2020-02-06 16:54:34 +00:00
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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_add_stores.h"
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#include "source/fuzz/fuzzer_util.h"
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#include "source/fuzz/transformation_store.h"
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namespace spvtools {
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namespace fuzz {
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FuzzerPassAddStores::FuzzerPassAddStores(
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2020-04-02 14:54:46 +00:00
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opt::IRContext* ir_context, TransformationContext* transformation_context,
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2020-02-06 16:54:34 +00:00
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FuzzerContext* fuzzer_context,
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protobufs::TransformationSequence* transformations)
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2020-04-02 14:54:46 +00:00
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: FuzzerPass(ir_context, transformation_context, fuzzer_context,
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transformations) {}
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2020-02-06 16:54:34 +00:00
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FuzzerPassAddStores::~FuzzerPassAddStores() = default;
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void FuzzerPassAddStores::Apply() {
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2020-03-06 12:25:57 +00:00
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ForEachInstructionWithInstructionDescriptor(
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2020-02-10 23:22:34 +00:00
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[this](opt::Function* function, opt::BasicBlock* block,
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2020-02-06 16:54:34 +00:00
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opt::BasicBlock::iterator inst_it,
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const protobufs::InstructionDescriptor& instruction_descriptor)
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-> void {
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assert(inst_it->opcode() ==
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instruction_descriptor.target_instruction_opcode() &&
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"The opcode of the instruction we might insert before must be "
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"the same as the opcode in the descriptor for the instruction");
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// Check whether it is legitimate to insert a store before this
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// instruction.
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if (!fuzzerutil::CanInsertOpcodeBeforeInstruction(SpvOpStore,
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inst_it)) {
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return;
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}
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// Randomly decide whether to try inserting a store here.
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if (!GetFuzzerContext()->ChoosePercentage(
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GetFuzzerContext()->GetChanceOfAddingStore())) {
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return;
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}
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// Look for pointers we might consider storing to.
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std::vector<opt::Instruction*> relevant_pointers =
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FindAvailableInstructions(
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function, block, inst_it,
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[this, block](opt::IRContext* context,
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opt::Instruction* instruction) -> bool {
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if (!instruction->result_id() || !instruction->type_id()) {
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return false;
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}
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auto type_inst = context->get_def_use_mgr()->GetDef(
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instruction->type_id());
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if (type_inst->opcode() != SpvOpTypePointer) {
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// Not a pointer.
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return false;
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}
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if (type_inst->GetSingleWordInOperand(0) ==
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SpvStorageClassInput) {
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// Read-only: cannot store to it.
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return false;
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}
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switch (instruction->result_id()) {
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case SpvOpConstantNull:
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case SpvOpUndef:
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// Do not allow storing to a null or undefined pointer;
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// this might be OK if the block is dead, but for now we
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// conservatively avoid it.
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return false;
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default:
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break;
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}
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2020-04-02 14:54:46 +00:00
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return GetTransformationContext()
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->GetFactManager()
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->BlockIsDead(block->id()) ||
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GetTransformationContext()
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->GetFactManager()
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->PointeeValueIsIrrelevant(
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instruction->result_id());
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});
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// At this point, |relevant_pointers| contains all the pointers we might
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// think of storing to.
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if (relevant_pointers.empty()) {
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return;
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}
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auto pointer = relevant_pointers[GetFuzzerContext()->RandomIndex(
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relevant_pointers)];
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std::vector<opt::Instruction*> relevant_values =
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FindAvailableInstructions(
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function, block, inst_it,
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[pointer](opt::IRContext* context,
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opt::Instruction* instruction) -> bool {
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if (!instruction->result_id() || !instruction->type_id()) {
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return false;
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}
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return instruction->type_id() ==
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context->get_def_use_mgr()
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->GetDef(pointer->type_id())
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->GetSingleWordInOperand(1);
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});
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if (relevant_values.empty()) {
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return;
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}
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// Choose a value at random, and create and apply a storing
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// transformation based on it and the pointer.
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ApplyTransformation(TransformationStore(
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pointer->result_id(),
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relevant_values[GetFuzzerContext()->RandomIndex(relevant_values)]
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->result_id(),
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instruction_descriptor));
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});
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}
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} // namespace fuzz
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} // namespace spvtools
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