luaur-code-gen 0.1.0

Native (A64/X64) code generation for Luau (Rust).
Documentation 
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use crate::enums::size_x_64::SizeX64;
use crate::functions::byte_reg::byte_reg;
use crate::functions::dword_reg::dword_reg;
use crate::macros::codegen_assert::CODEGEN_ASSERT;
use crate::records::assembly_builder_x_64::AssemblyBuilderX64;
use crate::records::operand_x_64::OperandX64;
use crate::records::register_x_64::RegisterX64;
use luaur_vm::records::lua_table::LuaTable;

const K_STACK_OFFSET_TO_LOCALS: i32 = 16 + 32;
const SIZEOF_INSTRUCTION: i32 = 4;
// EmitCommon.h: kOffsetOfInstructionC = 3, kLuaNodeSizeLog2 = 5
const K_OFFSET_OF_INSTRUCTION_C: i32 = 3;
const K_LUA_NODE_SIZE_LOG2: i32 = 5;

fn s_code() -> OperandX64 {
    OperandX64::mem(
        SizeX64::qword,
        RegisterX64::noreg,
        1,
        RegisterX64::rsp,
        K_STACK_OFFSET_TO_LOCALS + 8,
    )
}

pub fn get_table_node_at_cached_slot(
    build: &mut AssemblyBuilderX64,
    tmp: RegisterX64,
    node: RegisterX64,
    table: RegisterX64,
    pcpos: i32,
) {
    CODEGEN_ASSERT!(tmp != node);
    CODEGEN_ASSERT!(table != node);

    build.mov(
        OperandX64::reg(node),
        OperandX64::mem(
            SizeX64::qword,
            RegisterX64::noreg,
            1,
            table,
            core::mem::offset_of!(LuaTable, node) as i32,
        ),
    );

    // compute cached slot
    build.mov(OperandX64::reg(tmp), s_code());
    build.movzx(
        dword_reg(tmp),
        OperandX64::mem(
            SizeX64::byte,
            RegisterX64::noreg,
            1,
            tmp,
            pcpos * SIZEOF_INSTRUCTION + K_OFFSET_OF_INSTRUCTION_C,
        ),
    );
    build.and_(
        OperandX64::reg(byte_reg(tmp)),
        OperandX64::mem(
            SizeX64::byte,
            RegisterX64::noreg,
            1,
            table,
            core::mem::offset_of!(LuaTable, nodemask8) as i32,
        ),
    );

    // LuaNode* n = &h->node[slot];
    build.shl(
        OperandX64::reg(dword_reg(tmp)),
        OperandX64::imm(K_LUA_NODE_SIZE_LOG2),
    );
    build.add(OperandX64::reg(node), OperandX64::reg(tmp));
}