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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_table_h
#define wasm_ir_table_h
#include "ir/literal-utils.h"
#include "wasm-traversal.h"
#include "wasm.h"
namespace wasm {
namespace TableUtils {
struct FlatTable {
std::vector<Name> names;
bool valid;
FlatTable(Table& table) {
valid = true;
for (auto& segment : table.segments) {
auto offset = segment.offset;
if (!offset->is<Const>()) {
// TODO: handle some non-constant segments
valid = false;
return;
}
Index start = offset->cast<Const>()->value.geti32();
Index end = start + segment.data.size();
if (end > names.size()) {
names.resize(end);
}
for (Index i = 0; i < segment.data.size(); i++) {
names[start + i] = segment.data[i];
}
}
}
};
inline Table::Segment& getSingletonSegment(Table& table, Module& wasm) {
if (table.segments.size() != 1) {
Fatal() << "Table doesn't have a singleton segment.";
}
return table.segments[0];
}
// Appends a name to the table. This assumes the table has 0 or 1 segments,
// as with 2 or more it's ambiguous what we should do (use a hole in the middle
// or not).
// This works on code from wasm-ld, but on arbitrary code it may not be valid
// in the presence of a dynamic linking section. Specifically, we assume the
// module has a single table segment, and that the dylink section indicates
// we can validly append to that segment, see the check below.
inline Index append(Table& table, Name name, Module& wasm) {
auto& segment = getSingletonSegment(table, wasm);
auto tableIndex = segment.data.size();
if (wasm.dylinkSection) {
if (segment.data.size() != wasm.dylinkSection->tableSize) {
Fatal() << "Appending to the table in a module with a dylink section "
"that has tableSize which indicates it wants to reserve more "
"table space than the actual table elements in the module. "
"We don't know how to correctly update the dylink section in "
"that case.";
}
wasm.dylinkSection->tableSize++;
}
segment.data.push_back(name);
table.initial = table.initial + 1;
return tableIndex;
}
// Checks if a function is already in the table. Returns that index if so,
// otherwise appends it.
inline Index getOrAppend(Table& table, Name name, Module& wasm) {
auto& segment = getSingletonSegment(table, wasm);
for (Index i = 0; i < segment.data.size(); i++) {
if (segment.data[i] == name) {
return i;
}
}
return append(table, name, wasm);
}
} // namespace TableUtils
} // namespace wasm
#endif // wasm_ir_table_h
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