use {
    self::strong_ref::StrongRef,
    crate::{
        backend::{
            hbvm::{Comptime, HbvmBackend},
            Backend,
        },
        debug,
        lexer::TokenKind,
        nodes::*,
        parser::{
            self,
            idfl::{self},
            CapturedIdent, CommentOr, CtorField, DeclId, Expr, ExprRef, FieldList, ListKind,
            MatchBranch, Pos,
        },
        ty::{
            self, Arg, ArrayLen, CompState, ConstData, EnumData, EnumField, FTask, FuncData,
            GlobalData, List, Loc, Module, Offset, OffsetIter, OptLayout, Sig, StringRef,
            StructData, StructField, SymKey, TemplateData, TupleData, TypeBase, TypeIns, Types,
            UnionData, UnionField,
        },
        utils::{BitSet, EntSlice, Vc},
        Ident,
    },
    alloc::{string::String, vec::Vec},
    core::{
        assert_matches::debug_assert_matches,
        cell::RefCell,
        fmt::{self, Debug, Display, Write},
        format_args as fa, mem,
    },
    hbbytecode::DisasmError,
    std::panic,
};

const DEFAULT_ACLASS: usize = 0;
const GLOBAL_ACLASS: usize = 1;

macro_rules! inference {
    ($ty:ident, $ctx:expr, $self:expr, $pos:expr, $subject:literal, $example:literal) => {
        let Some($ty) = $ctx.ty else {
            $self.error(
                $pos,
                concat!(
                    "resulting ",
                    $subject,
                    " cannot be inferred from context, consider using `",
                    $example,
                    "` to hint the type",
                ),
            );
            return Value::NEVER;
        };
    };
}

impl Nodes {
    fn load_loop_var(&mut self, index: usize, var: &mut Variable, loops: &mut [Loop]) {
        if var.value() != VOID {
            return;
        }

        debug_assert!(!var.ptr);

        let [loops @ .., loob] = loops else { unreachable!() };
        let &mut Loop::Runtime { node, ref mut scope, .. } = loob else {
            self.load_loop_var(index, var, loops);
            return;
        };
        let lvar = &mut scope.vars[index];

        debug_assert!(!lvar.ptr);

        self.load_loop_var(index, lvar, loops);

        if !self[lvar.value()].is_lazy_phi(node) {
            let lvalue = lvar.value();
            let inps = [node, lvalue, VOID];
            lvar.set_value(self.new_node_nop(lvar.ty, Kind::Phi, inps), self);

            self.pass_aclass(self.aclass_index(lvalue).1, lvar.value());
        }
        var.set_value(lvar.value(), self);
    }

    fn load_loop_aclass(&mut self, index: usize, aclass: &mut AClass, loops: &mut [Loop]) {
        if aclass.last_store.get() != VOID {
            return;
        }

        let [loops @ .., loob] = loops else { unreachable!() };
        let &mut Loop::Runtime { node, ref mut scope, .. } = loob else {
            self.load_loop_aclass(index, aclass, loops);
            return;
        };
        let lvar = &mut scope.aclasses[index];

        self.load_loop_aclass(index, lvar, loops);

        if !self[lvar.last_store.get()].is_lazy_phi(node) {
            let inps = [node, lvar.last_store.get(), VOID];
            lvar.last_store.set(self.new_node_nop(ty::Id::VOID, Kind::Phi, inps), self);
        }
        aclass.last_store.set(lvar.last_store.get(), self);
    }

    fn merge_scopes(
        &mut self,
        loops: &mut [Loop],
        ctrl: &StrongRef,
        to: &mut Scope,
        from: &mut Scope,
        tys: &Types,
    ) {
        for (i, (to_value, from_value)) in to.vars.iter_mut().zip(from.vars.iter_mut()).enumerate()
        {
            debug_assert_eq!(to_value.ty, from_value.ty);
            if to_value.value() != from_value.value() {
                self.load_loop_var(i, from_value, loops);
                self.load_loop_var(i, to_value, loops);
                if to_value.value() != from_value.value() {
                    debug_assert!(!to_value.ptr);
                    debug_assert!(!from_value.ptr);
                    let inps = [ctrl.get(), from_value.value(), to_value.value()];
                    to_value
                        .set_value_remove(self.new_node(from_value.ty, Kind::Phi, inps, tys), self);
                }
            }
        }

        for (i, (to_class, from_class)) in
            to.aclasses.iter_mut().zip(from.aclasses.iter_mut()).enumerate()
        {
            if to_class.last_store.get() != from_class.last_store.get() {
                self.load_loop_aclass(i, from_class, loops);
                self.load_loop_aclass(i, to_class, loops);
                if to_class.last_store.get() != from_class.last_store.get() {
                    let inps = [ctrl.get(), from_class.last_store.get(), to_class.last_store.get()];
                    to_class
                        .last_store
                        .set_remove(self.new_node(ty::Id::VOID, Kind::Phi, inps, tys), self);
                }
            }
        }
    }

    fn new_const_lit(&mut self, ty: ty::Id, value: impl Into<i64>) -> Value {
        Value::new(self.new_const(ty, value)).ty(ty)
    }

    fn new_node_lit(&mut self, ty: ty::Id, kind: Kind, inps: impl Into<Vc>, tys: &Types) -> Value {
        Value::new(self.new_node(ty, kind, inps, tys)).ty(ty)
    }
}

#[derive(Clone, Copy)]
pub enum CtLoopState {
    Terminated,
    Continued,
}

#[derive(Clone)]
enum Loop {
    Comptime {
        state: Option<(CtLoopState, Pos)>,
        defer_base: usize,
    },
    Runtime {
        node: Nid,
        ctrl: [StrongRef; 2],
        ctrl_scope: [Scope; 2],
        scope: Scope,
        defer_base: usize,
    },
}

mod strong_ref {
    use {
        super::{Kind, Nid, Nodes},
        crate::debug,
        core::ops::Not,
    };

    #[derive(Clone)]
    pub struct StrongRef(Nid);

    impl StrongRef {
        pub const DEFAULT: Self = Self(Nid::MAX);

        pub fn new(value: Nid, nodes: &mut Nodes) -> Self {
            nodes.lock(value);
            Self(value)
        }

        pub fn get(&self) -> Nid {
            debug_assert!(self.0 != Nid::MAX);
            self.0
        }

        pub fn unwrap(self, nodes: &mut Nodes) -> Option<Nid> {
            let nid = self.0;
            if nid != Nid::MAX {
                nodes.unlock(nid);
                core::mem::forget(self);
                Some(nid)
            } else {
                None
            }
        }

        pub fn set(&mut self, mut new_value: Nid, nodes: &mut Nodes) -> Nid {
            nodes.unlock(self.0);
            core::mem::swap(&mut self.0, &mut new_value);
            nodes.lock(self.0);
            new_value
        }

        pub fn dup(&self, nodes: &mut Nodes) -> Self {
            nodes.lock(self.0);
            Self(self.0)
        }

        pub fn remove(self, nodes: &mut Nodes) -> Option<Nid> {
            let ret = nodes.unlock_remove(self.0).not().then_some(self.0);
            core::mem::forget(self);
            ret
        }

        pub fn set_remove(&mut self, new_value: Nid, nodes: &mut Nodes) {
            let old = self.set(new_value, nodes);
            nodes.remove(old);
        }

        pub fn remove_ignore_arg(self, nodes: &mut Nodes) {
            if nodes[self.0].kind == Kind::Arg {
                nodes.unlock(self.0);
            } else {
                nodes.unlock_remove(self.0);
            }
            core::mem::forget(self);
        }

        pub fn soft_remove(self, nodes: &mut Nodes) -> Nid {
            let nid = self.0;
            nodes.unlock(self.0);
            core::mem::forget(self);
            nid
        }

        pub fn is_live(&self) -> bool {
            self.0 != Nid::MAX
        }
    }

    impl Default for StrongRef {
        fn default() -> Self {
            Self::DEFAULT
        }
    }

    impl Drop for StrongRef {
        fn drop(&mut self) {
            if self.0 != Nid::MAX && !debug::panicking() {
                panic!("variable unproperly deinitialized")
            }
        }
    }
}

// makes sure value inside is laways locked for this instance of variable
#[derive(Default, Clone)]
struct Variable {
    id: Ident,
    ty: ty::Id,
    ptr: bool,
    value: StrongRef,
}

impl Variable {
    fn new(id: Ident, ty: ty::Id, ptr: bool, value: Nid, nodes: &mut Nodes) -> Self {
        Self { id, ty, ptr, value: StrongRef::new(value, nodes) }
    }

    fn value(&self) -> Nid {
        self.value.get()
    }

    fn set_value(&mut self, new_value: Nid, nodes: &mut Nodes) -> Nid {
        self.value.set(new_value, nodes)
    }

    fn dup(&self, nodes: &mut Nodes) -> Self {
        Self { id: self.id, ty: self.ty, ptr: self.ptr, value: self.value.dup(nodes) }
    }

    fn remove(self, nodes: &mut Nodes) {
        self.value.remove(nodes);
    }

    fn set_value_remove(&mut self, new_value: Nid, nodes: &mut Nodes) {
        self.value.set_remove(new_value, nodes);
    }

    fn remove_ignore_arg(self, nodes: &mut Nodes) {
        self.value.remove_ignore_arg(nodes);
    }
}

#[derive(Default, Clone)]
pub struct AClass {
    last_store: StrongRef,
    clobber: StrongRef,
}

impl AClass {
    fn dup(&self, nodes: &mut Nodes) -> Self {
        Self { last_store: self.last_store.dup(nodes), clobber: self.clobber.dup(nodes) }
    }

    fn remove(self, nodes: &mut Nodes) {
        self.last_store.remove(nodes);
        self.clobber.remove(nodes);
    }

    fn new(nodes: &mut Nodes) -> Self {
        Self { last_store: StrongRef::new(MEM, nodes), clobber: StrongRef::new(VOID, nodes) }
    }
}

#[derive(Default, Clone)]
pub struct Scope {
    vars: Vec<Variable>,
    aclasses: Vec<AClass>,
}

impl Scope {
    fn dup(&self, nodes: &mut Nodes) -> Self {
        Self {
            vars: self.vars.iter().map(|v| v.dup(nodes)).collect(),
            aclasses: self.aclasses.iter().map(|v| v.dup(nodes)).collect(),
        }
    }

    fn clear(&mut self, nodes: &mut Nodes) {
        self.vars.drain(..).for_each(|n| n.remove(nodes));
        self.aclasses.drain(..).for_each(|l| l.remove(nodes));
    }
}

#[derive(Default, Clone)]
pub struct ItemCtx {
    file: Module,
    parent: ty::Id,
    pos: Vec<Pos>,
    ret: Option<ty::Id>,
    task_base: usize,
    inline_var_base: usize,
    inline_aclass_base: usize,
    inline_depth: u16,
    inline_defer_base: usize,
    inline_ret: Option<(Value, StrongRef, Scope, Option<AClass>)>,
    nodes: Nodes,
    ctrl: StrongRef,
    loops: Vec<Loop>,
    defers: Vec<(Pos, ExprRef)>,
    scope: Scope,
}

impl ItemCtx {
    fn init(&mut self, file: Module, parent: ty::Id, ret: Option<ty::Id>, task_base: usize) {
        debug_assert_eq!(self.loops.len(), 0);
        debug_assert_eq!(self.defers.len(), 0);
        debug_assert_eq!(self.scope.vars.len(), 0);
        debug_assert_eq!(self.scope.aclasses.len(), 0);
        debug_assert!(self.inline_ret.is_none());
        debug_assert_eq!(self.inline_depth, 0);
        debug_assert_eq!(self.inline_var_base, 0);
        debug_assert_eq!(self.inline_aclass_base, 0);
        debug_assert_eq!(self.inline_defer_base, 0);

        self.file = file;
        self.parent = parent;
        self.ret = ret;
        self.task_base = task_base;

        self.nodes.clear();
        self.scope.vars.clear();

        let start = self.nodes.new_node_nop(ty::Id::VOID, Kind::Start, []);
        debug_assert_eq!(start, VOID);
        let end = self.nodes.new_node_nop(ty::Id::NEVER, Kind::End, []);
        debug_assert_eq!(end, NEVER);
        self.nodes.lock(end);
        self.ctrl = StrongRef::new(
            self.nodes.new_node_nop(ty::Id::VOID, Kind::Entry, [VOID]),
            &mut self.nodes,
        );
        debug_assert_eq!(self.ctrl.get(), ENTRY);
        let mem = self.nodes.new_node_nop(ty::Id::VOID, Kind::Mem, [VOID]);
        debug_assert_eq!(mem, MEM);
        self.nodes.lock(mem);
        let loops = self.nodes.new_node_nop(ty::Id::VOID, Kind::Loops, [VOID]);
        debug_assert_eq!(loops, LOOPS);
        self.nodes.lock(loops);
        self.scope.aclasses.push(AClass::new(&mut self.nodes)); // DEFAULT
        self.scope.aclasses.push(AClass::new(&mut self.nodes)); // GLOBAL
    }

    fn finalize(
        &mut self,
        stack: &mut Vec<Nid>,
        tys: &Types,
        _files: &EntSlice<Module, parser::Ast>,
    ) {
        self.scope.clear(&mut self.nodes);
        mem::take(&mut self.ctrl).soft_remove(&mut self.nodes);

        self.nodes.iter_peeps(1000, stack, tys);

        self.nodes.unlock(MEM);
        self.nodes.unlock(NEVER);
        self.nodes.unlock(LOOPS);
    }
}

#[derive(Default, Debug)]
struct Ctx {
    ty: Option<ty::Id>,
}

impl Ctx {
    fn with_ty(self, ty: ty::Id) -> Self {
        Self { ty: Some(ty) }
    }
}

#[derive(Default)]
pub struct Pool {
    cis: Vec<ItemCtx>,
    used_cis: usize,
    scratch1: Vec<Nid>,
    scratch2: Vec<Nid>,
    lit_buf: Vec<u8>,
    nid_set: BitSet,
}

impl Pool {
    fn push_ci(
        &mut self,
        file: Module,
        parent: ty::Id,
        ret: Option<ty::Id>,
        task_base: usize,
        target: &mut ItemCtx,
    ) -> &mut ItemCtx {
        if let Some(slot) = self.cis.get_mut(self.used_cis) {
            mem::swap(slot, target);
        } else {
            self.cis.push(ItemCtx::default());
            mem::swap(self.cis.last_mut().unwrap(), target);
        }
        target.init(file, parent, ret, task_base);
        self.used_cis += 1;
        &mut self.cis[self.used_cis - 1]
    }

    fn pop_ci(&mut self, target: &mut ItemCtx) {
        self.used_cis -= 1;
        mem::swap(&mut self.cis[self.used_cis], target);
    }

    fn save_ci(&mut self, ci: &ItemCtx) {
        if let Some(slot) = self.cis.get_mut(self.used_cis) {
            slot.clone_from(ci);
        } else {
            self.cis.push(ci.clone());
        }
        self.used_cis += 1;
    }

    fn restore_ci(&mut self, dst: &mut ItemCtx) {
        self.used_cis -= 1;
        dst.scope.clear(&mut dst.nodes);
        dst.loops.drain(..).for_each(|l| {
            if let Loop::Runtime { ctrl, ctrl_scope, mut scope, .. } = l {
                ctrl.map(|c| {
                    if c.is_live() {
                        c.remove(&mut dst.nodes);
                    }
                });
                scope.clear(&mut dst.nodes);
                ctrl_scope.map(|mut s| s.clear(&mut dst.nodes));
            }
        });
        if let Some((_, ctrl, mut scope, acl)) = dst.inline_ret.take() {
            ctrl.remove(&mut dst.nodes);
            if let Some(acl) = acl {
                acl.remove(&mut dst.nodes)
            };
            scope.clear(&mut dst.nodes);
        }
        mem::take(&mut dst.ctrl).remove(&mut dst.nodes);
        *dst = mem::take(&mut self.cis[self.used_cis]);
    }

    fn clear(&mut self) {
        debug_assert_eq!(self.used_cis, 0);
    }
}

#[derive(Default, Clone, Copy, PartialEq, Eq, Debug)]
struct Value {
    ty: ty::Id,
    var: bool,
    ptr: bool,
    id: Nid,
}

impl Value {
    const NEVER: Option<Value> =
        Some(Self { ty: ty::Id::NEVER, var: false, ptr: false, id: NEVER });
    const VOID: Value = Self { ty: ty::Id::VOID, var: false, ptr: false, id: VOID };

    fn new(id: Nid) -> Self {
        Self { id, ..Default::default() }
    }

    fn var(id: usize) -> Self {
        Self { id: u16::MAX - (id as Nid), var: true, ..Default::default() }
    }

    fn ptr(id: Nid) -> Self {
        Self { id, ptr: true, ..Default::default() }
    }

    #[inline(always)]
    fn ty(self, ty: ty::Id) -> Self {
        Self { ty, ..self }
    }
}

#[derive(Default)]
pub struct CodegenCtx {
    pub parser: parser::Ctx,
    tys: Types,
    pool: Pool,
    ct: Comptime,
    ct_backend: HbvmBackend,
}

impl CodegenCtx {
    pub fn clear(&mut self) {
        self.parser.clear();
        self.tys.clear();
        self.pool.clear();
        self.ct.clear();
    }
}

pub struct Codegen<'a> {
    pub files: &'a EntSlice<Module, parser::Ast>,
    pub errors: &'a RefCell<String>,
    pub warnings: &'a RefCell<String>,
    tys: &'a mut Types,
    ci: ItemCtx,
    pool: &'a mut Pool,
    ct: &'a mut Comptime,
    ct_backend: &'a mut HbvmBackend,
    backend: &'a mut dyn Backend,
}

impl Drop for Codegen<'_> {
    fn drop(&mut self) {
        if debug::panicking() {
            if let Some(&pos) = self.ci.pos.last() {
                self.error(pos, "panic occured here");
            }

            if !self.errors.borrow().is_empty() {
                log::error!("{}", self.errors.borrow());
            }
        }
    }
}

impl<'a> Codegen<'a> {
    pub fn new(
        backend: &'a mut dyn Backend,
        files: &'a [parser::Ast],
        ctx: &'a mut CodegenCtx,
    ) -> Self {
        Self {
            files: files.into(),
            errors: &ctx.parser.errors,
            warnings: &ctx.parser.warnings,
            tys: &mut ctx.tys,
            ci: Default::default(),
            pool: &mut ctx.pool,
            ct: &mut ctx.ct,
            ct_backend: &mut ctx.ct_backend,
            backend,
        }
    }

    pub fn generate(&mut self, entry: Module) {
        self.find_type(0, entry, entry, "main");
        if self.tys.ins.funcs.is_empty() {
            return;
        }
        self.make_func_reachable(ty::Func::MAIN);
        self.complete_call_graph();
    }

    pub fn assemble_comptime(&mut self) -> Comptime {
        self.ct.code.clear();
        self.backend.assemble_bin(ty::Func::MAIN, self.tys, &mut self.ct.code);
        self.ct.reset();
        core::mem::take(self.ct)
    }

    pub fn assemble(&mut self, buf: &mut Vec<u8>) {
        self.backend.assemble_bin(ty::Func::MAIN, self.tys, buf);
    }

    pub fn disasm(&mut self, output: &mut String, bin: &[u8]) -> Result<(), DisasmError> {
        self.backend.disasm(bin, &mut |_| {}, self.tys, self.files, output)
    }

    pub fn push_embeds(&mut self, embeds: Vec<Vec<u8>>) {
        for data in embeds {
            let g = GlobalData {
                ty: self.tys.make_array(ty::Id::U8, data.len() as _),
                data,
                ..Default::default()
            };
            self.tys.ins.globals.push(g);
        }
    }

    fn emit_and_eval(&mut self, file: Module, ret: ty::Id, ret_loc: &mut [u8]) -> u64 {
        let mut rets = self.ci.nodes[NEVER]
            .inputs
            .iter()
            .filter(|&&i| matches!(self.ci.nodes[i].kind, Kind::Return { .. }));
        if let Some(&ret) = rets.next()
            && rets.next().is_none()
            && let Kind::CInt { value } = self.ci.nodes[self.ci.nodes[ret].inputs[1]].kind
        {
            if let len @ 1..=8 = ret_loc.len() {
                ret_loc.copy_from_slice(&value.to_ne_bytes()[..len])
            }
            return value as _;
        }

        if !self.complete_call_graph() {
            return 1;
        }

        let fuc = self.tys.ins.funcs.push(FuncData {
            file,
            sig: Sig { args: List::empty(), ret },
            ..Default::default()
        });

        self.ct_backend.emit_ct_body(fuc, &self.ci.nodes, self.tys, self.files);

        // TODO: return them back

        let entry = self.ct_backend.assemble_reachable(fuc, self.tys, &mut self.ct.code).entry;

        #[cfg(debug_assertions)]
        {
            let mut vc = String::new();
            if let Err(e) =
                self.ct_backend.disasm(&self.ct.code, &mut |_| {}, self.tys, self.files, &mut vc)
            {
                panic!("{e} {}", vc);
            } else {
                log::info!("{}", vc);
            }
        }

        self.ct.run(ret_loc, entry)
    }

    fn new_stack(&mut self, pos: Pos, ty: ty::Id) -> Nid {
        let stck = self.ci.nodes.new_node_nop(ty, Kind::Stck, [VOID, MEM]);
        self.ci.nodes[stck].aclass = self.ci.scope.aclasses.len() as _;
        self.ci.nodes[stck].pos = pos;
        self.ci.scope.aclasses.push(AClass::new(&mut self.ci.nodes));
        stck
    }

    fn store_mem(&mut self, region: Nid, ty: ty::Id, value: Nid) -> Nid {
        if value == NEVER {
            return NEVER;
        }

        debug_assert!(
            self.ci.nodes[region].kind != Kind::Load || self.ci.nodes[region].ty.is_pointer()
        );
        debug_assert!(self.ci.nodes[region].kind != Kind::Stre);

        let (value_index, value_region) = self.ci.nodes.aclass_index(value);
        if value_index != 0 {
            self.ci.nodes[value_region].aclass = 0;
            self.ci.nodes.load_loop_aclass(0, &mut self.ci.scope.aclasses[0], &mut self.ci.loops);
            self.ci.nodes.load_loop_aclass(
                value_index,
                &mut self.ci.scope.aclasses[value_index],
                &mut self.ci.loops,
            );
            let base_class = self.ci.scope.aclasses[0].last_store.get();
            let last_store = self.ci.scope.aclasses[value_index].last_store.get();
            match [base_class, last_store] {
                [_, MEM] => {}
                [MEM, a] => {
                    self.ci.scope.aclasses[0].last_store.set(a, &mut self.ci.nodes);
                }
                [a, b] => {
                    let a = self.ci.nodes.new_node_nop(ty::Id::VOID, Kind::Join, [0, a, b]);
                    self.ci.scope.aclasses[0].last_store.set(a, &mut self.ci.nodes);
                }
            }
        }

        let (index, _) = self.ci.nodes.aclass_index(region);
        if self.ci.nodes[value].kind == Kind::Load {
            let (lindex, ..) = self.ci.nodes.aclass_index(self.ci.nodes[value].inputs[1]);
            let clobber = self.ci.scope.aclasses[lindex].clobber.get();
            if self.ci.nodes.idepth(clobber, None)
                > self.ci.nodes.idepth(self.ci.scope.aclasses[index].clobber.get(), None)
            {
                self.ci.scope.aclasses[index].clobber.set(clobber, &mut self.ci.nodes);
            }
        }
        let aclass = &mut self.ci.scope.aclasses[index];
        self.ci.nodes.load_loop_aclass(index, aclass, &mut self.ci.loops);
        let vc = Vc::from([aclass.clobber.get(), value, region, aclass.last_store.get()]);
        mem::take(&mut aclass.last_store).soft_remove(&mut self.ci.nodes);
        let store = self.ci.nodes.new_node(ty, Kind::Stre, vc, self.tys);
        aclass.last_store = StrongRef::new(store, &mut self.ci.nodes);
        store
    }

    fn load_mem(&mut self, region: Nid, ty: ty::Id) -> Nid {
        debug_assert_ne!(region, VOID);
        debug_assert_ne!({ self.ci.nodes[region].ty }, ty::Id::VOID, "{:?}", {
            self.ci.nodes[region].lock_rc.set(Nid::MAX);
            self.ci.nodes.graphviz_in_browser(self.ty_display(ty::Id::VOID));
        });
        debug_assert!(
            self.ci.nodes[region].kind != Kind::Load
                || self.ci.nodes[region].kind == Kind::Stck
                || self.ci.nodes[region].ty.is_pointer(),
            "{:?} {} {} {:?}",
            self.ci.nodes.graphviz_in_browser(self.ty_display(ty::Id::VOID)),
            self.file().path,
            self.ty_display(self.ci.nodes[region].ty),
            self.ci.nodes[region],
        );
        debug_assert!(self.ci.nodes[region].kind != Kind::Stre);
        let (index, _) = self.ci.nodes.aclass_index(region);
        let aclass = &mut self.ci.scope.aclasses[index];
        self.ci.nodes.load_loop_aclass(index, aclass, &mut self.ci.loops);
        let vc = [aclass.clobber.get(), region, aclass.last_store.get()];
        self.ci.nodes.new_node(ty, Kind::Load, vc, self.tys)
    }

    fn make_func_reachable(&mut self, func: ty::Func) {
        let state_slot = self.ct.active() as usize;
        let fuc = &mut self.tys.ins.funcs[func];
        if CompState::from(fuc.comp_state[state_slot]) == CompState::Dead {
            fuc.comp_state[state_slot] = CompState::Queued(self.tys.tasks.len() as _).into();
            self.tys.tasks.push(Some(FTask { file: fuc.file, id: func, ct: self.ct.active() }));
        }
    }

    fn raw_expr(&mut self, expr: &Expr) -> Option<Value> {
        self.raw_expr_ctx(expr, Ctx::default())
    }

    fn raw_expr_ctx(&mut self, expr: &Expr, ctx: Ctx) -> Option<Value> {
        self.ci.pos.push(expr.pos());
        let res = self.raw_expr_ctx_low(expr, ctx);
        self.ci.pos.pop().unwrap();
        res
    }

    fn raw_expr_ctx_low(&mut self, expr: &Expr, mut ctx: Ctx) -> Option<Value> {
        // ordered by complexity of the expression
        match *expr {
            Expr::Null { pos } => {
                inference!(oty, ctx, self, pos, "null pointer", "@as(^<ty>, null)");

                let Some(ty) = self.tys.inner_of(oty) else {
                    self.error(
                        pos,
                        fa!(
                            "'null' expression was inferred to be '{}',
                            which is not optional",
                            self.ty_display(oty)
                        ),
                    );
                    return Value::NEVER;
                };

                match oty.loc(self.tys) {
                    Loc::Reg => Some(self.ci.nodes.new_const_lit(oty, 0)),
                    Loc::Stack => {
                        let OptLayout { flag_ty, flag_offset, .. } = self.tys.opt_layout(ty);
                        let stack = self.new_stack(pos, oty);
                        let offset = self.offset(stack, flag_offset);
                        let value = self.ci.nodes.new_const(flag_ty, 0);
                        self.store_mem(offset, flag_ty, value);
                        Some(Value::ptr(stack).ty(oty))
                    }
                }
            }
            Expr::Idk { pos } => {
                inference!(ty, ctx, self, pos, "value", "@as(<ty>, idk)");

                if ty.loc(self.tys) == Loc::Stack {
                    Some(Value::ptr(self.new_stack(pos, ty)).ty(ty))
                } else {
                    Some(self.ci.nodes.new_const_lit(ty, 0))
                }
            }
            Expr::Bool { value, .. } => Some(self.ci.nodes.new_const_lit(ty::Id::BOOL, value)),
            Expr::Number { value, .. } => self.gen_inferred_const(ctx, ty::Id::DINT, value),
            Expr::Float { value, .. } => {
                self.gen_inferred_const_low(ctx, ty::Id::F32, value as i64, true)
            }
            Expr::Ident { id, .. } if let Ok(bt) = ty::Builtin::try_from(id) => {
                Some(self.ci.nodes.new_const_lit(ty::Id::TYPE, bt))
            }
            Expr::Ident { id, .. }
                if let Some(index) = self.ci.scope.vars.iter().rposition(|v| v.id == id) =>
            {
                let var = &mut self.ci.scope.vars[index];
                self.ci.nodes.load_loop_var(index, var, &mut self.ci.loops);

                Some(Value::var(index).ty(var.ty))
            }
            Expr::Ident { id, .. }
                if let Some(vl) = {
                    let mut piter = self.ci.parent;
                    let f = self.file();
                    loop {
                        if let Some((captures, capture_tuple)) = self.tys.captures_of(piter, f)
                            && let Some(idx) = captures.iter().position(|&cid| cid.id == id)
                        {
                            let ty = if captures[idx].is_ct {
                                ty::Id::TYPE
                            } else {
                                self.tys.ins.args[capture_tuple.range().start + idx]
                            };
                            break Some(Value::new(NEVER).ty(ty));
                        }

                        piter = match self.tys.parent_of(piter) {
                            Some(p) => p,
                            None => break None,
                        };
                    }
                } =>
            {
                Some(vl)
            }
            Expr::Ident { id, pos, .. } => self.find_type_as_value(pos, self.ci.parent, id, ctx),
            Expr::Comment { .. } => Some(Value::VOID),
            Expr::Char { pos, literal } | Expr::String { pos, literal } => {
                let literal = &literal[1..literal.len() - 1];
                let mut data = core::mem::take(&mut self.pool.lit_buf);
                debug_assert!(data.is_empty());

                let report = |bytes: &core::str::Bytes, message: &str| {
                    self.error(pos + (literal.len() - bytes.len()) as u32 - 1, message);
                };

                let char_count = crate::endoce_string(literal, &mut data, report).unwrap();

                if matches!(expr, Expr::Char { .. }) {
                    if char_count != 1 {
                        return self.error(
                            pos,
                            fa!("character literal can only contain one character, \
                            but you supplied {char_count}"),
                        );
                    }

                    let value = match data.as_slice() {
                        &[v] => v as i64,
                        _ => return self.error(pos, "TODO: support utf-8 characters"),
                    };

                    data.clear();
                    self.pool.lit_buf = data;

                    self.gen_inferred_const(ctx, ty::Id::U8, value)
                } else {
                    if data.last() != Some(&0) {
                        self.error(pos, "string literal must end with null byte (for now)");
                    }

                    let (global, ty) = self.create_string_global(&data);

                    data.clear();
                    self.pool.lit_buf = data;

                    Some(Value::new(global).ty(ty))
                }
            }
            Expr::Defer { pos, value } => {
                self.ci.defers.push((pos, ExprRef::new(value)));
                Some(Value::VOID)
            }
            Expr::Return { pos, val } => {
                let mut value = if let Some(val) = val {
                    self.ptr_expr_ctx(val, Ctx { ty: self.ci.ret })?
                } else {
                    Value { ty: ty::Id::VOID, ..Default::default() }
                };

                let expected = *self.ci.ret.get_or_insert(value.ty);
                self.assert_ty(pos, &mut value, expected, "return value");
                self.strip_ptr(&mut value);
                self.gen_defers(self.ci.inline_defer_base);

                if self.ci.inline_depth == 0 {
                    debug_assert_ne!(self.ci.ctrl.get(), VOID);
                    let mut inps = Vc::from([self.ci.ctrl.get(), value.id]);
                    for (i, aclass) in self.ci.scope.aclasses.iter_mut().enumerate() {
                        self.ci.nodes.load_loop_aclass(i, aclass, &mut self.ci.loops);
                        if aclass.last_store.get() != MEM {
                            inps.push(aclass.last_store.get());
                        }
                    }

                    let ret = self.ci.nodes.new_node_nop(
                        ty::Id::VOID,
                        Kind::Return { file: self.ci.file },
                        inps,
                    );
                    self.ci.ctrl.set(NEVER, &mut self.ci.nodes);
                    self.ci.nodes[ret].pos = pos;
                    self.ci.nodes.bind(ret, NEVER);
                } else if let Some((mut pv, mut ctrl, mut scope, aclass)) =
                    self.ci.inline_ret.take()
                {
                    if value.ty.loc(self.tys) == Loc::Stack {
                        self.spill(pos, &mut value);
                    }

                    debug_assert!(
                        aclass.is_none(),
                        "TODO: oh no, we cant return structs from divergent branches"
                    );
                    ctrl.set(
                        self.ci.nodes.new_node(
                            ty::Id::VOID,
                            Kind::Region,
                            [self.ci.ctrl.get(), ctrl.get()],
                            self.tys,
                        ),
                        &mut self.ci.nodes,
                    );
                    self.ci.nodes.merge_scopes(
                        &mut self.ci.loops,
                        &ctrl,
                        &mut scope,
                        &mut self.ci.scope,
                        self.tys,
                    );
                    self.ci.nodes.unlock(pv.id);
                    pv.id = self.ci.nodes.new_node(
                        value.ty,
                        Kind::Phi,
                        [ctrl.get(), value.id, pv.id],
                        self.tys,
                    );
                    self.ci.nodes.lock(pv.id);
                    self.ci.ctrl.set(NEVER, &mut self.ci.nodes);
                    self.ci.inline_ret = Some((pv, ctrl, scope, aclass));
                } else {
                    if value.ty.loc(self.tys) == Loc::Stack {
                        self.spill(pos, &mut value);
                    }

                    for (i, aclass) in self.ci.scope.aclasses[..2].iter_mut().enumerate() {
                        self.ci.nodes.load_loop_aclass(i, aclass, &mut self.ci.loops);
                    }

                    self.ci.nodes.lock(value.id);
                    let mut scope = self.ci.scope.dup(&mut self.ci.nodes);
                    scope
                        .vars
                        .drain(self.ci.inline_var_base..)
                        .for_each(|v| v.remove(&mut self.ci.nodes));
                    scope
                        .aclasses
                        .drain(self.ci.inline_aclass_base..)
                        .for_each(|v| v.remove(&mut self.ci.nodes));

                    let repl = StrongRef::new(NEVER, &mut self.ci.nodes);
                    let (index, _) = self.ci.nodes.aclass_index(value.id);
                    let aclass = (self.ci.inline_aclass_base <= index)
                        .then(|| self.ci.scope.aclasses[index].dup(&mut self.ci.nodes));
                    self.ci.inline_ret =
                        Some((value, mem::replace(&mut self.ci.ctrl, repl), scope, aclass));
                }

                None
            }
            Expr::Die { .. } => {
                self.ci.ctrl.set(
                    self.ci.nodes.new_node_nop(ty::Id::VOID, Kind::Die, [self.ci.ctrl.get()]),
                    &mut self.ci.nodes,
                );
                self.ci.nodes.bind(self.ci.ctrl.get(), NEVER);
                None
            }
            Expr::Field { target, name, pos } => {
                self.gen_field(ctx, target, pos, name)?.ok().or_else(|| {
                    self.error(pos, "method can not be used like this");
                    Value::NEVER
                })
            }
            Expr::UnOp { op: TokenKind::Band, val, pos } => {
                let ctx = Ctx { ty: ctx.ty.and_then(|ty| self.tys.base_of(ty)) };

                let mut val = self.ptr_expr_ctx(val, ctx)?;

                if val.ptr {
                    val.ptr = false;
                    val.ty = self.tys.make_ptr(val.ty);
                    return Some(val);
                }

                let stack = self.new_stack(pos, val.ty);
                self.store_mem(stack, val.ty, val.id);

                Some(Value::new(stack).ty(self.tys.make_ptr(val.ty)))
            }
            Expr::UnOp { op: TokenKind::Mul, val, pos } => {
                let ctx = Ctx { ty: ctx.ty.map(|ty| self.tys.make_ptr(ty)) };
                let mut vl = self.expr_ctx(val, ctx)?;

                self.implicit_unwrap(val.pos(), &mut vl);

                let Some(base) = self.tys.base_of(vl.ty) else {
                    return self.error(
                        pos,
                        fa!("the '{}' can not be dereferneced", self.ty_display(vl.ty)),
                    );
                };
                vl.ptr = true;
                vl.ty = base;
                Some(vl)
            }
            Expr::UnOp { pos, op: TokenKind::Dot, val: &Expr::Ident { id, .. } } => {
                inference!(ty, ctx, self, pos, "enum type", "<EnumTy>.Variant");

                let ty::Kind::Enum(e) = ty.expand() else {
                    return self.error(
                        pos,
                        fa!("expected inferred type to be enum but got '{}'", self.ty_display(ty)),
                    );
                };

                let intrnd = self.tys.names.project(self.file().ident_str(id));
                self.gen_enum_variant(pos, e, intrnd)
            }
            Expr::UnOp { pos, op: op @ TokenKind::Sub, val } => {
                let val =
                    self.expr_ctx(val, Ctx::default().with_ty(ctx.ty.unwrap_or(ty::Id::INT)))?;
                if val.ty.is_integer() {
                    Some(self.ci.nodes.new_node_lit(
                        val.ty,
                        Kind::UnOp { op },
                        [VOID, val.id],
                        self.tys,
                    ))
                } else if val.ty.is_float() {
                    let value = self.ci.nodes.new_const(val.ty, (-1f64).to_bits() as i64);
                    Some(self.ci.nodes.new_node_lit(
                        val.ty,
                        Kind::BinOp { op: TokenKind::Mul },
                        [VOID, val.id, value],
                        self.tys,
                    ))
                } else {
                    self.error(pos, fa!("cant negate '{}'", self.ty_display(val.ty)))
                }
            }
            Expr::UnOp { pos, op: op @ TokenKind::Not, val } => {
                let val =
                    self.expr_ctx(val, Ctx::default().with_ty(ctx.ty.unwrap_or(ty::Id::INT)))?;
                if val.ty == ty::Id::BOOL {
                    Some(self.ci.nodes.new_node_lit(
                        val.ty,
                        Kind::UnOp { op },
                        [VOID, val.id],
                        self.tys,
                    ))
                } else {
                    self.error(pos, fa!("cant logically negate '{}'", self.ty_display(val.ty)))
                }
            }
            Expr::BinOp {
                left,
                op: TokenKind::Colon,
                right: &Expr::BinOp { left: ty, op: TokenKind::Assign, right, pos },
                ..
            } => {
                let ty = self.ty(ty);
                let mut right = self.checked_expr(right, ty, "declaration")?;

                if right.ty.loc(self.tys) == Loc::Stack {
                    self.spill(pos, &mut right);
                }
                self.assign_pattern(left, right);
                Some(Value::VOID)
            }
            Expr::BinOp { left, op: TokenKind::Decl, right, pos } => {
                let mut right = self.expr(right)?;

                if right.ty.loc(self.tys) == Loc::Stack {
                    self.spill(pos, &mut right);
                }
                self.assign_pattern(left, right);
                Some(Value::VOID)
            }
            Expr::BinOp { left: Expr::Wildcard { .. }, op: TokenKind::Assign, right, .. } => {
                self.expr(right)?;
                Some(Value::VOID)
            }
            Expr::BinOp { left, pos, op: TokenKind::Assign, right } => {
                let dest = self.raw_expr(left)?;
                let value = self.checked_expr(right, dest.ty, "assignment source")?;

                if dest.var {
                    let var = &mut self.ci.scope.vars[(u16::MAX - dest.id) as usize];

                    if var.ptr {
                        let val = var.value();
                        let ty = var.ty;
                        self.store_mem(val, ty, value.id);
                    } else {
                        var.set_value_remove(value.id, &mut self.ci.nodes);
                    }
                } else if dest.ptr {
                    self.store_mem(dest.id, dest.ty, value.id);
                } else {
                    self.error(pos, "cannot assign to this expression");
                }

                Some(Value::VOID)
            }
            Expr::BinOp { left: &Expr::Null { pos }, .. } => {
                self.error(pos, "'null' must always be no the right side of an expression")
            }
            Expr::BinOp {
                left,
                op: op @ (TokenKind::Eq | TokenKind::Ne),
                right: Expr::Null { .. },
                ..
            } => {
                let cmped = self.ptr_expr(left)?;

                let Some(ty) = self.tys.inner_of(cmped.ty) else {
                    return self.error(
                        left.pos(),
                        fa!("'{}' is never null, remove this check", self.ty_display(cmped.ty)),
                    );
                };

                Some(Value::new(self.gen_null_check(cmped, ty, op)).ty(ty::Id::BOOL))
            }
            Expr::BinOp { left, pos, op, right } => {
                debug_assert!(!matches!(
                    op,
                    TokenKind::Assign | TokenKind::Decl | TokenKind::Colon
                ));
                let mut lhs = self.ptr_expr_ctx(left, ctx)?;
                self.implicit_unwrap(left.pos(), &mut lhs);

                fn is_scalar_op(op: TokenKind, ty: ty::Id) -> bool {
                    ty.is_pointer()
                        || ty.is_integer()
                        || ty == ty::Id::BOOL
                        || (ty == ty::Id::TYPE && matches!(op, TokenKind::Eq | TokenKind::Ne))
                        || (ty.is_float() && op.is_supported_float_op())
                }

                match lhs.ty.expand() {
                    ty::Kind::Struct(s) if op.is_homogenous() => {
                        debug_assert!(lhs.ptr);
                        self.ci.nodes.lock(lhs.id);
                        let rhs = self.ptr_expr_ctx(right, Ctx::default().with_ty(lhs.ty));
                        self.ci.nodes.unlock(lhs.id);
                        let mut rhs = rhs?;
                        debug_assert!(rhs.ptr);
                        self.assert_ty(pos, &mut rhs, lhs.ty, "struct operand");
                        let dst = self.new_stack(pos, lhs.ty);
                        self.struct_op(left.pos(), op, s, dst, lhs.id, rhs.id);
                        Some(Value::ptr(dst).ty(lhs.ty))
                    }
                    ty::Kind::Struct(s) if op.is_compatison() => {
                        let binding_op = match op {
                            TokenKind::Eq => TokenKind::Band,
                            _ => TokenKind::Bor,
                        };

                        self.ci.nodes.lock(lhs.id);
                        let rhs = self.ptr_expr_ctx(right, Ctx::default().with_ty(lhs.ty));
                        self.ci.nodes.unlock(lhs.id);
                        let mut rhs = rhs?;
                        self.assert_ty(pos, &mut rhs, lhs.ty, "struct operand");

                        self.struct_fold_op(left.pos(), op, binding_op, s, lhs.id, rhs.id)
                            .or(Value::NEVER)
                    }
                    _ if is_scalar_op(op, lhs.ty) => {
                        self.strip_ptr(&mut lhs);
                        self.ci.nodes.lock(lhs.id);
                        let rhs = self.expr_ctx(right, Ctx::default().with_ty(lhs.ty));
                        self.ci.nodes.unlock(lhs.id);
                        let mut rhs = rhs?;
                        self.implicit_unwrap(right.pos(), &mut rhs);
                        let (ty, aclass) = self.binop_ty(pos, &mut lhs, &mut rhs, op);
                        if op.is_compatison() {
                            if lhs.ty.is_float() {
                            } else {
                                self.ci.nodes.lock(rhs.id);
                                let lty = lhs.ty.extend();
                                if lty != lhs.ty {
                                    self.extend(&mut lhs, lty);
                                }
                                self.ci.nodes.unlock(rhs.id);
                                let rty = rhs.ty.extend();
                                if rty != rhs.ty {
                                    self.extend(&mut rhs, rty);
                                }
                            }
                        }
                        let bop = self.ci.nodes.new_node_lit(
                            ty.bin_ret(op),
                            Kind::BinOp { op },
                            [VOID, lhs.id, rhs.id],
                            self.tys,
                        );
                        self.ci.nodes.pass_aclass(aclass, bop.id);
                        Some(bop)
                    }
                    _ => self
                        .error(pos, fa!("'{} {op} _' is not supported", self.ty_display(lhs.ty))),
                }
            }
            Expr::Index { base, index } => {
                let mut bs = self.ptr_expr(base)?;

                if let Some(base) = self.tys.base_of(bs.ty) {
                    bs.ptr = true;
                    bs.ty = base;
                }

                let idx = self.checked_expr(index, ty::Id::DINT, "subscript")?;

                match bs.ty.expand() {
                    ty::Kind::Slice(s) => {
                        let elem = self.tys.ins.slices[s].elem;
                        let size = self.ci.nodes.new_const(ty::Id::INT, self.tys.size_of(elem));
                        let inps = [VOID, idx.id, size];
                        let offset = self.ci.nodes.new_node(
                            ty::Id::INT,
                            Kind::BinOp { op: TokenKind::Mul },
                            inps,
                            self.tys,
                        );
                        let aclass = self.ci.nodes.aclass_index(bs.id).1;
                        let inps = [VOID, bs.id, offset];
                        let ptr = self.ci.nodes.new_node(
                            ty::Id::INT,
                            Kind::BinOp { op: TokenKind::Add },
                            inps,
                            self.tys,
                        );
                        self.ci.nodes.pass_aclass(aclass, ptr);

                        Some(Value::ptr(ptr).ty(elem))
                    }
                    ty::Kind::Struct(s) => {
                        let Kind::CInt { value: idx } = self.ci.nodes[idx.id].kind else {
                            return self.error(
                                index.pos(),
                                "field index needs to be known at compile time",
                            );
                        };

                        let Some((f, offset)) = OffsetIter::new(s, self.tys)
                            .into_iter(self.tys)
                            .nth(idx as _)
                            .map(|(f, off)| (f.ty, off))
                        else {
                            return self.error(
                                index.pos(),
                                fa!(
                                    "struct '{}' has only `{}' fields, \
                                    but index was '{}'",
                                    self.ty_display(bs.ty),
                                    self.tys.struct_fields(s).len(),
                                    idx
                                ),
                            );
                        };

                        Some(Value::ptr(self.offset(bs.id, offset)).ty(f))
                    }
                    ty::Kind::Tuple(t) => {
                        let Kind::CInt { value: idx } = self.ci.nodes[idx.id].kind else {
                            return self.error(
                                index.pos(),
                                "field index needs to be known at compile time",
                            );
                        };

                        let Some((f, offset)) = OffsetIter::new(t, self.tys)
                            .into_iter(self.tys)
                            .nth(idx as _)
                            .map(|(&f, off)| (f, off))
                        else {
                            return self.error(
                                index.pos(),
                                fa!(
                                    "struct '{}' has only `{}' fields, \
                                    but index was '{}'",
                                    self.ty_display(bs.ty),
                                    self.tys.tuple_fields(t).len(),
                                    idx
                                ),
                            );
                        };

                        Some(Value::ptr(self.offset(bs.id, offset)).ty(f))
                    }
                    _ => self.error(
                        base.pos(),
                        fa!(
                            "cant index into '{}' which is not array nor slice or tuple or struct",
                            self.ty_display(bs.ty)
                        ),
                    ),
                }
            }
            Expr::Embed { id, .. } => {
                let glob = &self.tys.ins.globals[id];
                let g =
                    self.ci.nodes.new_node(glob.ty, Kind::Global { global: id }, [VOID], self.tys);
                Some(Value::ptr(g).ty(glob.ty))
            }
            Expr::Directive { name: "kindof", args: [ty], .. } => {
                let ty = self.ty(ty);
                self.gen_inferred_const(ctx, ty::Id::U8, ty.kind())
            }
            Expr::Directive { name: "nameof", args: [ty], .. } => {
                let ty = self.ty(ty);
                let mut data = core::mem::take(&mut self.pool.lit_buf);
                self.tys.name_of(ty, self.files, &mut data);
                data.push(0);

                let (global, ty) = self.create_string_global(&data);

                data.clear();
                self.pool.lit_buf = data;

                Some(Value::new(global).ty(ty))
            }
            Expr::Directive { name: "sizeof", args: [ty], .. } => {
                let ty = self.ty(ty);
                self.gen_inferred_const(ctx, ty::Id::DINT, self.tys.size_of(ty))
            }
            Expr::Directive { name: "alignof", args: [ty], .. } => {
                let ty = self.ty(ty);
                let align = self.tys.align_of(ty);
                self.gen_inferred_const(ctx, ty::Id::DINT, align)
            }
            Expr::Directive { name: "lenof", args: [ety], .. } => {
                let ty = self.expr(ety)?;
                let len = match self.ci.nodes[ty.id].kind {
                    Kind::CInt { value } => match self.tys.len_of(ty::Id::from(value as u64)) {
                        Some(len) => len,
                        None => {
                            return self.error(
                                ety.pos(),
                                fa!(
                                    "'@len' only supports structs and arrays or strings. got {}",
                                    self.ty_display(ty::Id::from(value as u64))
                                ),
                            )
                        }
                    },
                    Kind::Global { global } => self.tys.ins.globals[global].data.len() as u32 - 1,
                    _ => {
                        return self
                            .error(ety.pos(), "'@len' only supports structs and arrays or strings")
                    }
                };
                self.gen_inferred_const(ctx, ty::Id::DINT, len)
            }
            Expr::Directive { name: "bitcast", args: [val], pos } => {
                let mut val = self.ptr_expr(val)?;

                inference!(ty, ctx, self, pos, "type", "@as(<ty>, @bitcast(<expr>))");

                let (got, expected) = (self.tys.size_of(val.ty), self.tys.size_of(ty));
                if got != expected {
                    self.error(
                        pos,
                        fa!(
                            "cast from '{}' to '{}' is not supported, \
                            sizes dont match ({got} != {expected})",
                            self.ty_display(val.ty),
                            self.ty_display(ty)
                        ),
                    );
                }

                match ty.loc(self.tys) {
                    Loc::Reg if mem::take(&mut val.ptr) => val.id = self.load_mem(val.id, ty),
                    Loc::Stack if !val.ptr => self.spill(pos, &mut val),
                    _ => {}
                }

                val.ty = ty;
                Some(val)
            }
            Expr::Directive { name: "unwrap", args: [expr], .. } => {
                let mut val = self.ptr_expr(expr)?;

                if !val.ty.is_optional() {
                    return self.error(
                        expr.pos(),
                        fa!(
                            "only optional types can be unwrapped ('{}' is not optional)",
                            self.ty_display(val.ty)
                        ),
                    );
                };

                self.explicit_unwrap(expr.pos(), &mut val);
                Some(val)
            }
            Expr::Directive { name: "intcast", args: [expr], pos } => {
                let mut val = self.expr(expr)?;

                if !val.ty.is_integer() {
                    return self.error(
                        expr.pos(),
                        fa!(
                            "only integers can be truncated ('{}' is not an integer)",
                            self.ty_display(val.ty)
                        ),
                    );
                }

                inference!(ty, ctx, self, pos, "integer", "@as(<ty>, @intcast(<expr>))");

                if !ty.is_integer() {
                    self.error(
                        expr.pos(),
                        fa!(
                            "intcast is inferred to output '{}', which is not an integer",
                            self.ty_display(ty)
                        ),
                    );
                }

                if self.tys.size_of(val.ty) < self.tys.size_of(ty) {
                    self.extend(&mut val, ty);
                    Some(val)
                } else {
                    Some(val.ty(ty))
                }
            }
            Expr::Directive { pos, name: "floatcast", args: [expr] } => {
                let val = self.expr(expr)?;

                if !val.ty.is_float() {
                    return self.error(
                        expr.pos(),
                        fa!(
                            "only floats can be truncated ('{}' is not a float)",
                            self.ty_display(val.ty)
                        ),
                    );
                }

                inference!(ty, ctx, self, pos, "float", "@as(<floaty>, @floatcast(<expr>))");

                if !ty.is_float() {
                    self.error(
                        expr.pos(),
                        fa!(
                            "floatcast is inferred to output '{}', which is not a float",
                            self.ty_display(ty)
                        ),
                    );
                }

                if self.tys.size_of(val.ty) != self.tys.size_of(ty) {
                    Some(self.ci.nodes.new_node_lit(
                        ty,
                        Kind::UnOp { op: TokenKind::Float },
                        [VOID, val.id],
                        self.tys,
                    ))
                } else {
                    Some(val.ty(ty))
                }
            }
            Expr::Directive { name: "fti", args: [expr], .. } => {
                let val = self.expr(expr)?;

                let ret_ty = match val.ty {
                    ty::Id::F32 | ty::Id::F64 => ty::Id::INT,
                    _ => {
                        return self.error(
                            expr.pos(),
                            fa!("expected float ('{}' is not a float)", self.ty_display(val.ty)),
                        )
                    }
                };

                Some(self.ci.nodes.new_node_lit(
                    ret_ty,
                    Kind::UnOp { op: TokenKind::Number },
                    [VOID, val.id],
                    self.tys,
                ))
            }
            Expr::Directive { name: "itf", args: [expr], pos } => {
                let mut val = self.expr_ctx(expr, Ctx::default().with_ty(ty::Id::INT))?;

                inference!(fty, ctx, self, pos, "float", "@as(<float-ty, @itf(<expr>))");

                self.assert_ty(expr.pos(), &mut val, ty::Id::INT, "converted integer");

                Some(self.ci.nodes.new_node_lit(
                    fty,
                    Kind::UnOp { op: TokenKind::Float },
                    [VOID, val.id],
                    self.tys,
                ))
            }
            Expr::Directive { name: "as", args: [ty, expr], pos } => {
                let ty = self.ty(ty);
                let mut val = self.ptr_expr_ctx(expr, Ctx::default().with_ty(ty))?;

                if let Some(ity) = ctx.ty
                    && ity.try_upcast(ty) == Some(ty)
                    && val.ty == ity
                {
                    _ = pos;
                    //self.error(pos, "the type is known at this point, remove the hint");
                }
                self.assert_ty(expr.pos(), &mut val, ty, "hinted expr");
                Some(val)
            }
            Expr::Directive { pos, name: "error", args } => {
                let mut error_msg = String::new();
                for arg in args {
                    let Some(val) = self.expr(arg) else {
                        self.error(arg.pos(), "unreachable argument");
                        continue;
                    };
                    match self.ci.nodes[val.id].kind {
                        Kind::Global { global }
                            if let Ok(str) = core::str::from_utf8(
                                &self.tys.ins.globals[global].data
                                    [..self.tys.ins.globals[global].data.len() - 1],
                            ) =>
                        {
                            error_msg.push_str(str)
                        }
                        Kind::CInt { value } if val.ty == ty::Id::TYPE => {
                            _ = write!(
                                error_msg,
                                "{}",
                                ty::Display::new(self.tys, self.files, ty::Id::from(value as u64))
                            )
                        }
                        _ => _ = self.error(arg.pos(), "expression can not (yet) be displayed"),
                    }
                }
                self.error(pos, error_msg);
                None
            }
            Expr::Directive { pos, name: "eca", args } => {
                inference!(
                    ret_ty,
                    ctx,
                    self,
                    pos,
                    "return type",
                    "@as(<return_ty>, @eca(<expr>...))"
                );

                let mut inps = Vc::from([NEVER]);
                let arg_base = self.tys.tmp.args.len();
                let mut clobbered_aliases = BitSet::default();
                for arg in args {
                    let value = self.expr(arg)?;
                    self.add_clobbers(value, &mut clobbered_aliases);
                    self.tys.tmp.args.push(value.ty);
                    debug_assert_ne!(self.ci.nodes[value.id].kind, Kind::Stre);
                    self.ci.nodes.lock(value.id);
                    inps.push(value.id);
                }

                let args = self.tys.pack_args(arg_base).expect("TODO");

                for &n in inps.iter().skip(1) {
                    self.ci.nodes.unlock(n);
                }

                self.append_clobbers(&mut inps, &mut clobbered_aliases);

                let alt_value = match ret_ty.loc(self.tys) {
                    Loc::Reg => None,
                    Loc::Stack => {
                        let stck = self.new_stack(pos, ret_ty);
                        inps.push(stck);
                        Some(Value::ptr(stck).ty(ret_ty))
                    }
                };

                inps[0] = self.ci.ctrl.get();
                self.ci.ctrl.set(
                    self.ci.nodes.new_node_nop(
                        ret_ty,
                        Kind::Call { func: ty::Func::ECA, args, unreachable: false },
                        inps,
                    ),
                    &mut self.ci.nodes,
                );

                self.add_clobber_stores(clobbered_aliases);

                Some(alt_value.unwrap_or_else(|| {
                    let ret =
                        self.ci.nodes.new_node_nop(ret_ty, Kind::RetVal, [self.ci.ctrl.get()]);
                    Value::new(ret).ty(ret_ty)
                }))
            }
            Expr::Call { func, args, .. } => self.gen_call(func, args, false),
            Expr::Directive { name: "inline", args: [func, args @ ..], .. } => {
                self.gen_call(func, args, true)
            }
            Expr::List { pos, kind, ty, fields, .. } => {
                let rty = ty
                    .map(|ty| self.ty(ty))
                    .or(ctx.ty.map(|ty| self.tys.inner_of(ty).unwrap_or(ty)))
                    .map(ty::Id::expand);

                match (rty, kind) {
                    (None, ListKind::Tuple) => {
                        let arg_base = self.tys.tmp.args.len();
                        let mut values = Vec::with_capacity(fields.len());
                        for field in fields {
                            let val = self.expr(field)?;
                            self.tys.tmp.args.push(val.ty);
                            self.ci.nodes.lock(val.id);
                            values.push(val);
                        }

                        let Some(fields) = self.tys.pack_args(arg_base) else {
                            return self.error(pos, "this tuple exceeded the reasonable limit");
                        };

                        let key = SymKey::Tuple(fields);
                        let ty::Kind::Tuple(tupl) = self
                            .tys
                            .syms
                            .get_or_insert(key, &mut self.tys.ins, |ins| {
                                ins.tuples.push(TupleData { fields, ..Default::default() }).into()
                            })
                            .expand()
                        else {
                            unreachable!()
                        };

                        let mem = self.new_stack(pos, tupl.into());
                        let mut offs = OffsetIter::new(tupl, self.tys);
                        for value in values {
                            let (ty, offset) = offs.next_ty(self.tys).unwrap();
                            let mem = self.offset(mem, offset);
                            self.ci.nodes.unlock(value.id);
                            self.store_mem(mem, ty, value.id);
                        }

                        Some(Value::ptr(mem).ty(tupl.into()))
                    }
                    (None, ListKind::Array) => {
                        let mut array_meta = None::<(ty::Id, Nid)>;
                        let mut offset = 0;
                        for field in fields {
                            let (elem, mem) = match array_meta {
                                Some((ty, mem)) => {
                                    (self.checked_expr(field, ty, "array element")?, mem)
                                }
                                None => {
                                    let expr = self.expr(field)?;
                                    let aty = self.tys.make_array(expr.ty, fields.len() as _);
                                    let mem = self.new_stack(pos, aty);
                                    array_meta = Some((expr.ty, mem));
                                    (expr, mem)
                                }
                            };
                            let mem = self.offset(mem, offset);
                            self.store_mem(mem, elem.ty, elem.id);
                            offset += self.tys.size_of(elem.ty);
                        }

                        let Some((_, mem)) = array_meta else {
                            return self.error(pos, "can not infer the type of the array element, \
                                array is empty, has no explicit type, and type is not obvious from the context");
                        };

                        Some(Value::ptr(mem).ty(self.ci.nodes[mem].ty))
                    }
                    (Some(ty::Kind::Struct(s)), ListKind::Tuple) => {
                        let mem = self.new_stack(pos, s.into());
                        let mut offs = OffsetIter::new(s, self.tys);
                        for field in fields {
                            let Some((ty, offset)) = offs.next_ty(self.tys) else {
                                self.error(
                                    field.pos(),
                                    "this init argumen overflows the field count",
                                );
                                break;
                            };

                            let value = self.checked_expr(field, ty, "tuple field")?;
                            let mem = self.offset(mem, offset);
                            self.store_mem(mem, ty, value.id);
                        }

                        let field_list = offs
                            .into_iter(self.tys)
                            .map(|(f, ..)| self.tys.names.ident_str(f.name))
                            .intersperse(", ")
                            .collect::<String>();

                        if !field_list.is_empty() {
                            self.error(
                                pos,
                                fa!("the struct initializer is missing {field_list} \
                                    (append them to the end of the constructor)"),
                            );
                        }
                        Some(Value::ptr(mem).ty(s.into()))
                    }
                    (Some(kty), ListKind::Array) => {
                        let (len, elem) = if ty.is_none()
                            && let ty::Kind::Slice(a) = kty
                        {
                            let arr = &self.tys.ins.slices[a];
                            (arr.len().unwrap_or(fields.len()), arr.elem)
                        } else {
                            (fields.len(), kty.compress())
                        };
                        let elem_size = self.tys.size_of(elem);
                        let aty = self.tys.make_array(elem, len as ArrayLen);

                        if len != fields.len() {
                            return self.error(
                                pos,
                                fa!(
                                    "expected '{}' but constructor has {} elements",
                                    self.ty_display(aty),
                                    fields.len()
                                ),
                            );
                        }

                        let mem = self.new_stack(pos, aty);

                        for (field, offset) in
                            fields.iter().zip((0u32..).step_by(elem_size as usize))
                        {
                            let value = self.checked_expr(field, elem, "array value")?;
                            let mem = self.offset(mem, offset);
                            self.store_mem(mem, elem, value.id);
                        }

                        Some(Value::ptr(mem).ty(aty))
                    }
                    (Some(ty::Kind::Tuple(tupl)), ListKind::Tuple) => {
                        let mem = self.new_stack(pos, tupl.into());
                        let mut offs = OffsetIter::new(tupl, self.tys);
                        for field in fields {
                            let Some((ty, offset)) = offs.next_ty(self.tys) else {
                                self.error(
                                    field.pos(),
                                    "this init argumen overflows the field count",
                                );
                                break;
                            };

                            let value = self.checked_expr(field, ty, "tuple field")?;
                            let mem = self.offset(mem, offset);
                            self.store_mem(mem, ty, value.id);
                        }

                        Some(Value::ptr(mem).ty(tupl.into()))
                    }
                    (Some(t), ListKind::Tuple) => self.error(
                        pos,
                        fa!(
                            "the {}type of the constructor is `{}`, but thats not a struct",
                            if ty.is_some() { "" } else { "inferred " },
                            self.ty_display(t.compress()),
                        ),
                    ),
                }
            }
            Expr::Struct { .. } => {
                let value = self.ty(expr).repr();
                Some(self.ci.nodes.new_const_lit(ty::Id::TYPE, value))
            }
            Expr::Ctor { pos, ty, fields, .. } => {
                ctx.ty = ty
                    .map(|ty| self.ty(ty))
                    .or(ctx.ty.map(|ty| self.tys.inner_of(ty).unwrap_or(ty)));
                inference!(sty, ctx, self, pos, "struct", "<struct_ty>.{...}");

                match sty.expand() {
                    ty::Kind::Union(u) => {
                        let &[CtorField { pos: fpos, name, value }] = fields else {
                            return self.error(
                                pos,
                                fa!("union initializer needs to have exactly one field"),
                            );
                        };

                        let mem = self.new_stack(pos, sty);

                        let Some((_, field)) = self.tys.find_union_field(u, name) else {
                            return self.error(
                                fpos,
                                fa!("union '{}' does not have this field", self.ty_display(sty)),
                            );
                        };

                        let (ty, offset) = (field.ty, 0);

                        let value = self.checked_expr(&value, ty, fa!("field {}", name))?;
                        let mem = self.offset(mem, offset);
                        self.store_mem(mem, ty, value.id);

                        Some(Value::ptr(mem).ty(sty))
                    }
                    ty::Kind::Struct(s) => {
                        let mut offs = OffsetIter::new(s, self.tys)
                            .into_iter(self.tys)
                            .map(|(f, o)| (f.ty, o))
                            .collect::<Vec<_>>();
                        let mem = self.new_stack(pos, sty);
                        for field in fields {
                            let Some(index) = self.tys.find_struct_field(s, field.name) else {
                                self.error(
                                    field.pos,
                                    fa!(
                                        "struct '{}' does not have this field",
                                        self.ty_display(sty)
                                    ),
                                );
                                continue;
                            };

                            let (ty, offset) =
                                mem::replace(&mut offs[index], (ty::Id::UNDECLARED, field.pos));

                            if ty == ty::Id::UNDECLARED {
                                self.error(field.pos, "the struct field is already initialized");
                                self.error(offset, "previous initialization is here");
                                continue;
                            }

                            let value =
                                self.checked_expr(&field.value, ty, fa!("field {}", field.name))?;
                            let mem = self.offset(mem, offset);
                            self.store_mem(mem, ty, value.id);
                        }

                        for (i, &mut (ref mut ty, offset)) in
                            self.tys.struct_field_range(s).zip(&mut offs)
                        {
                            if *ty == ty::Id::UNDECLARED {
                                continue;
                            }

                            let field = &self.tys.ins.struct_fields[i];
                            let Some(deva) = field.default_value else { continue };
                            let value = self.gen_const(deva, Ctx::default().with_ty(*ty))?;
                            let mem = self.offset(mem, offset);
                            self.store_mem(mem, *ty, value.id);

                            *ty = ty::Id::UNDECLARED;
                        }

                        let field_list = self
                            .tys
                            .struct_fields(s)
                            .iter()
                            .zip(offs)
                            .filter(|&(_, (ty, _))| ty != ty::Id::UNDECLARED)
                            .map(|(f, _)| self.tys.names.ident_str(f.name))
                            .intersperse(", ")
                            .collect::<String>();

                        if !field_list.is_empty() {
                            self.error(pos, fa!("the struct initializer is missing {field_list}"));
                        }

                        Some(Value::ptr(mem).ty(sty))
                    }
                    _ => self.error(
                        pos,
                        fa!(
                            "the {}type of the constructor is `{}`, \
                            but thats not a struct or union",
                            if ty.is_some() { "" } else { "inferred " },
                            self.ty_display(sty)
                        ),
                    ),
                }
            }
            Expr::Block { stmts, .. } => {
                let base = self.ci.scope.vars.len();
                let aclass_base = self.ci.scope.aclasses.len();
                let defer_base = self.ci.defers.len();

                let mut ret = Some(Value::VOID);
                for stmt in stmts {
                    ret = ret.and(self.expr_ctx(stmt, Ctx::default().with_ty(ty::Id::VOID)));
                    if let Some(id) = ret {
                        if id.ty != ty::Id::VOID {
                            self.warn(
                                stmt.pos(),
                                fa!(
                                    "statements need to evaluate to 'void', \
                                    but this statements evaluates '{}', \
                                    use '_ = <stmt>' to discard the value if its intentional",
                                    self.ty_display(id.ty)
                                ),
                            );
                        }
                    } else {
                        break;
                    }
                }

                if ret.is_some() {
                    self.gen_defers(defer_base);
                }
                self.ci.defers.truncate(defer_base);

                for var in self.ci.scope.vars.drain(base..) {
                    var.remove(&mut self.ci.nodes);
                }

                for aclass in self.ci.scope.aclasses.drain(aclass_base..) {
                    aclass.remove(&mut self.ci.nodes);
                }

                ret
            }
            Expr::Loop { unrolled: true, body, pos } => {
                let mut loop_fuel = 100;

                self.ci
                    .loops
                    .push(Loop::Comptime { state: None, defer_base: self.ci.defers.len() });

                loop {
                    if loop_fuel == 0 {
                        return self.error(
                            pos,
                            "unrolled loop exceeded 100 iterations, use normal loop instead, TODO: add escape hatch",
                        );
                    }
                    loop_fuel -= 1;

                    let terminated = self.expr(body).is_none();

                    let Some(&Loop::Comptime { state, .. }) = self.ci.loops.last() else {
                        unreachable!()
                    };

                    if !terminated && let Some((_, prev)) = state {
                        self.error(
                            pos,
                            "reached a constrol flow keyword inside an unrolled loop, \
                            as well ast the end of the loop, make sure control flow is \
                            not dependant on a runtime value",
                        );
                        return self.error(prev, "previous reachable control flow found here");
                    }

                    match state {
                        Some((CtLoopState::Terminated, _)) => break,
                        Some((CtLoopState::Continued, _)) | None => {}
                    }
                }

                self.ci.loops.pop().unwrap();

                Some(Value::VOID)
            }
            Expr::Loop { body, unrolled: false, .. } => {
                self.ci.ctrl.set(
                    self.ci.nodes.new_node(
                        ty::Id::VOID,
                        Kind::Loop,
                        [self.ci.ctrl.get(), self.ci.ctrl.get(), LOOPS],
                        self.tys,
                    ),
                    &mut self.ci.nodes,
                );

                self.ci.loops.push(Loop::Runtime {
                    node: self.ci.ctrl.get(),
                    ctrl: [StrongRef::DEFAULT; 2],
                    ctrl_scope: core::array::from_fn(|_| Default::default()),
                    scope: self.ci.scope.dup(&mut self.ci.nodes),
                    defer_base: self.ci.defers.len(),
                });

                for var in self.ci.scope.vars.iter_mut().skip(self.ci.inline_var_base) {
                    if var.ty != ty::Id::TYPE && !var.ptr {
                        var.set_value(VOID, &mut self.ci.nodes);
                    }
                }

                for aclass in self.ci.scope.aclasses[..2].iter_mut() {
                    aclass.last_store.set(VOID, &mut self.ci.nodes);
                }
                for aclass in self.ci.scope.aclasses.iter_mut().skip(self.ci.inline_aclass_base) {
                    aclass.last_store.set(VOID, &mut self.ci.nodes);
                }

                self.expr(body);

                let Some(Loop::Runtime { ctrl: [con, ..], ctrl_scope: [cons, ..], .. }) =
                    self.ci.loops.last_mut()
                else {
                    unreachable!()
                };
                let mut cons = mem::take(cons);

                if let Some(con) = mem::take(con).unwrap(&mut self.ci.nodes) {
                    self.ci.ctrl.set(
                        self.ci.nodes.new_node(
                            ty::Id::VOID,
                            Kind::Region,
                            [con, self.ci.ctrl.get()],
                            self.tys,
                        ),
                        &mut self.ci.nodes,
                    );
                    self.ci.nodes.merge_scopes(
                        &mut self.ci.loops,
                        &self.ci.ctrl,
                        &mut self.ci.scope,
                        &mut cons,
                        self.tys,
                    );
                    cons.clear(&mut self.ci.nodes);
                }

                let Some(Loop::Runtime {
                    node,
                    ctrl: [.., bre],
                    ctrl_scope: [.., mut bres],
                    mut scope,
                    defer_base,
                }) = self.ci.loops.pop()
                else {
                    unreachable!()
                };

                self.gen_defers(defer_base);
                self.ci.defers.truncate(defer_base);

                self.ci.nodes.modify_input(node, 1, self.ci.ctrl.get());

                if let Some(idx) =
                    self.ci.nodes[node].outputs.iter().position(|&n| self.ci.nodes.is_cfg(n))
                {
                    self.ci.nodes[node].outputs.swap(idx, 0);
                }

                let Some(bre) = bre.unwrap(&mut self.ci.nodes) else {
                    for (loop_var, scope_var) in
                        self.ci.scope.vars.iter_mut().zip(scope.vars.iter_mut())
                    {
                        if self.ci.nodes[scope_var.value()].is_lazy_phi(node) {
                            if loop_var.value() != scope_var.value() {
                                scope_var.set_value(
                                    self.ci.nodes.modify_input(
                                        scope_var.value(),
                                        2,
                                        loop_var.value(),
                                    ),
                                    &mut self.ci.nodes,
                                );
                            } else {
                                let phi = &self.ci.nodes[scope_var.value()];
                                let prev = phi.inputs[1];
                                self.ci.nodes.replace(scope_var.value(), prev);
                                scope_var.set_value(prev, &mut self.ci.nodes);
                            }
                        }
                    }

                    for (loop_class, scope_class) in
                        self.ci.scope.aclasses.iter_mut().zip(scope.aclasses.iter_mut())
                    {
                        if self.ci.nodes[scope_class.last_store.get()].is_lazy_phi(node) {
                            if loop_class.last_store.get() != scope_class.last_store.get()
                                && loop_class.last_store.get() != 0
                            {
                                scope_class.last_store.set(
                                    self.ci.nodes.modify_input(
                                        scope_class.last_store.get(),
                                        2,
                                        loop_class.last_store.get(),
                                    ),
                                    &mut self.ci.nodes,
                                );
                            } else {
                                let phi = &self.ci.nodes[scope_class.last_store.get()];
                                let prev = phi.inputs[1];
                                self.ci.nodes.replace(scope_class.last_store.get(), prev);
                                scope_class.last_store.set(prev, &mut self.ci.nodes);
                            }
                        }

                        if loop_class.last_store.get() == 0 {
                            loop_class
                                .last_store
                                .set(scope_class.last_store.get(), &mut self.ci.nodes);
                        }
                    }

                    debug_assert!(self.ci.scope.aclasses.iter().all(|a| a.last_store.get() != 0));

                    scope.clear(&mut self.ci.nodes);
                    self.ci.ctrl.set(NEVER, &mut self.ci.nodes);

                    return None;
                };

                self.ci.ctrl.set(bre, &mut self.ci.nodes);

                mem::swap(&mut self.ci.scope, &mut bres);

                debug_assert_eq!(self.ci.scope.vars.len(), scope.vars.len());
                debug_assert_eq!(self.ci.scope.vars.len(), bres.vars.len());

                self.ci.nodes.lock(node);

                for ((dest_var, scope_var), loop_var) in self
                    .ci
                    .scope
                    .vars
                    .iter_mut()
                    .zip(scope.vars.iter_mut())
                    .zip(bres.vars.iter_mut())
                {
                    if self.ci.nodes[scope_var.value()].is_lazy_phi(node) {
                        if loop_var.value() != scope_var.value() && loop_var.value() != 0 {
                            scope_var.set_value(
                                self.ci.nodes.modify_input(scope_var.value(), 2, loop_var.value()),
                                &mut self.ci.nodes,
                            );
                        } else {
                            if dest_var.value() == scope_var.value() {
                                dest_var.set_value(VOID, &mut self.ci.nodes);
                            }
                            let phi = &self.ci.nodes[scope_var.value()];
                            let prev = phi.inputs[1];
                            self.ci.nodes.replace(scope_var.value(), prev);
                            scope_var.set_value(prev, &mut self.ci.nodes);
                        }
                    }

                    if dest_var.value() == VOID {
                        dest_var.set_value(scope_var.value(), &mut self.ci.nodes);
                    }

                    debug_assert!(!self.ci.nodes[dest_var.value()].is_lazy_phi(node));
                }

                for ((dest_class, scope_class), loop_class) in self
                    .ci
                    .scope
                    .aclasses
                    .iter_mut()
                    .zip(scope.aclasses.iter_mut())
                    .zip(bres.aclasses.iter_mut())
                {
                    if self.ci.nodes[scope_class.last_store.get()].is_lazy_phi(node) {
                        if loop_class.last_store.get() != scope_class.last_store.get()
                            && loop_class.last_store.get() != 0
                        {
                            scope_class.last_store.set(
                                self.ci.nodes.modify_input(
                                    scope_class.last_store.get(),
                                    2,
                                    loop_class.last_store.get(),
                                ),
                                &mut self.ci.nodes,
                            );
                        } else {
                            if dest_class.last_store.get() == scope_class.last_store.get() {
                                dest_class.last_store.set(VOID, &mut self.ci.nodes);
                            }
                            let phi = &self.ci.nodes[scope_class.last_store.get()];
                            let prev = phi.inputs[1];
                            self.ci.nodes.replace(scope_class.last_store.get(), prev);
                            scope_class.last_store.set(prev, &mut self.ci.nodes);
                        }
                    }

                    if dest_class.last_store.get() == VOID {
                        dest_class.last_store.set(scope_class.last_store.get(), &mut self.ci.nodes);
                    }

                    debug_assert!(
                        !self.ci.nodes[dest_class.last_store.get()].is_lazy_phi(node),
                        "{:?}",
                        self.ci.nodes[dest_class.last_store.get()]
                    );
                }

                scope.clear(&mut self.ci.nodes);
                bres.clear(&mut self.ci.nodes);

                self.ci.nodes.unlock(node);
                let rpl = self.ci.nodes.late_peephole(node, self.tys).unwrap_or(node);
                if self.ci.ctrl.get() == node {
                    self.ci.ctrl.set_remove(rpl, &mut self.ci.nodes);
                }

                Some(Value::VOID)
            }
            Expr::Break { pos } => self.jump_to(pos, 1),
            Expr::Continue { pos } => self.jump_to(pos, 0),
            Expr::If { cond, then, else_, .. } => {
                let cnd = self.checked_expr(cond, ty::Id::BOOL, "condition")?;

                let if_node = self.ci.nodes.new_node(
                    ty::Id::VOID,
                    Kind::If,
                    [self.ci.ctrl.get(), cnd.id],
                    self.tys,
                );

                'b: {
                    let branch = match self.ci.nodes[if_node].ty {
                        ty::Id::LEFT_UNREACHABLE => else_,
                        ty::Id::RIGHT_UNREACHABLE => Some(then),
                        _ => break 'b,
                    };

                    self.ci.nodes.remove(if_node);

                    if let Some(branch) = branch {
                        return self.expr(branch);
                    } else {
                        return Some(Value::VOID);
                    }
                }

                let else_scope = self.ci.scope.dup(&mut self.ci.nodes);

                self.ci.ctrl.set(
                    self.ci.nodes.new_node(ty::Id::VOID, Kind::Then, [if_node], self.tys),
                    &mut self.ci.nodes,
                );
                let lcntrl = self.expr(then).map_or(Nid::MAX, |_| self.ci.ctrl.get());

                let then_scope = mem::replace(&mut self.ci.scope, else_scope);
                self.ci.ctrl.set(
                    self.ci.nodes.new_node(ty::Id::VOID, Kind::Else, [if_node], self.tys),
                    &mut self.ci.nodes,
                );
                let rcntrl = if let Some(else_) = else_ {
                    self.expr(else_).map_or(Nid::MAX, |_| self.ci.ctrl.get())
                } else {
                    self.ci.ctrl.get()
                };

                self.close_if(lcntrl, rcntrl, then_scope)?;
                Some(Value::VOID)
            }
            Expr::Match { pos, value, branches } => {
                let value = self.expr(value)?;

                let ty::Kind::Enum(e) = value.ty.expand() else {
                    return self.error(
                        pos,
                        fa!(
                            "match operates on enums (for now), '{}' is not an enum",
                            self.ty_display(value.ty)
                        ),
                    );
                };

                let mut covered_values = vec![Pos::MAX; self.tys.enum_field_range(e).len()];
                let mut else_branch = None::<Expr>;

                if let Kind::CInt { value: cnst } = self.ci.nodes[value.id].kind {
                    let mut matching_branch = None::<Expr>;
                    for &MatchBranch { pat, pos: bp, body } in branches {
                        if let Expr::Wildcard { .. } = pat {
                            if let Some(prev) = else_branch {
                                self.error(bp, "duplicate branch");
                                self.error(prev.pos(), "...first branch declared here");
                            }

                            else_branch = Some(body);
                            continue;
                        }

                        let pat_val = self.eval_const(self.ci.file, self.ci.parent, &pat, value.ty);
                        if covered_values[pat_val as usize] != Pos::MAX {
                            self.error(bp, "duplicate branch");
                            self.error(
                                covered_values[pat_val as usize],
                                "...first branch declared here",
                            );
                            continue;
                        }
                        covered_values[pat_val as usize] = bp;

                        if pat_val == cnst as u64 {
                            matching_branch = Some(body);
                        }
                    }

                    if let Some(body) = matching_branch.or(else_branch) {
                        self.expr(&body)?;
                    }
                } else {
                    let mut scopes = vec![];
                    for &MatchBranch { pat, pos: bp, body } in branches {
                        if let Expr::Wildcard { .. } = pat {
                            if let Some(prev) = else_branch {
                                self.error(bp, "duplicate branch");
                                self.error(prev.pos(), "...first branch declared here");
                            }

                            else_branch = Some(body);
                            continue;
                        }

                        let pat_val = self.eval_const(self.ci.file, self.ci.parent, &pat, value.ty);
                        if covered_values[pat_val as usize] != Pos::MAX {
                            self.error(bp, "duplicate branch");
                            self.error(
                                covered_values[pat_val as usize],
                                "...first branch declared here",
                            );
                            continue;
                        }
                        covered_values[pat_val as usize] = bp;

                        let pat_val = self.ci.nodes.new_const(value.ty, pat_val as i64);
                        let cnd = self.ci.nodes.new_node(
                            ty::Id::BOOL,
                            Kind::BinOp { op: TokenKind::Eq },
                            [VOID, value.id, pat_val],
                            self.tys,
                        );

                        let if_node = self.ci.nodes.new_node(
                            ty::Id::VOID,
                            Kind::If,
                            [self.ci.ctrl.get(), cnd],
                            self.tys,
                        );

                        let cached_scope = self.ci.scope.dup(&mut self.ci.nodes);
                        self.ci.ctrl.set(
                            self.ci.nodes.new_node(ty::Id::VOID, Kind::Then, [if_node], self.tys),
                            &mut self.ci.nodes,
                        );
                        let ctrl = self.expr(&body).map_or(Nid::MAX, |_| self.ci.ctrl.get());
                        scopes.push((ctrl, mem::replace(&mut self.ci.scope, cached_scope)));

                        self.ci.ctrl.set(
                            self.ci.nodes.new_node(ty::Id::VOID, Kind::Else, [if_node], self.tys),
                            &mut self.ci.nodes,
                        );
                    }
                    let mut rcntrl = if let Some(ebr) = else_branch {
                        self.expr(&ebr).map_or(Nid::MAX, |_| self.ci.ctrl.get())
                    } else {
                        self.ci.ctrl.get()
                    };

                    for (lcntrl, then_scope) in scopes.into_iter().rev() {
                        if let Some(v) = self.close_if(lcntrl, rcntrl, then_scope)
                            && v != VOID
                        {
                            rcntrl = v;
                        }
                    }

                    if rcntrl == Nid::MAX {
                        return None;
                    }
                }

                if else_branch.is_none() {
                    let missing_branches = covered_values
                        .into_iter()
                        .zip(self.tys.enum_fields(e))
                        .filter(|&(f, _)| f == Pos::MAX)
                        .map(|(_, f)| self.tys.names.ident_str(f.name))
                        .intersperse("', '")
                        .collect::<String>();

                    if !missing_branches.is_empty() {
                        self.error(pos, fa!("not all cases covered, missing '{missing_branches}'"));
                    }
                }

                Some(Value::VOID)
            }
            ref e => {
                let ty = self.parse_ty(
                    TyScope { file: self.ci.file, parent: self.ci.parent, ..Default::default() },
                    e,
                );
                Some(self.ci.nodes.new_const_lit(ty::Id::TYPE, ty))
            }
        }
    }

    fn spill(&mut self, pos: Pos, value: &mut Value) {
        debug_assert!(!value.ptr);
        let stck = self.new_stack(pos, value.ty);
        self.store_mem(stck, value.ty, value.id);
        value.id = stck;
        value.ptr = true;
    }

    fn checked_expr(
        &mut self,
        expr: &Expr,
        expected_ty: ty::Id,
        hint: impl Display,
    ) -> Option<Value> {
        let mut value = self.ptr_expr_ctx(expr, Ctx::default().with_ty(expected_ty))?;
        self.assert_ty(expr.pos(), &mut value, expected_ty, hint);
        self.strip_ptr(&mut value);
        Some(value)
    }

    fn gen_field(
        &mut self,
        ctx: Ctx,
        target: &Expr,
        pos: Pos,
        name: &str,
    ) -> Option<Result<Value, (ty::Id, Value)>> {
        let mut vtarget = self.ptr_expr(target)?;
        self.implicit_unwrap(pos, &mut vtarget);
        let tty = vtarget.ty;

        match self.tys.base_of(tty).unwrap_or(tty).expand() {
            ty::Kind::Module(m) => self.find_type_as_value(pos, m, name, ctx),
            ty::Kind::Enum(e) => {
                let intrnd = self.tys.names.project(name);
                self.gen_enum_variant(pos, e, intrnd)
            }
            ty::Kind::Union(u) => {
                if let Some((_, f)) = self.tys.find_union_field(u, name) {
                    Some(Value::ptr(vtarget.id).ty(f.ty))
                } else if let ty = self.find_type(pos, self.ci.file, u, name)
                    && let ty::Kind::Func(_) = ty.expand()
                {
                    return Some(Err((ty, vtarget)));
                } else {
                    self.error(
                        pos,
                        fa!(
                            "the '{}' does not have this field, \
                            but it does have '{}'",
                            self.ty_display(tty),
                            self.tys
                                .union_fields(u)
                                .iter()
                                .map(|f| self.tys.names.ident_str(f.name))
                                .intersperse("', '")
                                .collect::<String>()
                        ),
                    )
                }
            }
            ty::Kind::Struct(s) => {
                if let Some((offset, ty)) = OffsetIter::offset_of(self.tys, s, name) {
                    Some(Value::ptr(self.offset(vtarget.id, offset)).ty(ty))
                } else if let ty = self.find_type(pos, self.ci.file, s, name)
                    && let ty::Kind::Func(_) = ty.expand()
                {
                    return Some(Err((ty, vtarget)));
                } else {
                    self.error(
                        pos,
                        fa!(
                            "the '{}' does not have this field, \
                            but it does have '{}'",
                            self.ty_display(tty),
                            self.tys
                                .struct_fields(s)
                                .iter()
                                .map(|f| self.tys.names.ident_str(f.name))
                                .intersperse("', '")
                                .collect::<String>()
                        ),
                    )
                }
            }
            ty::Kind::TYPE => match self.ci.nodes.as_ty(vtarget.id).expand() {
                ty::Kind::Module(m) => self.find_type_as_value(pos, m, name, ctx),
                ty::Kind::Enum(e)
                    if let intrnd = self.tys.names.project(name)
                        && let Some(index) =
                            self.tys.enum_fields(e).iter().position(|f| Some(f.name) == intrnd) =>
                {
                    Some(self.ci.nodes.new_const_lit(e.into(), index as i64))
                }
                ty @ (ty::Kind::Struct(_) | ty::Kind::Enum(_) | ty::Kind::Union(_)) => {
                    self.find_type_as_value(pos, ty.compress(), name, ctx)
                }
                ty @ (ty::Kind::Builtin(_)
                | ty::Kind::Ptr(_)
                | ty::Kind::Slice(_)
                | ty::Kind::Opt(_)
                | ty::Kind::Func(_)
                | ty::Kind::Template(_)
                | ty::Kind::Global(_)
                | ty::Kind::Tuple(_)
                | ty::Kind::Const(_)) => self.error(
                    pos,
                    fa!(
                        "accesing scope on '{}' is not supported yet",
                        self.ty_display(ty.compress())
                    ),
                ),
            },
            _ => self.error(
                pos,
                fa!(
                    "the '{}' is not a struct, or pointer to one, or enum, \
                                fo field access does not make sense",
                    self.ty_display(tty)
                ),
            ),
        }
        .map(Ok)
    }

    fn close_if(&mut self, lcntrl: Nid, rcntrl: Nid, mut then_scope: Scope) -> Option<Nid> {
        if lcntrl == Nid::MAX && rcntrl == Nid::MAX {
            then_scope.clear(&mut self.ci.nodes);
            return None;
        } else if lcntrl == Nid::MAX {
            then_scope.clear(&mut self.ci.nodes);
            return Some(VOID);
        } else if rcntrl == Nid::MAX {
            self.ci.scope.clear(&mut self.ci.nodes);
            self.ci.scope = then_scope;
            self.ci.ctrl.set(lcntrl, &mut self.ci.nodes);
            return Some(VOID);
        }

        self.ci.ctrl.set(
            self.ci.nodes.new_node(ty::Id::VOID, Kind::Region, [lcntrl, rcntrl], self.tys),
            &mut self.ci.nodes,
        );

        self.ci.nodes.merge_scopes(
            &mut self.ci.loops,
            &self.ci.ctrl,
            &mut self.ci.scope,
            &mut then_scope,
            self.tys,
        );
        then_scope.clear(&mut self.ci.nodes);
        Some(self.ci.ctrl.get())
    }

    fn gen_enum_variant(&mut self, pos: Pos, e: ty::Enum, intrnd: Option<Ident>) -> Option<Value> {
        let Some(index) = self.tys.enum_fields(e).iter().position(|f| Some(f.name) == intrnd)
        else {
            return self.error(
                pos,
                fa!(
                    "the '{}' does not have this variant, \
                            but it does have '{}'",
                    self.ty_display(e.into()),
                    self.tys
                        .enum_fields(e)
                        .iter()
                        .map(|f| self.tys.names.ident_str(f.name))
                        .intersperse("', '")
                        .collect::<String>()
                ),
            );
        };

        Some(self.ci.nodes.new_const_lit(e.into(), index as i64))
    }

    fn gen_inferred_const(
        &mut self,
        ctx: Ctx,
        fallback: ty::Id,
        value: impl Into<i64>,
    ) -> Option<Value> {
        self.gen_inferred_const_low(ctx, fallback, value, false)
    }

    fn gen_inferred_const_low(
        &mut self,
        ctx: Ctx,
        fallback: ty::Id,
        value: impl Into<i64>,
        is_float: bool,
    ) -> Option<Value> {
        let ty = ctx
            .ty
            .map(|ty| self.tys.inner_of(ty).unwrap_or(ty))
            .filter(|&ty| (ty.is_integer() && !is_float) || ty.is_float())
            .unwrap_or(fallback);
        let value = value.into();
        Some(self.ci.nodes.new_const_lit(
            ty,
            if ty.is_float() && !is_float { (value as f64).to_bits() as i64 } else { value },
        ))
    }

    fn gen_call(&mut self, func: &Expr, args: &[Expr], mut inline: bool) -> Option<Value> {
        let (ty, mut caller) = match *func {
            Expr::Field { target, pos, name } => {
                match self.gen_field(Ctx::default(), target, pos, name)? {
                    Ok(mut fexpr) => {
                        self.assert_ty(func.pos(), &mut fexpr, ty::Id::TYPE, "function");
                        (self.ci.nodes.as_ty(fexpr.id), None)
                    }
                    Err((ty, val)) => (ty, Some(val)),
                }
            }
            ref e => (self.ty(e), None),
        };

        let Some(fu) = self.compute_signature(ty, func.pos(), args) else {
            return Value::NEVER;
        };

        let FuncData { expr, file, is_inline, parent, sig, .. } = self.tys.ins.funcs[fu];
        let ast = &self.files[file];
        let &Expr::Closure { args: cargs, body, .. } = expr.get(ast) else { unreachable!() };

        let arg_count = args.len() + caller.is_some() as usize;
        if arg_count != cargs.len() {
            self.error(
                func.pos(),
                fa!(
                    "expected {} function argumenr{}, got {}",
                    cargs.len(),
                    if cargs.len() == 1 { "" } else { "s" },
                    arg_count
                ),
            );
        }

        if inline && is_inline {
            self.error(
                func.pos(),
                "function is declared as inline so this @inline directive only reduces readability",
            );
        }

        inline |= sig.ret == ty::Id::TYPE;

        let (mut tys, mut args, mut cargs) = (sig.args.args(), args.iter(), cargs.iter());
        if is_inline || inline {
            let var_base = self.ci.scope.vars.len();
            let aclass_base = self.ci.scope.aclasses.len();

            if let Some(caller) = &mut caller
                && let (Some(Arg::Value(ty)), Some(carg)) = (tys.next(self.tys), cargs.next())
            {
                match (caller.ty.is_pointer(), ty.is_pointer()) {
                    (true, false) => {
                        caller.ty = self.tys.base_of(caller.ty).unwrap();
                        caller.ptr = true;
                    }
                    (false, true) => {
                        caller.ty = self.tys.make_ptr(caller.ty);
                        caller.ptr = false;
                    }
                    _ => {}
                }

                self.assert_ty(func.pos(), caller, ty, "caller");
                self.ci.scope.vars.push(Variable::new(
                    carg.id,
                    ty,
                    caller.ptr,
                    caller.id,
                    &mut self.ci.nodes,
                ))
            }

            while let (Some(aty), Some(arg)) = (tys.next(self.tys), args.next()) {
                let carg = cargs.next().unwrap();
                let var = match aty {
                    Arg::Type(id) => Variable::new(
                        carg.id,
                        ty::Id::TYPE,
                        false,
                        self.ci.nodes.new_const(ty::Id::TYPE, id),
                        &mut self.ci.nodes,
                    ),
                    Arg::Value(ty) => {
                        let mut value = self.ptr_expr_ctx(arg, Ctx::default().with_ty(ty))?;
                        debug_assert_ne!(self.ci.nodes[value.id].kind, Kind::Stre);
                        debug_assert_ne!(value.id, 0);
                        self.assert_ty(arg.pos(), &mut value, ty, fa!("argument {}", carg.name));
                        Variable::new(carg.id, ty, value.ptr, value.id, &mut self.ci.nodes)
                    }
                };
                self.ci.scope.vars.push(var);
            }

            let prev_var_base = mem::replace(&mut self.ci.inline_var_base, var_base);
            let prev_aclass_base = mem::replace(&mut self.ci.inline_aclass_base, aclass_base);
            let prev_defer_base =
                mem::replace(&mut self.ci.inline_defer_base, self.ci.defers.len());
            let prev_inline_ret = self.ci.inline_ret.take();
            self.ci.inline_depth += 1;
            let prev_ret = self.ci.ret.replace(sig.ret);
            let prev_file = mem::replace(&mut self.ci.file, file);
            let prev_parent = mem::replace(&mut self.ci.parent, parent);
            let prev_ctrl = self.ci.ctrl.get();

            if self.expr(body).is_some() {
                if sig.ret == ty::Id::VOID {
                    self.expr(&Expr::Return { pos: body.pos(), val: None });
                } else {
                    self.error(
                        body.pos(),
                        "expected all paths in the fucntion to return \
                        or the return type to be 'void'",
                    );
                }
            }

            self.ci.ret = prev_ret;
            self.ci.inline_depth -= 1;
            self.ci.inline_var_base = prev_var_base;
            self.ci.inline_aclass_base = prev_aclass_base;
            self.ci.inline_defer_base = prev_defer_base;
            for var in self.ci.scope.vars.drain(var_base..) {
                var.remove(&mut self.ci.nodes);
            }
            for var in self.ci.scope.aclasses.drain(aclass_base..) {
                var.remove(&mut self.ci.nodes);
            }

            let (v, ctrl, mut scope, aclass) =
                mem::replace(&mut self.ci.inline_ret, prev_inline_ret)?;
            if is_inline
                && ctrl.get() != prev_ctrl
                && (!self.ci.nodes[ctrl.get()].kind.is_call()
                    || self.ci.nodes[ctrl.get()].inputs[0] != prev_ctrl)
            {
                self.error(body.pos(), "function is makred inline but it contains controlflow");
            }

            // this is here because we report error in the inline function file
            self.ci.file = prev_file;
            self.ci.parent = prev_parent;

            scope.vars.drain(var_base..).for_each(|v| v.remove(&mut self.ci.nodes));
            scope.aclasses.drain(aclass_base..).for_each(|v| v.remove(&mut self.ci.nodes));
            self.ci.nodes.unlock(v.id);
            self.ci.scope.clear(&mut self.ci.nodes);
            self.ci.scope = scope;

            if let Some(aclass) = aclass {
                let (_, reg) = self.ci.nodes.aclass_index(v.id);
                self.ci.nodes[reg].aclass = self.ci.scope.aclasses.len() as _;
                self.ci.scope.aclasses.push(aclass);
            }

            mem::replace(&mut self.ci.ctrl, ctrl).remove(&mut self.ci.nodes);

            Some(v)
        } else {
            self.make_func_reachable(fu);
            let mut inps = Vc::from([NEVER]);
            let mut clobbered_aliases = BitSet::default();

            if let Some(caller) = &mut caller
                && let (Some(Arg::Value(ty)), Some(carg)) = (tys.next(self.tys), cargs.next())
            {
                match (caller.ty.is_pointer(), ty.is_pointer()) {
                    (true, false) => {
                        caller.ty = self.tys.base_of(caller.ty).unwrap();
                        caller.ptr = true;
                    }
                    (false, true) => {
                        caller.ty = self.tys.make_ptr(caller.ty);
                        caller.ptr = false;
                    }
                    _ => {}
                }
                self.assert_ty(func.pos(), caller, ty, fa!("caller argument {}", carg.name));
                self.strip_ptr(caller);
                self.add_clobbers(*caller, &mut clobbered_aliases);
                self.ci.nodes.lock(caller.id);
                inps.push(caller.id);
            }

            while let (Some(ty), Some(arg)) = (tys.next(self.tys), args.next()) {
                let carg = cargs.next().unwrap();
                let Arg::Value(ty) = ty else { continue };

                let value = self.checked_expr(arg, ty, fa!("argument {}", carg.name))?;
                debug_assert_ne!(self.ci.nodes[value.id].kind, Kind::Stre);
                self.add_clobbers(value, &mut clobbered_aliases);

                self.ci.nodes.lock(value.id);
                inps.push(value.id);
            }

            for &n in inps.iter().skip(1) {
                self.ci.nodes.unlock(n);
            }

            self.append_clobbers(&mut inps, &mut clobbered_aliases);

            let alt_value = match sig.ret.loc(self.tys) {
                Loc::Reg => None,
                Loc::Stack => {
                    let stck = self.new_stack(func.pos(), sig.ret);
                    clobbered_aliases.set(self.ci.nodes.aclass_index(stck).0 as _);
                    inps.push(stck);
                    Some(Value::ptr(stck).ty(sig.ret))
                }
            };

            inps[0] = self.ci.ctrl.get();
            self.ci.ctrl.set(
                self.ci.nodes.new_node_nop(
                    sig.ret,
                    Kind::Call { func: fu, args: sig.args, unreachable: sig.ret == ty::Id::NEVER },
                    inps,
                ),
                &mut self.ci.nodes,
            );

            self.add_clobber_stores(clobbered_aliases);

            if sig.ret == ty::Id::NEVER {
                self.ci.nodes.bind(self.ci.ctrl.get(), NEVER);
                self.ci.ctrl.set(NEVER, &mut self.ci.nodes);
                return None;
            }

            Some(alt_value.unwrap_or_else(|| {
                let ret = self.ci.nodes.new_node_nop(sig.ret, Kind::RetVal, [self.ci.ctrl.get()]);
                Value::new(ret).ty(sig.ret)
            }))
        }
    }

    fn gen_global(&mut self, global: ty::Global) -> Option<Value> {
        let gl = &self.tys.ins.globals[global];
        let value = self.ci.nodes.new_node_nop(gl.ty, Kind::Global { global }, [VOID]);
        self.ci.nodes[value].aclass = GLOBAL_ACLASS as _;
        Some(Value::ptr(value).ty(gl.ty))
    }

    fn gen_const(&mut self, cnst: ty::Const, ctx: Ctx) -> Option<Value> {
        let c = &self.tys.ins.consts[cnst];
        let prev_file = mem::replace(&mut self.ci.file, c.file);
        let prev_parent = mem::replace(&mut self.ci.parent, c.parent);
        let f = &self.files[c.file];
        let value = match c.ast.get(f) {
            &Expr::BinOp { left, op: TokenKind::Decl, right, .. }
            | &Expr::BinOp {
                left, op: TokenKind::Colon, right: &Expr::BinOp { right, .. }, ..
            } => left
                .find_pattern_path(c.name, right, |expr, is_ct| {
                    debug_assert!(is_ct);
                    self.ptr_expr_ctx(expr, ctx)
                })
                .unwrap_or_else(|_| unreachable!()),
            v => self.ptr_expr_ctx(v, ctx),
        }?;

        self.ci.file = prev_file;
        self.ci.parent = prev_parent;
        Some(value)
    }

    fn add_clobbers(&mut self, value: Value, clobbered_aliases: &mut BitSet) {
        if let Some(base) = self.tys.base_of(value.ty) {
            clobbered_aliases.set(self.ci.nodes.aclass_index(value.id).0 as _);
            if base.has_pointers(self.tys) {
                clobbered_aliases.set(DEFAULT_ACLASS as _);
            }
        } else if value.ty.has_pointers(self.tys) {
            clobbered_aliases.set(DEFAULT_ACLASS as _);
        }
    }

    fn append_clobbers(&mut self, inps: &mut Vc, clobbered_aliases: &mut BitSet) {
        clobbered_aliases.set(GLOBAL_ACLASS as _);
        for clobbered in clobbered_aliases.iter() {
            let aclass = &mut self.ci.scope.aclasses[clobbered];
            self.ci.nodes.load_loop_aclass(clobbered, aclass, &mut self.ci.loops);
            inps.push(aclass.last_store.get());
        }
    }

    fn add_clobber_stores(&mut self, clobbered_aliases: BitSet) {
        for clobbered in clobbered_aliases.iter() {
            debug_assert_matches!(self.ci.nodes[self.ci.ctrl.get()].kind, Kind::Call { .. });
            self.ci.scope.aclasses[clobbered].clobber.set(self.ci.ctrl.get(), &mut self.ci.nodes);
        }
        self.ci.nodes[self.ci.ctrl.get()].clobbers = clobbered_aliases;
    }

    fn struct_op(
        &mut self,
        pos: Pos,
        op: TokenKind,
        s: ty::Struct,
        dst: Nid,
        lhs: Nid,
        rhs: Nid,
    ) -> bool {
        let mut offs = OffsetIter::new(s, self.tys);
        while let Some((ty, off)) = offs.next_ty(self.tys) {
            let lhs = self.offset(lhs, off);
            let rhs = self.offset(rhs, off);
            let dst = self.offset(dst, off);
            match ty.expand() {
                _ if ty.is_pointer() || ty.is_integer() || ty == ty::Id::BOOL => {
                    let lhs = self.load_mem(lhs, ty);
                    let rhs = self.load_mem(rhs, ty);
                    let res =
                        self.ci.nodes.new_node(ty, Kind::BinOp { op }, [VOID, lhs, rhs], self.tys);
                    self.store_mem(dst, ty, res);
                }
                ty::Kind::Struct(is) => {
                    if !self.struct_op(pos, op, is, dst, lhs, rhs) {
                        self.error(
                            pos,
                            fa!("... when appliing '{0} {op} {0}'", self.ty_display(s.into())),
                        );
                    }
                }
                _ => {
                    _ = self.error(pos, fa!("'{0} {op} {0}' is not supported", self.ty_display(ty)))
                }
            }
        }

        true
    }

    fn struct_fold_op(
        &mut self,
        pos: Pos,
        op: TokenKind,
        fold_op: TokenKind,
        s: ty::Struct,
        lhs: Nid,
        rhs: Nid,
    ) -> Option<Value> {
        debug_assert!(op.is_compatison());

        let mut fold = None;
        let mut offs = OffsetIter::new(s, self.tys);
        while let Some((ty, off)) = offs.next_ty(self.tys) {
            let lhs = self.offset(lhs, off);
            let rhs = self.offset(rhs, off);
            let vl = match ty.expand() {
                _ if ty.is_pointer() || ty.is_integer() || ty == ty::Id::BOOL => {
                    let lhs = self.load_mem(lhs, ty);
                    let rhs = self.load_mem(rhs, ty);
                    self.ci.nodes.new_node(
                        ty::Id::BOOL,
                        Kind::BinOp { op },
                        [VOID, lhs, rhs],
                        self.tys,
                    )
                }
                ty::Kind::Struct(is) => match self.struct_fold_op(pos, op, fold_op, is, lhs, rhs) {
                    Some(v) => v.id,
                    None => {
                        self.error(
                            pos,
                            fa!("...when appliing '{0} {op} {0}'", self.ty_display(s.into())),
                        );
                        return None;
                    }
                },
                _ => {
                    self.error(pos, fa!("'{0} {op} {0}' is not supported", self.ty_display(ty)));
                    return None;
                }
            };

            fold = Some(match fold {
                None => vl,
                Some(o) => self.ci.nodes.new_node(
                    ty::Id::BOOL,
                    Kind::BinOp { op: fold_op },
                    [VOID, o, vl],
                    self.tys,
                ),
            });
        }

        match op {
            _ if let Some(fold) = fold => Some(Value::new(fold).ty(ty::Id::BOOL)),
            TokenKind::Eq => Some(self.ci.nodes.new_const_lit(ty::Id::BOOL, true)),
            _ => Some(self.ci.nodes.new_const_lit(ty::Id::BOOL, false)),
        }
    }

    fn compute_signature(&mut self, func: ty::Id, pos: Pos, args: &[Expr]) -> Option<ty::Func> {
        let template = match func.expand() {
            ty::Kind::Func(f) => return Some(f),
            ty::Kind::Template(t) => t,
            ty::Kind::NEVER => return None,
            _ => {
                self.error(pos, fa!("compiler cant (yet) call '{}'", self.ty_display(func)));
                return None;
            }
        };

        let TemplateData { file, expr, parent, name, is_inline, .. } =
            self.tys.ins.templates[template];
        let fast = &self.files[file];
        let &Expr::Closure { pos, args: cargs, ret, .. } = expr.get(fast) else {
            unreachable!();
        };

        let arg_base = self.tys.tmp.args.len();

        let base = self.ci.scope.vars.len();
        for (arg, carg) in args.iter().zip(cargs) {
            let ty = self.ty_in(file, parent, &carg.ty);

            self.tys.tmp.args.push(ty);
            let sym = parser::find_symbol(&fast.symbols, carg.id);
            if ty == ty::Id::ANY_TYPE {
                let ty = self.infer_type(arg);
                *self.tys.tmp.args.last_mut().unwrap() = ty;
                self.ci.scope.vars.push(Variable::new(
                    carg.id,
                    ty,
                    false,
                    NEVER,
                    &mut self.ci.nodes,
                ));
            } else if sym.flags & idfl::COMPTIME == 0 {
                self.ci.scope.vars.push(Variable::new(
                    carg.id,
                    ty,
                    false,
                    NEVER,
                    &mut self.ci.nodes,
                ));
            } else {
                if ty != ty::Id::TYPE {
                    self.error(
                        arg.pos(),
                        fa!(
                            "arbitrary comptime types are not supported yet \
                            (expected '{}' got '{}')",
                            self.ty_display(ty::Id::TYPE),
                            self.ty_display(ty)
                        ),
                    );
                    return None;
                }
                let ty = self.ty(arg);
                self.tys.tmp.args.push(ty);
                self.ci.scope.vars.push(Variable::new(
                    carg.id,
                    ty::Id::TYPE,
                    false,
                    self.ci.nodes.new_const(ty::Id::TYPE, ty),
                    &mut self.ci.nodes,
                ));
            }
        }

        let Some(args) = self.tys.pack_args(arg_base) else {
            self.error(pos, "function instance has too many arguments");
            return None;
        };
        let ret = self.ty_in(file, parent, ret);

        self.ci.scope.vars.drain(base..).for_each(|v| v.remove(&mut self.ci.nodes));

        let sym = SymKey::Type(parent, pos, args);
        let ct = |ins: &mut TypeIns| {
            ins.funcs
                .push(FuncData {
                    file,
                    parent,
                    name,
                    pos,
                    expr,
                    sig: Sig { args, ret },
                    is_inline,
                    is_generic: true,
                    comp_state: Default::default(),
                })
                .into()
        };
        let ty::Kind::Func(f) = self.tys.syms.get_or_insert(sym, &mut self.tys.ins, ct).expand()
        else {
            unreachable!()
        };
        Some(f)
    }

    fn assign_pattern(&mut self, pat: &Expr, mut right: Value) {
        match *pat {
            Expr::Ident { id, pos, .. } => {
                if parser::find_symbol(&self.file().symbols, id).flags & idfl::REFERENCED != 0
                    && !right.ptr
                {
                    self.spill(pos, &mut right);
                }
                self.ci.scope.vars.push(Variable::new(
                    id,
                    right.ty,
                    right.ptr,
                    right.id,
                    &mut self.ci.nodes,
                ));
            }
            Expr::Ctor { pos, fields, .. } => {
                let ty::Kind::Struct(idx) = right.ty.expand() else {
                    self.error(pos, "can't use struct destruct on non struct value (TODO: shold work with modules)");
                    return;
                };

                for &CtorField { pos, name, ref value } in fields {
                    let Some((offset, ty)) = OffsetIter::offset_of(self.tys, idx, name) else {
                        self.error(pos, format_args!("field not found: {name:?}"));
                        continue;
                    };
                    let off = self.offset(right.id, offset);
                    self.assign_pattern(value, Value::ptr(off).ty(ty));
                }
            }
            ref pat => self.error_unhandled_ast(pat, "pattern"),
        }
    }

    fn ptr_expr_ctx(&mut self, expr: &Expr, ctx: Ctx) -> Option<Value> {
        let mut n = self.raw_expr_ctx(expr, ctx)?;
        if mem::take(&mut n.var) {
            let id = (u16::MAX - n.id) as usize;
            n.ptr = self.ci.scope.vars[id].ptr;
            n.id = self.ci.scope.vars[id].value();
        }
        Some(n)
    }

    fn expr_ctx(&mut self, expr: &Expr, ctx: Ctx) -> Option<Value> {
        let mut n = self.ptr_expr_ctx(expr, ctx)?;
        self.strip_ptr(&mut n);
        Some(n)
    }

    fn ptr_expr(&mut self, expr: &Expr) -> Option<Value> {
        self.ptr_expr_ctx(expr, Default::default())
    }

    fn expr(&mut self, expr: &Expr) -> Option<Value> {
        self.expr_ctx(expr, Default::default())
    }

    fn strip_ptr(&mut self, target: &mut Value) {
        if mem::take(&mut target.ptr) {
            target.id = self.load_mem(target.id, target.ty);
        }
    }

    fn offset(&mut self, val: Nid, off: Offset) -> Nid {
        if off == 0 {
            return val;
        }

        let off = self.ci.nodes.new_const(ty::Id::INT, off);
        let aclass = self.ci.nodes.aclass_index(val).1;
        let inps = [VOID, val, off];
        let seted =
            self.ci.nodes.new_node(ty::Id::INT, Kind::BinOp { op: TokenKind::Add }, inps, self.tys);
        self.ci.nodes.pass_aclass(aclass, seted);
        seted
    }

    fn gen_defers(&mut self, base: usize) -> Option<()> {
        let defers = mem::take(&mut self.ci.defers);
        for &(_, defer) in defers.iter().skip(base).rev() {
            self.expr(defer.get(self.file()))?;
        }
        self.ci.defers = defers;
        Some(())
    }

    fn jump_to(&mut self, pos: Pos, id: usize) -> Option<Value> {
        let Some(loob) = self.ci.loops.last_mut() else {
            self.error(pos, "break outside a loop");
            return None;
        };

        match *loob {
            Loop::Comptime { state: Some((_, prev)), .. } => {
                self.error(
                    pos,
                    "reached multiple control flow keywords inside an unrolled loop, \
                    make sure control flow is not dependant on a runtime value",
                );
                self.error(prev, "previous reachable control flow found here");
            }
            Loop::Comptime { state: ref mut state @ None, defer_base } => {
                *state = Some(([CtLoopState::Continued, CtLoopState::Terminated][id], pos));
                self.gen_defers(defer_base)?;
            }
            Loop::Runtime { defer_base, .. } => {
                self.gen_defers(defer_base)?;

                let Loop::Runtime { ctrl: lctrl, ctrl_scope, scope, .. } =
                    self.ci.loops.last_mut().unwrap()
                else {
                    unreachable!()
                };

                if lctrl[id].is_live() {
                    lctrl[id].set(
                        self.ci.nodes.new_node(
                            ty::Id::VOID,
                            Kind::Region,
                            [self.ci.ctrl.get(), lctrl[id].get()],
                            self.tys,
                        ),
                        &mut self.ci.nodes,
                    );
                    let mut scope = mem::take(&mut ctrl_scope[id]);
                    let ctrl = mem::take(&mut lctrl[id]);

                    self.ci.nodes.merge_scopes(
                        &mut self.ci.loops,
                        &ctrl,
                        &mut scope,
                        &mut self.ci.scope,
                        self.tys,
                    );

                    let Loop::Runtime { ctrl: lctrl, ctrl_scope, .. } =
                        self.ci.loops.last_mut().unwrap()
                    else {
                        unreachable!()
                    };
                    ctrl_scope[id] = scope;
                    lctrl[id] = ctrl;
                    self.ci.ctrl.set(NEVER, &mut self.ci.nodes);
                } else {
                    let term = StrongRef::new(NEVER, &mut self.ci.nodes);
                    lctrl[id] = mem::replace(&mut self.ci.ctrl, term);
                    ctrl_scope[id] = self.ci.scope.dup(&mut self.ci.nodes);
                    ctrl_scope[id]
                        .vars
                        .drain(scope.vars.len()..)
                        .for_each(|v| v.remove(&mut self.ci.nodes));
                    ctrl_scope[id]
                        .aclasses
                        .drain(scope.aclasses.len()..)
                        .for_each(|v| v.remove(&mut self.ci.nodes));
                }
            }
        }

        None
    }

    fn complete_call_graph(&mut self) -> bool {
        let prev_err_len = self.errors.borrow().len();
        while self.ci.task_base < self.tys.tasks.len()
            && let Some(task_slot) = self.tys.tasks.pop()
        {
            let Some(task) = task_slot else { continue };
            self.emit_func(task);
        }
        self.errors.borrow().len() == prev_err_len
    }

    fn emit_func(&mut self, FTask { file, id, ct }: FTask) {
        let func = &mut self.tys.ins.funcs[id];
        debug_assert_eq!(func.file, file);
        let cct = self.ct.active();
        debug_assert_eq!(cct, ct);
        func.comp_state[cct as usize] = CompState::Compiled.into();
        let sig = func.sig;
        let ast = &self.files[file];
        let expr = func.expr.get(ast);

        self.pool.push_ci(file, func.parent, Some(sig.ret), 0, &mut self.ci);
        let prev_err_len = self.errors.borrow().len();

        log::info!("{}", self.ast_display(expr));

        let &Expr::Closure { body, args, pos, .. } = expr else {
            unreachable!("{}", self.ast_display(expr))
        };
        self.ci.pos.push(pos);

        let mut tys = sig.args.args();
        let mut argsi = args.iter();
        while let Some(aty) = tys.next(self.tys) {
            let arg = argsi.next().unwrap();
            match aty {
                Arg::Type(_) => {}
                Arg::Value(ty) => {
                    let mut deps = Vc::from([VOID]);
                    if ty.loc(self.tys) == Loc::Stack && self.tys.size_of(ty) <= 16 {
                        deps.push(MEM);
                    }
                    // TODO: whe we not using the deps?
                    let value = self.ci.nodes.new_node_nop(ty, Kind::Arg, deps);
                    let ptr = ty.loc(self.tys) == Loc::Stack;
                    self.ci.scope.vars.push(Variable::new(
                        arg.id,
                        ty,
                        ptr,
                        value,
                        &mut self.ci.nodes,
                    ));
                    if ty.loc(self.tys) == Loc::Stack {
                        self.ci.nodes[value].aclass = self.ci.scope.aclasses.len() as _;
                        self.ci.scope.aclasses.push(AClass::new(&mut self.ci.nodes));
                    }
                }
            }
        }

        let mut tys = sig.args.args();
        let mut args = args.iter();
        while let Some(aty) = tys.next(self.tys) {
            let arg = args.next().unwrap();
            match aty {
                Arg::Type(ty) => {
                    self.ci.scope.vars.push(Variable::new(
                        arg.id,
                        ty::Id::TYPE,
                        false,
                        self.ci.nodes.new_const(ty::Id::TYPE, ty),
                        &mut self.ci.nodes,
                    ));
                }
                Arg::Value(_) => {}
            }
        }

        if self.expr(body).is_some() {
            if sig.ret == ty::Id::VOID {
                self.expr(&Expr::Return { pos: body.pos(), val: None });
            } else {
                self.error(
                    body.pos(),
                    fa!(
                        "expected all paths in the fucntion to return \
                        or the return type to be 'void' (return type is '{}')",
                        self.ty_display(sig.ret),
                    ),
                );
            }
        }

        self.ci.scope.vars.drain(..).for_each(|v| v.remove_ignore_arg(&mut self.ci.nodes));

        if self.finalize(prev_err_len) {
            let backend = if !cct { &mut *self.backend } else { &mut *self.ct_backend };
            backend.emit_body(id, &self.ci.nodes, self.tys, self.files);
        }

        self.ci.pos.pop();
        self.pool.pop_ci(&mut self.ci);
    }

    fn finalize(&mut self, prev_err_len: usize) -> bool {
        use {AssertKind as AK, CondOptRes as CR};

        self.ci.finalize(&mut self.pool.scratch1, self.tys, self.files);

        //let mut to_remove = vec![];
        for (id, node) in self.ci.nodes.iter() {
            let Kind::Assert { kind, pos } = node.kind else { continue };

            let res = self.ci.nodes.try_match_cond(id);

            // TODO: highlight the pin position
            let msg = match (kind, res) {
                (AK::UnwrapCheck, CR::Known { value: false, .. }) => {
                    "unwrap is not needed since the value is (provably) never null, \
                    remove it, or replace with '@as(<expr_ty>, <opt_expr>)'"
                }
                (AK::UnwrapCheck, CR::Known { value: true, .. }) => {
                    "unwrap is incorrect since the value is (provably) always null, \
                    make sure your logic is correct"
                }
                (AK::NullCheck, CR::Known { value: true, .. }) => {
                    "the value is always null, some checks might need to be inverted"
                }
                (AK::NullCheck, CR::Unknown) => {
                    "can't prove the value is not 'null', \
                    use '@unwrap(<opt>)' if you believe compiler is stupid, \
                    or explicitly check for null and handle it \
                    ('if <opt> == null { /* handle */ } else { /* use opt */ }')"
                }
                _ => unreachable!(),
            };
            self.error(pos, msg);
        }

        for &node in self.ci.nodes[NEVER].inputs.iter() {
            if let Kind::Return { file } = self.ci.nodes[node].kind
                && let (_, stck) = self.ci.nodes.aclass_index(self.ci.nodes[node].inputs[1])
                && self.ci.nodes[stck].kind == Kind::Stck
            {
                let pfile = mem::replace(&mut self.ci.file, file);
                debug_assert!(self.ci.nodes[node].pos != 0);
                self.error(
                    self.ci.nodes[node].pos,
                    "returning value with local provenance \
                    (pointer will be invalid after function returns)",
                );
                self.error(
                    self.ci.nodes[stck].pos,
                    "...the pointer points to stack allocation created here",
                );
                self.ci.file = pfile;
            }
        }

        if self.errors.borrow().len() == prev_err_len {
            self.ci.nodes.check_final_integrity(self.ty_display(ty::Id::VOID));
            self.ci.nodes.graphviz(self.ty_display(ty::Id::VOID));
            self.ci.nodes.gcm(
                &mut self.pool.scratch1,
                &mut self.pool.scratch2,
                &mut self.pool.nid_set,
            );
            self.ci.nodes.check_loop_depth_integrity(self.ty_display(ty::Id::VOID));
            self.ci.nodes.basic_blocks();
            self.ci.nodes.graphviz(self.ty_display(ty::Id::VOID));
        } else {
            //self.ci.nodes.graphviz_in_browser(self.ty_display(ty::Id::VOID));
        }

        self.errors.borrow().len() == prev_err_len
    }

    fn ty(&mut self, expr: &Expr) -> ty::Id {
        self.ty_in(self.ci.file, self.ci.parent, expr)
    }

    fn ty_in(&mut self, file: Module, parent: ty::Id, expr: &Expr) -> ty::Id {
        self.parse_ty(TyScope { file, parent, alloc_const: true, ..Default::default() }, expr)
    }

    fn ty_display(&self, ty: ty::Id) -> ty::Display {
        ty::Display::new(self.tys, self.files, ty)
    }

    fn ast_display(&self, ast: &'a Expr<'a>) -> parser::Display<'a> {
        parser::Display::new(&self.file().file, ast)
    }

    #[must_use]
    #[track_caller]
    fn binop_ty(
        &mut self,
        pos: Pos,
        lhs: &mut Value,
        rhs: &mut Value,
        op: TokenKind,
    ) -> (ty::Id, Nid) {
        if let Some(upcasted) = lhs.ty.try_upcast_low(rhs.ty, true) {
            let to_correct = if lhs.ty != upcasted {
                Some((lhs, rhs))
            } else if rhs.ty != upcasted {
                Some((rhs, lhs))
            } else {
                None
            };

            if let Some((oper, other)) = to_correct {
                if self.tys.size_of(upcasted) > self.tys.size_of(oper.ty) {
                    self.extend(oper, upcasted);
                }
                if matches!(op, TokenKind::Add | TokenKind::Sub)
                    && let Some(elem) = self.tys.base_of(upcasted)
                {
                    let cnst = self.ci.nodes.new_const(ty::Id::INT, self.tys.size_of(elem));
                    oper.id = self.ci.nodes.new_node(
                        upcasted,
                        Kind::BinOp { op: TokenKind::Mul },
                        [VOID, oper.id, cnst],
                        self.tys,
                    );
                    return (upcasted, self.ci.nodes.aclass_index(other.id).1);
                }
            }

            (upcasted, VOID)
        } else {
            let ty = self.ty_display(lhs.ty);
            let expected = self.ty_display(rhs.ty);
            self.error(pos, fa!("'{ty} {op} {expected}' is not supported"));
            (ty::Id::NEVER, VOID)
        }
    }

    fn wrap_in_opt(&mut self, pos: Pos, val: &mut Value) {
        debug_assert!(!val.var);

        let oty = self.tys.make_opt(val.ty);

        if let Some((uninit, ..)) = self.tys.nieche_of(val.ty) {
            self.strip_ptr(val);
            val.ty = oty;
            assert!(!uninit, "TODO");
            return;
        }

        let OptLayout { flag_ty, flag_offset, payload_offset } = self.tys.opt_layout(val.ty);

        self.strip_ptr(val);
        match oty.loc(self.tys) {
            Loc::Reg => {
                // registers have inverted offsets so that accessing the inner type is a noop
                let flag_offset = self.tys.size_of(oty) * 8 - flag_offset * 8 - 1;
                let fill = self.ci.nodes.new_const(oty, 1i64 << flag_offset);
                val.id = self.ci.nodes.new_node(
                    oty,
                    Kind::BinOp { op: TokenKind::Bor },
                    [VOID, val.id, fill],
                    self.tys,
                );
                val.ty = oty;
            }
            Loc::Stack => {
                let stack = self.new_stack(pos, oty);
                let fill = self.ci.nodes.new_const(flag_ty, 1);
                self.store_mem(stack, flag_ty, fill);
                let off = self.offset(stack, payload_offset);
                self.store_mem(off, val.ty, val.id);
                val.id = stack;
                val.ptr = true;
                val.ty = oty;
            }
        }
    }

    fn implicit_unwrap(&mut self, pos: Pos, opt: &mut Value) {
        self.unwrap_low(pos, opt, AssertKind::NullCheck);
    }

    fn explicit_unwrap(&mut self, pos: Pos, opt: &mut Value) {
        self.unwrap_low(pos, opt, AssertKind::UnwrapCheck);
    }

    fn unwrap_low(&mut self, pos: Pos, opt: &mut Value, kind: AssertKind) {
        let Some(ty) = self.tys.inner_of(opt.ty) else { return };
        let null_check = self.gen_null_check(*opt, ty, TokenKind::Eq);

        let oty = mem::replace(&mut opt.ty, ty);
        self.unwrap_opt_unchecked(ty, oty, opt);

        // TODO: extract the if check int a fucntion
        let ass = self.ci.nodes.new_node_nop(oty, Kind::Assert { kind, pos }, [
            self.ci.ctrl.get(),
            null_check,
            opt.id,
        ]);
        self.ci.nodes.pass_aclass(self.ci.nodes.aclass_index(opt.id).1, ass);
        opt.id = ass;
    }

    fn unwrap_opt_unchecked(&mut self, ty: ty::Id, oty: ty::Id, opt: &mut Value) {
        if self.tys.nieche_of(ty).is_some() {
            return;
        }

        let OptLayout { payload_offset, .. } = self.tys.opt_layout(ty);

        match oty.loc(self.tys) {
            Loc::Reg => {}
            Loc::Stack => {
                opt.id = self.offset(opt.id, payload_offset);
            }
        }
    }

    fn gen_null_check(&mut self, mut cmped: Value, ty: ty::Id, op: TokenKind) -> Nid {
        let OptLayout { flag_ty, flag_offset, .. } = self.tys.opt_layout(ty);
        debug_assert!(cmped.ty.is_optional());

        match cmped.ty.loc(self.tys) {
            Loc::Reg => {
                self.strip_ptr(&mut cmped);
                let inps = [VOID, cmped.id, self.ci.nodes.new_const(cmped.ty, 0)];
                self.ci.nodes.new_node(ty::Id::BOOL, Kind::BinOp { op }, inps, self.tys)
            }
            Loc::Stack => {
                cmped.id = self.offset(cmped.id, flag_offset);
                cmped.ty = flag_ty;
                debug_assert!(cmped.ptr);
                self.strip_ptr(&mut cmped);
                let inps = [VOID, cmped.id, self.ci.nodes.new_const(flag_ty, 0)];
                self.ci.nodes.new_node(ty::Id::BOOL, Kind::BinOp { op }, inps, self.tys)
            }
        }
    }

    #[track_caller]
    fn assert_ty(
        &mut self,
        pos: Pos,
        src: &mut Value,
        expected: ty::Id,
        hint: impl fmt::Display,
    ) -> bool {
        if let Some(upcasted) = src.ty.try_upcast(expected)
            && upcasted == expected
        {
            if src.ty.is_never() {
                return true;
            }

            if src.ty != upcasted {
                if let Some(inner) = self.tys.inner_of(upcasted) {
                    if inner != src.ty {
                        self.assert_ty(pos, src, inner, hint);
                    }
                    self.wrap_in_opt(pos, src);
                } else {
                    debug_assert!(
                        src.ty.is_integer() || src.ty == ty::Id::BOOL,
                        "{} {}",
                        self.ty_display(src.ty),
                        self.ty_display(upcasted)
                    );
                    debug_assert!(
                        upcasted.is_integer() || src.ty == ty::Id::BOOL,
                        "{} {}",
                        self.ty_display(src.ty),
                        self.ty_display(upcasted)
                    );
                    self.extend(src, upcasted);
                }
            }
            true
        } else {
            if let Some(inner) = self.tys.inner_of(src.ty)
                && inner.try_upcast(expected) == Some(expected)
            {
                self.implicit_unwrap(pos, src);
                return self.assert_ty(pos, src, expected, hint);
            }

            let ty = self.ty_display(src.ty);

            let expected = self.ty_display(expected);
            self.error(pos, fa!("expected {hint} to be of type {expected}, got {ty}"));
            false
        }
    }

    fn extend(&mut self, value: &mut Value, to: ty::Id) {
        self.strip_ptr(value);
        let inps = [VOID, value.id];
        *value =
            self.ci.nodes.new_node_lit(to, Kind::UnOp { op: TokenKind::Number }, inps, self.tys);
        value.ty = to;
    }

    #[track_caller]
    fn warn(&self, pos: Pos, msg: impl core::fmt::Display) {
        let mut buf = self.warnings.borrow_mut();
        write!(buf, "(W) {}", self.file().report(pos, msg)).unwrap();
    }

    #[track_caller]
    fn error(&self, pos: Pos, msg: impl core::fmt::Display) -> Option<Value> {
        let mut buf = self.errors.borrow_mut();
        write!(buf, "{}", self.file().report(pos, msg)).unwrap();
        Value::NEVER
    }

    #[track_caller]
    fn error_unhandled_ast(&self, ast: &Expr, hint: impl Display) {
        log::info!("{ast:#?}");
        self.error(ast.pos(), fa!("compiler does not (yet) know how to handle ({hint})"));
    }

    fn file(&self) -> &'a parser::Ast {
        &self.files[self.ci.file]
    }

    fn eval_const(&mut self, file: Module, parent: ty::Id, expr: &Expr, ret: ty::Id) -> u64 {
        self.ct.activate();
        let prev = self.pool.push_ci(file, parent, Some(ret), self.tys.tasks.len(), &mut self.ci);

        prev.scope
            .vars
            .iter()
            .filter(|v| v.ty == ty::Id::TYPE)
            .map(|v| (prev.nodes.as_ty(v.value()), v.id))
            .map(|(v, id)| {
                Variable::new(
                    id,
                    ty::Id::TYPE,
                    false,
                    self.ci.nodes.new_const(ty::Id::TYPE, v),
                    &mut self.ci.nodes,
                )
            })
            .collect_into(&mut self.ci.scope.vars);

        let prev_err_len = self.errors.borrow().len();

        self.expr(&Expr::Return { pos: expr.pos(), val: Some(expr) });

        let res = if self.finalize(prev_err_len) {
            self.emit_and_eval(file, ret, &mut [])
        } else {
            i64::from(ty::Id::UNDECLARED) as _
        };

        self.pool.pop_ci(&mut self.ci);

        self.ct.deactivate();
        res
    }

    fn infer_type(&mut self, expr: &Expr) -> ty::Id {
        self.pool.save_ci(&self.ci);
        let ty = self.expr(expr).map_or(ty::Id::NEVER, |v| v.ty);
        self.pool.restore_ci(&mut self.ci);
        ty
    }

    fn on_reuse(&mut self, existing: ty::Id) {
        let state_slot = self.ct.active() as usize;
        if let ty::Kind::Func(id) = existing.expand()
            && let func = &mut self.tys.ins.funcs[id]
            && let CompState::Queued(idx) = func.comp_state[state_slot].into()
            && idx < self.tys.tasks.len()
        {
            func.comp_state[state_slot] = CompState::Queued(self.tys.tasks.len()).into();
            let task = self.tys.tasks[idx].take();
            self.tys.tasks.push(task);
        }
    }

    fn eval_global(&mut self, file: Module, parent: ty::Id, name: Ident, expr: &Expr) -> ty::Id {
        self.ct.activate();

        let gid = self.tys.ins.globals.push(GlobalData { file, name, ..Default::default() });

        self.pool.push_ci(file, parent, None, self.tys.tasks.len(), &mut self.ci);
        let prev_err_len = self.errors.borrow().len();

        self.expr(&(Expr::Return { pos: expr.pos(), val: Some(expr) }));

        let ret = self.ci.ret.expect("for return type to be infered");
        if self.finalize(prev_err_len) {
            let mut mem = vec![0u8; self.tys.size_of(ret) as usize];
            self.emit_and_eval(file, ret, &mut mem);
            self.tys.ins.globals[gid].data = mem;
        }

        self.pool.pop_ci(&mut self.ci);
        self.tys.ins.globals[gid].ty = ret;

        self.ct.deactivate();
        gid.into()
    }

    fn error_low(&self, file: Module, pos: Pos, msg: impl Display) -> ty::Id {
        let mut buf = self.errors.borrow_mut();
        write!(buf, "{}", self.files[file].report(pos, msg)).unwrap();
        ty::Id::NEVER
    }

    fn warn_low(&self, file: Module, pos: Pos, msg: impl Display) -> ty::Id {
        let mut buf = self.warnings.borrow_mut();
        write!(buf, "(W) {}", self.files[file].report(pos, msg)).unwrap();
        ty::Id::NEVER
    }

    fn find_local_ty(&mut self, ident: CapturedIdent) -> Option<ty::Id> {
        self.ci
            .scope
            .vars
            .iter()
            .rfind(|v| v.id == ident.id && (!ident.is_ct || v.ty == ty::Id::TYPE))
            .map(|v| if ident.is_ct { self.ci.nodes.as_ty(v.value()) } else { v.ty })
    }

    fn find_type_as_value(
        &mut self,
        pos: Pos,
        parent: impl Into<ty::Id>,
        id: impl Into<DeclId>,
        ctx: Ctx,
    ) -> Option<Value> {
        match self.find_type(pos, self.ci.file, parent, id).expand() {
            ty::Kind::NEVER => Value::NEVER,
            ty::Kind::Global(global) => self.gen_global(global),
            ty::Kind::Const(cnst) => self.gen_const(cnst, ctx),
            v => Some(self.ci.nodes.new_const_lit(ty::Id::TYPE, v.compress())),
        }
    }

    fn find_type(
        &mut self,
        pos: Pos,
        from_file: Module,
        parent: impl Into<ty::Id>,
        id: impl Into<DeclId>,
    ) -> ty::Id {
        self.find_type_low(pos, from_file, parent.into(), id.into())
    }

    fn find_type_low(&mut self, pos: Pos, from_file: Module, parent: ty::Id, id: DeclId) -> ty::Id {
        let file = match parent.expand() {
            ty::Kind::Module(m) => m,
            _ => self.tys.type_base_of(parent).unwrap().file,
        };

        let ty = if let DeclId::Ident(id) = id
            && let Some(ty) = self.find_local_ty(CapturedIdent { id, is_ct: true })
        {
            ty
        } else if let DeclId::Ident(id) = id
            && let Some(&ty) = self.tys.syms.get(SymKey::Decl(parent, id), &self.tys.ins)
        {
            self.on_reuse(ty);
            ty
        } else {
            let f = &self.files[file];

            let mut piter = parent;
            let Some((expr @ Expr::BinOp { left, right, .. }, name)) = (loop {
                if let Some(f) =
                    parser::find_decl(self.tys.scope_of(piter, f).expect("TODO"), &f.file, id)
                {
                    break Some(f);
                }

                if let Some((captures, capture_tuple)) = self.tys.captures_of(piter, f)
                    && let Some(idx) =
                        captures.iter().position(|&cid| cid.is_ct && DeclId::Ident(cid.id) == id)
                {
                    return self.tys.ins.args[capture_tuple.range().start + idx];
                }

                piter = match self.tys.parent_of(piter) {
                    Some(p) => p,
                    None => {
                        break None;
                    }
                };
            }) else {
                return match id {
                    DeclId::Ident(id) => {
                        debug_assert_eq!(from_file, file, "{}", f.ident_str(id));
                        self.error_low(file, pos, "somehow this was not found")
                    }
                    DeclId::Name("main") => self.error_low(
                        from_file,
                        pos,
                        format_args!(
                            "missing main function in '{}', compiler can't \
                            emmit libraries since such concept is not defined \
                            (minimal main function: `main := fn(): void {{}}`)",
                            f.path
                        ),
                    ),
                    DeclId::Name(name) => self.error_low(
                        from_file,
                        pos,
                        format_args!("undefined indentifier: {name}"),
                    ),
                };
            };

            let ty = if let Some(&ty) = self.tys.syms.get(SymKey::Decl(piter, name), &self.tys.ins)
            {
                ty
            } else {
                let ty = left
                    .find_pattern_path(name, right, |right, is_ct| {
                        if is_ct && !matches!(right, Expr::Closure { .. }) {
                            self.tys
                                .ins
                                .consts
                                .push(ConstData {
                                    ast: ExprRef::new(expr),
                                    name,
                                    file,
                                    parent: piter,
                                })
                                .into()
                        } else {
                            self.parse_ty(
                                TyScope {
                                    file,
                                    parent: piter,
                                    name: Some(name),
                                    alloc_const: true,
                                    is_ct,
                                },
                                right,
                            )
                        }
                    })
                    .unwrap_or_else(|_| unreachable!());
                self.tys.syms.insert(SymKey::Decl(piter, name), ty, &self.tys.ins);
                ty
            };

            if let Err(proper_case) = self.tys.case(ty, self.files)(f.ident_str(name)) {
                self.warn_low(
                    from_file,
                    pos,
                    format_args!(
                        "the declaration does not have conventional \
                        casing, expected '{proper_case}', \
                        because the declared type is '{}'",
                        self.ty_display(ty),
                    ),
                );
            }

            ty
        };

        if let ty::Kind::Global(g) = ty.expand() {
            let g = &self.tys.ins.globals[g];
            if g.ty == ty::Id::TYPE {
                return ty::Id::from(
                    u32::from_ne_bytes(g.data.as_slice().try_into().unwrap()) as u64
                );
            }
        }
        ty
    }

    /// returns none if comptime eval is required
    fn parse_ty(&mut self, sc: TyScope, expr: &Expr) -> ty::Id {
        match *expr {
            Expr::Slf { .. } => sc.parent,
            Expr::Mod { id, .. } => id.into(),
            Expr::UnOp { op: TokenKind::Xor, val, .. } => {
                let base = self.parse_ty(sc.anon(), val);
                self.tys.make_ptr(base)
            }
            Expr::UnOp { op: TokenKind::Que, val, .. } => {
                let base = self.parse_ty(sc.anon(), val);
                self.tys.make_opt(base)
            }
            Expr::Ident { id, .. } if let Ok(bt) = ty::Builtin::try_from(id) => bt.into(),
            Expr::Ident { id, pos, .. } => self.find_type(pos, sc.file, sc.parent, id),
            Expr::Field { target, pos, name }
                if let ty::Kind::Module(inside) = self.parse_ty(sc.anon(), target).expand() =>
            {
                self.find_type(pos, sc.file, inside, name)
            }
            Expr::Directive { name: "Any", args: [], .. } => ty::Id::ANY_TYPE,
            Expr::Directive { name: "TypeOf", args: [expr], .. } => self.infer_type(expr),
            Expr::Directive { name: "ChildOf", args: [aty], .. } => {
                let ty = self.parse_ty(sc.anon(), aty);
                let Some(ty) =
                    self.tys.base_of(ty).or(self.tys.inner_of(ty)).or(self.tys.elem_of(ty))
                else {
                    return self.error_low(
                        sc.file,
                        aty.pos(),
                        fa!("only work for pointers and optionals, not '{}'", self.ty_display(ty)),
                    );
                };
                ty
            }
            Expr::Slice { size: None, item, .. } => {
                let ty = self.parse_ty(sc.anon(), item);
                self.tys.make_array(ty, ArrayLen::MAX)
            }
            Expr::Slice { size: Some(&Expr::Number { value, .. }), item, .. } => {
                let ty = self.parse_ty(sc.anon(), item);
                self.tys.make_array(ty, value as _)
            }
            Expr::Slice { size, item, .. } => {
                let ty = self.parse_ty(sc.anon(), item);
                let len = size.map_or(ArrayLen::MAX, |expr| {
                    self.eval_const(sc.file, sc.parent, expr, ty::Id::U32) as _
                });
                self.tys.make_array(ty, len)
            }
            Expr::Struct { pos, fields, packed, captured, .. } => self.parse_base_ty(
                pos,
                expr,
                captured,
                fields,
                sc,
                |s| [&mut s.ins.struct_fields, &mut s.tmp.struct_fields],
                |s, field| {
                    let ty = s.parse_ty(sc.anon(), &field.ty);
                    StructField {
                        name: s.tys.names.intern(field.name),
                        ty,
                        default_value: field.default_value.as_ref().map(|expr| {
                            s.tys.ins.consts.push(ConstData {
                                ast: ExprRef::new(expr),
                                name: Default::default(),
                                file: sc.file,
                                parent: Default::default(),
                            })
                        }),
                    }
                },
                |s, base| {
                    let str = s.ins.structs.push(StructData {
                        base,
                        explicit_alignment: packed.then_some(1),
                        ..Default::default()
                    });

                    s.ins.struct_fields[s.struct_field_range(str)]
                        .iter()
                        .filter_map(|f| f.default_value)
                        .for_each(|c| s.ins.consts[c].parent = str.into());

                    str
                },
            ),
            Expr::Enum { pos, variants, captured, .. } => self.parse_base_ty(
                pos,
                expr,
                captured,
                variants,
                sc,
                |s| [&mut s.ins.enum_fields, &mut s.tmp.enum_fields],
                |s, field| EnumField { name: s.tys.names.intern(field.name) },
                |s, base| s.ins.enums.push(EnumData { base }),
            ),
            Expr::Union { pos, fields, captured, .. } => self.parse_base_ty(
                pos,
                expr,
                captured,
                fields,
                sc,
                |s| [&mut s.ins.union_fields, &mut s.tmp.union_fields],
                |s, field| {
                    let ty = s.parse_ty(sc.anon(), &field.ty);
                    UnionField { name: s.tys.names.intern(field.name), ty }
                },
                |s, base| s.ins.unions.push(UnionData { base, ..Default::default() }),
            ),
            Expr::Closure { pos, args, ret, .. } if let Some(name) = sc.name => {
                let sig = 'b: {
                    let arg_base = self.tys.tmp.args.len();
                    for arg in args {
                        let sym = parser::find_symbol(&self.files[sc.file].symbols, arg.id);
                        if sym.flags & idfl::COMPTIME != 0 {
                            self.tys.tmp.args.truncate(arg_base);
                            break 'b None;
                        }
                        let ty = self.parse_ty(sc.anon(), &arg.ty);
                        if ty == ty::Id::ANY_TYPE {
                            break 'b None;
                        }
                        self.tys.tmp.args.push(ty);
                    }

                    let Some(args) = self.tys.pack_args(arg_base) else {
                        return self.error_low(sc.file, pos, "function has too many argumnets");
                    };
                    let ret = self.parse_ty(sc.anon(), ret);

                    Some(Sig { args, ret })
                };
                //let returns_type = matches!(ret, &Expr::Ident { id, .. } if );

                match sig {
                    Some(sig) => {
                        let func = FuncData {
                            file: sc.file,
                            parent: sc.parent,
                            name,
                            pos,
                            sig,
                            expr: ExprRef::new(expr),
                            is_inline: sc.is_ct,
                            is_generic: false,
                            comp_state: Default::default(),
                        };
                        self.tys.ins.funcs.push(func).into()
                    }
                    None => {
                        let template = TemplateData {
                            file: sc.file,
                            parent: sc.parent,
                            name,
                            expr: ExprRef::new(expr),
                            is_inline: sc.is_ct,
                        };
                        self.tys.ins.templates.push(template).into()
                    }
                }
            }
            _ if sc.alloc_const
                && let Some(name) = sc.name =>
            {
                self.eval_global(sc.file, sc.parent, name, expr)
            }
            _ if sc.alloc_const => {
                let prev_file = mem::replace(&mut self.ci.file, sc.file);
                let prev_parent = mem::replace(&mut self.ci.parent, sc.parent);
                let id = self.expr(expr).unwrap().id;
                self.ci.file = prev_file;
                self.ci.parent = prev_parent;

                self.ci.nodes.as_ty(id)
            }
            ref e => {
                self.error_unhandled_ast(e, "bruh");
                ty::Id::NEVER
            }
        }
    }

    #[expect(clippy::too_many_arguments)]
    fn parse_base_ty<A, F, T: Into<ty::Id>>(
        &mut self,
        pos: Pos,
        expr: &Expr,
        captured: &[CapturedIdent],
        fields: FieldList<A>,
        sc: TyScope,
        get_fields: impl Fn(&mut Types) -> [&mut Vec<F>; 2],
        check_field: impl Fn(&mut Self, &A) -> F,
        check: impl Fn(&mut Types, TypeBase) -> T,
    ) -> ty::Id {
        let captures_start = self.tys.tmp.args.len();
        for &cp in captured {
            let ty = self.find_local_ty(cp).expect("TODO");
            self.tys.tmp.args.push(ty);
        }
        let captured = self.tys.pack_args(captures_start).expect("TODO");

        let sym = SymKey::Type(sc.parent, pos, captured);
        if let Some(&ty) = self.tys.syms.get(sym, &self.tys.ins) {
            return ty;
        }

        let prev_tmp = get_fields(self.tys)[1].len();
        for field in
            fields.iter().filter_map(CommentOr::or).map(Result::as_ref).filter_map(Result::ok)
        {
            let field = check_field(self, field);
            get_fields(self.tys)[1].push(field);
        }

        let base = TypeBase {
            file: sc.file,
            parent: sc.parent,
            pos,
            captured,
            name: sc.name.unwrap_or_default(),
            field_start: get_fields(self.tys)[0].len() as _,
            ast: ExprRef::new(expr),
        };

        let [ins, tmp] = get_fields(self.tys);
        ins.extend(tmp.drain(prev_tmp..));

        let ty = check(self.tys, base).into();

        self.tys.syms.insert(sym, ty, &self.tys.ins);

        ty
    }

    fn create_string_global(&mut self, data: &[u8]) -> (Nid, ty::Id) {
        let ty = self.tys.make_ptr(ty::Id::U8);
        let global = self
            .tys
            .strings
            .get_or_insert(data, &mut self.tys.ins.globals, |globals| {
                StringRef(globals.push(GlobalData {
                    data: data.to_vec(),
                    ty,
                    ..Default::default()
                }))
            })
            .0;
        let global = self.ci.nodes.new_node_nop(ty, Kind::Global { global }, [VOID]);
        self.ci.nodes[global].aclass = GLOBAL_ACLASS as _;
        (global, ty)
    }
}

#[derive(Clone, Copy, Default)]
struct TyScope {
    file: Module,
    parent: ty::Id,
    name: Option<Ident>,
    alloc_const: bool,
    is_ct: bool,
}

impl TyScope {
    fn anon(self) -> Self {
        Self { name: None, is_ct: false, ..self }
    }
}

#[cfg(test)]
mod tests {
    use {
        crate::{
            backend::hbvm::{self, HbvmBackend},
            son::CodegenCtx,
            ty,
        },
        alloc::{string::String, vec::Vec},
        core::fmt::Write,
    };

    fn generate(ident: &'static str, input: &'static str, output: &mut String) {
        _ = log::set_logger(&crate::fs::Logger);
        log::set_max_level(log::LevelFilter::Info);
        //log::set_max_level(log::LevelFilter::Trace);

        let mut ctx = CodegenCtx::default();
        let (ref files, embeds) = crate::test_parse_files(ident, input, &mut ctx.parser);
        let mut backend = HbvmBackend::default();
        let mut codegen = super::Codegen::new(&mut backend, files, &mut ctx);
        codegen.push_embeds(embeds);

        codegen.generate(ty::Module::MAIN);

        {
            let errors = codegen.errors.borrow();
            if !errors.is_empty() {
                output.push_str(&errors);
                return;
            }
        }

        let mut out = Vec::new();
        codegen.assemble(&mut out);

        let err = codegen.disasm(output, &out);
        if let Err(e) = err {
            writeln!(output, "!!! asm is invalid: {e}").unwrap();
        } else {
            log::info!("================ running {ident} ==============");
            log::trace!("{output}");
            hbvm::test_run_vm(&out, output);
        }
    }

    crate::run_tests! { generate:
        // Tour Examples
        main_fn;
        arithmetic;
        floating_point_arithmetic;
        functions;
        comments;
        if_statements;
        variables;
        hex_octal_binary_literals;
        loops;
        pointers;
        structs;
        tuples;
        struct_scopes;
        enums;
        unions;
        nullable_types;
        struct_operators;
        global_variables;
        constants;
        directives;
        c_strings;
        struct_patterns;
        arrays;
        inline;
        idk;
        generic_functions;
        die;
        defer;
        unrolled_loops;

        // Incomplete Examples;
        //comptime_pointers;
        generic_types;
        fb_driver;

        // Purely Testing Examples;
        proper_ident_propagation;
        method_receiver_by_value;
        comparing_floating_points;
        pointer_comparison;
        different_function_destinations;
        triggering_store_in_divergent_branch;
        wrong_dead_code_elimination;
        memory_swap;
        very_nested_loops;
        generic_type_mishap;
        storing_into_nullable_struct;
        scheduling_block_did_dirty;
        null_check_returning_small_global;
        null_check_in_the_loop;
        stack_provenance;
        advanced_floating_point_arithmetic;
        nullable_structure;
        needless_unwrap;
        inlining_issues;
        null_check_test;
        only_break_loop;
        reading_idk;
        nonexistent_ident_import;
        big_array_crash;
        returning_global_struct;
        small_struct_bitcast;
        small_struct_assignment;
        intcast_store;
        string_flip;
        signed_to_unsigned_upcast;
        wide_ret;
        comptime_min_reg_leak;
        different_types;
        struct_return_from_module_function;
        sort_something_viredly;
        struct_in_register;
        comptime_function_from_another_file;
        inline_test;
        inlined_generic_functions;
        some_generic_code;
        integer_inference_issues;
        writing_into_string;
        request_page;
        tests_ptr_to_ptr_copy;
        global_variable_wiredness;
        inline_return_stack;

        // Just Testing Optimizations;
        elide_stack_offsets_for_parameters_correctly;
        const_folding_with_arg;
        branch_assignments;
        exhaustive_loop_testing;
        pointer_opts;
        conditional_stores;
        loop_stores;
        dead_code_in_loop;
        infinite_loop_after_peephole;
        aliasing_overoptimization;
        global_aliasing_overptimization;
        overwrite_aliasing_overoptimization;
        more_if_opts;
        optional_from_eca;
        returning_optional_issues;
    }
}