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. :^)
67 lines
1.6 KiB
C++
67 lines
1.6 KiB
C++
/*
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* Copyright (c) 2021, Andreas Kling <kling@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/Bytecode/Instruction.h>
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#include <LibJS/Bytecode/Op.h>
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namespace JS::Bytecode {
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void Instruction::destroy(Instruction& instruction)
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{
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#define __BYTECODE_OP(op) \
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case Type::op: \
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static_cast<Op::op&>(instruction).~op(); \
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return;
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switch (instruction.type()) {
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ENUMERATE_BYTECODE_OPS(__BYTECODE_OP)
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default:
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VERIFY_NOT_REACHED();
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}
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#undef __BYTECODE_OP
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}
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void Instruction::visit_labels(Function<void(JS::Bytecode::Label&)> visitor)
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{
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#define __BYTECODE_OP(op) \
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case Type::op: \
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static_cast<Op::op&>(*this).visit_labels_impl(move(visitor)); \
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return;
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switch (type()) {
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ENUMERATE_BYTECODE_OPS(__BYTECODE_OP)
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default:
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VERIFY_NOT_REACHED();
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}
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#undef __BYTECODE_OP
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}
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UnrealizedSourceRange InstructionStreamIterator::source_range() const
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{
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VERIFY(m_executable);
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auto record = dereference().source_record();
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return {
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.source_code = m_executable->source_code,
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.start_offset = record.source_start_offset,
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.end_offset = record.source_end_offset,
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};
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}
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RefPtr<SourceCode> InstructionStreamIterator::source_code() const
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{
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return m_executable ? m_executable->source_code.ptr() : nullptr;
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}
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Operand::Operand(Register reg)
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: m_type(Type::Register)
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, m_index(reg.index())
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{
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}
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}
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