luaur-code-gen 0.1.0

Native (A64/X64) code generation for Luau (Rust).
Documentation 
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use crate::enums::condition_x_64::ConditionX64;
use crate::enums::size_x_64::SizeX64;
use crate::functions::dword_reg::dword_reg;
use crate::functions::luau_reg::luau_reg;
use crate::functions::luau_reg_address::luau_reg_address;
use crate::records::assembly_builder_x_64::AssemblyBuilderX64;
use crate::records::label::Label;
use crate::records::module_helpers::ModuleHelpers;
use crate::records::operand_x_64::OperandX64;
use crate::records::register_x_64::RegisterX64;
use luaur_vm::macros::lua_multret::LUA_MULTRET;
use luaur_vm::records::call_info::CallInfo;
use luaur_vm::records::lua_state::lua_State;
use luaur_vm::type_aliases::t_value::TValue;

pub fn emit_inst_return(
    build: &mut AssemblyBuilderX64,
    helpers: &mut ModuleHelpers,
    ra: i32,
    actual_results: i32,
    function_variadic: bool,
) {
    let res = RegisterX64::rdi;
    let written = dword_reg(RegisterX64::rcx);

    if function_variadic {
        build.mov(
            OperandX64::reg(res),
            mem(
                SizeX64::qword,
                r_state(),
                core::mem::offset_of!(lua_State, ci) as i32,
            ),
        );
        build.mov(
            OperandX64::reg(res),
            mem(
                SizeX64::qword,
                res,
                core::mem::offset_of!(CallInfo, func) as i32,
            ),
        );
    } else if actual_results != 1 {
        build.lea_operand_x_64_operand_x_64(
            OperandX64::reg(res),
            mem(
                SizeX64::none,
                r_base(),
                -(core::mem::size_of::<TValue>() as i32),
            ),
        );
    }

    if actual_results == 0 {
        build.xor_(OperandX64::reg(written), OperandX64::reg(written));
        build.jmp_label(&mut helpers.return_);
    } else if actual_results == 1 && !function_variadic {
        build.vmovups(OperandX64::reg(xmm(0)), luau_reg(ra));
        build.vmovups(
            mem(
                SizeX64::xmmword,
                r_base(),
                -(core::mem::size_of::<TValue>() as i32),
            ),
            OperandX64::reg(xmm(0)),
        );
        build.mov(OperandX64::reg(res), OperandX64::reg(r_base()));
        build.mov(OperandX64::reg(written), OperandX64::imm(1));
        build.jmp_label(&mut helpers.return_);
    } else if (1..=3).contains(&actual_results) {
        for r in 0..actual_results {
            build.vmovups(OperandX64::reg(xmm(0)), luau_reg(ra + r));
            build.vmovups(
                mem(
                    SizeX64::xmmword,
                    res,
                    r * core::mem::size_of::<TValue>() as i32,
                ),
                OperandX64::reg(xmm(0)),
            );
        }
        build.add(
            OperandX64::reg(res),
            OperandX64::imm(actual_results * core::mem::size_of::<TValue>() as i32),
        );
        build.mov(OperandX64::reg(written), OperandX64::imm(actual_results));
        build.jmp_label(&mut helpers.return_);
    } else {
        let vali = RegisterX64::rax;
        let valend = RegisterX64::rdx;

        build.lea_operand_x_64_operand_x_64(OperandX64::reg(vali), luau_reg_address(ra));

        if actual_results == LUA_MULTRET {
            build.mov(
                OperandX64::reg(valend),
                mem(
                    SizeX64::qword,
                    r_state(),
                    core::mem::offset_of!(lua_State, top) as i32,
                ),
            );
        } else {
            build.lea_operand_x_64_operand_x_64(
                OperandX64::reg(valend),
                luau_reg_address(ra + actual_results),
            );
        }

        build.xor_(OperandX64::reg(written), OperandX64::reg(written));

        let mut repeat_value_loop = Label::default();
        let mut exit_value_loop = Label::default();

        if actual_results == LUA_MULTRET {
            build.cmp(OperandX64::reg(vali), OperandX64::reg(valend));
            build.jcc(ConditionX64::NotBelow, &mut exit_value_loop);
        }

        build.set_label(&mut repeat_value_loop);
        build.vmovups(OperandX64::reg(xmm(0)), mem(SizeX64::xmmword, vali, 0));
        build.vmovups(mem(SizeX64::xmmword, res, 0), OperandX64::reg(xmm(0)));
        build.add(
            OperandX64::reg(vali),
            OperandX64::imm(core::mem::size_of::<TValue>() as i32),
        );
        build.add(
            OperandX64::reg(res),
            OperandX64::imm(core::mem::size_of::<TValue>() as i32),
        );
        build.inc(OperandX64::reg(written));
        build.cmp(OperandX64::reg(vali), OperandX64::reg(valend));
        build.jcc(ConditionX64::Below, &mut repeat_value_loop);

        build.set_label_label(&mut exit_value_loop);
        build.jmp_label(&mut helpers.return_);
    }
}

const fn reg(index: u8, size: SizeX64) -> RegisterX64 {
    RegisterX64 {
        bits: (index << RegisterX64::INDEX_SHIFT) | size as u8,
    }
}

const fn xmm(index: u8) -> RegisterX64 {
    reg(index, SizeX64::xmmword)
}

const fn r_state() -> RegisterX64 {
    reg(15, SizeX64::qword)
}

const fn r_base() -> RegisterX64 {
    reg(14, SizeX64::qword)
}

fn mem(size: SizeX64, base: RegisterX64, disp: i32) -> OperandX64 {
    OperandX64::mem(size, RegisterX64::noreg, 1, base, disp)
}