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https://github.com/KhronosGroup/SPIRV-Tools
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67f4838659
The fact manager maintains an equivalence relation on data descriptors that tracks when one data descriptor could be used in place of another. An algorithm to compute the closure of such facts allows deducing new synonym facts from existing facts. E.g., for two 2D vectors u and v it is known that u.x is synonymous with v.x and u.y is synonymous with v.y, it can be deduced that u and v are synonymous. The closure computation algorithm is very expensive if we get large equivalence relations. This change addresses this in three ways: - The size of equivalence relations is reduced by limiting the extent to which the components of a composite are recursively noted as being equivalent, so that when we have large synonymous arrays we do not record all array elements as being pairwise equivalent. - When computing the closure of facts, equivalence classes above a certain size are simply skipped (which can lead to missed facts) - The closure computation is performed less frequently - it is invoked explicitly before fuzzer passes that will benefit from data synonym facts. A new transformation is used to control its invocation, so that fuzzing and replaying do not get out of sync. The change also tidies up the order in which some getters are declared in FuzzerContext.
184 lines
9.0 KiB
C++
184 lines
9.0 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_context.h"
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#include <cmath>
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namespace spvtools {
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namespace fuzz {
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namespace {
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// Default <minimum, maximum> pairs of probabilities for applying various
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// transformations. All values are percentages. Keep them in alphabetical order.
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const std::pair<uint32_t, uint32_t> kChanceOfAddingAccessChain = {5, 50};
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const std::pair<uint32_t, uint32_t> kChanceOfAddingAnotherStructField = {20,
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90};
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const std::pair<uint32_t, uint32_t> kChanceOfAddingArrayOrStructType = {20, 90};
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const std::pair<uint32_t, uint32_t> kChanceOfAddingDeadBlock = {20, 90};
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const std::pair<uint32_t, uint32_t> kChanceOfAddingDeadBreak = {5, 80};
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const std::pair<uint32_t, uint32_t> kChanceOfAddingDeadContinue = {5, 80};
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const std::pair<uint32_t, uint32_t> kChanceOfAddingEquationInstruction = {5,
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90};
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const std::pair<uint32_t, uint32_t> kChanceOfAddingGlobalVariable = {20, 90};
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const std::pair<uint32_t, uint32_t> kChanceOfAddingLoad = {5, 50};
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const std::pair<uint32_t, uint32_t> kChanceOfAddingLocalVariable = {20, 90};
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const std::pair<uint32_t, uint32_t> kChanceOfAddingMatrixType = {20, 70};
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const std::pair<uint32_t, uint32_t> kChanceOfAddingNoContractionDecoration = {
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5, 70};
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const std::pair<uint32_t, uint32_t> kChanceOfAddingStore = {5, 50};
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const std::pair<uint32_t, uint32_t> kChanceOfAddingVectorType = {20, 70};
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const std::pair<uint32_t, uint32_t> kChanceOfAdjustingFunctionControl = {20,
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70};
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const std::pair<uint32_t, uint32_t> kChanceOfAdjustingLoopControl = {20, 90};
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const std::pair<uint32_t, uint32_t> kChanceOfAdjustingMemoryOperandsMask = {20,
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90};
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const std::pair<uint32_t, uint32_t> kChanceOfAdjustingSelectionControl = {20,
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90};
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const std::pair<uint32_t, uint32_t> kChanceOfCallingFunction = {1, 10};
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const std::pair<uint32_t, uint32_t> kChanceOfChoosingStructTypeVsArrayType = {
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20, 80};
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const std::pair<uint32_t, uint32_t> kChanceOfConstructingComposite = {20, 50};
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const std::pair<uint32_t, uint32_t> kChanceOfCopyingObject = {20, 50};
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const std::pair<uint32_t, uint32_t> kChanceOfDonatingAdditionalModule = {5, 50};
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const std::pair<uint32_t, uint32_t> kChanceOfGoingDeeperWhenMakingAccessChain =
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{50, 95};
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const std::pair<uint32_t, uint32_t> kChanceOfMakingDonorLivesafe = {40, 60};
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const std::pair<uint32_t, uint32_t> kChanceOfMergingBlocks = {20, 95};
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const std::pair<uint32_t, uint32_t> kChanceOfMovingBlockDown = {20, 50};
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const std::pair<uint32_t, uint32_t> kChanceOfObfuscatingConstant = {10, 90};
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const std::pair<uint32_t, uint32_t> kChanceOfOutliningFunction = {10, 90};
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const std::pair<uint32_t, uint32_t> kChanceOfPermutingParameters = {30, 90};
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const std::pair<uint32_t, uint32_t> kChanceOfReplacingIdWithSynonym = {10, 90};
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const std::pair<uint32_t, uint32_t> kChanceOfSplittingBlock = {40, 95};
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const std::pair<uint32_t, uint32_t> kChanceOfTogglingAccessChainInstruction = {
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20, 90};
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// Default limits for various quantities that are chosen during fuzzing.
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// Keep them in alphabetical order.
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const uint32_t kDefaultMaxEquivalenceClassSizeForDataSynonymFactClosure = 1000;
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const uint32_t kDefaultMaxLoopControlPartialCount = 100;
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const uint32_t kDefaultMaxLoopControlPeelCount = 100;
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const uint32_t kDefaultMaxLoopLimit = 20;
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const uint32_t kDefaultMaxNewArraySizeLimit = 100;
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// Default functions for controlling how deep to go during recursive
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// generation/transformation. Keep them in alphabetical order.
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const std::function<bool(uint32_t, RandomGenerator*)>
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kDefaultGoDeeperInConstantObfuscation =
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[](uint32_t current_depth, RandomGenerator* random_generator) -> bool {
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double chance = 1.0 / std::pow(3.0, static_cast<float>(current_depth + 1));
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return random_generator->RandomDouble() < chance;
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};
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} // namespace
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FuzzerContext::FuzzerContext(RandomGenerator* random_generator,
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uint32_t min_fresh_id)
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: random_generator_(random_generator),
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next_fresh_id_(min_fresh_id),
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max_equivalence_class_size_for_data_synonym_fact_closure_(
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kDefaultMaxEquivalenceClassSizeForDataSynonymFactClosure),
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max_loop_control_partial_count_(kDefaultMaxLoopControlPartialCount),
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max_loop_control_peel_count_(kDefaultMaxLoopControlPeelCount),
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max_loop_limit_(kDefaultMaxLoopLimit),
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max_new_array_size_limit_(kDefaultMaxNewArraySizeLimit),
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go_deeper_in_constant_obfuscation_(
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kDefaultGoDeeperInConstantObfuscation) {
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chance_of_adding_access_chain_ =
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ChooseBetweenMinAndMax(kChanceOfAddingAccessChain);
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chance_of_adding_another_struct_field_ =
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ChooseBetweenMinAndMax(kChanceOfAddingAnotherStructField);
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chance_of_adding_array_or_struct_type_ =
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ChooseBetweenMinAndMax(kChanceOfAddingArrayOrStructType);
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chance_of_adding_dead_block_ =
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ChooseBetweenMinAndMax(kChanceOfAddingDeadBlock);
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chance_of_adding_dead_break_ =
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ChooseBetweenMinAndMax(kChanceOfAddingDeadBreak);
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chance_of_adding_dead_continue_ =
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ChooseBetweenMinAndMax(kChanceOfAddingDeadContinue);
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chance_of_adding_equation_instruction_ =
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ChooseBetweenMinAndMax(kChanceOfAddingEquationInstruction);
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chance_of_adding_global_variable_ =
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ChooseBetweenMinAndMax(kChanceOfAddingGlobalVariable);
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chance_of_adding_load_ = ChooseBetweenMinAndMax(kChanceOfAddingLoad);
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chance_of_adding_local_variable_ =
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ChooseBetweenMinAndMax(kChanceOfAddingLocalVariable);
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chance_of_adding_matrix_type_ =
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ChooseBetweenMinAndMax(kChanceOfAddingMatrixType);
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chance_of_adding_no_contraction_decoration_ =
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ChooseBetweenMinAndMax(kChanceOfAddingNoContractionDecoration);
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chance_of_adding_store_ = ChooseBetweenMinAndMax(kChanceOfAddingStore);
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chance_of_adding_vector_type_ =
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ChooseBetweenMinAndMax(kChanceOfAddingVectorType);
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chance_of_adjusting_function_control_ =
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ChooseBetweenMinAndMax(kChanceOfAdjustingFunctionControl);
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chance_of_adjusting_loop_control_ =
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ChooseBetweenMinAndMax(kChanceOfAdjustingLoopControl);
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chance_of_adjusting_memory_operands_mask_ =
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ChooseBetweenMinAndMax(kChanceOfAdjustingMemoryOperandsMask);
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chance_of_adjusting_selection_control_ =
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ChooseBetweenMinAndMax(kChanceOfAdjustingSelectionControl);
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chance_of_calling_function_ =
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ChooseBetweenMinAndMax(kChanceOfCallingFunction);
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chance_of_choosing_struct_type_vs_array_type_ =
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ChooseBetweenMinAndMax(kChanceOfChoosingStructTypeVsArrayType);
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chance_of_constructing_composite_ =
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ChooseBetweenMinAndMax(kChanceOfConstructingComposite);
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chance_of_copying_object_ = ChooseBetweenMinAndMax(kChanceOfCopyingObject);
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chance_of_donating_additional_module_ =
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ChooseBetweenMinAndMax(kChanceOfDonatingAdditionalModule);
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chance_of_going_deeper_when_making_access_chain_ =
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ChooseBetweenMinAndMax(kChanceOfGoingDeeperWhenMakingAccessChain);
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chance_of_making_donor_livesafe_ =
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ChooseBetweenMinAndMax(kChanceOfMakingDonorLivesafe);
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chance_of_merging_blocks_ = ChooseBetweenMinAndMax(kChanceOfMergingBlocks);
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chance_of_moving_block_down_ =
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ChooseBetweenMinAndMax(kChanceOfMovingBlockDown);
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chance_of_obfuscating_constant_ =
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ChooseBetweenMinAndMax(kChanceOfObfuscatingConstant);
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chance_of_outlining_function_ =
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ChooseBetweenMinAndMax(kChanceOfOutliningFunction);
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chance_of_permuting_parameters_ =
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ChooseBetweenMinAndMax(kChanceOfPermutingParameters);
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chance_of_replacing_id_with_synonym_ =
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ChooseBetweenMinAndMax(kChanceOfReplacingIdWithSynonym);
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chance_of_splitting_block_ = ChooseBetweenMinAndMax(kChanceOfSplittingBlock);
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chance_of_toggling_access_chain_instruction_ =
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ChooseBetweenMinAndMax(kChanceOfTogglingAccessChainInstruction);
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}
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FuzzerContext::~FuzzerContext() = default;
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uint32_t FuzzerContext::GetFreshId() { return next_fresh_id_++; }
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bool FuzzerContext::ChooseEven() { return random_generator_->RandomBool(); }
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bool FuzzerContext::ChoosePercentage(uint32_t percentage_chance) {
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assert(percentage_chance <= 100);
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return random_generator_->RandomPercentage() < percentage_chance;
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}
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uint32_t FuzzerContext::ChooseBetweenMinAndMax(
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const std::pair<uint32_t, uint32_t>& min_max) {
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assert(min_max.first <= min_max.second);
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return min_max.first +
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random_generator_->RandomUint32(min_max.second - min_max.first + 1);
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}
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} // namespace fuzz
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} // namespace spvtools
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