlockId()
<< " does not end with a branch instruction.";
errors_.Insert(error.str());
}
// Visit this block's list of phis.
for (HInstructionIterator it(block->GetPhis()); !it.Done(); it.Advance()) {
// Ensure this block's list of phis contains only phis.
if (!it.Current()->IsPhi()) {
std::stringstream error;
error << "Block " << current_block_->GetBlockId()
<< " has a non-phi in its phi list.";
errors_.Insert(error.str());
}
it.Current()->Accept(this);
}
// Visit this block's list of instructions.
for (HInstructionIterator it(block->GetInstructions()); !it.Done();
it.Advance()) {
// Ensure this block's list of instructions does not contains phis.
if (it.Current()->IsPhi()) {
std::stringstream error;
error << "Block " << current_block_->GetBlockId()
<< " has a phi in its non-phi list.";
errors_.Insert(error.str());
}
it.Current()->Accept(this);
}
}
void GraphChecker::VisitInstruction(HInstruction* instruction) {
// Ensure `instruction` is associated with `current_block_`.
if (instruction->GetBlock() != current_block_) {
std::stringstream error;
if (instruction->IsPhi()) {
error << "Phi ";
} else {
error << "Instruction ";
}
error << instruction->GetId() << " in block "
<< current_block_->GetBlockId();
if (instruction->GetBlock() != nullptr) {
error << " associated with block "
<< instruction->GetBlock()->GetBlockId() << ".";
} else {
error << " not associated with any block.";
}
errors_.Insert(error.str());
}
}
void SSAChecker::VisitBasicBlock(HBasicBlock* block) {
super_type::VisitBasicBlock(block);
// Ensure there is no critical edge (i.e., an edge connecting a
// block with multiple successors to a block with multiple
// predecessors).
if (block->GetSuccessors().Size() > 1) {
for (size_t j = 0; j < block->GetSuccessors().Size(); ++j) {
HBasicBlock* successor = block->GetSuccessors().Get(j);
if (successor->GetPredecessors().Size() > 1) {
std::stringstream error;
error << "Critical edge between blocks " << block->GetBlockId()
<< " and " << successor->GetBlockId() << ".";
errors_.Insert(error.str());
}
}
}
}
void SSAChecker::VisitInstruction(HInstruction* instruction) {
super_type::VisitInstruction(instruction);
// Ensure an instruction dominates all its uses (or in the present
// case, that all uses of an instruction (used as input) are
// dominated by its definition).
for (HInputIterator input_it(instruction); !input_it.Done();
input_it.Advance()) {
HInstruction* input = input_it.Current();
if (!input->Dominates(instruction)) {
std::stringstream error;
error << "Instruction " << input->GetId()
<< " in block " << input->GetBlock()->GetBlockId()
<< " does not dominate use " << instruction->GetId()
<< " in block " << current_block_->GetBlockId() << ".";
errors_.Insert(error.str());
}
}
}
} // namespace art
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