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/*
* Copyright 2015 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.
*/
//
// Removes names from locations that are never branched to.
//
#include <wasm.h>
#include <pass.h>
namespace wasm {
struct RemoveUnusedNames : public WalkerPass<PostWalker<RemoveUnusedNames, Visitor<RemoveUnusedNames>>> {
bool isFunctionParallel() { return true; }
// We maintain a list of branches that we saw in children, then when we reach
// a parent block, we know if it was branched to
std::set<Name> branchesSeen;
void visitBreak(Break *curr) {
branchesSeen.insert(curr->name);
}
void visitBlock(Block *curr) {
if (curr->name.is() && branchesSeen.count(curr->name) == 0) {
curr->name = Name();
}
}
void visitSwitch(Switch *curr) {
for (auto name : curr->targets) {
branchesSeen.insert(name);
}
branchesSeen.insert(curr->default_);
}
void visitFunction(Function *curr) {
branchesSeen.clear();
}
};
static RegisterPass<RemoveUnusedNames> registerPass("remove-unused-names", "removes names from locations that are never branched to");
} // namespace wasm
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