deferring all null checks after the peepholes

f.txt

@@ -1,47 +0,0 @@
-start: 0
-  46-c65535:    +:       [0, 38, 45]    [47]
-  45-c65535:    &:       [0, 43, 44]    [46]
-  44-c65535: cint: #255  [0]            [45]
-  43-c65535: load:       [0, 42, 23]    [45]
-  42-c65535:    +:       [0, 22, 18]    [43]
-  39-c65535: stre:       [0, 0, 36, 37] [47]
-  39-c65535: stre:       [0, 0, 36, 37] [47]
-  37-c65535: stre:       [0, 35, 36, 3] [38, 39]
-  36-c65535: stck:       [0, 3]         [37, 38, 39]
-  35-c65535: load:       [0, 24, 34]    [37]
-  34-c65535: stre:       [0, 31, 33, 30] [35, 47]
-  33-c65535:    +:       [0, 24, 32]    [34]
-  32-c65535: cint: #16   [0]            [33]
-  31-c65535: cint: #4    [0]            [34]
-  30-c65535: stre:       [0, 27, 29, 26] [34]
-  29-c65535:    +:       [0, 24, 28]    [30]
-  28-c65535: cint: #8    [0]            [29]
-  27-c65535: cint: #2    [0]            [30]
-  26-c65535: stre:       [0, 25, 24, 3] [30]
-  25-c65535: cint: #1    [0]            [26]
-  24-c65535: stck:       [0, 3]         [26, 29, 33, 35]
-  23-c65535: stre:       [0, 21, 22, 3] [43, 47]
-  22-c65535: stck:       [0, 3]         [23, 42]
-  21-c65535: load:       [0, 6, 20]     [23]
-  20-c65535: stre:       [0, 17, 19, 14] [21, 47]
-  19-c65535:    +:       [0, 6, 18]     [20]
-  18-c65535: cint: #3    [0]            [19, 42]
-  17-c65535: cint: #1    [0]            [20]
-  14-c65535: stre:       [0, 5, 13, 11] [20]
-  13-c65535:    +:       [0, 6, 12]     [14]
-  12-c65535: cint: #2    [0]            [13]
-  11-c65535: stre:       [0, 7, 10, 8]  [14]
-  10-c65535:    +:       [0, 6, 9]      [11]
-   9-c65535: cint: #1    [0]            [10]
-   8-c65535: stre:       [0, 7, 6, 3]   [11]
-   7-c65535: cint: #0    [0]            [8, 11]
-   6-c65535: stck:       [0, 3]         [8, 10, 13, 19, 21]
-   5-c65535: cint: #511  [0]            [14]
-   4-c65535:  loops:       [0]            []
-   3-c65535:  mem:       [0]            [6, 8, 22, 23, 24, 26, 36, 37, 47]
-   2-c65535: ctrl: entry [0]            [38]
-b2: 0 0 [38]
-  38-c65535: call: 1 0   [2, 36, 37]    [46, 47]
-  47-c65535:  ret:       [38, 46, 3, 20, 23, 34, 39] [1]
-
-

f1.txt

@@ -1,38 +0,0 @@
-
-start: 0
-  34-c65535: stre:       [0, 31, 51, 30] [39, 47, 38]
-  51-c65535:    +:       [0, 36, 32]    [34]
-  32-c65535: cint: #16   [0]            [51]
-  31-c65535: cint: #4    [0]            [34]
-  30-c65535: stre:       [0, 27, 50, 26] [34]
-  50-c65535:    +:       [0, 36, 28]    [30]
-  28-c65535: cint: #8    [0]            [50]
-  27-c65535: cint: #2    [0]            [30]
-  26-c65535: stre:       [0, 25, 36, 3] [30]
-  25-c65535: cint: #1    [0]            [26, 46]
-  39-c65535: stre:       [0, 0, 36, 34] [47]
-  36-c65535: stck:       [0, 3]         [51, 38, 39, 26, 50]
-  22-c65535: stck:       [0, 3]         [49, 42, 8, 48]
-  39-c65535: stre:       [0, 0, 36, 34] [47]
-  20-c65535: stre:       [0, 17, 42, 14] [47, 47]
-  46-c65535:    +:       [0, 38, 25]    [47]
-  18-c65535: cint: #3    [0]            [42]
-  17-c65535: cint: #1    [0]            [20]
-  14-c65535: stre:       [0, 5, 49, 11] [20]
-  49-c65535:    +:       [0, 22, 12]    [14]
-  12-c65535: cint: #2    [0]            [49]
-  11-c65535: stre:       [0, 7, 48, 8]  [14]
-  48-c65535:    +:       [0, 22, 9]     [11]
-   9-c65535: cint: #1    [0]            [48]
-   8-c65535: stre:       [0, 7, 22, 3]  [11]
-   7-c65535: cint: #0    [0]            [8, 11]
-  42-c65535:    +:       [0, 22, 18]    [20]
-   5-c65535: cint: #511  [0]            [14]
-   4-c65535:  loops:       [0]            []
-   3-c65535:  mem:       [0]            [47, 8, 22, 26, 36]
-   2-c65535: ctrl: entry [0]            [38]
-b2: 0 0 [38]
-  38-c65535: call: 1 0   [2, 36, 34]    [46, 47]
-  47-c65535:  ret:       [38, 46, 3, 20, 20, 34, 39] [1]
-
-

f2.txt

@@ -1,39 +0,0 @@
-start: 0
-  42-c65535:    +:       [0, 22, 18]    [43, 20]
-  36-c65535: stck:       [0, 3]         [51, 38, 39, 26, 50]
-  39-c65535: stre:       [0, 0, 36, 34] [47]
-  34-c65535: stre:       [0, 31, 51, 30] [39, 47, 38]
-  51-c65535:    +:       [0, 36, 32]    [34]
-  32-c65535: cint: #16   [0]            [51]
-  31-c65535: cint: #4    [0]            [34]
-  30-c65535: stre:       [0, 27, 50, 26] [34]
-  50-c65535:    +:       [0, 36, 28]    [30]
-  28-c65535: cint: #8    [0]            [50]
-  27-c65535: cint: #2    [0]            [30]
-  26-c65535: stre:       [0, 25, 36, 3] [30]
-  25-c65535: cint: #1    [0]            [26]
-  39-c65535: stre:       [0, 0, 36, 34] [47]
-  45-c65535:    &:       [0, 43, 44]    [46]
-  22-c65535: stck:       [0, 3]         [49, 42, 8, 48]
-  44-c65535: cint: #255  [0]            [45]
-  20-c65535: stre:       [0, 17, 42, 14] [47, 47, 43]
-  46-c65535:    +:       [0, 38, 45]    [47]
-  18-c65535: cint: #3    [0]            [42]
-  17-c65535: cint: #1    [0]            [20]
-  14-c65535: stre:       [0, 5, 49, 11] [20]
-  49-c65535:    +:       [0, 22, 12]    [14]
-  12-c65535: cint: #2    [0]            [49]
-  11-c65535: stre:       [0, 7, 48, 8]  [14]
-  48-c65535:    +:       [0, 22, 9]     [11]
-   9-c65535: cint: #1    [0]            [48]
-   8-c65535: stre:       [0, 7, 22, 3]  [11]
-   7-c65535: cint: #0    [0]            [8, 11]
-  43-c65535: load:       [0, 42, 20]    [45]
-   5-c65535: cint: #511  [0]            [14]
-   4-c65535:  loops:       [0]            []
-   3-c65535:  mem:       [0]            [47, 8, 22, 26, 36]
-   2-c65535: ctrl: entry [0]            [38]
-b2: 0 0 [38]
-  38-c65535: call: 1 0   [2, 36, 34]    [46, 47]
-  47-c65535:  ret:       [38, 46, 3, 20, 20, 34, 39] [1]
-

lang/README.md

@@ -1044,6 +1044,28 @@ main := fn(): uint {
 
 ### Just Testing Optimizations
 
+#### null_check_test
+```hb
+get_ptr := fn(): ?^uint {
+	value := 0
+	return &value
+}
+
+main := fn(): uint {
+	ptr := get_ptr()
+
+	if ptr == null {
+		return 0
+	}
+
+	loop if *ptr != 10 {
+		*ptr += 1
+	} else break
+
+	return *ptr
+}
+```
+
 #### const_folding_with_arg
 ```hb
 main := fn(arg: uint): uint {

lang/src/son.rs

@@ -879,6 +879,46 @@ impl Nodes {
                     return Some(self.new_const(ty, op.apply_unop(value, is_float)));
                 }
             }
+            K::Assert { kind, pos } => {
+                if self[target].ty == ty::Id::VOID {
+                    let &[ctrl, cond] = self[target].inputs.as_slice() else { unreachable!() };
+                    if let K::CInt { value } = self[cond].kind {
+                        let ty = if value != 0 {
+                            ty::Id::NEVER
+                        } else {
+                            return Some(ctrl);
+                        };
+                        return Some(self.new_node_nop(ty, K::Assert { kind, pos }, [ctrl, cond]));
+                    }
+
+                    'b: {
+                        let mut cursor = ctrl;
+                        loop {
+                            if cursor == ENTRY {
+                                break 'b;
+                            }
+
+                            // TODO: do more inteligent checks on the condition
+                            if self[cursor].kind == Kind::Else
+                                && self[self[cursor].inputs[0]].inputs[1] == cond
+                            {
+                                return Some(ctrl);
+                            }
+                            if self[cursor].kind == Kind::Then
+                                && self[self[cursor].inputs[0]].inputs[1] == cond
+                            {
+                                return Some(self.new_node_nop(
+                                    ty::Id::NEVER,
+                                    K::Assert { kind, pos },
+                                    [ctrl, cond],
+                                ));
+                            }
+
+                            cursor = self.idom(cursor);
+                        }
+                    }
+                }
+            }
             K::If => {
                 if self[target].ty == ty::Id::VOID {
                     let &[ctrl, cond] = self[target].inputs.as_slice() else { unreachable!() };
@@ -1295,7 +1335,7 @@ impl Nodes {
             write!(out, "  {node:>2}-c{:>2}: ", self[node].ralloc_backref)?;
         }
         match self[node].kind {
-            Kind::Start => unreachable!(),
+            Kind::Assert { .. } | Kind::Start => unreachable!(),
             Kind::End => return Ok(()),
             Kind::If => write!(out, "  if:      "),
             Kind::Region | Kind::Loop => writeln!(out, "      goto: {node}"),
@@ -1561,6 +1601,11 @@ impl ops::IndexMut<Nid> for Nodes {
     }
 }
 
+#[derive(Clone, Copy, Debug, PartialEq, Eq, Hash, PartialOrd, Ord)]
+pub enum AssertKind {
+    NullCheck,
+}
+
 #[derive(Clone, Copy, Debug, PartialEq, Eq, Hash, PartialOrd, Ord, Default)]
 #[repr(u8)]
 pub enum Kind {
@@ -1586,6 +1631,11 @@ pub enum Kind {
     Return,
     // [ctrl]
     Die,
+    // [ctrl, cond]
+    Assert {
+        kind: AssertKind,
+        pos: Pos,
+    },
     // [ctrl]
     CInt {
         value: i64,
@@ -1634,6 +1684,7 @@ impl Kind {
                 | Self::Then
                 | Self::Else
                 | Self::Call { .. }
+                | Self::Assert { .. }
                 | Self::If
                 | Self::Region
                 | Self::Loop
@@ -3981,9 +4032,7 @@ impl<'a> Codegen<'a> {
 
         self.ci.scope.vars.drain(..).for_each(|v| v.remove_ignore_arg(&mut self.ci.nodes));
 
-        self.ci.finalize(&mut self.pool.nid_stack, self.tys, self.files);
+        if self.finalize(prev_err_len) {
-
-        if self.errors.borrow().len() == prev_err_len {
             self.ci.emit_body(self.tys, self.files, sig, self.pool);
             self.tys.ins.funcs[id as usize].code.append(&mut self.ci.code);
             self.tys.ins.funcs[id as usize].relocs.append(&mut self.ci.relocs);
@@ -3992,6 +4041,32 @@ impl<'a> Codegen<'a> {
         self.pool.pop_ci(&mut self.ci);
     }
 
+    fn finalize(&mut self, prev_err_len: usize) -> bool {
+        self.ci.finalize(&mut self.pool.nid_stack, self.tys, self.files);
+        for (_, node) in self.ci.nodes.iter() {
+            if let Kind::Assert { kind: AssertKind::NullCheck, pos } = node.kind {
+                match node.ty {
+                    ty::Id::NEVER => {
+                        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', \
+                            use '@unwrap(<opt>)' if you believe compiler is stupid, \
+                            or explicitly check for null and handle it \
+                            ('if <opt> == null { /* handle */ } else { /* use opt */ }')",
+                        );
+                    }
+                }
+            }
+        }
+        self.errors.borrow().len() == prev_err_len
+    }
+
     fn ty(&mut self, expr: &Expr) -> ty::Id {
         self.parse_ty(self.ci.file, expr, None, self.files)
     }
@@ -4096,27 +4171,16 @@ impl<'a> Codegen<'a> {
         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]);
+        self.ci.ctrl.set(
-        let ctrl_ty = self.ci.nodes[ctrl].ty;
+            self.ci.nodes.new_node(
-        self.ci.nodes.remove(ctrl);
+                ty::Id::VOID,
+                Kind::Assert { kind: AssertKind::NullCheck, pos },
+                [self.ci.ctrl.get(), null_check],
+            ),
+            &mut self.ci.nodes,
+        );
         let oty = mem::replace(&mut opt.ty, ty);
-        match ctrl_ty {
+        self.unwrap_opt_unchecked(ty, oty, opt);
-            ty::Id::LEFT_UNREACHABLE => {
-                self.unwrap_opt_unchecked(ty, oty, opt);
-            }
-            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', \
-                    use '@unwrap(<opt>)' if you believe compiler is stupid, \
-                    or explicitly check for null and handle it \
-                    ('if <opt> == null { /* handle */ } else { /* use opt */ }')",
-                );
-            }
-        }
     }
 
     fn unwrap_opt_unchecked(&mut self, ty: ty::Id, oty: ty::Id, opt: &mut Value) {
@@ -4247,13 +4311,9 @@ impl TypeParser for Codegen<'_> {
         self.expr(&Expr::Return { pos: expr.pos(), val: Some(expr) });
 
         scope = mem::take(&mut self.ci.scope.vars);
-        self.ci.finalize(&mut self.pool.nid_stack, self.tys, self.files);
 
-        let res = if self.errors.borrow().len() == prev_err_len {
+        let res =
-            self.emit_and_eval(file, ret, &mut [])
+            if self.finalize(prev_err_len) { self.emit_and_eval(file, ret, &mut []) } else { 1 };
-        } else {
-            1
-        };
 
         self.pool.pop_ci(&mut self.ci);
         self.ci.scope.vars = scope;
@@ -4291,10 +4351,8 @@ impl TypeParser for Codegen<'_> {
 
         self.expr(&(Expr::Return { pos: expr.pos(), val: Some(expr) }));
 
-        self.ci.finalize(&mut self.pool.nid_stack, self.tys, self.files);
-
         let ret = self.ci.ret.expect("for return type to be infered");
-        if self.errors.borrow().len() == prev_err_len {
+        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 as usize].data = mem;
@@ -4388,6 +4446,7 @@ mod tests {
         fb_driver;
 
         // Purely Testing Examples;
+        null_check_test;
         only_break_loop;
         reading_idk;
         nonexistent_ident_import;

lang/src/son/hbvm.rs

@@ -493,6 +493,7 @@ impl ItemCtx {
                         }
                     }
                     Kind::Start
+                    | Kind::Assert { .. }
                     | Kind::Entry
                     | Kind::Mem
                     | Kind::End
@@ -1021,6 +1022,7 @@ impl<'a> Function<'a> {
                 let ops = vec![self.drg(nid)];
                 self.add_instr(nid, ops);
             }
+            Kind::Assert { .. } => unreachable!(),
             Kind::End |
             Kind::Phi | Kind::Arg | Kind::Mem | Kind::Loops  => {}
             Kind::Load { .. } if node.ty.loc(self.tys) == Loc::Stack => {

lang/tests/son_tests_null_check_test.txt

@@ -0,0 +1,26 @@
+get_ptr:
+    ADDI64 r254, r254, -8d
+    ADDI64 r1, r254, 0d
+    ADDI64 r254, r254, 8d
+    JALA r0, r31, 0a
+main:
+    ADDI64 r254, r254, -8d
+    ST r31, r254, 0a, 8h
+    JAL r31, r0, :get_ptr
+    LI64 r3, 0d
+    JNE r1, r3, :0
+    LI64 r1, 0d
+    JMP :1
+ 0: LI64 r10, 10d
+    CP r2, r1
+ 2: LD r1, r2, 0a, 8h
+    JEQ r1, r10, :1
+    ADDI64 r3, r1, 1d
+    ST r3, r2, 0a, 8h
+    JMP :2
+ 1: LD r31, r254, 0a, 8h
+    ADDI64 r254, r254, 8d
+    JALA r0, r31, 0a
+code size: 208
+ret: 10
+status: Ok(())