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// Copyright (c) 2020 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
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
#include "source/fuzz/fuzzer_pass_add_stores.h"
#include "source/fuzz/fuzzer_util.h"
#include "source/fuzz/transformation_store.h"
namespace spvtools {
namespace fuzz {
FuzzerPassAddStores::FuzzerPassAddStores(
opt::IRContext* ir_context, TransformationContext* transformation_context,
FuzzerContext* fuzzer_context,
protobufs::TransformationSequence* transformations)
: FuzzerPass(ir_context, transformation_context, fuzzer_context,
transformations) {}
FuzzerPassAddStores::~FuzzerPassAddStores() = default;
void FuzzerPassAddStores::Apply() {
ForEachInstructionWithInstructionDescriptor(
[this](opt::Function* function, opt::BasicBlock* block,
opt::BasicBlock::iterator inst_it,
const protobufs::InstructionDescriptor& instruction_descriptor)
-> void {
assert(inst_it->opcode() ==
instruction_descriptor.target_instruction_opcode() &&
"The opcode of the instruction we might insert before must be "
"the same as the opcode in the descriptor for the instruction");
// Check whether it is legitimate to insert a store before this
// instruction.
if (!fuzzerutil::CanInsertOpcodeBeforeInstruction(SpvOpStore,
inst_it)) {
return;
}
// Randomly decide whether to try inserting a store here.
if (!GetFuzzerContext()->ChoosePercentage(
GetFuzzerContext()->GetChanceOfAddingStore())) {
return;
}
// Look for pointers we might consider storing to.
std::vector<opt::Instruction*> relevant_pointers =
FindAvailableInstructions(
function, block, inst_it,
[this, block](opt::IRContext* context,
opt::Instruction* instruction) -> bool {
if (!instruction->result_id() || !instruction->type_id()) {
return false;
}
auto type_inst = context->get_def_use_mgr()->GetDef(
instruction->type_id());
if (type_inst->opcode() != SpvOpTypePointer) {
// Not a pointer.
return false;
}
if (instruction->IsReadOnlyPointer()) {
// Read only: cannot store to it.
return false;
}
switch (instruction->opcode()) {
case SpvOpConstantNull:
case SpvOpUndef:
// Do not allow storing to a null or undefined pointer;
// this might be OK if the block is dead, but for now we
// conservatively avoid it.
return false;
default:
break;
}
return GetTransformationContext()
->GetFactManager()
->BlockIsDead(block->id()) ||
GetTransformationContext()
->GetFactManager()
->PointeeValueIsIrrelevant(
instruction->result_id());
});
// At this point, |relevant_pointers| contains all the pointers we might
// think of storing to.
if (relevant_pointers.empty()) {
return;
}
auto pointer = relevant_pointers[GetFuzzerContext()->RandomIndex(
relevant_pointers)];
std::vector<opt::Instruction*> relevant_values =
FindAvailableInstructions(
function, block, inst_it,
[pointer](opt::IRContext* context,
opt::Instruction* instruction) -> bool {
if (!instruction->result_id() || !instruction->type_id()) {
return false;
}
return instruction->type_id() ==
context->get_def_use_mgr()
->GetDef(pointer->type_id())
->GetSingleWordInOperand(1);
});
if (relevant_values.empty()) {
return;
}
// Choose a value at random, and create and apply a storing
// transformation based on it and the pointer.
ApplyTransformation(TransformationStore(
pointer->result_id(),
relevant_values[GetFuzzerContext()->RandomIndex(relevant_values)]
->result_id(),
instruction_descriptor));
});
}
} // namespace fuzz
} // namespace spvtools
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