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LibJS: Cache symbolicated stack frames on ExecutionContext

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Instead of re-symbolicating entire stacks from scratch every time
we want a JS VM backtrace, we now use the ExecutionContext object as
cache storage via a new CachedSourceRange object.

This means that once a stack frame has been symbolicated, we don't
have to resymbolicate it again (unless the program counter moves
within that stack frame).

This drastically reduces time spent in symbolication in some WPT tests.
This commit is contained in:
Andreas Kling 2024-10-14 07:49:12 +02:00 • committed by Andreas Kling
commit 5b060da4f4
Notes: github-actions[bot] 2024-10-14 07:52:03 +00:00
5 changed files with 36 additions and 16 deletions
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21
Userland/Libraries/LibJS/Runtime/Error.cpp
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@ -17,19 +17,21 @@ namespace JS {
JS_DEFINE_ALLOCATOR(Error);
static SourceRange dummy_source_range { SourceCode::create(String {}, String {}), {}, {} };
SourceRange const& TracebackFrame::source_range() const
{
if (auto* unrealized = source_range_storage.get_pointer<UnrealizedSourceRange>()) {
if (!cached_source_range)
return dummy_source_range;
if (auto* unrealized = cached_source_range->source_range.get_pointer<UnrealizedSourceRange>()) {
auto source_range = [&] {
if (!unrealized->source_code) {
static auto dummy_source_code = SourceCode::create(String {}, String {});
return SourceRange { dummy_source_code, {}, {} };
}
if (!unrealized->source_code)
return dummy_source_range;
return unrealized->realize();
}();
source_range_storage = move(source_range);
cached_source_range->source_range = move(source_range);
}
return source_range_storage.get<SourceRange>();
return cached_source_range->source_range.get<SourceRange>();
}
NonnullGCPtr<Error> Error::create(Realm& realm)
@ -81,12 +83,9 @@ void Error::populate_stack()
m_traceback.ensure_capacity(stack_trace.size());
for (auto& element : stack_trace) {
auto* context = element.execution_context;
UnrealizedSourceRange range = {};
if (element.source_range.has_value())
range = element.source_range.value();
TracebackFrame frame {
.function_name = context->function_name ? context->function_name->byte_string() : "",
.source_range_storage = range,
.cached_source_range = element.source_range,
};
m_traceback.append(move(frame));