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https://github.com/KhronosGroup/SPIRV-Tools
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9c4481419e
spirv-fuzz features transformations that should be applicable by construction. Assertions are used to detect when such transformations turn out to be inapplicable. Failures of such assertions indicate bugs in the fuzzer. However, when using the fuzzer at scale (e.g. in ClusterFuzz) reports of these assertion failures create noise, and cause the fuzzer to exit early. This change adds an option whereby inapplicable transformations can be ignored. This reduces noise and allows fuzzing to continue even when a transformation that should be applicable but is not has been erroneously created.
84 lines
3.3 KiB
C++
84 lines
3.3 KiB
C++
// Copyright (c) 2019 Google LLC
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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#include "source/fuzz/fuzzer_pass_add_dead_blocks.h"
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#include <algorithm>
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#include "source/fuzz/fuzzer_util.h"
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#include "source/fuzz/transformation_add_dead_block.h"
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namespace spvtools {
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namespace fuzz {
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namespace {
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const size_t kMaxTransformationsInOnePass = 100U;
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} // namespace
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FuzzerPassAddDeadBlocks::FuzzerPassAddDeadBlocks(
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opt::IRContext* ir_context, TransformationContext* transformation_context,
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FuzzerContext* fuzzer_context,
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protobufs::TransformationSequence* transformations,
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bool ignore_inapplicable_transformations)
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: FuzzerPass(ir_context, transformation_context, fuzzer_context,
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transformations, ignore_inapplicable_transformations) {}
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void FuzzerPassAddDeadBlocks::Apply() {
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// We iterate over all blocks in the module collecting up those at which we
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// might add a branch to a new dead block. We then loop over all such
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// candidates and actually apply transformations. This separation is to
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// avoid modifying the module as we traverse it.
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std::vector<TransformationAddDeadBlock> candidate_transformations;
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for (auto& function : *GetIRContext()->module()) {
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for (auto& block : function) {
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if (!GetFuzzerContext()->ChoosePercentage(
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GetFuzzerContext()->GetChanceOfAddingDeadBlock())) {
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continue;
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}
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// Make sure the module contains a boolean constant equal to
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// |condition_value|.
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bool condition_value = GetFuzzerContext()->ChooseEven();
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FindOrCreateBoolConstant(condition_value, false);
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// We speculatively create a transformation, and then apply it (below) if
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// it turns out to be applicable. This avoids duplicating the logic for
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// applicability checking.
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//
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// It means that fresh ids for transformations that turn out not to be
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// applicable end up being unused.
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candidate_transformations.emplace_back(TransformationAddDeadBlock(
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GetFuzzerContext()->GetFreshId(), block.id(), condition_value));
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}
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}
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// Applying transformations can be expensive as each transformation requires
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// dominator information and also invalidates dominator information. We thus
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// limit the number of transformations that one application of this fuzzer
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// pass can apply. We choose to do this after identifying all the
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// transformations that we *might* want to apply, rather than breaking the
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// above loops once the limit is reached, to avoid biasing towards
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// transformations that target early parts of the module.
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GetFuzzerContext()->Shuffle(&candidate_transformations);
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for (size_t i = 0; i < std::min(kMaxTransformationsInOnePass,
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candidate_transformations.size());
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i++) {
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MaybeApplyTransformation(candidate_transformations[i]);
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}
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}
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} // namespace fuzz
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} // namespace spvtools
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