source/fuzz/transformation_composite_extract.cpp

// Copyright (c) 2019 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
//
//     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 "source/fuzz/transformation_composite_extract.h"

#include <vector>

#include "source/fuzz/data_descriptor.h"
#include "source/fuzz/fuzzer_util.h"
#include "source/fuzz/instruction_descriptor.h"

namespace spvtools {
namespace fuzz {

TransformationCompositeExtract::TransformationCompositeExtract(
    const spvtools::fuzz::protobufs::TransformationCompositeExtract& message)
    : message_(message) {}

TransformationCompositeExtract::TransformationCompositeExtract(
    const protobufs::InstructionDescriptor& instruction_to_insert_before,
    uint32_t fresh_id, uint32_t composite_id,
    const std::vector<uint32_t>& index) {
  *message_.mutable_instruction_to_insert_before() =
      instruction_to_insert_before;
  message_.set_fresh_id(fresh_id);
  message_.set_composite_id(composite_id);
  for (auto an_index : index) {
    message_.add_index(an_index);
  }
}

bool TransformationCompositeExtract::IsApplicable(
    opt::IRContext* ir_context, const TransformationContext& /*unused*/) const {
  if (!fuzzerutil::IsFreshId(ir_context, message_.fresh_id())) {
    return false;
  }
  auto instruction_to_insert_before =
      FindInstruction(message_.instruction_to_insert_before(), ir_context);
  if (!instruction_to_insert_before) {
    return false;
  }
  auto composite_instruction =
      ir_context->get_def_use_mgr()->GetDef(message_.composite_id());
  if (!composite_instruction) {
    return false;
  }
  if (auto block = ir_context->get_instr_block(composite_instruction)) {
    if (composite_instruction == instruction_to_insert_before ||
        !ir_context->GetDominatorAnalysis(block->GetParent())
             ->Dominates(composite_instruction, instruction_to_insert_before)) {
      return false;
    }
  }
  assert(composite_instruction->type_id() &&
         "An instruction in a block cannot have a result id but no type id.");

  auto composite_type =
      ir_context->get_type_mgr()->GetType(composite_instruction->type_id());
  if (!composite_type) {
    return false;
  }

  if (!fuzzerutil::CanInsertOpcodeBeforeInstruction(
          SpvOpCompositeExtract, instruction_to_insert_before)) {
    return false;
  }

  return fuzzerutil::WalkCompositeTypeIndices(ir_context,
                                              composite_instruction->type_id(),
                                              message_.index()) != 0;
}

void TransformationCompositeExtract::Apply(
    opt::IRContext* ir_context,
    TransformationContext* transformation_context) const {
  opt::Instruction::OperandList extract_operands;
  extract_operands.push_back({SPV_OPERAND_TYPE_ID, {message_.composite_id()}});
  for (auto an_index : message_.index()) {
    extract_operands.push_back({SPV_OPERAND_TYPE_LITERAL_INTEGER, {an_index}});
  }
  auto composite_instruction =
      ir_context->get_def_use_mgr()->GetDef(message_.composite_id());
  auto extracted_type = fuzzerutil::WalkCompositeTypeIndices(
      ir_context, composite_instruction->type_id(), message_.index());

  FindInstruction(message_.instruction_to_insert_before(), ir_context)
      ->InsertBefore(MakeUnique<opt::Instruction>(
          ir_context, SpvOpCompositeExtract, extracted_type,
          message_.fresh_id(), extract_operands));

  fuzzerutil::UpdateModuleIdBound(ir_context, message_.fresh_id());

  ir_context->InvalidateAnalysesExceptFor(
      opt::IRContext::Analysis::kAnalysisNone);

  AddDataSynonymFacts(ir_context, transformation_context);
}

protobufs::Transformation TransformationCompositeExtract::ToMessage() const {
  protobufs::Transformation result;
  *result.mutable_composite_extract() = message_;
  return result;
}

std::unordered_set<uint32_t> TransformationCompositeExtract::GetFreshIds()
    const {
  return {message_.fresh_id()};
}

void TransformationCompositeExtract::AddDataSynonymFacts(
    opt::IRContext* ir_context,
    TransformationContext* transformation_context) const {
  // Don't add synonyms if the composite being extracted from is not suitable,
  // or if the result id into which we are extracting is irrelevant.
  if (!fuzzerutil::CanMakeSynonymOf(
          ir_context, *transformation_context,
          ir_context->get_def_use_mgr()->GetDef(message_.composite_id())) ||
      transformation_context->GetFactManager()->IdIsIrrelevant(
          message_.fresh_id())) {
    return;
  }

  // Add the fact that the id storing the extracted element is synonymous with
  // the index into the structure.
  if (!transformation_context->GetFactManager()->IdIsIrrelevant(
          message_.composite_id())) {
    std::vector<uint32_t> indices;
    for (auto an_index : message_.index()) {
      indices.push_back(an_index);
    }
    protobufs::DataDescriptor data_descriptor_for_extracted_element =
        MakeDataDescriptor(message_.composite_id(), indices);
    protobufs::DataDescriptor data_descriptor_for_result_id =
        MakeDataDescriptor(message_.fresh_id(), {});
    transformation_context->GetFactManager()->AddFactDataSynonym(
        data_descriptor_for_extracted_element, data_descriptor_for_result_id);
  }
}

}  // namespace fuzz
}  // namespace spvtools