ladybird/Libraries/LibJS/Bytecode/Executable.cpp
Andreas Kling 21cbfb3cb1 LibJS: Drop source ranges from bytecode source maps
Store source map locations as bytecode offset, line, and column.
Runtime consumers only emit the start line and column, so source end
positions and source text offsets do not need to be carried through
Executable source maps, bytecode cache serialization, or the Rust FFI.

Keep SourceCode's internal position cache able to track source text
offsets so callers can still translate source offsets to line and
column pairs when needed. Hash dump-bytecode IDs from the name, first
source position, and bytecode size instead of source slices that need
end offsets.

Bump the bytecode cache format version for the slimmer serialized
source map entry shape.
2026-05-14 09:41:03 +02:00

460 lines
18 KiB
C++

/*
* Copyright (c) 2021-2025, Andreas Kling <andreas@ladybird.org>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#include <AK/BinarySearch.h>
#include <LibGC/Heap.h>
#include <LibGC/HeapBlock.h>
#include <LibJS/Bytecode/BasicBlock.h>
#include <LibJS/Bytecode/Executable.h>
#include <LibJS/Bytecode/FormatOperand.h>
#include <LibJS/Bytecode/Instruction.h>
#include <LibJS/Bytecode/Op.h>
#include <LibJS/Bytecode/RegexTable.h>
#include <LibJS/Runtime/Array.h>
#include <LibJS/Runtime/ExternalMemory.h>
#include <LibJS/Runtime/SharedFunctionInstanceData.h>
#include <LibJS/Runtime/Value.h>
#include <LibJS/SourceCode.h>
namespace JS::Bytecode {
GC_DEFINE_ALLOCATOR(Executable);
GC_DEFINE_ALLOCATOR(ObjectPropertyIteratorCacheData);
ObjectPropertyIteratorCacheData::ObjectPropertyIteratorCacheData(VM& vm, Vector<PropertyKey> properties, ObjectPropertyIteratorFastPath fast_path, u32 indexed_property_count, bool receiver_has_magical_length_property, GC::Ref<Shape> shape, GC::Ptr<PrototypeChainValidity> prototype_chain_validity)
: m_properties(move(properties))
, m_shape(shape)
, m_prototype_chain_validity(prototype_chain_validity)
, m_indexed_property_count(indexed_property_count)
, m_receiver_has_magical_length_property(receiver_has_magical_length_property)
, m_fast_path(fast_path)
{
// The iterator fast path returns JS Values directly, so materialize the
// cached key list once up front instead of converting PropertyKeys during
// every ObjectPropertyIteratorNext.
m_property_values.ensure_capacity(indexed_property_count + m_properties.size());
for (u32 i = 0; i < indexed_property_count; ++i)
m_property_values.append(PropertyKey { i }.to_value(vm));
for (auto const& key : m_properties)
m_property_values.append(key.to_value(vm));
if (m_shape->is_dictionary())
m_shape_dictionary_generation = m_shape->dictionary_generation();
}
void ObjectPropertyIteratorCacheData::visit_edges(Visitor& visitor)
{
Base::visit_edges(visitor);
visitor.visit(m_shape);
visitor.visit(m_prototype_chain_validity);
visitor.visit(m_property_values.span());
for (auto& key : m_properties)
key.visit_edges(visitor);
}
size_t ObjectPropertyIteratorCacheData::external_memory_size() const
{
auto size = vector_external_memory_size(m_properties);
size = saturating_add_external_memory_size(size, vector_external_memory_size(m_property_values));
return size;
}
Executable::Executable(
Vector<u8> bytecode,
NonnullOwnPtr<IdentifierTable> identifier_table,
NonnullOwnPtr<PropertyKeyTable> property_key_table,
NonnullOwnPtr<StringTable> string_table,
NonnullOwnPtr<RegexTable> regex_table,
Vector<Value> constants,
NonnullRefPtr<SourceCode const> source_code,
size_t number_of_property_lookup_caches,
size_t number_of_global_variable_caches,
size_t number_of_template_object_caches,
size_t number_of_object_shape_caches,
size_t number_of_object_property_iterator_caches,
size_t number_of_registers,
Strict strict)
: GC::WeakContainer(heap())
, bytecode(move(bytecode))
, string_table(move(string_table))
, identifier_table(move(identifier_table))
, property_key_table(move(property_key_table))
, regex_table(move(regex_table))
, constants(move(constants))
, source_code(move(source_code))
, number_of_registers(number_of_registers)
, is_strict_mode(strict == Strict::Yes)
{
property_lookup_caches.resize(number_of_property_lookup_caches);
global_variable_caches.resize(number_of_global_variable_caches);
template_object_caches.resize(number_of_template_object_caches);
object_shape_caches.resize(number_of_object_shape_caches);
object_property_iterator_caches.resize(number_of_object_property_iterator_caches);
asm_constants_size = this->constants.size();
asm_constants_data = this->constants.data();
}
Executable::~Executable() = default;
void Executable::fixup_cache_pointers()
{
for (auto it = InstructionStreamIterator(bytecode); !it.at_end(); ++it) {
fixup_instruction_cache(
const_cast<Instruction&>(*it),
property_lookup_caches.span(),
global_variable_caches.span(),
template_object_caches.span(),
object_shape_caches.span(),
object_property_iterator_caches.span());
}
}
static SourceMapEntry const* first_real_source_map_entry(Executable const& executable)
{
SourceMapEntry const* first_entry = nullptr;
for (auto const& entry : executable.source_map) {
if (entry.line == 0 && entry.column == 0)
continue;
if (!first_entry || entry.line < first_entry->line || (entry.line == first_entry->line && entry.column < first_entry->column))
first_entry = &entry;
}
return first_entry;
}
static void dump_header(StringBuilder& output, Executable const& executable, bool use_color)
{
auto const white_bold = use_color ? "\033[37;1m"sv : ""sv;
auto const reset = use_color ? "\033[0m"sv : ""sv;
auto const* first_source_map_entry = first_real_source_map_entry(executable);
u32 hash = 2166136261u; // FNV-1a offset basis
auto update_hash = [&](u32 value) {
for (size_t i = 0; i < sizeof(value); ++i) {
hash ^= (value >> (i * 8)) & 0xFF;
hash *= 16777619u;
}
};
auto update_hash_with_code_unit = [&](u16 code_unit) {
hash ^= code_unit & 0xFF;
hash *= 16777619u;
hash ^= (code_unit >> 8) & 0xFF;
hash *= 16777619u;
};
auto name_view = executable.name.view();
for (size_t i = 0; i < name_view.length_in_code_units(); ++i)
update_hash_with_code_unit(name_view.code_unit_at(i));
if (first_source_map_entry) {
update_hash(first_source_map_entry->line);
update_hash(first_source_map_entry->column);
}
update_hash(static_cast<u32>(min(executable.bytecode.size(), static_cast<size_t>(NumericLimits<u32>::max()))));
if (executable.name.is_empty())
output.appendff("{}${:08x}{}", white_bold, hash, reset);
else
output.appendff("{}{}${:08x}{}", white_bold, executable.name, hash, reset);
// Show source location if available.
if (first_source_map_entry) {
auto filename = executable.source_code->filename();
if (!filename.is_empty()) {
// Show just the basename to keep output portable across machines.
auto last_slash = filename.bytes_as_string_view().find_last('/');
if (last_slash.has_value())
filename = MUST(filename.substring_from_byte_offset(last_slash.value() + 1));
output.appendff(" {}:{}:{}", filename, first_source_map_entry->line, first_source_map_entry->column);
} else {
output.appendff(" line {}, column {}", first_source_map_entry->line, first_source_map_entry->column);
}
}
output.append('\n');
}
static void dump_metadata(StringBuilder& output, Executable const& executable, bool use_color)
{
auto const green = use_color ? "\033[32m"sv : ""sv;
auto const yellow = use_color ? "\033[33m"sv : ""sv;
auto const blue = use_color ? "\033[34m"sv : ""sv;
auto const cyan = use_color ? "\033[36m"sv : ""sv;
auto const reset = use_color ? "\033[0m"sv : ""sv;
output.appendff(" {}Registers{}: {}\n", green, reset, executable.number_of_registers);
output.appendff(" {}Blocks{}: {}\n", green, reset, executable.basic_block_start_offsets.size());
if (!executable.local_variable_names.is_empty()) {
output.appendff(" {}Locals{}: ", green, reset);
for (size_t i = 0; i < executable.local_variable_names.size(); ++i) {
if (i != 0)
output.append(", "sv);
output.appendff("{}{}~{}{}", blue, executable.local_variable_names[i].name, i, reset);
}
output.append('\n');
}
if (!executable.constants.is_empty()) {
output.appendff(" {}Constants{}:\n", green, reset);
for (size_t i = 0; i < executable.constants.size(); ++i) {
auto value = executable.constants[i];
output.append(" "sv);
output.appendff("{}[{}]{} = ", yellow, i, reset);
output.append(cyan);
if (value.is_special_empty_value())
output.append("<Empty>"sv);
else if (value.is_boolean())
output.appendff("Bool({})", value.as_bool() ? "true"sv : "false"sv);
else if (value.is_int32())
output.appendff("Int32({})", value.as_i32());
else if (value.is_double())
output.appendff("Double({})", value.as_double());
else if (value.is_bigint())
output.appendff("BigInt({})", MUST(value.as_bigint().to_string()));
else if (value.is_string())
output.appendff("String(\"{}\")", value.as_string().utf8_string_view());
else if (value.is_undefined())
output.append("Undefined"sv);
else if (value.is_null())
output.append("Null"sv);
else
output.appendff("Value({})", value);
output.append(reset);
output.append('\n');
}
}
}
static void dump_bytecode(StringBuilder& output, Executable const& executable, bool use_color)
{
auto const magenta = use_color ? "\033[35;1m"sv : ""sv;
auto const reset = use_color ? "\033[0m"sv : ""sv;
InstructionStreamIterator it(executable.bytecode, &executable);
size_t basic_block_offset_index = 0;
while (!it.at_end()) {
if (basic_block_offset_index < executable.basic_block_start_offsets.size()
&& it.offset() == executable.basic_block_start_offsets[basic_block_offset_index]) {
if (basic_block_offset_index > 0)
output.append('\n');
output.appendff("{}block{}{}:\n", magenta, basic_block_offset_index, reset);
++basic_block_offset_index;
}
output.appendff(" [{:4x}] {}\n", it.offset(), (*it).to_byte_string(executable));
++it;
}
}
void Executable::dump() const
{
StringBuilder output;
dump_header(output, *this, true);
dump_metadata(output, *this, true);
output.append('\n');
dump_bytecode(output, *this, true);
if (!exception_handlers.is_empty()) {
output.append("\nException handlers:\n"sv);
for (auto const& handler : exception_handlers) {
output.appendff(" [{:4x} .. {:4x}] => handler ", handler.start_offset, handler.end_offset);
Label handler_label(static_cast<u32>(handler.handler_offset));
output.appendff("{}\n", format_label(""sv, handler_label, *this));
}
}
output.append('\n');
warnln("{}", output.string_view());
}
String Executable::dump_to_string() const
{
StringBuilder output;
dump_header(output, *this, false);
dump_metadata(output, *this, false);
output.append('\n');
dump_bytecode(output, *this, false);
if (!exception_handlers.is_empty()) {
output.append("\nException handlers:\n"sv);
for (auto const& handler : exception_handlers) {
output.appendff(" [{:4x} .. {:4x}] => handler ", handler.start_offset, handler.end_offset);
Label handler_label(static_cast<u32>(handler.handler_offset));
output.appendff("{}\n", format_label(""sv, handler_label, *this));
}
}
return output.to_string_without_validation();
}
void Executable::visit_edges(Visitor& visitor)
{
Base::visit_edges(visitor);
visitor.visit(constants);
for (auto& cache : template_object_caches)
visitor.visit(cache.cached_template_object);
for (auto& cache : object_property_iterator_caches)
visitor.visit(cache.data);
for (auto& cache : object_property_iterator_caches)
visitor.visit(cache.reusable_property_name_iterator);
for (auto& data : shared_function_data)
visitor.visit(data);
for (auto& blueprint : class_blueprints) {
for (auto& element : blueprint.elements) {
if (element.literal_value.has_value() && element.literal_value->is_cell())
visitor.visit(element.literal_value->as_cell());
}
}
property_key_table->visit_edges(visitor);
}
size_t Executable::external_memory_size() const
{
size_t size = vector_external_memory_size(bytecode);
size = saturating_add_external_memory_size(size, vector_external_memory_size(property_lookup_caches));
size = saturating_add_external_memory_size(size, vector_external_memory_size(global_variable_caches));
size = saturating_add_external_memory_size(size, vector_external_memory_size(template_object_caches));
size = saturating_add_external_memory_size(size, vector_external_memory_size(object_shape_caches));
for (auto const& cache : object_shape_caches)
size = saturating_add_external_memory_size(size, vector_external_memory_size(cache.property_offsets));
size = saturating_add_external_memory_size(size, vector_external_memory_size(object_property_iterator_caches));
size = saturating_add_external_memory_size(size, string_table->external_memory_size());
size = saturating_add_external_memory_size(size, identifier_table->external_memory_size());
size = saturating_add_external_memory_size(size, property_key_table->external_memory_size());
size = saturating_add_external_memory_size(size, regex_table->external_memory_size());
size = saturating_add_external_memory_size(size, vector_external_memory_size(constants));
size = saturating_add_external_memory_size(size, vector_external_memory_size(shared_function_data));
size = saturating_add_external_memory_size(size, vector_external_memory_size(class_blueprints));
for (auto const& blueprint : class_blueprints)
size = saturating_add_external_memory_size(size, vector_external_memory_size(blueprint.elements));
size = saturating_add_external_memory_size(size, vector_external_memory_size(exception_handlers));
size = saturating_add_external_memory_size(size, vector_external_memory_size(basic_block_start_offsets));
size = saturating_add_external_memory_size(size, vector_external_memory_size(source_map));
size = saturating_add_external_memory_size(size, vector_external_memory_size(local_variable_names));
size = saturating_add_external_memory_size(size, hash_map_external_memory_size(m_source_range_cache));
return size;
}
static Vector<PropertyLookupCache*>& static_property_lookup_caches()
{
static Vector<PropertyLookupCache*> caches;
return caches;
}
StaticPropertyLookupCache::StaticPropertyLookupCache()
{
static_property_lookup_caches().append(this);
}
static bool cell_is_dead(Cell const* cell)
{
auto* block = GC::HeapBlock::from_cell(cell);
if (!GC::Heap::the().is_live_heap_block(block))
return true;
return cell->state() != Cell::State::Live || !cell->is_marked();
}
static void clear_cache_entry_if_dead(PropertyLookupCache::Entry& entry)
{
if (entry.from_shape && cell_is_dead(entry.from_shape))
entry.from_shape = nullptr;
if (entry.shape && cell_is_dead(entry.shape))
entry.shape = nullptr;
if (entry.prototype && cell_is_dead(entry.prototype))
entry.prototype = nullptr;
if (entry.prototype_chain_validity && cell_is_dead(entry.prototype_chain_validity))
entry.prototype_chain_validity = nullptr;
}
void StaticPropertyLookupCache::sweep_all()
{
for (auto* cache : static_property_lookup_caches()) {
for (auto& entry : cache->entries)
clear_cache_entry_if_dead(entry);
}
}
void Executable::remove_dead_cells(Badge<GC::Heap>)
{
for (auto& cache : property_lookup_caches) {
for (auto& entry : cache.entries)
clear_cache_entry_if_dead(entry);
}
for (auto& cache : global_variable_caches) {
for (auto& entry : cache.entries)
clear_cache_entry_if_dead(entry);
}
for (auto& cache : object_shape_caches) {
auto* shape = cache.shape.ptr();
if (shape && cell_is_dead(shape))
cache.shape = nullptr;
}
}
Optional<Executable::ExceptionHandlers const&> Executable::exception_handlers_for_offset(size_t offset) const
{
// NB: exception_handlers is sorted by start_offset.
auto* entry = binary_search(exception_handlers, offset, nullptr, [](size_t needle, ExceptionHandlers const& entry) -> int {
if (needle < entry.start_offset)
return -1;
if (needle >= entry.end_offset)
return 1;
return 0;
});
if (!entry)
return {};
return *entry;
}
Optional<SourceRange> Executable::source_range_at(size_t offset) const
{
if (offset >= bytecode.size())
return {};
if (source_map.is_empty())
return {};
size_t low = 0;
size_t high = source_map.size();
while (low < high) {
auto middle = low + (high - low) / 2;
if (source_map[middle].bytecode_offset <= offset)
low = middle + 1;
else
high = middle;
}
if (low == 0)
return {};
auto& entry = source_map[low - 1];
return SourceRange {
.code = source_code,
.start = { .line = entry.line, .column = entry.column },
};
}
SourceRange const& Executable::get_source_range(u32 program_counter)
{
return m_source_range_cache.ensure(program_counter, [&] {
if (auto source_range = source_range_at(program_counter); source_range.has_value())
return *source_range;
static SourceRange dummy { SourceCode::create({}, {}), {} };
return dummy;
});
}
Operand Executable::original_operand_from_raw(u32 raw) const
{
// NB: Layout is [registers | locals | constants | arguments]
if (raw < number_of_registers)
return Operand { Operand::Type::Register, raw };
if (raw < registers_and_locals_count)
return Operand { Operand::Type::Local, raw - local_index_base };
if (raw < argument_index_base)
return Operand { Operand::Type::Constant, raw - registers_and_locals_count };
return Operand { Operand::Type::Argument, raw - argument_index_base };
}
}