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/*
* Copyright 2022 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 "ir/memory-utils.h"
#include "support/stdckdint.h"
#include "wasm.h"
namespace wasm::MemoryUtils {
bool flatten(Module& wasm) {
// If there are no memories then they are already flat, in the empty sense.
if (wasm.memories.empty()) {
return true;
}
// Flatten does not currently have support for multimemory
if (wasm.memories.size() != 1) {
return false;
}
// The presence of any instruction that cares about segment identity is a
// problem because flattening gets rid of that (when it merges them all into
// one big segment).
struct Scanner : public WalkerPass<
PostWalker<Scanner, UnifiedExpressionVisitor<Scanner>>> {
std::atomic<bool>& noticesSegmentIdentity;
Scanner(std::atomic<bool>& noticesSegmentIdentity)
: noticesSegmentIdentity(noticesSegmentIdentity) {}
std::unique_ptr<Pass> create() override {
return std::make_unique<Scanner>(noticesSegmentIdentity);
}
void visitExpression(Expression* curr) {
#define DELEGATE_ID curr->_id
#define DELEGATE_START(id) [[maybe_unused]] auto* cast = curr->cast<id>();
#define DELEGATE_GET_FIELD(id, field) cast->field
#define DELEGATE_FIELD_TYPE(id, field)
#define DELEGATE_FIELD_HEAPTYPE(id, field)
#define DELEGATE_FIELD_CHILD(id, field)
#define DELEGATE_FIELD_OPTIONAL_CHILD(id, field)
#define DELEGATE_FIELD_INT(id, field)
#define DELEGATE_FIELD_LITERAL(id, field)
#define DELEGATE_FIELD_NAME(id, field)
#define DELEGATE_FIELD_SCOPE_NAME_DEF(id, field)
#define DELEGATE_FIELD_SCOPE_NAME_USE(id, field)
#define DELEGATE_FIELD_ADDRESS(id, field)
#define DELEGATE_FIELD_NAME_KIND(id, field, kind) \
if (kind == ModuleItemKind::DataSegment) { \
noticesSegmentIdentity = true; \
}
#include "wasm-delegations-fields.def"
}
};
std::atomic<bool> noticesSegmentIdentity = false;
PassRunner runner(&wasm);
Scanner scanner(noticesSegmentIdentity);
scanner.setPassRunner(&runner);
scanner.run(&wasm);
scanner.runOnModuleCode(&runner, &wasm);
if (noticesSegmentIdentity) {
return false;
}
auto& dataSegments = wasm.dataSegments;
if (dataSegments.size() == 0) {
return true;
}
std::vector<char> data;
for (auto& segment : dataSegments) {
if (segment->isPassive) {
return false;
}
auto* offset = segment->offset->dynCast<Const>();
if (!offset) {
return false;
}
}
for (auto& segment : dataSegments) {
auto* offset = segment->offset->dynCast<Const>();
Index start = offset->value.getInteger();
Index size = segment->data.size();
Index end;
if (std::ckd_add(&end, start, size)) {
return false;
}
if (end > data.size()) {
data.resize(end);
}
std::copy(segment->data.begin(), segment->data.end(), data.begin() + start);
}
dataSegments[0]->offset->cast<Const>()->value =
Literal::makeFromInt32(0, wasm.memories[0]->addressType);
dataSegments[0]->data.swap(data);
wasm.removeDataSegments(
[&](DataSegment* curr) { return curr->name != dataSegments[0]->name; });
return true;
}
} // namespace wasm::MemoryUtils
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