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https://github.com/KhronosGroup/SPIRV-Tools
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60aaafbc70
Fixes #2604 * Allow selection constructs to branch to the nearest selection merge whose header is terminated by an OpSwitch * Cleanup break and continue checks generally * add tests
215 lines
7.0 KiB
C++
215 lines
7.0 KiB
C++
// Copyright (c) 2015-2016 The Khronos Group 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 "source/val/construct.h"
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#include <cassert>
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#include <cstddef>
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#include <unordered_set>
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#include "source/val/function.h"
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#include "source/val/validation_state.h"
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namespace spvtools {
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namespace val {
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Construct::Construct(ConstructType construct_type, BasicBlock* entry,
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BasicBlock* exit, std::vector<Construct*> constructs)
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: type_(construct_type),
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corresponding_constructs_(constructs),
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entry_block_(entry),
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exit_block_(exit) {}
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ConstructType Construct::type() const { return type_; }
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const std::vector<Construct*>& Construct::corresponding_constructs() const {
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return corresponding_constructs_;
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}
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std::vector<Construct*>& Construct::corresponding_constructs() {
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return corresponding_constructs_;
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}
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bool ValidateConstructSize(ConstructType type, size_t size) {
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switch (type) {
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case ConstructType::kSelection:
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return size == 0;
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case ConstructType::kContinue:
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return size == 1;
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case ConstructType::kLoop:
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return size == 1;
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case ConstructType::kCase:
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return size >= 1;
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default:
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assert(1 == 0 && "Type not defined");
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}
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return false;
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}
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void Construct::set_corresponding_constructs(
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std::vector<Construct*> constructs) {
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assert(ValidateConstructSize(type_, constructs.size()));
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corresponding_constructs_ = constructs;
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}
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const BasicBlock* Construct::entry_block() const { return entry_block_; }
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BasicBlock* Construct::entry_block() { return entry_block_; }
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const BasicBlock* Construct::exit_block() const { return exit_block_; }
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BasicBlock* Construct::exit_block() { return exit_block_; }
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void Construct::set_exit(BasicBlock* block) { exit_block_ = block; }
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Construct::ConstructBlockSet Construct::blocks(Function* function) const {
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auto header = entry_block();
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auto merge = exit_block();
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assert(header);
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int header_depth = function->GetBlockDepth(const_cast<BasicBlock*>(header));
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ConstructBlockSet construct_blocks;
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std::unordered_set<BasicBlock*> corresponding_headers;
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for (auto& other : corresponding_constructs()) {
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corresponding_headers.insert(other->entry_block());
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}
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std::vector<BasicBlock*> stack;
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stack.push_back(const_cast<BasicBlock*>(header));
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while (!stack.empty()) {
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BasicBlock* block = stack.back();
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stack.pop_back();
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if (merge == block && ExitBlockIsMergeBlock()) {
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// Merge block is not part of the construct.
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continue;
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}
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if (corresponding_headers.count(block)) {
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// Entered a corresponding construct.
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continue;
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}
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int block_depth = function->GetBlockDepth(block);
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if (block_depth < header_depth) {
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// Broke to outer construct.
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continue;
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}
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// In a loop, the continue target is at a depth of the loop construct + 1.
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// A selection construct nested directly within the loop construct is also
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// at the same depth. It is valid, however, to branch directly to the
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// continue target from within the selection construct.
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if (block != header && block_depth == header_depth &&
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type() == ConstructType::kSelection &&
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block->is_type(kBlockTypeContinue)) {
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// Continued to outer construct.
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continue;
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}
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if (!construct_blocks.insert(block).second) continue;
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if (merge != block) {
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for (auto succ : *block->successors()) {
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// All blocks in the construct must be dominated by the header.
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if (header->dominates(*succ)) {
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stack.push_back(succ);
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}
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}
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}
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}
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return construct_blocks;
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}
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bool Construct::IsStructuredExit(ValidationState_t& _, BasicBlock* dest) const {
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// Structured Exits:
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// - Selection:
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// - branch to its merge
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// - branch to nearest enclosing loop merge or continue
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// - branch to nearest enclosing switch selection merge
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// - Loop:
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// - branch to its merge
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// - branch to its continue
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// - Continue:
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// - branch to loop header
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// - branch to loop merge
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//
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// Note: we will never see a case construct here.
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assert(type() != ConstructType::kCase);
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if (type() == ConstructType::kLoop) {
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auto header = entry_block();
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auto terminator = header->terminator();
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auto index = terminator - &_.ordered_instructions()[0];
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auto merge_inst = &_.ordered_instructions()[index - 1];
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auto merge_block_id = merge_inst->GetOperandAs<uint32_t>(0u);
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auto continue_block_id = merge_inst->GetOperandAs<uint32_t>(1u);
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if (dest->id() == merge_block_id || dest->id() == continue_block_id) {
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return true;
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}
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} else if (type() == ConstructType::kContinue) {
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auto loop_construct = corresponding_constructs()[0];
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auto header = loop_construct->entry_block();
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auto terminator = header->terminator();
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auto index = terminator - &_.ordered_instructions()[0];
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auto merge_inst = &_.ordered_instructions()[index - 1];
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auto merge_block_id = merge_inst->GetOperandAs<uint32_t>(0u);
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if (dest == header || dest->id() == merge_block_id) {
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return true;
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}
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} else {
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assert(type() == ConstructType::kSelection);
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if (dest == exit_block()) {
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return true;
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}
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bool seen_switch = false;
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auto header = entry_block();
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auto block = header->immediate_dominator();
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while (block) {
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auto terminator = block->terminator();
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auto index = terminator - &_.ordered_instructions()[0];
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auto merge_inst = &_.ordered_instructions()[index - 1];
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if (merge_inst->opcode() == SpvOpLoopMerge ||
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(header->terminator()->opcode() != SpvOpSwitch &&
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merge_inst->opcode() == SpvOpSelectionMerge &&
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terminator->opcode() == SpvOpSwitch)) {
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auto merge_target = merge_inst->GetOperandAs<uint32_t>(0u);
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auto merge_block = merge_inst->function()->GetBlock(merge_target).first;
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if (merge_block->dominates(*header)) {
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block = block->immediate_dominator();
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continue;
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}
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if ((!seen_switch || merge_inst->opcode() == SpvOpLoopMerge) &&
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dest->id() == merge_target) {
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return true;
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} else if (merge_inst->opcode() == SpvOpLoopMerge) {
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auto continue_target = merge_inst->GetOperandAs<uint32_t>(1u);
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if (dest->id() == continue_target) {
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return true;
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}
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}
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if (terminator->opcode() == SpvOpSwitch) seen_switch = true;
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// Hit an enclosing loop and didn't break or continue.
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if (merge_inst->opcode() == SpvOpLoopMerge) return false;
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}
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block = block->immediate_dominator();
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}
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}
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return false;
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}
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} // namespace val
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} // namespace spvtools
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