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LibJS/JIT: Consolidate exits from the jitted code

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Instead of emitting the "restore callee-saved registers and return"
sequence again and again, just emit it once at the end of the generated
code, and have everyone jump to it.

This is a code size optimization that saves 207KiB on Kraken/ai-astar.js
This commit is contained in:
Andreas Kling 2023-10-28 13:57:50 +02:00
parent 0768bf2623
commit 9afd12a8ba
2 changed files with 15 additions and 4 deletions
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16
Userland/Libraries/LibJS/JIT/Compiler.cpp
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@ -337,7 +337,7 @@ void Compiler::check_exception()
Assembler::Operand::Imm(0),
handle_exception);
m_assembler.exit();
jump_to_exit();
// handle_exception:
handle_exception.link(m_assembler);
@ -593,7 +593,7 @@ void Compiler::compile_return(Bytecode::Op::Return const&)
// normal_return:
normal_return.link(m_assembler);
store_vm_register(Bytecode::Register::return_value(), GPR0);
m_assembler.exit();
jump_to_exit();
}
static Value cxx_new_string(VM& vm, DeprecatedString const& string)
@ -971,7 +971,7 @@ void Compiler::compile_continue_pending_unwind(Bytecode::Op::ContinuePendingUnwi
// finish the pending return from the try block
store_vm_register(Bytecode::Register::return_value(), GPR0);
m_assembler.exit();
jump_to_exit();
}
static void cxx_create_lexical_environment(VM& vm)
@ -999,6 +999,11 @@ void Compiler::compile_leave_lexical_environment(Bytecode::Op::LeaveLexicalEnvir
m_assembler.native_call((void*)cxx_leave_lexical_environment);
}
void Compiler::jump_to_exit()
{
m_assembler.jump(m_exit_label);
}
OwnPtr<NativeExecutable> Compiler::compile(Bytecode::Executable& bytecode_executable)
{
if (!getenv("LIBJS_JIT"))
@ -1158,9 +1163,12 @@ OwnPtr<NativeExecutable> Compiler::compile(Bytecode::Executable& bytecode_execut
++it;
}
if (!block->is_terminated())
compiler.m_assembler.exit();
compiler.jump_to_exit();
}
compiler.m_exit_label.link(compiler.m_assembler);
compiler.m_assembler.exit();
auto* executable_memory = mmap(nullptr, compiler.m_output.size(), PROT_READ | PROT_WRITE, MAP_ANONYMOUS | MAP_PRIVATE, 0, 0);
if (executable_memory == MAP_FAILED) {
dbgln("mmap: {}", strerror(errno));