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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.
94 lines
3.8 KiB
C++
94 lines
3.8 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_continues.h"
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#include "source/fuzz/fuzzer_util.h"
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#include "source/fuzz/transformation_add_dead_continue.h"
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#include "source/opt/ir_context.h"
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namespace spvtools {
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namespace fuzz {
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FuzzerPassAddDeadContinues::FuzzerPassAddDeadContinues(
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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 FuzzerPassAddDeadContinues::Apply() {
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// Consider every block in every function.
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for (auto& function : *GetIRContext()->module()) {
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for (auto& block : function) {
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// Get the label id of the continue target of the innermost loop.
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auto continue_block_id =
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block.IsLoopHeader()
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? block.ContinueBlockId()
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: GetIRContext()->GetStructuredCFGAnalysis()->LoopContinueBlock(
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block.id());
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// This transformation is not applicable if current block is not inside a
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// loop.
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if (continue_block_id == 0) {
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continue;
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}
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auto* continue_block =
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fuzzerutil::MaybeFindBlock(GetIRContext(), continue_block_id);
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assert(continue_block && "Continue block is null");
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// Analyze return type of each OpPhi instruction in the continue target
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// and provide an id for the transformation if needed.
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std::vector<uint32_t> phi_ids;
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// Check whether current block has an edge to the continue target.
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// If this is the case, we don't need to do anything.
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if (!block.IsSuccessor(continue_block)) {
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continue_block->ForEachPhiInst([this, &phi_ids](opt::Instruction* phi) {
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// Add an additional operand for OpPhi instruction. Use a constant
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// if possible, and an undef otherwise.
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if (fuzzerutil::CanCreateConstant(GetIRContext(), phi->type_id())) {
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// We mark the constant as irrelevant so that we can replace it with
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// a more interesting value later.
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phi_ids.push_back(FindOrCreateZeroConstant(phi->type_id(), true));
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} else {
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phi_ids.push_back(FindOrCreateGlobalUndef(phi->type_id()));
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}
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});
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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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// Make a transformation to add a dead continue from this node; if the
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// node turns out to be inappropriate (e.g. by not being in a loop) the
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// precondition for the transformation will fail and it will be ignored.
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auto candidate_transformation = TransformationAddDeadContinue(
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block.id(), condition_value, std::move(phi_ids));
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// Probabilistically decide whether to apply the transformation in the
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// case that it is applicable.
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if (GetFuzzerContext()->ChoosePercentage(
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GetFuzzerContext()->GetChanceOfAddingDeadContinue())) {
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MaybeApplyTransformation(candidate_transformation);
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}
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}
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}
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}
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} // namespace fuzz
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} // namespace spvtools
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