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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.
*/
#include "wasm.h"
#include "wasm-traversal.h"
#include "ast_utils.h"
namespace wasm {
struct BlockTypeSeeker : public PostWalker<BlockTypeSeeker, Visitor<BlockTypeSeeker>> {
Block* target; // look for this one
std::vector<WasmType> types;
BlockTypeSeeker(Block* target) : target(target) {}
void visitBreak(Break *curr) {
if (curr->name == target->name) {
types.push_back(curr->value ? curr->value->type : none);
}
}
void visitSwitch(Switch *curr) {
for (auto name : curr->targets) {
if (name == target->name) types.push_back(curr->value ? curr->value->type : none);
}
}
void visitBlock(Block *curr) {
if (curr == target) {
if (curr->list.size() > 0) {
types.push_back(curr->list.back()->type);
} else {
types.push_back(none);
}
} else if (curr->name == target->name) {
types.clear(); // ignore all breaks til now, they were captured by someone with the same name
}
}
};
void Block::finalize() {
if (!name.is()) {
// nothing branches here, so this is easy
if (list.size() > 0) {
type = list.back()->type;
} else {
type = unreachable;
}
return;
}
BlockTypeSeeker seeker(this);
Expression* temp = this;
seeker.walk(temp);
type = unreachable;
for (auto other : seeker.types) {
// once none, stop. it then indicates a poison value, that must not be consumed
// and ignore unreachable
if (type != none) {
if (other == none) {
type = none;
} else if (other != unreachable) {
if (type == unreachable) {
type = other;
} else if (type != other) {
type = none; // poison value, we saw multiple types; this should not be consumed
}
}
}
}
}
} // namespace wasm
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