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// Copyright (c) 2021 ZHOU He
//
// 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 "remove_unused_interface_variables_pass.h"
#include "source/spirv_constant.h"
namespace spvtools {
namespace opt {
class RemoveUnusedInterfaceVariablesContext {
RemoveUnusedInterfaceVariablesPass& parent_;
Instruction& entry_;
std::unordered_set<uint32_t> used_variables_;
std::vector<uint32_t> operands_to_add_;
IRContext::ProcessFunction pfn_ =
std::bind(&RemoveUnusedInterfaceVariablesContext::processFunction, this,
std::placeholders::_1);
bool processFunction(Function* func) {
for (const auto& basic_block : *func)
for (const auto& instruction : basic_block)
instruction.ForEachInId([&](const uint32_t* id) {
if (used_variables_.count(*id)) return;
auto* var = parent_.get_def_use_mgr()->GetDef(*id);
if (!var || var->opcode() != spv::Op::OpVariable) return;
auto storage_class =
spv::StorageClass(var->GetSingleWordInOperand(0));
if (storage_class != spv::StorageClass::Function &&
(parent_.get_module()->version() >=
SPV_SPIRV_VERSION_WORD(1, 4) ||
storage_class == spv::StorageClass::Input ||
storage_class == spv::StorageClass::Output)) {
used_variables_.insert(*id);
operands_to_add_.push_back(*id);
}
});
return false;
}
public:
RemoveUnusedInterfaceVariablesContext(
RemoveUnusedInterfaceVariablesPass& parent, Instruction& entry)
: parent_(parent), entry_(entry) {}
void CollectUsedVariables() {
std::queue<uint32_t> roots;
const int op_i =
entry_.opcode() == spv::Op::OpConditionalEntryPointINTEL ? 2 : 1;
roots.push(entry_.GetSingleWordInOperand(op_i));
parent_.context()->ProcessCallTreeFromRoots(pfn_, &roots);
}
bool ShouldModify() {
std::unordered_set<uint32_t> old_variables;
for (int i = entry_.NumInOperands() - 1; i >= 3; --i) {
auto variable = entry_.GetInOperand(i).words[0];
if (!used_variables_.count(variable)) return true; // It is unused.
if (old_variables.count(variable)) return true; // It is duplicate.
old_variables.insert(variable);
}
if (old_variables.size() != used_variables_.size()) // Missing IDs.
return true;
return false;
}
void Modify() {
const int min_num_operands =
entry_.opcode() == spv::Op::OpConditionalEntryPointINTEL ? 4 : 3;
for (int i = entry_.NumInOperands() - 1; i >= min_num_operands; --i)
entry_.RemoveInOperand(i);
for (auto id : operands_to_add_) {
entry_.AddOperand(Operand(SPV_OPERAND_TYPE_ID, {id}));
}
}
};
RemoveUnusedInterfaceVariablesPass::Status
RemoveUnusedInterfaceVariablesPass::Process() {
bool modified = false;
for (auto& entry : get_module()->entry_points()) {
RemoveUnusedInterfaceVariablesContext context(*this, entry);
context.CollectUsedVariables();
if (context.ShouldModify()) {
context.Modify();
modified = true;
}
}
return (modified ? Status::SuccessWithChange : Status::SuccessWithoutChange);
}
} // namespace opt
} // namespace spvtools
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