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	Using mmap was quite punishing on inputs with lots of basic blocks, such as test262 tests with eval() in a loop that goes 64k times.. ~27% speed-up on language/literals/regexp/S7.8.5_A2.1_T2.js but presumably everything everywhere will benefit from this. :^)
		
			
				
	
	
		
			65 lines
		
	
	
	
		
			2 KiB
		
	
	
	
		
			C++
		
	
	
	
	
	
			
		
		
	
	
			65 lines
		
	
	
	
		
			2 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 <AK/DeprecatedString.h>
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#include <LibJS/Bytecode/BasicBlock.h>
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#include <LibJS/Bytecode/Op.h>
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namespace JS::Bytecode {
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NonnullOwnPtr<BasicBlock> BasicBlock::create(DeprecatedString name, size_t size)
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{
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    return adopt_own(*new BasicBlock(move(name), max(size, static_cast<size_t>(4 * KiB))));
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}
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BasicBlock::BasicBlock(DeprecatedString name, size_t size)
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    : m_name(move(name))
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{
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    // FIXME: This is not the smartest solution ever. Find something cleverer!
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    // The main issue we're working around here is that we don't want pointers into the bytecode stream to become invalidated
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    // during code generation due to dynamic buffer resizing. Otherwise we could just use a Vector.
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    m_buffer_capacity = size;
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    m_buffer = new u8[m_buffer_capacity];
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}
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BasicBlock::~BasicBlock()
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{
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    Bytecode::InstructionStreamIterator it(instruction_stream());
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    while (!it.at_end()) {
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        auto& to_destroy = (*it);
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        ++it;
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        Instruction::destroy(const_cast<Instruction&>(to_destroy));
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    }
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    delete[] m_buffer;
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}
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void BasicBlock::seal()
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{
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    // FIXME: mprotect the instruction stream as PROT_READ
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    // This is currently not possible because instructions can have destructors (that clean up strings)
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    // Instructions should instead be destructor-less and refer to strings in a string table on the Bytecode::Block.
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    // It also doesn't work because instructions that have String members use RefPtr internally which must be in writable memory.
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}
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void BasicBlock::dump(Bytecode::Executable const& executable) const
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{
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    Bytecode::InstructionStreamIterator it(instruction_stream());
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    if (!m_name.is_empty())
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        warnln("{}:", m_name);
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    while (!it.at_end()) {
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        warnln("[{:4x}] {}", it.offset(), (*it).to_deprecated_string(executable));
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        ++it;
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    }
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}
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void BasicBlock::grow(size_t additional_size)
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{
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    m_buffer_size += additional_size;
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    VERIFY(m_buffer_size <= m_buffer_capacity);
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}
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}
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