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/*
* Copyright 2016 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.
*/
//
// Stops using return values from set_local and store nodes.
//
#include <wasm.h>
#include <pass.h>
#include <ast_utils.h>
#include <wasm-builder.h>
namespace wasm {
struct DropReturnValues : public WalkerPass<PostWalker<DropReturnValues, Visitor<DropReturnValues>>> {
bool isFunctionParallel() { return true; }
std::vector<Expression*> expressionStack;
void visitSetLocal(SetLocal* curr) {
if (ExpressionAnalyzer::isResultUsed(expressionStack, getFunction())) {
Builder builder(*getModule());
replaceCurrent(builder.makeSequence(
curr,
builder.makeGetLocal(curr->index, curr->type)
));
}
}
void visitStore(Store* curr) {
if (ExpressionAnalyzer::isResultUsed(expressionStack, getFunction())) {
Index index = getFunction()->getNumLocals();
getFunction()->vars.emplace_back(curr->type);
Builder builder(*getModule());
replaceCurrent(builder.makeSequence(
builder.makeSequence(
builder.makeSetLocal(index, curr->value),
curr
),
builder.makeGetLocal(index, curr->type)
));
curr->value = builder.makeGetLocal(index, curr->type);
}
}
static void visitPre(DropReturnValues* self, Expression** currp) {
self->expressionStack.push_back(*currp);
}
static void visitPost(DropReturnValues* self, Expression** currp) {
self->expressionStack.pop_back();
}
static void scan(DropReturnValues* self, Expression** currp) {
self->pushTask(visitPost, currp);
WalkerPass<PostWalker<DropReturnValues, Visitor<DropReturnValues>>>::scan(self, currp);
self->pushTask(visitPre, currp);
}
};
static RegisterPass<DropReturnValues> registerPass("drop-return-values", "stops relying on return values from set_local and store");
} // namespace wasm
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