SPIRV-Tools/source/fuzz/fuzzer_pass_merge_blocks.cpp
Alastair Donaldson 9c4481419e
spirv-fuzz: Allow inapplicable transformations to be ignored (#4407)
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.
2021-07-28 22:59:37 +01:00

63 lines
2.3 KiB
C++

// 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_merge_blocks.h"
#include <vector>
#include "source/fuzz/transformation_merge_blocks.h"
namespace spvtools {
namespace fuzz {
FuzzerPassMergeBlocks::FuzzerPassMergeBlocks(
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 FuzzerPassMergeBlocks::Apply() {
// First we populate a sequence of transformations that we might consider
// applying.
std::vector<TransformationMergeBlocks> potential_transformations;
// We do this by considering every block of every function.
for (auto& function : *GetIRContext()->module()) {
for (auto& block : function) {
// We probabilistically decide to ignore some blocks.
if (!GetFuzzerContext()->ChoosePercentage(
GetFuzzerContext()->GetChanceOfMergingBlocks())) {
continue;
}
// For other blocks, we add a transformation to merge the block into its
// predecessor if that transformation would be applicable.
TransformationMergeBlocks transformation(block.id());
if (transformation.IsApplicable(GetIRContext(),
*GetTransformationContext())) {
potential_transformations.push_back(transformation);
}
}
}
while (!potential_transformations.empty()) {
auto transformation =
GetFuzzerContext()->RemoveAtRandomIndex(&potential_transformations);
MaybeApplyTransformation(transformation);
}
}
} // namespace fuzz
} // namespace spvtools