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LibJS: Drop AST after first compilation on SourceTextModule

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Now that initialize_environment() uses pre-computed data and
execute_module() caches its executable / uses TLA shared data,
we can drop the AST reference after it's no longer needed.

For TLA modules, the AST is dropped immediately after constructing
the SharedFunctionInstanceData (which takes its own ref). For non-TLA
modules, the AST is dropped after the first bytecode compilation.

Also remove the m_default_export field (replaced by the pre-computed
m_default_export_binding_name) and extract default export info in
parse() instead of the constructor.
This commit is contained in:
Andreas Kling 2026-02-11 10:01:50 +01:00 committed by Andreas Kling
parent ef943505e2
commit 09a11a1a5c
3 changed files with 18 additions and 22 deletions
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28
Libraries/LibJS/SourceTextModule.cpp
View file

@ -108,7 +108,7 @@ static Vector<ModuleRequest> module_requests(Program& program)
SourceTextModule::SourceTextModule(Realm& realm, StringView filename, Script::HostDefined* host_defined, bool has_top_level_await, NonnullRefPtr<Program> body, Vector<ModuleRequest> requested_modules,
Vector<ImportEntry> import_entries, Vector<ExportEntry> local_export_entries,
Vector<ExportEntry> indirect_export_entries, Vector<ExportEntry> star_export_entries,
RefPtr<ExportStatement const> default_export)
Optional<Utf16FlyString> default_export_binding_name)
: CyclicModule(realm, filename, has_top_level_await, move(requested_modules), host_defined)
, m_ecmascript_code(move(body))
, m_execution_context(ExecutionContext::create(0, 0, 0))
@ -116,7 +116,7 @@ SourceTextModule::SourceTextModule(Realm& realm, StringView filename, Script::Ho
, m_local_export_entries(move(local_export_entries))
, m_indirect_export_entries(move(indirect_export_entries))
, m_star_export_entries(move(star_export_entries))
, m_default_export(move(default_export))
, m_default_export_binding_name(move(default_export_binding_name))
{
auto& vm = realm.vm();
@ -148,13 +148,6 @@ SourceTextModule::SourceTextModule(Realm& realm, StringView filename, Script::Ho
});
}));
// Pre-compute default export binding name (initialize_environment default export block).
if (m_default_export) {
VERIFY(m_default_export->has_statement());
if (!is<Declaration>(m_default_export->statement()))
m_default_export_binding_name = m_default_export->entries()[0].local_or_import_name.value();
}
// For TLA modules, pre-create the SharedFunctionInstanceData for the
// async wrapper function so that execute_module() doesn't need the AST.
if (has_top_level_await) {
@ -164,9 +157,10 @@ SourceTextModule::SourceTextModule(Realm& realm, StringView filename, Script::Ho
m_tla_shared_data = vm.heap().allocate<SharedFunctionInstanceData>(
vm, FunctionKind::Async,
"module code with top-level await"_utf16_fly_string,
0, FunctionParameters::empty(), m_ecmascript_code,
0, FunctionParameters::empty(), *m_ecmascript_code,
Utf16View {}, true, false, parsing_insights, Vector<LocalVariable> {});
m_tla_shared_data->m_is_module_wrapper = true;
m_ecmascript_code = nullptr;
}
}
@ -216,13 +210,13 @@ Result<GC::Ref<SourceTextModule>, Vector<ParserError>> SourceTextModule::parse(S
Vector<ExportEntry> star_export_entries;
// NOTE: Not in the spec but makes it easier to find the default.
RefPtr<ExportStatement const> default_export;
Optional<Utf16FlyString> default_export_binding_name;
// 9. Let exportEntries be ExportEntries of body.
// 10. For each ExportEntry Record ee of exportEntries, do
for (auto const& export_statement : body->exports()) {
if (export_statement->is_default_export()) {
VERIFY(!default_export);
VERIFY(!default_export_binding_name.has_value());
VERIFY(export_statement->entries().size() == 1);
VERIFY(export_statement->has_statement());
@ -234,7 +228,10 @@ Result<GC::Ref<SourceTextModule>, Vector<ParserError>> SourceTextModule::parse(S
return import_entry.local_name == entry.local_or_import_name;
})
.is_end());
default_export = export_statement;
// Extract the binding name if the default export is a non-declaration statement.
if (!is<Declaration>(export_statement->statement()))
default_export_binding_name = entry.local_or_import_name.value();
}
for (auto const& export_entry : export_statement->entries()) {
@ -313,7 +310,7 @@ Result<GC::Ref<SourceTextModule>, Vector<ParserError>> SourceTextModule::parse(S
move(local_export_entries),
move(indirect_export_entries),
move(star_export_entries),
move(default_export));
move(default_export_binding_name));
}
// 16.2.1.7.2.1 GetExportedNames ( [ exportStarSet ] ), https://tc39.es/ecma262/#sec-getexportednames
@ -710,10 +707,11 @@ ThrowCompletionOr<void> SourceTextModule::execute_module(VM& vm, GC::Ptr<Promise
dbgln_if(JS_MODULE_DEBUG, "[JS MODULE] SourceTextModule::execute_module({}, PromiseCapability @ {})", filename(), capability.ptr());
if (!m_has_top_level_await && !m_executable) {
auto maybe_executable = Bytecode::compile(vm, m_ecmascript_code, FunctionKind::Normal, "ShadowRealmEval"_utf16_fly_string);
auto maybe_executable = Bytecode::compile(vm, *m_ecmascript_code, FunctionKind::Normal, "ShadowRealmEval"_utf16_fly_string);
if (maybe_executable.is_error())
return maybe_executable.release_error();
m_executable = maybe_executable.release_value();
m_ecmascript_code = nullptr;
}
u32 registers_and_locals_count = 0;

8
Libraries/LibJS/SourceTextModule.h
View file

@ -24,7 +24,7 @@ public:
static Result<GC::Ref<SourceTextModule>, Vector<ParserError>> parse(StringView source_text, Realm&, StringView filename = {}, Script::HostDefined* host_defined = nullptr);
Program const& parse_node() const { return *m_ecmascript_code; }
Program const* parse_node() const { return m_ecmascript_code; }
virtual Vector<Utf16FlyString> get_exported_names(VM& vm, HashTable<Module const*>& export_star_set) override;
virtual ResolvedBinding resolve_export(VM& vm, Utf16FlyString const& export_name, Vector<ResolvedBinding> resolve_set = {}) override;
@ -37,11 +37,11 @@ protected:
virtual ThrowCompletionOr<void> execute_module(VM& vm, GC::Ptr<PromiseCapability> capability) override;
private:
SourceTextModule(Realm&, StringView filename, Script::HostDefined* host_defined, bool has_top_level_await, NonnullRefPtr<Program> body, Vector<ModuleRequest> requested_modules, Vector<ImportEntry> import_entries, Vector<ExportEntry> local_export_entries, Vector<ExportEntry> indirect_export_entries, Vector<ExportEntry> star_export_entries, RefPtr<ExportStatement const> default_export);
SourceTextModule(Realm&, StringView filename, Script::HostDefined* host_defined, bool has_top_level_await, NonnullRefPtr<Program> body, Vector<ModuleRequest> requested_modules, Vector<ImportEntry> import_entries, Vector<ExportEntry> local_export_entries, Vector<ExportEntry> indirect_export_entries, Vector<ExportEntry> star_export_entries, Optional<Utf16FlyString> default_export_binding_name);
virtual void visit_edges(Cell::Visitor&) override;
NonnullRefPtr<Program> m_ecmascript_code; // [[ECMAScriptCode]]
RefPtr<Program> m_ecmascript_code; // [[ECMAScriptCode]]
NonnullOwnPtr<ExecutionContext> m_execution_context; // [[Context]]
GC::Ptr<Object> m_import_meta; // [[ImportMeta]]
Vector<ImportEntry> m_import_entries; // [[ImportEntries]]
@ -49,8 +49,6 @@ private:
Vector<ExportEntry> m_indirect_export_entries; // [[IndirectExportEntries]]
Vector<ExportEntry> m_star_export_entries; // [[StarExportEntries]]
RefPtr<ExportStatement const> m_default_export; // Note: Not from the spec
// Pre-computed module declaration instantiation data.
// These are extracted from the AST at construction time so that
// initialize_environment() can run without walking the AST.

4
Utilities/js.cpp
View file

@ -233,8 +233,8 @@ static ErrorOr<bool> parse_and_run(JS::Realm& realm, StringView source, StringVi
result = vm.throw_completion<JS::SyntaxError>(move(error_string));
} else {
auto module = module_or_error.release_value();
if (s_dump_ast)
dump_ast(module->parse_node());
if (s_dump_ast && module->parse_node())
dump_ast(*module->parse_node());
if (!parse_only)
result = vm.bytecode_interpreter().run(*module);
}