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https://github.com/KhronosGroup/SPIRV-Tools
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94bec26afe
Mark structured conditional branches live only if one or more instructions in their associated construct is marked live. After closure, replace dead structured conditional branches with a branch to its merge and remove dead blocks. ADCE: Dead If Elim: Remove duplicate StructuredOrder code Also generalize ComputeStructuredOrder so that the caller can specify the root block for the order. Phi insertion uses pseudo_entry_block and adce and dead branch elim use the first block of the function. ADCE: Dead If Elim: Pull redundant code out of InsertPhiInstructions ADCE: Dead If Elim: Encapsulate CFG Cleanup Initialization ADCE: Dead If Elim: Remove redundant code from ADCE initialization ADCE: Dead If: Use CFGCleanup to eliminate newly dead blocks Moved bulk of CFG Cleanup code into MemPass.
201 lines
6.7 KiB
C++
201 lines
6.7 KiB
C++
// Copyright (c) 2017 The Khronos Group Inc.
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// Copyright (c) 2017 Valve Corporation
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// Copyright (c) 2017 LunarG Inc.
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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 "pass.h"
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#include "cfa.h"
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#include "iterator.h"
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namespace spvtools {
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namespace opt {
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namespace {
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const uint32_t kEntryPointFunctionIdInIdx = 1;
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const uint32_t kLoopMergeContinueBlockIdInIdx = 1;
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const uint32_t kLoopMergeMergeBlockIdInIdx = 0;
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const uint32_t kSelectionMergeMergeBlockIdInIdx = 0;
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const uint32_t kTypePointerTypeIdInIdx = 1;
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// Universal Limit of ResultID + 1
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const int kInvalidId = 0x400000;
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} // namespace
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Pass::Pass()
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: pseudo_entry_block_(std::unique_ptr<ir::Instruction>(
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new ir::Instruction(SpvOpLabel, 0, 0, {}))),
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pseudo_exit_block_(std::unique_ptr<ir::Instruction>(
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new ir::Instruction(SpvOpLabel, 0, kInvalidId, {}))),
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consumer_(nullptr),
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def_use_mgr_(nullptr),
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next_id_(0),
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module_(nullptr) {}
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void Pass::AddCalls(ir::Function* func, std::queue<uint32_t>* todo) {
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for (auto bi = func->begin(); bi != func->end(); ++bi)
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for (auto ii = bi->begin(); ii != bi->end(); ++ii)
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if (ii->opcode() == SpvOpFunctionCall)
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todo->push(ii->GetSingleWordInOperand(0));
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}
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bool Pass::ProcessEntryPointCallTree(ProcessFunction& pfn, ir::Module* module) {
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// Map from function's result id to function
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std::unordered_map<uint32_t, ir::Function*> id2function;
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for (auto& fn : *module) id2function[fn.result_id()] = &fn;
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// Collect all of the entry points as the roots.
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std::queue<uint32_t> roots;
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for (auto& e : module->entry_points())
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roots.push(e.GetSingleWordInOperand(kEntryPointFunctionIdInIdx));
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return ProcessCallTreeFromRoots(pfn, id2function, &roots);
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}
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bool Pass::ProcessReachableCallTree(ProcessFunction& pfn, ir::Module* module) {
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// Map from function's result id to function
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std::unordered_map<uint32_t, ir::Function*> id2function;
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for (auto& fn : *module) id2function[fn.result_id()] = &fn;
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std::queue<uint32_t> roots;
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// Add all entry points since they can be reached from outside the module.
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for (auto& e : module->entry_points())
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roots.push(e.GetSingleWordInOperand(kEntryPointFunctionIdInIdx));
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// Add all exported functions since they can be reached from outside the
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// module.
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for (auto& a : module->annotations()) {
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// TODO: Handle group decorations as well. Currently not generate by any
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// front-end, but could be coming.
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if (a.opcode() == SpvOp::SpvOpDecorate) {
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if (a.GetSingleWordOperand(1) ==
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SpvDecoration::SpvDecorationLinkageAttributes) {
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uint32_t lastOperand = a.NumOperands() - 1;
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if (a.GetSingleWordOperand(lastOperand) ==
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SpvLinkageType::SpvLinkageTypeExport) {
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uint32_t id = a.GetSingleWordOperand(0);
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if (id2function.count(id) != 0) roots.push(id);
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}
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}
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}
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}
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return ProcessCallTreeFromRoots(pfn, id2function, &roots);
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}
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bool Pass::ProcessCallTreeFromRoots(
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ProcessFunction& pfn,
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const std::unordered_map<uint32_t, ir::Function*>& id2function,
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std::queue<uint32_t>* roots) {
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// Process call tree
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bool modified = false;
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std::unordered_set<uint32_t> done;
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while (!roots->empty()) {
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const uint32_t fi = roots->front();
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roots->pop();
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if (done.insert(fi).second) {
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ir::Function* fn = id2function.at(fi);
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modified = pfn(fn) || modified;
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AddCalls(fn, roots);
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}
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}
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return modified;
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}
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bool Pass::IsLoopHeader(ir::BasicBlock* block_ptr) const {
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auto iItr = block_ptr->end();
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--iItr;
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if (iItr == block_ptr->begin())
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return false;
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--iItr;
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return iItr->opcode() == SpvOpLoopMerge;
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}
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uint32_t Pass::GetPointeeTypeId(const ir::Instruction* ptrInst) const {
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const uint32_t ptrTypeId = ptrInst->type_id();
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const ir::Instruction* ptrTypeInst = get_def_use_mgr()->GetDef(ptrTypeId);
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return ptrTypeInst->GetSingleWordInOperand(kTypePointerTypeIdInIdx);
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}
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void Pass::ComputeStructuredOrder(ir::Function* func, ir::BasicBlock* root,
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std::list<ir::BasicBlock*>* order) {
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// Compute structured successors and do DFS
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ComputeStructuredSuccessors(func);
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auto ignore_block = [](cbb_ptr) {};
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auto ignore_edge = [](cbb_ptr, cbb_ptr) {};
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auto get_structured_successors = [this](const ir::BasicBlock* block) {
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return &(block2structured_succs_[block]);
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};
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// TODO(greg-lunarg): Get rid of const_cast by making moving const
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// out of the cfa.h prototypes and into the invoking code.
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auto post_order = [&](cbb_ptr b) {
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order->push_front(const_cast<ir::BasicBlock*>(b));
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};
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spvtools::CFA<ir::BasicBlock>::DepthFirstTraversal(
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root, get_structured_successors, ignore_block, post_order,
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ignore_edge);
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}
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void Pass::ComputeStructuredSuccessors(ir::Function *func) {
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block2structured_succs_.clear();
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for (auto& blk : *func) {
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// If no predecessors in function, make successor to pseudo entry
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if (label2preds_[blk.id()].size() == 0)
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block2structured_succs_[&pseudo_entry_block_].push_back(&blk);
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// If header, make merge block first successor and continue block second
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// successor if there is one.
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uint32_t cbid;
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const uint32_t mbid = MergeBlockIdIfAny(blk, &cbid);
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if (mbid != 0) {
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block2structured_succs_[&blk].push_back(id2block_[mbid]);
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if (cbid != 0)
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block2structured_succs_[&blk].push_back(id2block_[cbid]);
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}
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// add true successors
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blk.ForEachSuccessorLabel([&blk, this](uint32_t sbid) {
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block2structured_succs_[&blk].push_back(id2block_[sbid]);
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});
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}
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}
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uint32_t Pass::MergeBlockIdIfAny(const ir::BasicBlock& blk, uint32_t* cbid) {
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auto merge_ii = blk.cend();
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--merge_ii;
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if (cbid != nullptr) {
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*cbid = 0;
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}
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uint32_t mbid = 0;
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if (merge_ii != blk.cbegin()) {
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--merge_ii;
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if (merge_ii->opcode() == SpvOpLoopMerge) {
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mbid = merge_ii->GetSingleWordInOperand(kLoopMergeMergeBlockIdInIdx);
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if (cbid != nullptr) {
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*cbid =
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merge_ii->GetSingleWordInOperand(kLoopMergeContinueBlockIdInIdx);
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}
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} else if (merge_ii->opcode() == SpvOpSelectionMerge) {
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mbid = merge_ii->GetSingleWordInOperand(kSelectionMergeMergeBlockIdInIdx);
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}
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}
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return mbid;
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}
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} // namespace opt
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} // namespace spvtools
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