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/*
* Copyright (c) 2021, Andreas Kling <kling@serenityos.org>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#include <AK/String.h>
#include <LibJS/Bytecode/BasicBlock.h>
#include <LibJS/Bytecode/Op.h>
#include <sys/mman.h>
namespace JS::Bytecode {
NonnullOwnPtr<BasicBlock> BasicBlock::create(String name, size_t size)
{
return adopt_own(*new BasicBlock(move(name), max(size, static_cast<size_t>(4 * KiB))));
}
BasicBlock::BasicBlock(String name, size_t size)
: m_name(move(name))
{
// FIXME: This is not the smartest solution ever. Find something cleverer!
// The main issue we're working around here is that we don't want pointers into the bytecode stream to become invalidated
// during code generation due to dynamic buffer resizing. Otherwise we could just use a Vector.
m_buffer_capacity = size;
m_buffer = (u8*)mmap(nullptr, m_buffer_capacity, PROT_READ | PROT_WRITE, MAP_ANONYMOUS | MAP_PRIVATE, 0, 0);
VERIFY(m_buffer != MAP_FAILED);
}
BasicBlock::~BasicBlock()
{
Bytecode::InstructionStreamIterator it(instruction_stream());
while (!it.at_end()) {
auto& to_destroy = (*it);
++it;
Instruction::destroy(const_cast<Instruction&>(to_destroy));
}
munmap(m_buffer, m_buffer_capacity);
}
void BasicBlock::seal()
{
// FIXME: mprotect the instruction stream as PROT_READ
// This is currently not possible because instructions can have destructors (that clean up strings)
// Instructions should instead be destructor-less and refer to strings in a string table on the Bytecode::Block.
// It also doesn't work because instructions that have String members use RefPtr internally which must be in writable memory.
}
void BasicBlock::dump(Bytecode::Executable const& executable) const
{
Bytecode::InstructionStreamIterator it(instruction_stream());
if (!m_name.is_empty())
warnln("{}:", m_name);
while (!it.at_end()) {
warnln("[{:4x}] {}", it.offset(), (*it).to_string(executable));
++it;
}
}
void BasicBlock::grow(size_t additional_size)
{
m_buffer_size += additional_size;
VERIFY(m_buffer_size <= m_buffer_capacity);
}
void InstructionStreamIterator::operator++()
{
VERIFY(!at_end());
m_offset += dereference().length();
}
}
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