| // Copyright (c) 2020 Vasyl Teliman |
| // |
| // 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/transformation_swap_conditional_branch_operands.h" |
| |
| #include "source/fuzz/fuzzer_util.h" |
| #include "source/fuzz/instruction_descriptor.h" |
| |
| namespace spvtools { |
| namespace fuzz { |
| |
| TransformationSwapConditionalBranchOperands:: |
| TransformationSwapConditionalBranchOperands( |
| protobufs::TransformationSwapConditionalBranchOperands message) |
| : message_(std::move(message)) {} |
| |
| TransformationSwapConditionalBranchOperands:: |
| TransformationSwapConditionalBranchOperands( |
| const protobufs::InstructionDescriptor& instruction_descriptor, |
| uint32_t fresh_id) { |
| *message_.mutable_instruction_descriptor() = instruction_descriptor; |
| message_.set_fresh_id(fresh_id); |
| } |
| |
| bool TransformationSwapConditionalBranchOperands::IsApplicable( |
| opt::IRContext* ir_context, const TransformationContext& /*unused*/) const { |
| const auto* inst = |
| FindInstruction(message_.instruction_descriptor(), ir_context); |
| return fuzzerutil::IsFreshId(ir_context, message_.fresh_id()) && inst && |
| inst->opcode() == SpvOpBranchConditional; |
| } |
| |
| void TransformationSwapConditionalBranchOperands::Apply( |
| opt::IRContext* ir_context, TransformationContext* /*unused*/) const { |
| auto* branch_inst = |
| FindInstruction(message_.instruction_descriptor(), ir_context); |
| assert(branch_inst); |
| |
| auto* block = ir_context->get_instr_block(branch_inst); |
| assert(block); |
| |
| // Compute the last instruction in the |block| that allows us to insert |
| // OpLogicalNot above it. |
| auto iter = fuzzerutil::GetIteratorForInstruction(block, branch_inst); |
| if (!fuzzerutil::CanInsertOpcodeBeforeInstruction(SpvOpLogicalNot, iter)) { |
| // There might be a merge instruction before OpBranchConditional. |
| --iter; |
| } |
| |
| assert(fuzzerutil::CanInsertOpcodeBeforeInstruction(SpvOpLogicalNot, iter) && |
| "We should now be able to insert SpvOpLogicalNot before |iter|"); |
| |
| // Get the instruction whose result is used as a condition for |
| // OpBranchConditional. |
| const auto* condition_inst = ir_context->get_def_use_mgr()->GetDef( |
| branch_inst->GetSingleWordInOperand(0)); |
| assert(condition_inst); |
| |
| // We are swapping the labels in OpBranchConditional. This means that we must |
| // invert the guard as well. We are using OpLogicalNot for that purpose here. |
| auto new_instruction = MakeUnique<opt::Instruction>( |
| ir_context, SpvOpLogicalNot, condition_inst->type_id(), |
| message_.fresh_id(), |
| opt::Instruction::OperandList{ |
| {SPV_OPERAND_TYPE_ID, {condition_inst->result_id()}}}); |
| auto new_instruction_ptr = new_instruction.get(); |
| iter.InsertBefore(std::move(new_instruction)); |
| |
| fuzzerutil::UpdateModuleIdBound(ir_context, message_.fresh_id()); |
| |
| // Update OpBranchConditional condition operand. |
| branch_inst->GetInOperand(0).words[0] = message_.fresh_id(); |
| |
| // Swap label operands. |
| std::swap(branch_inst->GetInOperand(1), branch_inst->GetInOperand(2)); |
| |
| // Additionally, swap branch weights if present. |
| if (branch_inst->NumInOperands() > 3) { |
| std::swap(branch_inst->GetInOperand(3), branch_inst->GetInOperand(4)); |
| } |
| |
| ir_context->get_def_use_mgr()->AnalyzeInstDefUse(new_instruction_ptr); |
| ir_context->set_instr_block(new_instruction_ptr, block); |
| ir_context->get_def_use_mgr()->EraseUseRecordsOfOperandIds(branch_inst); |
| ir_context->get_def_use_mgr()->AnalyzeInstUse(branch_inst); |
| |
| // No analyses need to be invalidated since the transformation is local to a |
| // block and the def-use and instruction-to-block mappings have been updated. |
| } |
| |
| protobufs::Transformation |
| TransformationSwapConditionalBranchOperands::ToMessage() const { |
| protobufs::Transformation result; |
| *result.mutable_swap_conditional_branch_operands() = message_; |
| return result; |
| } |
| |
| std::unordered_set<uint32_t> |
| TransformationSwapConditionalBranchOperands::GetFreshIds() const { |
| return {message_.fresh_id()}; |
| } |
| |
| } // namespace fuzz |
| } // namespace spvtools |