branch.cpp

template<typename CodegenI32, typename CodegenDouble>
void Compiler::branch_if_both_numbers(Assembler::Reg lhs, Assembler::Reg rhs, CodegenI32 codegen_i32, CodegenDouble codegen_double)
{
    Assembler::Label end {};

    // The only case where we can take the int32 fastpath
    branch_if_both_int32(lhs, rhs, [&] {
        codegen_i32(lhs, rhs);
    });

    // check if lhs is int32
    Assembler::Label rhs_check {};
    Assembler::Label lhs_is_int32 {};
    Assembler::Label double_check {};
    jump_if_int32(lhs, lhs_is_int32);
    // lhs is not int32, store it to GPR0
    m_assembler.mov(
        Assembler::Operand::Register(GPR0),
        Assembler::Operand::Register(lhs));
    m_assembler.jump(rhs_check);
    // lhs is int32, convert lhs to double and store it to GPR0
    lhs_is_int32.link(m_assembler);
    m_assembler.convert_to_double(
        Assembler::Operand::FloatRegister(FPR0),
        Assembler::Operand::Register(lhs));
    m_assembler.mov(
        Assembler::Operand::Register(GPR0),
        Assembler::Operand::FloatRegister(FPR0));
    // check if rhs is int32
    rhs_check.link(m_assembler);
    Assembler::Label rhs_is_int32 {};
    jump_if_int32(rhs, rhs_is_int32);
    // rhs is not int32, store it to GPR1
    m_assembler.mov(
        Assembler::Operand::Register(GPR1),
        Assembler::Operand::Register(rhs));
    m_assembler.jump(double_check);
    // rhs is int32, convert rhs to double and store it to GPR1
    rhs_is_int32.link(m_assembler);
    m_assembler.convert_to_double(
        Assembler::Operand::FloatRegister(FPR1),
        Assembler::Operand::Register(rhs));
    m_assembler.mov(
        Assembler::Operand::Register(GPR1),
        Assembler::Operand::FloatRegister(FPR1));

    // If we reach this point, both lhs and rhs should be doubles (if numbers)
    // GPR2 = CANON_NAN_BITS
    double_check.link(m_assembler);
    m_assembler.mov(Assembler::Operand::Register(GPR2), Assembler::Operand::Imm(CANON_NAN_BITS));
    jump_if_not_double(GPR0, GPR2, end);
    jump_if_not_double(GPR1, GPR2, end);
    m_assembler.trap();

    // Both are doubles, call codegen_double
    m_assembler.mov(
        Assembler::Operand::FloatRegister(FPR0),
        Assembler::Operand::Register(GPR0));
    m_assembler.mov(
        Assembler::Operand::FloatRegister(FPR1),
        Assembler::Operand::Register(GPR1));
    codegen_double(FPR0, FPR1);
    end.link(m_assembler);
}