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LibJS: Make Error stack traces lazier

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Instead of eagerly populating the stack trace with a textual
representation of every call frame, just store the raw source code range
(code, start offset, end offset). From that, we can generate the full
rich backtrace when requested, and save ourselves the trouble otherwise.

This makes test-wasm take ~7 seconds on my machine instead of ~60. :^)
This commit is contained in:
Andreas Kling 2023-05-28 08:28:43 +02:00
parent 6c81b90e5a
commit 87ac906ee6
8 changed files with 51 additions and 20 deletions
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41
Userland/Libraries/LibJS/Runtime/Error.cpp
View file

@ -15,6 +15,15 @@
namespace JS {
SourceRange const& TracebackFrame::source_range() const
{
if (auto* unrealized = source_range_storage.get_pointer<UnrealizedSourceRange>()) {
auto source_range = unrealized->source_code->range_from_offsets(unrealized->start_offset, unrealized->end_offset);
source_range_storage = move(source_range);
}
return source_range_storage.get<SourceRange>();
}
NonnullGCPtr<Error> Error::create(Realm& realm)
{
return realm.heap().allocate<Error>(realm, realm.intrinsics().error_prototype()).release_allocated_value_but_fixme_should_propagate_errors();
@ -69,13 +78,24 @@ void Error::populate_stack()
auto function_name = context->function_name;
if (function_name.is_empty())
function_name = "<unknown>"sv;
m_traceback.empend(
move(function_name),
// We might not have an AST node associated with the execution context, e.g. in promise
// reaction jobs (which aren't called anywhere from the source code).
// They're not going to generate any _unhandled_ exceptions though, so a meaningless
// source range is fine.
context->current_node ? context->current_node->source_range() : dummy_source_range);
TracebackFrame frame {
.function_name = move(function_name),
.source_range_storage = TracebackFrame::UnrealizedSourceRange {},
};
// We might not have an AST node associated with the execution context, e.g. in promise
// reaction jobs (which aren't called anywhere from the source code).
// They're not going to generate any _unhandled_ exceptions though, so a meaningless
// source range is fine.
if (context->current_node) {
auto* unrealized = frame.source_range_storage.get_pointer<TracebackFrame::UnrealizedSourceRange>();
unrealized->source_code = context->current_node->source_code();
unrealized->start_offset = context->current_node->start_offset();
unrealized->end_offset = context->current_node->end_offset();
}
m_traceback.append(move(frame));
}
}
@ -90,13 +110,14 @@ ThrowCompletionOr<String> Error::stack_string(VM& vm) const
for (size_t i = 0; i < m_traceback.size() - 1; ++i) {
auto const& frame = m_traceback[i];
auto function_name = frame.function_name;
auto source_range = frame.source_range();
// Note: Since we don't know whether we have a valid SourceRange here we just check for some default values.
if (!frame.source_range.filename().is_empty() || frame.source_range.start.offset != 0 || frame.source_range.end.offset != 0) {
if (!source_range.filename().is_empty() || source_range.start.offset != 0 || source_range.end.offset != 0) {
if (function_name == "<unknown>"sv)
MUST_OR_THROW_OOM(stack_string_builder.appendff(" at {}:{}:{}\n", frame.source_range.filename(), frame.source_range.start.line, frame.source_range.start.column));
MUST_OR_THROW_OOM(stack_string_builder.appendff(" at {}:{}:{}\n", source_range.filename(), source_range.start.line, source_range.start.column));
else
MUST_OR_THROW_OOM(stack_string_builder.appendff(" at {} ({}:{}:{})\n", function_name, frame.source_range.filename(), frame.source_range.start.line, frame.source_range.start.column));
MUST_OR_THROW_OOM(stack_string_builder.appendff(" at {} ({}:{}:{})\n", function_name, source_range.filename(), source_range.start.line, source_range.start.column));
} else {
MUST_OR_THROW_OOM(stack_string_builder.appendff(" at {}\n", function_name.is_empty() ? "<unknown>"sv : function_name.view()));
}