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LibJS/JIT: Add fast path for decrement

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Generate jitted code for the decrement opcode.
This commit is contained in:
Stephan Vedder 2023-11-07 16:56:14 +01:00 • committed by Andreas Kling
parent 0e69f744df
commit 13726fd3b7
2 changed files with 47 additions and 0 deletions
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32
Userland/Libraries/LibJS/JIT/Compiler.cpp
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@ -396,9 +396,41 @@ static Value cxx_decrement(VM& vm, Value value)
void Compiler::compile_decrement(Bytecode::Op::Decrement const&)
{
load_accumulator(ARG1);
Assembler::Label end {};
Assembler::Label slow_case {};
branch_if_int32(ARG1, [&] {
// GPR0 = ARG1;
m_assembler.mov(
Assembler::Operand::Register(GPR0),
Assembler::Operand::Register(ARG1));
// GPR0--;
m_assembler.dec32(
Assembler::Operand::Register(GPR0),
slow_case);
// accumulator = GPR0 | SHIFTED_INT32_TAG;
m_assembler.mov(
Assembler::Operand::Register(GPR1),
Assembler::Operand::Imm(SHIFTED_INT32_TAG));
m_assembler.bitwise_or(
Assembler::Operand::Register(GPR0),
Assembler::Operand::Register(GPR1));
// accumulator = GPR0;
store_accumulator(GPR0);
m_assembler.jump(end);
});
slow_case.link(m_assembler);
native_call((void*)cxx_decrement);
store_accumulator(RET);
check_exception();
end.link(m_assembler);
}
void Compiler::check_exception()