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// 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_apply_id_synonyms.h"
#include "source/fuzz/data_descriptor.h"
#include "source/fuzz/fuzzer_util.h"
#include "source/fuzz/id_use_descriptor.h"
#include "source/fuzz/instruction_descriptor.h"
#include "source/fuzz/transformation_composite_extract.h"
#include "source/fuzz/transformation_compute_data_synonym_fact_closure.h"
#include "source/fuzz/transformation_replace_id_with_synonym.h"
namespace spvtools {
namespace fuzz {
FuzzerPassApplyIdSynonyms::FuzzerPassApplyIdSynonyms(
opt::IRContext* ir_context, TransformationContext* transformation_context,
FuzzerContext* fuzzer_context,
protobufs::TransformationSequence* transformations,
bool ignore_inapplicable_transformations)
: FuzzerPass(ir_context, transformation_context, fuzzer_context,
transformations, ignore_inapplicable_transformations) {}
void FuzzerPassApplyIdSynonyms::Apply() {
// Compute a closure of data synonym facts, to enrich the pool of synonyms
// that are available.
ApplyTransformation(TransformationComputeDataSynonymFactClosure(
GetFuzzerContext()
->GetMaximumEquivalenceClassSizeForDataSynonymFactClosure()));
for (auto id_with_known_synonyms : GetTransformationContext()
->GetFactManager()
->GetIdsForWhichSynonymsAreKnown()) {
// Gather up all uses of |id_with_known_synonym| as a regular id, and
// subsequently iterate over these uses. We use this separation because,
// when considering a given use, we might apply a transformation that will
// invalidate the def-use manager.
std::vector<std::pair<opt::Instruction*, uint32_t>> uses;
GetIRContext()->get_def_use_mgr()->ForEachUse(
id_with_known_synonyms,
[&uses](opt::Instruction* use_inst, uint32_t use_index) -> void {
// We only gather up regular id uses; e.g. we do not include a use of
// the id as the scope for an atomic operation.
if (use_inst->GetOperand(use_index).type == SPV_OPERAND_TYPE_ID) {
uses.emplace_back(
std::pair<opt::Instruction*, uint32_t>(use_inst, use_index));
}
});
for (const auto& use : uses) {
auto use_inst = use.first;
auto use_index = use.second;
auto block_containing_use = GetIRContext()->get_instr_block(use_inst);
// The use might not be in a block; e.g. it could be a decoration.
if (!block_containing_use) {
continue;
}
if (!GetFuzzerContext()->ChoosePercentage(
GetFuzzerContext()->GetChanceOfReplacingIdWithSynonym())) {
continue;
}
// |use_index| is the absolute index of the operand. We require
// the index of the operand restricted to input operands only.
uint32_t use_in_operand_index =
fuzzerutil::InOperandIndexFromOperandIndex(*use_inst, use_index);
if (!fuzzerutil::IdUseCanBeReplaced(GetIRContext(),
*GetTransformationContext(), use_inst,
use_in_operand_index)) {
continue;
}
std::vector<const protobufs::DataDescriptor*> synonyms_to_try;
for (const auto* data_descriptor :
GetTransformationContext()->GetFactManager()->GetSynonymsForId(
id_with_known_synonyms)) {
protobufs::DataDescriptor descriptor_for_this_id =
MakeDataDescriptor(id_with_known_synonyms, {});
if (DataDescriptorEquals()(data_descriptor, &descriptor_for_this_id)) {
// Exclude the fact that the id is synonymous with itself.
continue;
}
if (DataDescriptorsHaveCompatibleTypes(
use_inst->opcode(), use_in_operand_index,
descriptor_for_this_id, *data_descriptor)) {
synonyms_to_try.push_back(data_descriptor);
}
}
while (!synonyms_to_try.empty()) {
auto synonym_to_try =
GetFuzzerContext()->RemoveAtRandomIndex(&synonyms_to_try);
// If the synonym's |index_size| is zero, the synonym represents an id.
// Otherwise it represents some element of a composite structure, in
// which case we need to be able to add an extract instruction to get
// that element out.
if (synonym_to_try->index_size() > 0 &&
!fuzzerutil::CanInsertOpcodeBeforeInstruction(SpvOpCompositeExtract,
use_inst) &&
use_inst->opcode() != SpvOpPhi) {
// We cannot insert an extract before this instruction, so this
// synonym is no good.
continue;
}
if (!fuzzerutil::IdIsAvailableAtUse(GetIRContext(), use_inst,
use_in_operand_index,
synonym_to_try->object())) {
continue;
}
// We either replace the use with an id known to be synonymous (when
// the synonym's |index_size| is 0), or an id that will hold the result
// of extracting a synonym from a composite (when the synonym's
// |index_size| is > 0).
uint32_t id_with_which_to_replace_use;
if (synonym_to_try->index_size() == 0) {
id_with_which_to_replace_use = synonym_to_try->object();
} else {
id_with_which_to_replace_use = GetFuzzerContext()->GetFreshId();
opt::Instruction* instruction_to_insert_before = nullptr;
if (use_inst->opcode() != SpvOpPhi) {
instruction_to_insert_before = use_inst;
} else {
auto parent_block_id =
use_inst->GetSingleWordInOperand(use_in_operand_index + 1);
auto parent_block_instruction =
GetIRContext()->get_def_use_mgr()->GetDef(parent_block_id);
auto parent_block =
GetIRContext()->get_instr_block(parent_block_instruction);
instruction_to_insert_before = parent_block->GetMergeInst()
? parent_block->GetMergeInst()
: parent_block->terminator();
}
if (GetTransformationContext()->GetFactManager()->BlockIsDead(
GetIRContext()
->get_instr_block(instruction_to_insert_before)
->id())) {
// We cannot create a synonym via a composite extraction in a dead
// block, as the resulting id is irrelevant.
continue;
}
assert(!GetTransformationContext()->GetFactManager()->IdIsIrrelevant(
synonym_to_try->object()) &&
"Irrelevant ids can't participate in DataSynonym facts");
ApplyTransformation(TransformationCompositeExtract(
MakeInstructionDescriptor(GetIRContext(),
instruction_to_insert_before),
id_with_which_to_replace_use, synonym_to_try->object(),
fuzzerutil::RepeatedFieldToVector(synonym_to_try->index())));
assert(GetTransformationContext()->GetFactManager()->IsSynonymous(
MakeDataDescriptor(id_with_which_to_replace_use, {}),
*synonym_to_try) &&
"The extracted id must be synonymous with the component from "
"which it was extracted.");
}
ApplyTransformation(TransformationReplaceIdWithSynonym(
MakeIdUseDescriptorFromUse(GetIRContext(), use_inst,
use_in_operand_index),
id_with_which_to_replace_use));
break;
}
}
}
}
bool FuzzerPassApplyIdSynonyms::DataDescriptorsHaveCompatibleTypes(
SpvOp opcode, uint32_t use_in_operand_index,
const protobufs::DataDescriptor& dd1,
const protobufs::DataDescriptor& dd2) {
auto base_object_type_id_1 =
fuzzerutil::GetTypeId(GetIRContext(), dd1.object());
auto base_object_type_id_2 =
fuzzerutil::GetTypeId(GetIRContext(), dd2.object());
assert(base_object_type_id_1 && base_object_type_id_2 &&
"Data descriptors are invalid");
auto type_id_1 = fuzzerutil::WalkCompositeTypeIndices(
GetIRContext(), base_object_type_id_1, dd1.index());
auto type_id_2 = fuzzerutil::WalkCompositeTypeIndices(
GetIRContext(), base_object_type_id_2, dd2.index());
assert(type_id_1 && type_id_2 && "Data descriptors have invalid types");
return fuzzerutil::TypesAreCompatible(
GetIRContext(), opcode, use_in_operand_index, type_id_1, type_id_2);
}
} // namespace fuzz
} // namespace spvtools
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