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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 {
Name WASM("wasm"),
RETURN_FLOW("*return:)*");
struct TypeSeeker : public PostWalker<TypeSeeker, Visitor<TypeSeeker>> {
Expression* target; // look for this one
Name targetName;
std::vector<WasmType> types;
TypeSeeker(Expression* target, Name targetName) : target(target), targetName(targetName) {
Expression* temp = target;
walk(temp);
}
void visitBreak(Break* curr) {
if (curr->name == targetName) {
types.push_back(curr->value ? curr->value->type : none);
}
}
void visitSwitch(Switch* curr) {
for (auto name : curr->targets) {
if (name == targetName) types.push_back(curr->value ? curr->value->type : none);
}
if (curr->default_ == targetName) 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 == targetName) {
types.clear(); // ignore all breaks til now, they were captured by someone with the same name
}
}
void visitLoop(Loop* curr) {
if (curr == target) {
types.push_back(curr->body->type);
} else if (curr->in == targetName || curr->out == targetName) {
types.clear(); // ignore all breaks til now, they were captured by someone with the same name
}
}
};
static WasmType mergeTypes(std::vector<WasmType>& types) {
WasmType type = unreachable;
for (auto other : 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
}
}
}
}
return type;
}
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;
}
TypeSeeker seeker(this, this->name);
type = mergeTypes(seeker.types);
}
void Loop::finalize() {
if (!out.is()) {
type = body->type;
return;
}
TypeSeeker seeker(this, this->out);
type = mergeTypes(seeker.types);
}
} // namespace wasm
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