adding optional values

lang/README.md

@@ -135,9 +135,6 @@ fib := fn(n: uint): uint {
 #### pointers
 ```hb
 main := fn(): uint {
-	n := @as(^uint, null)
-	if n != null return 9001
-
 	a := 1
 	b := &a
 
@@ -176,7 +173,12 @@ main := fn(): int {
 
 	if c != null return 42
 
-	return 0
+	d := @as(?u16, null)
+	if decide() d = 0
+
+	if d == null return 69
+
+	return d
 }
 
 decide := fn(): bool return true

lang/src/lib.rs

@@ -454,6 +454,7 @@ mod ty {
                 _ if oa == Self::from(NEVER) => ob,
                 _ if ob == Self::from(NEVER) => oa,
                 _ if oa == ob => oa,
+                _ if ob.is_optional() => ob,
                 _ if oa.is_pointer() && ob.is_pointer() => return None,
                 _ if a.is_signed() && b.is_signed() || a.is_unsigned() && b.is_unsigned() => ob,
                 _ if a.is_unsigned() && b.is_signed() && a.repr() - U8 < b.repr() - I8 => ob,
@@ -646,12 +647,12 @@ mod ty {
         pub enum Kind {
             Builtin,
             Struct,
-            Opt,
             Ptr,
+            Slice,
+            Opt,
             Func,
             Global,
             Module,
-            Slice,
         }
     }
 
@@ -1295,6 +1296,14 @@ impl Types {
                 self.ins.structs[stru as usize].size.set(oiter.offset);
                 oiter.offset
             }
+            ty::Kind::Opt(opt) => {
+                let base = self.ins.opts[opt as usize].base;
+                if self.nieche_of(base).is_some() {
+                    self.size_of(base)
+                } else {
+                    self.size_of(base) + self.align_of(base)
+                }
+            }
             _ if let Some(size) = ty.simple_size() => size,
             ty => unimplemented!("size_of: {:?}", ty),
         }
@@ -1344,10 +1353,27 @@ impl Types {
         }
     }
 
-    fn opt_flag_field(&self, ty: ty::Id) -> (Offset, ty::Id) {
+    fn opt_layout(&self, inner_ty: ty::Id) -> OptLayout {
+        match self.nieche_of(inner_ty) {
+            Some((_, flag_offset, flag_ty)) => {
+                OptLayout { flag_ty, flag_offset, payload_offset: 0 }
+            }
+            None => OptLayout {
+                flag_ty: ty::Id::BOOL,
+                flag_offset: 0,
+                payload_offset: self.align_of(inner_ty),
+            },
+        }
+    }
+
+    fn nieche_of(&self, ty: ty::Id) -> Option<(bool, Offset, ty::Id)> {
         match ty.expand() {
-            ty::Kind::Ptr(_) => (0, ty::Id::UINT),
+            ty::Kind::Ptr(_) => Some((false, 0, ty::Id::UINT)),
-            _ => todo!("{ty:?}"),
+            // TODO: cache this
+            ty::Kind::Struct(s) => OffsetIter::new(s, self).into_iter(self).find_map(|(f, off)| {
+                self.nieche_of(f.ty).map(|(uninit, o, ty)| (uninit, o + off, ty))
+            }),
+            _ => None,
         }
     }
 
@@ -1379,6 +1405,12 @@ impl Types {
     }
 }
 
+struct OptLayout {
+    flag_ty: ty::Id,
+    flag_offset: Offset,
+    payload_offset: Offset,
+}
+
 struct OffsetIter {
     strct: ty::Struct,
     offset: Offset,

lang/src/son.rs

@@ -12,8 +12,8 @@ use {
         task,
         ty::{self, Arg, ArrayLen, Loc, Tuple},
         utils::{BitSet, Vc},
-        FTask, Func, Global, Ident, Offset, OffsetIter, Reloc, Sig, StringRef, SymKey, TypeParser,
+        FTask, Func, Global, Ident, Offset, OffsetIter, OptLayout, Reloc, Sig, StringRef, SymKey,
-        TypedReloc, Types,
+        TypeParser, TypedReloc, Types,
     },
     alloc::{string::String, vec::Vec},
     core::{
@@ -2320,9 +2320,9 @@ impl<'a> Codegen<'a> {
                 match oty.loc(self.tys) {
                     Loc::Reg => Some(self.ci.nodes.new_const_lit(oty, 0)),
                     Loc::Stack => {
-                        let (off, flag_ty) = self.tys.opt_flag_field(ty);
+                        let OptLayout { flag_ty, flag_offset, .. } = self.tys.opt_layout(ty);
                         let stack = self.new_stack(oty);
-                        let offset = self.offset(stack, off);
+                        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))
@@ -2347,14 +2347,24 @@ impl<'a> Codegen<'a> {
                 }
             }
             Expr::Bool { value, .. } => Some(self.ci.nodes.new_const_lit(ty::Id::BOOL, value)),
-            Expr::Number { value, .. } => Some(self.ci.nodes.new_const_lit(
+            Expr::Number { value, .. } => Some(
-                ctx.ty.filter(|ty| ty.is_integer()).unwrap_or(ty::Id::DEFAULT_INT),
+                self.ci.nodes.new_const_lit(
+                    ctx.ty
+                        .map(|ty| self.tys.inner_of(ty).unwrap_or(ty))
+                        .filter(|ty| ty.is_integer())
+                        .unwrap_or(ty::Id::DEFAULT_INT),
                     value,
-            )),
+                ),
-            Expr::Float { value, .. } => Some(self.ci.nodes.new_const_lit(
+            ),
-                ctx.ty.filter(|ty| ty.is_float()).unwrap_or(ty::Id::F32),
+            Expr::Float { value, .. } => Some(
+                self.ci.nodes.new_const_lit(
+                    ctx.ty
+                        .map(|ty| self.tys.inner_of(ty).unwrap_or(ty))
+                        .filter(|ty| ty.is_float())
+                        .unwrap_or(ty::Id::F32),
                     value as i64,
-            )),
+                ),
+            ),
             Expr::Ident { id, .. }
                 if let Some(index) = self.ci.scope.vars.iter().rposition(|v| v.id == id) =>
             {
@@ -2534,6 +2544,8 @@ impl<'a> Codegen<'a> {
                 let ctx = Ctx { ty: ctx.ty.map(|ty| self.tys.make_ptr(ty)) };
                 let mut val = self.expr_ctx(val, ctx)?;
 
+                self.unwrap_opt(pos, &mut val);
+
                 let Some(base) = self.tys.base_of(val.ty) else {
                     self.report(
                         pos,
@@ -2596,6 +2608,25 @@ impl<'a> Codegen<'a> {
 
                 Some(Value::VOID)
             }
+            Expr::BinOp { left: &Expr::Null { pos }, .. } => {
+                self.report(pos, "'null' must always be no the right side of an expression");
+                Value::NEVER
+            }
+            Expr::BinOp {
+                left,
+                op: op @ (TokenKind::Eq | TokenKind::Ne),
+                right: Expr::Null { .. },
+                ..
+            } => {
+                let mut cmped = self.raw_expr(left)?;
+                self.strip_var(&mut cmped);
+
+                let Some(ty) = self.tys.inner_of(cmped.ty) else {
+                    return Some(self.ci.nodes.new_const_lit(ty::Id::BOOL, 1));
+                };
+
+                Some(Value::new(self.gen_null_check(cmped, ty, op)).ty(ty::BOOL))
+            }
             Expr::BinOp { left, pos, op, right }
                 if !matches!(op, TokenKind::Assign | TokenKind::Decl) =>
             {
@@ -2685,17 +2716,27 @@ impl<'a> Codegen<'a> {
             }
             Expr::Directive { name: "sizeof", args: [ty], .. } => {
                 let ty = self.ty(ty);
-                Some(self.ci.nodes.new_const_lit(
+                Some(
-                    ctx.ty.filter(|ty| ty.is_integer()).unwrap_or(ty::Id::DEFAULT_INT),
+                    self.ci.nodes.new_const_lit(
+                        ctx.ty
+                            .map(|ty| self.tys.inner_of(ty).unwrap_or(ty))
+                            .filter(|ty| ty.is_integer())
+                            .unwrap_or(ty::Id::DEFAULT_INT),
                         self.tys.size_of(ty),
-                ))
+                    ),
+                )
             }
             Expr::Directive { name: "alignof", args: [ty], .. } => {
                 let ty = self.ty(ty);
-                Some(self.ci.nodes.new_const_lit(
+                Some(
-                    ctx.ty.filter(|ty| ty.is_integer()).unwrap_or(ty::Id::DEFAULT_INT),
+                    self.ci.nodes.new_const_lit(
+                        ctx.ty
+                            .map(|ty| self.tys.inner_of(ty).unwrap_or(ty))
+                            .filter(|ty| ty.is_integer())
+                            .unwrap_or(ty::Id::DEFAULT_INT),
                         self.tys.align_of(ty),
-                ))
+                    ),
+                )
             }
             Expr::Directive { name: "bitcast", args: [val], pos } => {
                 let mut val = self.raw_expr(val)?;
@@ -3929,6 +3970,103 @@ impl<'a> Codegen<'a> {
         }
     }
 
+    fn wrap_in_opt(&mut self, 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);
+
+        match oty.loc(self.tys) {
+            Loc::Reg => {
+                self.strip_ptr(val);
+                // registers have inverted offsets so that accessing the inner type is a noop
+                let flag_offset = self.tys.size_of(oty) - flag_offset - 1;
+                let fill = self.ci.nodes.new_const(oty, 1i64 << (flag_offset * 8 - 1));
+                val.id = self
+                    .ci
+                    .nodes
+                    .new_node(oty, Kind::BinOp { op: TokenKind::Bor }, [VOID, val.id, fill]);
+                val.ty = oty;
+            }
+            Loc::Stack if val.ty.loc(self.tys) == Loc::Reg => {
+                self.strip_ptr(val);
+                let stack = self.new_stack(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;
+            }
+            _ => todo!(),
+        }
+    }
+
+    fn unwrap_opt(&mut self, pos: Pos, opt: &mut Value) {
+        let Some(ty) = self.tys.inner_of(opt.ty) else { return };
+        let null_check = self.gen_null_check(*opt, ty, TokenKind::Eq);
+
+        // TODO: extract the if check int a fucntion
+        let ctrl = self.ci.nodes.new_node(ty::Id::VOID, Kind::If, [self.ci.ctrl.get(), null_check]);
+        let ctrl_ty = self.ci.nodes[ctrl].ty;
+        self.ci.nodes.remove(ctrl);
+        let oty = mem::replace(&mut opt.ty, ty);
+        match ctrl_ty {
+            ty::Id::LEFT_UNREACHABLE => {
+                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);
+                    }
+                }
+            }
+            ty::Id::RIGHT_UNREACHABLE => {
+                self.report(pos, "the value is always null, some checks might need to be inverted");
+            }
+            _ => {
+                self.report(
+                    pos,
+                    "can't prove the value is not 'null', \
+                    there is not nice syntax for bypassing this, sorry",
+                );
+            }
+        }
+    }
+
+    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);
+
+        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)
+            }
+            Loc::Stack => {
+                cmped.id = self.offset(cmped.id, flag_offset);
+                cmped.ty = flag_ty;
+                self.strip_ptr(&mut cmped);
+                let inps = [VOID, cmped.id, self.ci.nodes.new_const(ty, 0)];
+                self.ci.nodes.new_node(ty::Id::BOOL, Kind::BinOp { op }, inps)
+            }
+        }
+    }
+
     #[track_caller]
     fn assert_ty(
         &mut self,
@@ -3940,7 +4078,17 @@ impl<'a> Codegen<'a> {
         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(src);
+                } else {
                     debug_assert!(
                         src.ty.is_integer() || src.ty == ty::Id::NEVER,
                         "{} {}",
@@ -3955,9 +4103,18 @@ impl<'a> Codegen<'a> {
                     );
                     self.extend(src, upcasted);
                 }
+            }
             true
         } else {
+            if let Some(inner) = self.tys.inner_of(src.ty)
+                && inner.try_upcast(expected) == Some(expected)
+            {
+                self.unwrap_opt(pos, src);
+                return self.assert_ty(pos, src, expected, hint);
+            }
+
             let ty = self.ty_display(src.ty);
+
             let expected = self.ty_display(expected);
             self.report(pos, fa!("expected {hint} to be of type {expected}, got {ty}"));
             false
@@ -3966,10 +4123,10 @@ impl<'a> Codegen<'a> {
 
     fn extend(&mut self, value: &mut Value, to: ty::Id) {
         self.strip_ptr(value);
-        value.ty = to;
         let mask = self.ci.nodes.new_const(to, (1i64 << (self.tys.size_of(value.ty) * 8)) - 1);
         let inps = [VOID, value.id, mask];
         *value = self.ci.nodes.new_node_lit(to, Kind::BinOp { op: TokenKind::Band }, inps);
+        value.ty = to;
     }
 
     #[track_caller]

lang/src/son/hbvm.rs

@@ -226,17 +226,20 @@ impl ItemCtx {
                 let node = &fuc.nodes[nid];
 
                 let mut extend = |base: ty::Id, dest: ty::Id, from: usize, to: usize| {
-                    if base.simple_size() == dest.simple_size() {
+                    let (bsize, dsize) = (tys.size_of(base), tys.size_of(dest));
+                    debug_assert!(bsize <= 8);
+                    debug_assert!(dsize <= 8);
+                    if bsize == dsize {
                         return Default::default();
                     }
                     match (base.is_signed(), dest.is_signed()) {
                         (true, true) => {
                             let op = [instrs::sxt8, instrs::sxt16, instrs::sxt32]
-                                [base.simple_size().unwrap().ilog2() as usize];
+                                [bsize.ilog2() as usize];
                             op(atr(allocs[to]), atr(allocs[from]))
                         }
                         _ => {
-                            let mask = (1u64 << (base.simple_size().unwrap() * 8)) - 1;
+                            let mask = (1u64 << (bsize * 8)) - 1;
                             instrs::andi(atr(allocs[to]), atr(allocs[from]), mask)
                         }
                     }

lang/tests/son_tests_nullable_types.txt

@@ -0,0 +1,51 @@
+decide:
+    LI8 r1, 1b
+    JALA r0, r31, 0a
+main:
+    ADDI64 r254, r254, -40d
+    ST r31, r254, 24a, 16h
+    JAL r31, r0, :decide
+    LI64 r3, 0d
+    ANDI r1, r1, 255d
+    JNE r1, r0, :0
+    CP r32, r3
+    JMP :1
+ 0: ADDI64 r32, r254, 16d
+ 1: JNE r32, r3, :2
+    LI64 r1, 9001d
+    JMP :3
+ 2: JAL r31, r0, :decide
+    ANDI r1, r1, 255d
+    JNE r1, r0, :4
+    LI8 r6, 1b
+    ST r6, r254, 0a, 1h
+    LD r7, r32, 0a, 8h
+    ST r7, r254, 8a, 8h
+    JMP :5
+ 4: LI8 r1, 0b
+    ST r1, r254, 0a, 1h
+ 5: LI64 r6, 0d
+    LD r7, r254, 0a, 1h
+    ANDI r7, r7, 255d
+    JEQ r7, r6, :6
+    LI64 r1, 42d
+    JMP :3
+ 6: JAL r31, r0, :decide
+    LI32 r2, 0w
+    ANDI r1, r1, 255d
+    JNE r1, r0, :7
+    CP r8, r2
+    JMP :8
+ 7: LI32 r8, 8388608w
+ 8: ANDI r8, r8, 4294967295d
+    ANDI r2, r2, 4294967295d
+    JNE r8, r2, :9
+    LI64 r1, 69d
+    JMP :3
+ 9: ANDI r1, r8, 65535d
+ 3: LD r31, r254, 24a, 16h
+    ADDI64 r254, r254, 40d
+    JALA r0, r31, 0a
+code size: 389
+ret: 0
+status: Ok(())