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//===-- IRMutator.h - Mutation engine for fuzzing IR ------------*- C++ -*-===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// Provides the IRMutator class, which drives mutations on IR based on a
// configurable set of strategies. Some common strategies are also included
// here.
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_FUZZMUTATE_IRMUTATOR_H
#define LLVM_FUZZMUTATE_IRMUTATOR_H
#include "llvm/ADT/Optional.h"
#include "llvm/FuzzMutate/OpDescriptor.h"
#include "llvm/Support/ErrorHandling.h"
namespace llvm {
class BasicBlock;
class Function;
class Instruction;
class Module;
struct RandomIRBuilder;
/// Base class for describing how to mutate a module. mutation functions for
/// each IR unit forward to the contained unit.
class IRMutationStrategy {
public:
virtual ~IRMutationStrategy() = default;
/// Provide a weight to bias towards choosing this strategy for a mutation.
///
/// The value of the weight is arbitrary, but a good default is "the number of
/// distinct ways in which this strategy can mutate a unit". This can also be
/// used to prefer strategies that shrink the overall size of the result when
/// we start getting close to \c MaxSize.
virtual uint64_t getWeight(size_t CurrentSize, size_t MaxSize,
uint64_t CurrentWeight) = 0;
/// @{
/// Mutators for each IR unit. By default these forward to a contained
/// instance of the next smaller unit.
virtual void mutate(Module &M, RandomIRBuilder &IB);
virtual void mutate(Function &F, RandomIRBuilder &IB);
virtual void mutate(BasicBlock &BB, RandomIRBuilder &IB);
virtual void mutate(Instruction &I, RandomIRBuilder &IB) {
llvm_unreachable("Strategy does not implement any mutators");
}
/// @}
};
using TypeGetter = std::function<Type *(LLVMContext &)>;
/// Entry point for configuring and running IR mutations.
class IRMutator {
std::vector<TypeGetter> AllowedTypes;
std::vector<std::unique_ptr<IRMutationStrategy>> Strategies;
public:
IRMutator(std::vector<TypeGetter> &&AllowedTypes,
std::vector<std::unique_ptr<IRMutationStrategy>> &&Strategies)
: AllowedTypes(std::move(AllowedTypes)),
Strategies(std::move(Strategies)) {}
void mutateModule(Module &M, int Seed, size_t CurSize, size_t MaxSize);
};
/// Strategy that injects operations into the function.
class InjectorIRStrategy : public IRMutationStrategy {
std::vector<fuzzerop::OpDescriptor> Operations;
Optional<fuzzerop::OpDescriptor> chooseOperation(Value *Src,
RandomIRBuilder &IB);
public:
InjectorIRStrategy(std::vector<fuzzerop::OpDescriptor> &&Operations)
: Operations(std::move(Operations)) {}
static std::vector<fuzzerop::OpDescriptor> getDefaultOps();
uint64_t getWeight(size_t CurrentSize, size_t MaxSize,
uint64_t CurrentWeight) override {
return Operations.size();
}
using IRMutationStrategy::mutate;
void mutate(Function &F, RandomIRBuilder &IB) override;
void mutate(BasicBlock &BB, RandomIRBuilder &IB) override;
};
class InstDeleterIRStrategy : public IRMutationStrategy {
public:
uint64_t getWeight(size_t CurrentSize, size_t MaxSize,
uint64_t CurrentWeight) override;
using IRMutationStrategy::mutate;
void mutate(Function &F, RandomIRBuilder &IB) override;
void mutate(Instruction &Inst, RandomIRBuilder &IB) override;
};
} // end llvm namespace
#endif // LLVM_FUZZMUTATE_IRMUTATOR_H
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