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/*
* Copyright 2019 WebAssembly Community Group participants
*
* 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.
*/
#ifndef wasm_ir_local_utils_h
#define wasm_ir_local_utils_h
#include <ir/effects.h>
namespace wasm {
struct GetLocalCounter : public PostWalker<GetLocalCounter> {
std::vector<Index> num;
GetLocalCounter() = default;
GetLocalCounter(Function* func) {
analyze(func, func->body);
}
GetLocalCounter(Function* func, Expression* ast) {
analyze(func, ast);
}
void analyze(Function* func) {
analyze(func, func->body);
}
void analyze(Function* func, Expression* ast) {
num.resize(func->getNumLocals());
std::fill(num.begin(), num.end(), 0);
walk(ast);
}
void visitGetLocal(GetLocal *curr) {
num[curr->index]++;
}
};
struct UnneededSetRemover : public PostWalker<UnneededSetRemover> {
PassOptions& passOptions;
GetLocalCounter* getLocalCounter = nullptr;
UnneededSetRemover(Function* func, PassOptions& passOptions) : passOptions(passOptions) {
GetLocalCounter counter(func);
UnneededSetRemover inner(counter, func, passOptions);
removed = inner.removed;
}
UnneededSetRemover(GetLocalCounter& getLocalCounter, Function* func, PassOptions& passOptions) : passOptions(passOptions), getLocalCounter(&getLocalCounter) {
walk(func->body);
}
bool removed = false;
void visitSetLocal(SetLocal *curr) {
if (getLocalCounter->num[curr->index] == 0) {
auto* value = curr->value;
if (curr->isTee()) {
this->replaceCurrent(value);
} else if (EffectAnalyzer(passOptions, curr->value).hasSideEffects()) {
Drop* drop = ExpressionManipulator::convert<SetLocal, Drop>(curr);
drop->value = value;
drop->finalize();
} else {
ExpressionManipulator::nop(curr);
}
removed = true;
}
}
};
} // namespace wasm
#endif // wasm_ir_local_utils_h
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