| // 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/fuzzer_pass_construct_composites.h" |
| |
| #include <cmath> |
| #include <memory> |
| |
| #include "source/fuzz/fuzzer_util.h" |
| #include "source/fuzz/transformation_composite_construct.h" |
| #include "source/util/make_unique.h" |
| |
| namespace spvtools { |
| namespace fuzz { |
| |
| FuzzerPassConstructComposites::FuzzerPassConstructComposites( |
| opt::IRContext* ir_context, FactManager* fact_manager, |
| FuzzerContext* fuzzer_context, |
| protobufs::TransformationSequence* transformations) |
| : FuzzerPass(ir_context, fact_manager, fuzzer_context, transformations) {} |
| |
| FuzzerPassConstructComposites::~FuzzerPassConstructComposites() = default; |
| |
| void FuzzerPassConstructComposites::Apply() { |
| // Gather up the ids of all composite types. |
| std::vector<uint32_t> composite_type_ids; |
| for (auto& inst : GetIRContext()->types_values()) { |
| if (fuzzerutil::IsCompositeType( |
| GetIRContext()->get_type_mgr()->GetType(inst.result_id()))) { |
| composite_type_ids.push_back(inst.result_id()); |
| } |
| } |
| |
| ForEachInstructionWithInstructionDescriptor( |
| [this, &composite_type_ids]( |
| opt::Function* function, opt::BasicBlock* block, |
| opt::BasicBlock::iterator inst_it, |
| const protobufs::InstructionDescriptor& instruction_descriptor) |
| -> void { |
| // Check whether it is legitimate to insert a composite construction |
| // before the instruction. |
| if (!fuzzerutil::CanInsertOpcodeBeforeInstruction( |
| SpvOpCompositeConstruct, inst_it)) { |
| return; |
| } |
| |
| // Randomly decide whether to try inserting an object copy here. |
| if (!GetFuzzerContext()->ChoosePercentage( |
| GetFuzzerContext()->GetChanceOfConstructingComposite())) { |
| return; |
| } |
| |
| // For each instruction that is available at this program point (i.e. an |
| // instruction that is global or whose definition strictly dominates the |
| // program point) and suitable for making a synonym of, associate it |
| // with the id of its result type. |
| TypeIdToInstructions type_id_to_available_instructions; |
| for (auto instruction : FindAvailableInstructions( |
| function, block, inst_it, fuzzerutil::CanMakeSynonymOf)) { |
| RecordAvailableInstruction(instruction, |
| &type_id_to_available_instructions); |
| } |
| |
| // At this point, |composite_type_ids| captures all the composite types |
| // we could try to create, while |type_id_to_available_instructions| |
| // captures all the available result ids we might use, organized by |
| // type. |
| |
| // Now we try to find a composite that we can construct. We might not |
| // manage, if there is a paucity of available ingredients in the module |
| // (e.g. if our only available composite was a boolean vector and we had |
| // no instructions generating boolean result types available). |
| // |
| // If we succeed, |chosen_composite_type| will end up being non-zero, |
| // and |constructor_arguments| will end up giving us result ids suitable |
| // for constructing a composite of that type. Otherwise these variables |
| // will remain 0 and null respectively. |
| uint32_t chosen_composite_type = 0; |
| std::unique_ptr<std::vector<uint32_t>> constructor_arguments = nullptr; |
| |
| // Initially, all composite type ids are available for us to try. Keep |
| // trying until we run out of options. |
| auto composites_to_try_constructing = composite_type_ids; |
| while (!composites_to_try_constructing.empty()) { |
| // Remove a composite type from the composite types left for us to |
| // try. |
| auto index = |
| GetFuzzerContext()->RandomIndex(composites_to_try_constructing); |
| auto next_composite_to_try_constructing = |
| composites_to_try_constructing[index]; |
| composites_to_try_constructing.erase( |
| composites_to_try_constructing.begin() + index); |
| |
| // Now try to construct a composite of this type, using an appropriate |
| // helper method depending on the kind of composite type. |
| auto composite_type = GetIRContext()->get_type_mgr()->GetType( |
| next_composite_to_try_constructing); |
| if (auto array_type = composite_type->AsArray()) { |
| constructor_arguments = TryConstructingArrayComposite( |
| *array_type, type_id_to_available_instructions); |
| } else if (auto matrix_type = composite_type->AsMatrix()) { |
| constructor_arguments = TryConstructingMatrixComposite( |
| *matrix_type, type_id_to_available_instructions); |
| } else if (auto struct_type = composite_type->AsStruct()) { |
| constructor_arguments = TryConstructingStructComposite( |
| *struct_type, type_id_to_available_instructions); |
| } else { |
| auto vector_type = composite_type->AsVector(); |
| assert(vector_type && |
| "The space of possible composite types should be covered by " |
| "the above cases."); |
| constructor_arguments = TryConstructingVectorComposite( |
| *vector_type, type_id_to_available_instructions); |
| } |
| if (constructor_arguments != nullptr) { |
| // We succeeded! Note the composite type we finally settled on, and |
| // exit from the loop. |
| chosen_composite_type = next_composite_to_try_constructing; |
| break; |
| } |
| } |
| |
| if (!chosen_composite_type) { |
| // We did not manage to make a composite; return 0 to indicate that no |
| // instructions were added. |
| assert(constructor_arguments == nullptr); |
| return; |
| } |
| assert(constructor_arguments != nullptr); |
| |
| // Make and apply a transformation. |
| TransformationCompositeConstruct transformation( |
| chosen_composite_type, *constructor_arguments, |
| instruction_descriptor, GetFuzzerContext()->GetFreshId()); |
| assert(transformation.IsApplicable(GetIRContext(), *GetFactManager()) && |
| "This transformation should be applicable by construction."); |
| transformation.Apply(GetIRContext(), GetFactManager()); |
| *GetTransformations()->add_transformation() = |
| transformation.ToMessage(); |
| }); |
| } |
| |
| void FuzzerPassConstructComposites::RecordAvailableInstruction( |
| opt::Instruction* inst, |
| TypeIdToInstructions* type_id_to_available_instructions) { |
| if (type_id_to_available_instructions->count(inst->type_id()) == 0) { |
| (*type_id_to_available_instructions)[inst->type_id()] = {}; |
| } |
| type_id_to_available_instructions->at(inst->type_id()).push_back(inst); |
| } |
| |
| std::unique_ptr<std::vector<uint32_t>> |
| FuzzerPassConstructComposites::TryConstructingArrayComposite( |
| const opt::analysis::Array& array_type, |
| const TypeIdToInstructions& type_id_to_available_instructions) { |
| // At present we assume arrays have a constant size. |
| assert(array_type.length_info().words.size() == 2); |
| assert(array_type.length_info().words[0] == |
| opt::analysis::Array::LengthInfo::kConstant); |
| |
| auto result = MakeUnique<std::vector<uint32_t>>(); |
| |
| // Get the element type for the array. |
| auto element_type_id = |
| GetIRContext()->get_type_mgr()->GetId(array_type.element_type()); |
| |
| // Get all instructions at our disposal that compute something of this element |
| // type. |
| auto available_instructions = |
| type_id_to_available_instructions.find(element_type_id); |
| |
| if (available_instructions == type_id_to_available_instructions.cend()) { |
| // If there are not any instructions available that compute the element type |
| // of the array then we are not in a position to construct a composite with |
| // this array type. |
| return nullptr; |
| } |
| for (uint32_t index = 0; index < array_type.length_info().words[1]; index++) { |
| result->push_back(available_instructions |
| ->second[GetFuzzerContext()->RandomIndex( |
| available_instructions->second)] |
| ->result_id()); |
| } |
| return result; |
| } |
| |
| std::unique_ptr<std::vector<uint32_t>> |
| FuzzerPassConstructComposites::TryConstructingMatrixComposite( |
| const opt::analysis::Matrix& matrix_type, |
| const TypeIdToInstructions& type_id_to_available_instructions) { |
| auto result = MakeUnique<std::vector<uint32_t>>(); |
| |
| // Get the element type for the matrix. |
| auto element_type_id = |
| GetIRContext()->get_type_mgr()->GetId(matrix_type.element_type()); |
| |
| // Get all instructions at our disposal that compute something of this element |
| // type. |
| auto available_instructions = |
| type_id_to_available_instructions.find(element_type_id); |
| |
| if (available_instructions == type_id_to_available_instructions.cend()) { |
| // If there are not any instructions available that compute the element type |
| // of the matrix then we are not in a position to construct a composite with |
| // this matrix type. |
| return nullptr; |
| } |
| for (uint32_t index = 0; index < matrix_type.element_count(); index++) { |
| result->push_back(available_instructions |
| ->second[GetFuzzerContext()->RandomIndex( |
| available_instructions->second)] |
| ->result_id()); |
| } |
| return result; |
| } |
| |
| std::unique_ptr<std::vector<uint32_t>> |
| FuzzerPassConstructComposites::TryConstructingStructComposite( |
| const opt::analysis::Struct& struct_type, |
| const TypeIdToInstructions& type_id_to_available_instructions) { |
| auto result = MakeUnique<std::vector<uint32_t>>(); |
| // Consider the type of each field of the struct. |
| for (auto element_type : struct_type.element_types()) { |
| auto element_type_id = GetIRContext()->get_type_mgr()->GetId(element_type); |
| // Find the instructions at our disposal that compute something of the field |
| // type. |
| auto available_instructions = |
| type_id_to_available_instructions.find(element_type_id); |
| if (available_instructions == type_id_to_available_instructions.cend()) { |
| // If there are no such instructions, we cannot construct a composite of |
| // this struct type. |
| return nullptr; |
| } |
| result->push_back(available_instructions |
| ->second[GetFuzzerContext()->RandomIndex( |
| available_instructions->second)] |
| ->result_id()); |
| } |
| return result; |
| } |
| |
| std::unique_ptr<std::vector<uint32_t>> |
| FuzzerPassConstructComposites::TryConstructingVectorComposite( |
| const opt::analysis::Vector& vector_type, |
| const TypeIdToInstructions& type_id_to_available_instructions) { |
| // Get details of the type underlying the vector, and the width of the vector, |
| // for convenience. |
| auto element_type = vector_type.element_type(); |
| auto element_count = vector_type.element_count(); |
| |
| // Collect a mapping, from type id to width, for scalar/vector types that are |
| // smaller in width than |vector_type|, but that have the same underlying |
| // type. For example, if |vector_type| is vec4, the mapping will be: |
| // { float -> 1, vec2 -> 2, vec3 -> 3 } |
| // The mapping will have missing entries if some of these types do not exist. |
| |
| std::map<uint32_t, uint32_t> smaller_vector_type_id_to_width; |
| // Add the underlying type. This id must exist, in order for |vector_type| to |
| // exist. |
| auto scalar_type_id = GetIRContext()->get_type_mgr()->GetId(element_type); |
| smaller_vector_type_id_to_width[scalar_type_id] = 1; |
| |
| // Now add every vector type with width at least 2, and less than the width of |
| // |vector_type|. |
| for (uint32_t width = 2; width < element_count; width++) { |
| opt::analysis::Vector smaller_vector_type(vector_type.element_type(), |
| width); |
| auto smaller_vector_type_id = |
| GetIRContext()->get_type_mgr()->GetId(&smaller_vector_type); |
| // We might find that there is no declared type of this smaller width. |
| // For example, a module can declare vec4 without having declared vec2 or |
| // vec3. |
| if (smaller_vector_type_id) { |
| smaller_vector_type_id_to_width[smaller_vector_type_id] = width; |
| } |
| } |
| |
| // Now we know the types that are available to us, we set about populating a |
| // vector of the right length. We do this by deciding, with no order in mind, |
| // which instructions we will use to populate the vector, and subsequently |
| // randomly choosing an order. This is to avoid biasing construction of |
| // vectors with smaller vectors to the left and scalars to the right. That is |
| // a concern because, e.g. in the case of populating a vec4, if we populate |
| // the constructor instructions left-to-right, we can always choose a vec3 to |
| // construct the first three elements, but can only choose a vec3 to construct |
| // the last three elements if we chose a float to construct the first element |
| // (otherwise there will not be space left for a vec3). |
| |
| uint32_t vector_slots_used = 0; |
| // The instructions we will use to construct the vector, in no particular |
| // order at this stage. |
| std::vector<opt::Instruction*> instructions_to_use; |
| |
| while (vector_slots_used < vector_type.element_count()) { |
| std::vector<opt::Instruction*> instructions_to_choose_from; |
| for (auto& entry : smaller_vector_type_id_to_width) { |
| if (entry.second > |
| std::min(vector_type.element_count() - 1, |
| vector_type.element_count() - vector_slots_used)) { |
| continue; |
| } |
| auto available_instructions = |
| type_id_to_available_instructions.find(entry.first); |
| if (available_instructions == type_id_to_available_instructions.cend()) { |
| continue; |
| } |
| instructions_to_choose_from.insert(instructions_to_choose_from.end(), |
| available_instructions->second.begin(), |
| available_instructions->second.end()); |
| } |
| if (instructions_to_choose_from.empty()) { |
| // We may get unlucky and find that there are not any instructions to |
| // choose from. In this case we give up constructing a composite of this |
| // vector type. It might be that we could construct the composite in |
| // another manner, so we could opt to retry a few times here, but it is |
| // simpler to just give up on the basis that this will not happen |
| // frequently. |
| return nullptr; |
| } |
| auto instruction_to_use = |
| instructions_to_choose_from[GetFuzzerContext()->RandomIndex( |
| instructions_to_choose_from)]; |
| instructions_to_use.push_back(instruction_to_use); |
| auto chosen_type = |
| GetIRContext()->get_type_mgr()->GetType(instruction_to_use->type_id()); |
| if (chosen_type->AsVector()) { |
| assert(chosen_type->AsVector()->element_type() == element_type); |
| assert(chosen_type->AsVector()->element_count() < element_count); |
| assert(chosen_type->AsVector()->element_count() <= |
| element_count - vector_slots_used); |
| vector_slots_used += chosen_type->AsVector()->element_count(); |
| } else { |
| assert(chosen_type == element_type); |
| vector_slots_used += 1; |
| } |
| } |
| assert(vector_slots_used == vector_type.element_count()); |
| |
| auto result = MakeUnique<std::vector<uint32_t>>(); |
| std::vector<uint32_t> operands; |
| while (!instructions_to_use.empty()) { |
| auto index = GetFuzzerContext()->RandomIndex(instructions_to_use); |
| result->push_back(instructions_to_use[index]->result_id()); |
| instructions_to_use.erase(instructions_to_use.begin() + index); |
| } |
| assert(result->size() > 1); |
| return result; |
| } |
| |
| } // namespace fuzz |
| } // namespace spvtools |