mirror of
https://github.com/fergalmoran/ladybird.git
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f6aee2b9e8
Instead of keeping bytecode as a set of disjoint basic blocks on the
malloc heap, bytecode is now a contiguous sequence of bytes(!)
The transformation happens at the end of Bytecode::Generator::generate()
and the only really hairy part is rerouting jump labels.
This required solving a few problems:
- The interpreter execution loop had to change quite a bit, since we
were storing BasicBlock pointers all over the place, and control
transfer was done by redirecting the interpreter's current block.
- Exception handlers & finalizers are now stored per-bytecode-range
in a side table in Executable.
- The interpreter now has a plain program counter instead of a stream
iterator. This actually makes error stack generation a bit nicer
since we just have to deal with a number instead of reaching into
the iterator.
This yields a 25% performance improvement on this microbenchmark:
for (let i = 0; i < 1_000_000; ++i) { }
But basically everything gets faster. :^)
79 lines
2.2 KiB
C++
79 lines
2.2 KiB
C++
/*
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* Copyright (c) 2020-2021, Andreas Kling <kling@serenityos.org>
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* Copyright (c) 2020-2021, Linus Groh <linusg@serenityos.org>
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* Copyright (c) 2022, Luke Wilde <lukew@serenityos.org>
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*
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* SPDX-License-Identifier: BSD-2-Clause
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*/
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#include <LibJS/Bytecode/Executable.h>
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#include <LibJS/Heap/Heap.h>
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#include <LibJS/Runtime/ExecutionContext.h>
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#include <LibJS/Runtime/FunctionObject.h>
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namespace JS {
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NonnullOwnPtr<ExecutionContext> ExecutionContext::create(Heap& heap)
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{
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return adopt_own(*new ExecutionContext(heap));
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}
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ExecutionContext::ExecutionContext(Heap& heap)
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: m_heap(heap)
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{
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}
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ExecutionContext::~ExecutionContext()
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{
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}
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NonnullOwnPtr<ExecutionContext> ExecutionContext::copy() const
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{
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auto copy = create(m_heap);
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copy->function = function;
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copy->realm = realm;
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copy->script_or_module = script_or_module;
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copy->lexical_environment = lexical_environment;
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copy->variable_environment = variable_environment;
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copy->private_environment = private_environment;
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copy->program_counter = program_counter;
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copy->function_name = function_name;
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copy->this_value = this_value;
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copy->is_strict_mode = is_strict_mode;
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copy->executable = executable;
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copy->arguments = arguments;
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copy->locals = locals;
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copy->registers = registers;
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copy->unwind_contexts = unwind_contexts;
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copy->saved_lexical_environments = saved_lexical_environments;
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copy->previously_scheduled_jumps = previously_scheduled_jumps;
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return copy;
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}
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void ExecutionContext::visit_edges(Cell::Visitor& visitor)
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{
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visitor.visit(function);
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visitor.visit(realm);
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visitor.visit(variable_environment);
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visitor.visit(lexical_environment);
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visitor.visit(private_environment);
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visitor.visit(context_owner);
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visitor.visit(this_value);
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visitor.visit(executable);
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visitor.visit(function_name);
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visitor.visit(arguments);
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visitor.visit(locals);
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visitor.visit(registers);
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for (auto& context : unwind_contexts) {
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visitor.visit(context.lexical_environment);
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}
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visitor.visit(saved_lexical_environments);
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script_or_module.visit(
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[](Empty) {},
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[&](auto& script_or_module) {
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visitor.visit(script_or_module);
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});
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}
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}
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