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https://github.com/KhronosGroup/SPIRV-Tools
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f9893c4549
The new pass will removed interface variable on the OpEntryPoint instruction when they are not statically referenced in the call tree of the entry point. It can be enabled on the command line using the options `remove-unused-interface-variables`.
93 lines
3.3 KiB
C++
93 lines
3.3 KiB
C++
// Copyright (c) 2021 ZHOU He
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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 "remove_unused_interface_variables_pass.h"
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#include "source/spirv_constant.h"
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namespace spvtools {
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namespace opt {
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class RemoveUnusedInterfaceVariablesContext {
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RemoveUnusedInterfaceVariablesPass& parent_;
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Instruction& entry_;
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std::unordered_set<uint32_t> used_variables_;
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IRContext::ProcessFunction pfn_ =
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std::bind(&RemoveUnusedInterfaceVariablesContext::processFunction, this,
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std::placeholders::_1);
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bool processFunction(Function* func) {
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for (const auto& basic_block : *func)
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for (const auto& instruction : basic_block)
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instruction.ForEachInId([&](const uint32_t* id) {
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if (used_variables_.count(*id)) return;
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auto* var = parent_.get_def_use_mgr()->GetDef(*id);
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if (!var || var->opcode() != SpvOpVariable) return;
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auto storage_class = var->GetSingleWordInOperand(0);
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if (storage_class != SpvStorageClassFunction &&
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(parent_.get_module()->version() >=
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SPV_SPIRV_VERSION_WORD(1, 4) ||
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storage_class == SpvStorageClassInput ||
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storage_class == SpvStorageClassOutput))
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used_variables_.insert(*id);
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});
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return false;
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}
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public:
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RemoveUnusedInterfaceVariablesContext(
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RemoveUnusedInterfaceVariablesPass& parent, Instruction& entry)
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: parent_(parent), entry_(entry) {}
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void CollectUsedVariables() {
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std::queue<uint32_t> roots;
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roots.push(entry_.GetSingleWordInOperand(1));
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parent_.context()->ProcessCallTreeFromRoots(pfn_, &roots);
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}
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bool ShouldModify() {
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std::unordered_set<uint32_t> old_variables;
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for (int i = entry_.NumInOperands() - 1; i >= 3; --i) {
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auto variable = entry_.GetInOperand(i).words[0];
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if (!used_variables_.count(variable)) return true; // It is unused.
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if (old_variables.count(variable)) return true; // It is duplicate.
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old_variables.insert(variable);
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}
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if (old_variables.size() != used_variables_.size()) // Missing IDs.
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return true;
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return false;
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}
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void Modify() {
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for (int i = entry_.NumInOperands() - 1; i >= 3; --i)
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entry_.RemoveInOperand(i);
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for (auto id : used_variables_) {
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entry_.AddOperand(Operand(SPV_OPERAND_TYPE_ID, {id}));
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}
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}
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};
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RemoveUnusedInterfaceVariablesPass::Status
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RemoveUnusedInterfaceVariablesPass::Process() {
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bool modified = false;
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for (auto& entry : get_module()->entry_points()) {
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RemoveUnusedInterfaceVariablesContext context(*this, entry);
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context.CollectUsedVariables();
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if (context.ShouldModify()) {
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context.Modify();
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modified = true;
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}
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}
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return (modified ? Status::SuccessWithChange : Status::SuccessWithoutChange);
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}
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} // namespace opt
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} // namespace spvtools
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