| // Copyright (c) 2018 Google Inc. |
| // |
| // 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/opt/workaround1209.h" |
| |
| #include <list> |
| #include <memory> |
| #include <stack> |
| #include <utility> |
| |
| namespace spvtools { |
| namespace opt { |
| |
| Pass::Status Workaround1209::Process() { |
| bool modified = false; |
| modified = RemoveOpUnreachableInLoops(); |
| return (modified ? Status::SuccessWithChange : Status::SuccessWithoutChange); |
| } |
| |
| bool Workaround1209::RemoveOpUnreachableInLoops() { |
| bool modified = false; |
| for (auto& func : *get_module()) { |
| std::list<BasicBlock*> structured_order; |
| cfg()->ComputeStructuredOrder(&func, &*func.begin(), &structured_order); |
| |
| // Keep track of the loop merges. The top of the stack will always be the |
| // loop merge for the loop that immediately contains the basic block being |
| // processed. |
| std::stack<uint32_t> loop_merges; |
| for (BasicBlock* bb : structured_order) { |
| if (!loop_merges.empty() && bb->id() == loop_merges.top()) { |
| loop_merges.pop(); |
| } |
| |
| if (bb->tail()->opcode() == SpvOpUnreachable) { |
| if (!loop_merges.empty()) { |
| // We found an OpUnreachable inside a loop. |
| // Replace it with an unconditional branch to the loop merge. |
| context()->KillInst(&*bb->tail()); |
| std::unique_ptr<Instruction> new_branch( |
| new Instruction(context(), SpvOpBranch, 0, 0, |
| {{spv_operand_type_t::SPV_OPERAND_TYPE_ID, |
| {loop_merges.top()}}})); |
| context()->AnalyzeDefUse(&*new_branch); |
| bb->AddInstruction(std::move(new_branch)); |
| modified = true; |
| } |
| } else { |
| if (bb->GetLoopMergeInst()) { |
| loop_merges.push(bb->MergeBlockIdIfAny()); |
| } |
| } |
| } |
| } |
| return modified; |
| } |
| } // namespace opt |
| } // namespace spvtools |