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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.
115 lines
4.3 KiB
C++
115 lines
4.3 KiB
C++
// Copyright (c) 2020 Stefano Milizia
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// Copyright (c) 2020 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_interchange_zero_like_constants.h"
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#include "source/fuzz/fuzzer_util.h"
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#include "source/fuzz/id_use_descriptor.h"
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#include "source/fuzz/transformation_record_synonymous_constants.h"
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#include "source/fuzz/transformation_replace_id_with_synonym.h"
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namespace spvtools {
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namespace fuzz {
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FuzzerPassInterchangeZeroLikeConstants::FuzzerPassInterchangeZeroLikeConstants(
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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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uint32_t FuzzerPassInterchangeZeroLikeConstants::FindOrCreateToggledConstant(
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opt::Instruction* declaration) {
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// |declaration| must not be a specialization constant because we do not know
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// the value of specialization constants.
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if (opt::IsSpecConstantInst(declaration->opcode())) {
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return 0;
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}
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auto constant = GetIRContext()->get_constant_mgr()->FindDeclaredConstant(
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declaration->result_id());
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// This pass only toggles zero-like constants
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if (!constant->IsZero()) {
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return 0;
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}
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if (constant->AsScalarConstant()) {
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return FindOrCreateNullConstant(declaration->type_id());
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} else if (constant->AsNullConstant()) {
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// Add declaration of equivalent scalar constant
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auto kind = constant->type()->kind();
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if (kind == opt::analysis::Type::kBool ||
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kind == opt::analysis::Type::kInteger ||
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kind == opt::analysis::Type::kFloat) {
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return FindOrCreateZeroConstant(declaration->type_id(), false);
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}
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}
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return 0;
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}
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void FuzzerPassInterchangeZeroLikeConstants::Apply() {
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// Make vector keeping track of all the uses we want to replace.
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// This is a vector of pairs, where the first element is an id use descriptor
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// identifying the use of a constant id and the second is the id that should
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// be used to replace it.
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std::vector<std::pair<protobufs::IdUseDescriptor, uint32_t>> uses_to_replace;
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for (auto constant : GetIRContext()->GetConstants()) {
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uint32_t constant_id = constant->result_id();
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if (GetTransformationContext()->GetFactManager()->IdIsIrrelevant(
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constant_id)) {
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continue;
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}
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uint32_t toggled_id = FindOrCreateToggledConstant(constant);
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if (!toggled_id) {
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// Not a zero-like constant
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continue;
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}
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assert(!GetTransformationContext()->GetFactManager()->IdIsIrrelevant(
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toggled_id) &&
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"FindOrCreateToggledConstant can't produce an irrelevant id");
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// Record synonymous constants
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ApplyTransformation(
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TransformationRecordSynonymousConstants(constant_id, toggled_id));
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// Find all the uses of the constant and, for each, probabilistically
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// decide whether to replace it.
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GetIRContext()->get_def_use_mgr()->ForEachUse(
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constant_id,
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[this, toggled_id, &uses_to_replace](opt::Instruction* use_inst,
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uint32_t use_index) -> void {
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if (GetFuzzerContext()->ChoosePercentage(
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GetFuzzerContext()
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->GetChanceOfInterchangingZeroLikeConstants())) {
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MaybeAddUseToReplace(use_inst, use_index, toggled_id,
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&uses_to_replace);
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}
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});
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}
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// Replace the ids if it is allowed.
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for (auto use_to_replace : uses_to_replace) {
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MaybeApplyTransformation(TransformationReplaceIdWithSynonym(
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use_to_replace.first, use_to_replace.second));
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}
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}
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} // namespace fuzz
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} // namespace spvtools
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