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// 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
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// See the License for the specific language governing permissions and
// limitations under the License.
#include <functional>
#include <utility>
#include "source/fuzz/random_generator.h"
#include "source/opt/function.h"
namespace spvtools {
namespace fuzz {
// Encapsulates all parameters that control the fuzzing process, such as the
// source of randomness and the probabilities with which transformations are
// applied.
class FuzzerContext {
// Constructs a fuzzer context with a given random generator and the minimum
// value that can be used for fresh ids.
FuzzerContext(RandomGenerator* random_generator, uint32_t min_fresh_id);
// Returns a random boolean.
bool ChooseEven();
// Returns true if and only if a randomly-chosen integer in the range [0, 100]
// is less than |percentage_chance|.
bool ChoosePercentage(uint32_t percentage_chance);
// Returns a random index into |sequence|, which is expected to have a 'size'
// method, and which must be non-empty. Typically 'HasSizeMethod' will be an
// std::vector.
template <typename HasSizeMethod>
uint32_t RandomIndex(const HasSizeMethod& sequence) {
assert(sequence.size() > 0);
return random_generator_->RandomUint32(
// Yields an id that is guaranteed not to be used in the module being fuzzed,
// or to have been issued before.
uint32_t GetFreshId();
// Probabilities associated with applying various transformations.
// Keep them in alphabetical order.
uint32_t GetChanceOfAddingDeadBreak() { return chance_of_adding_dead_break_; }
uint32_t GetChanceOfAddingDeadContinue() {
return chance_of_adding_dead_continue_;
uint32_t GetChanceOfAddingNoContractionDecoration() {
return chance_of_adding_no_contraction_decoration_;
uint32_t GetChanceOfAdjustingFunctionControl() {
return chance_of_adjusting_function_control_;
uint32_t GetChanceOfAdjustingLoopControl() {
return chance_of_adjusting_loop_control_;
uint32_t GetChanceOfAdjustingMemoryOperandsMask() {
return chance_of_adjusting_memory_operands_mask_;
uint32_t GetChanceOfAdjustingSelectionControl() {
return chance_of_adjusting_selection_control_;
uint32_t GetChanceOfConstructingComposite() {
return chance_of_constructing_composite_;
uint32_t GetChanceOfCopyingObject() { return chance_of_copying_object_; }
uint32_t GetChanceOfDonatingAdditionalModule() {
return chance_of_donating_additional_module_;
uint32_t GetChanceOfMergingBlocks() { return chance_of_merging_blocks_; }
uint32_t GetChanceOfMovingBlockDown() { return chance_of_moving_block_down_; }
uint32_t GetChanceOfObfuscatingConstant() {
return chance_of_obfuscating_constant_;
uint32_t GetChanceOfOutliningFunction() {
return chance_of_outlining_function_;
uint32_t GetChanceOfReplacingIdWithSynonym() {
return chance_of_replacing_id_with_synonym_;
uint32_t GetChanceOfSplittingBlock() { return chance_of_splitting_block_; }
uint32_t GetRandomLoopControlPeelCount() {
return random_generator_->RandomUint32(max_loop_control_peel_count_);
uint32_t GetRandomLoopControlPartialCount() {
return random_generator_->RandomUint32(max_loop_control_partial_count_);
// Functions to control how deeply to recurse.
// Keep them in alphabetical order.
bool GoDeeperInConstantObfuscation(uint32_t depth) {
return go_deeper_in_constant_obfuscation_(depth, random_generator_);
// The source of randomness.
RandomGenerator* random_generator_;
// The next fresh id to be issued.
uint32_t next_fresh_id_;
// Probabilities associated with applying various transformations.
// Keep them in alphabetical order.
uint32_t chance_of_adding_dead_break_;
uint32_t chance_of_adding_dead_continue_;
uint32_t chance_of_adding_no_contraction_decoration_;
uint32_t chance_of_adjusting_function_control_;
uint32_t chance_of_adjusting_loop_control_;
uint32_t chance_of_adjusting_memory_operands_mask_;
uint32_t chance_of_adjusting_selection_control_;
uint32_t chance_of_constructing_composite_;
uint32_t chance_of_copying_object_;
uint32_t chance_of_donating_additional_module_;
uint32_t chance_of_merging_blocks_;
uint32_t chance_of_moving_block_down_;
uint32_t chance_of_obfuscating_constant_;
uint32_t chance_of_outlining_function_;
uint32_t chance_of_replacing_id_with_synonym_;
uint32_t chance_of_splitting_block_;
// Limits associated with various quantities for which random values are
// chosen during fuzzing.
// Keep them in alphabetical order.
uint32_t max_loop_control_partial_count_;
uint32_t max_loop_control_peel_count_;
// Functions to determine with what probability to go deeper when generating
// or mutating constructs recursively.
const std::function<bool(uint32_t, RandomGenerator*)>&
// Requires |min_max.first| <= |min_max.second|, and returns a value in the
// range [ |min_max.first|, |min_max.second| ]
uint32_t ChooseBetweenMinAndMax(const std::pair<uint32_t, uint32_t>& min_max);
} // namespace fuzz
} // namespace spvtools