basic_block.cc

// Copyright 2011-2024 Google LLC
//
// 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
//
//     https://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 "third_party/zynamics/binexport/basic_block.h"

#include <ostream>
#include <utility>

#include "third_party/zynamics/binexport/call_graph.h"
#include "third_party/zynamics/binexport/util/format.h"

using security::binexport::FormatAddress;

thread_local BasicBlock::Cache BasicBlock::cache_;

void BasicBlockInstructions::AddInstruction(
    Instructions::iterator instruction) {
  auto last_range = ranges_.end();
  if (last_range != ranges_.begin() && instruction == (--last_range)->end()) {
    *last_range = InstructionRange(last_range->begin(), last_range->end() + 1);
  } else {
    ranges_.emplace_back(instruction, instruction + 1);
  }
}

BasicBlock* BasicBlock::Create(BasicBlockInstructions* instructions) {
  using Iterator = NestedIterator<
      typename BasicBlockInstructions::InstructionRanges::const_iterator>;

  auto ranges_end = instructions->ranges_.end();
  Iterator instruction_first(instructions->ranges_.begin(), ranges_end);
  if (instruction_first == Iterator(ranges_end)) {
    return nullptr;
  }

  // Create the BasicBlock later if one does not exist here already.
  auto [entry, found] = cache_.emplace(instruction_first->GetAddress(),
                                       nullptr /* no BasicBlock */);
  if (!found) {
    return nullptr;
  }

  auto& ptr = entry->second;
  ptr.reset(new BasicBlock(instructions));
  instructions->Clear();
  return ptr.get();
}

void BasicBlock::Render(std::ostream* stream, const CallGraph& call_graph,
                        const FlowGraph& flow_graph) const {
  for (const auto& instruction : *this) {
    *stream << FormatAddress(instruction.GetAddress()) << " ";
    instruction.Render(stream, flow_graph);
    std::pair<Comments::const_iterator, Comments::const_iterator> comments =
        call_graph.GetComments(instruction.GetAddress());
    if (comments.first != comments.second) {
      for (; comments.first != comments.second; ++comments.first) {
        *stream << "  // " << *comments.first->comment << "\n";
      }
    } else {
      *stream << std::endl;
    }
  }
}

int BasicBlock::GetInstructionCount() const {
  int count = 0;
  for (const auto& r : ranges_) {
    count += r.size();
  }
  return count;
}

BasicBlock::InstructionConstIterator BasicBlock::GetInstruction(
    Address address) const {
  // This is O(n) on ranges, however there should be only one range usually.
  for (auto range = ranges_.begin(), ranges_end = ranges_.end();
       range != ranges_end; ++range) {
    if (address >= range->begin()->GetAddress() &&
        address <= (range->end() - 1)->GetAddress()) {
      auto it(::GetInstructionFromRange(*range, address));
      if (it != range->end()) {
        assert(address == it->GetAddress());
        return InstructionConstIterator(range, ranges_end, it);
      }
    }
  }
  return end();
}

BasicBlock::RangeConstIterator BasicBlock::BeforeEndRange() const {
  auto last = ranges_.before_begin();
  // This is O(n) on ranges, however there should be only one range usually.
  for (auto range(ranges_.begin()), ranges_end(ranges_.end());
       range != ranges_end; ++range) {
    ++last;
  }
  return last;
}