fixing overoptimization of load -> store

lang/README.md

@@ -544,10 +544,23 @@ main := fn(): int {
 ```hb
 Color := struct {r: u8, g: u8, b: u8, a: u8}
 white := Color.(255, 255, 255, 255)
-u32_to_color := fn(v: u32): Color return @bitcast(v)
+u32_to_color := fn(v: u32): Color return @as(Color, @bitcast(u32_to_u32(@bitcast(v))))
 u32_to_u32 := fn(v: u32): u32 return v
 main := fn(): int {
-	return u32_to_color(@bitcast(white)).r + @as(Color, @bitcast(u32_to_u32(@bitcast(white)))).g
+	return u32_to_color(@bitcast(white)).r
+}
+```
+
+#### small_struct_assignment
+```hb
+
+Color := struct {r: u8, g: u8, b: u8, a: u8}
+white := Color.(255, 255, 255, 255)
+black := Color.(0, 0, 0, 0)
+main := fn(): int {
+	f := black
+	f = white
+	return f.a
 }
 ```
 

lang/src/son.rs

@@ -39,16 +39,6 @@ type Nid = u16;
 
 type Lookup = crate::ctx_map::CtxMap<Nid>;
 
-trait StoreId: Sized {
-    fn to_store(self) -> Option<Self>;
-}
-
-impl StoreId for Nid {
-    fn to_store(self) -> Option<Self> {
-        (self != MEM).then_some(self)
-    }
-}
-
 impl crate::ctx_map::CtxEntry for Nid {
     type Ctx = [Result<Node, (Nid, debug::Trace)>];
     type Key<'a> = (Kind, &'a [Nid], ty::Id);
@@ -457,6 +447,7 @@ impl Nodes {
             K::Stre => {
                 if self[target].inputs[2] != VOID
                     && self[target].inputs.len() == 4
+                    && self[self[target].inputs[1]].kind != Kind::Load
                     && self[self[target].inputs[3]].kind == Kind::Stre
                     && self[self[target].inputs[3]].lock_rc == 0
                     && self[self[target].inputs[3]].inputs[2] == self[target].inputs[2]
@@ -872,7 +863,7 @@ impl Nodes {
     #[allow(dead_code)]
     fn eliminate_stack_temporaries(&mut self) {
         'o: for stack in self[MEM].outputs.clone() {
-            if self[stack].kind != Kind::Stck {
+            if self.values[stack as usize].is_err() || self[stack].kind != Kind::Stck {
                 continue;
             }
             let mut full_read_into = None;
@@ -1032,7 +1023,7 @@ pub enum Kind {
 
 impl Kind {
     fn is_pinned(&self) -> bool {
-        self.is_cfg() || matches!(self, Self::Phi | Self::Mem | Self::Arg)
+        self.is_cfg() || matches!(self, Self::Phi | Self::Arg | Self::Mem)
     }
 
     fn is_cfg(&self) -> bool {
@@ -1629,7 +1620,7 @@ impl ItemCtx {
                 if !matches!(self.nodes[stck].kind, Kind::Stck | Kind::Arg) {
                     debug_assert_matches!(
                         self.nodes[stck].kind,
-                        Kind::Phi | Kind::Return | Kind::Load
+                        Kind::Phi | Kind::Return | Kind::Load | Kind::Call { .. } | Kind::Stre
                     );
                     continue;
                 }
@@ -2045,11 +2036,8 @@ impl<'a> Codegen<'a> {
         );
         debug_assert!(self.ci.nodes[region].kind != Kind::Stre);
 
-        let mut vc = Vc::from([VOID, value, region]);
         self.ci.nodes.load_loop_store(&mut self.ci.scope.store, &mut self.ci.loops);
-        if let Some(str) = self.ci.scope.store.value().to_store() {
-            vc.push(str);
-        }
+        let mut vc = Vc::from([VOID, value, region, self.ci.scope.store.value()]);
         for load in self.ci.scope.loads.drain(..) {
             if load == value {
                 self.ci.nodes.unlock(load);
@@ -2080,11 +2068,8 @@ impl<'a> Codegen<'a> {
             self.ty_display(self.ci.nodes[region].ty)
         );
         debug_assert!(self.ci.nodes[region].kind != Kind::Stre);
-        let mut vc = Vc::from([VOID, region]);
         self.ci.nodes.load_loop_store(&mut self.ci.scope.store, &mut self.ci.loops);
-        if let Some(str) = self.ci.scope.store.value().to_store() {
-            vc.push(str);
-        }
+        let vc = [VOID, region, self.ci.scope.store.value()];
         let load = self.ci.nodes.new_node(ty, Kind::Load, vc);
         self.ci.nodes.lock(load);
         self.ci.scope.loads.push(load);
@@ -2206,9 +2191,7 @@ impl<'a> Codegen<'a> {
                     debug_assert_ne!(self.ci.ctrl, VOID);
                     let mut inps = Vc::from([self.ci.ctrl, value.id]);
                     self.ci.nodes.load_loop_store(&mut self.ci.scope.store, &mut self.ci.loops);
-                    if let Some(str) = self.ci.scope.store.value().to_store() {
-                        inps.push(str);
-                    }
+                    inps.push(self.ci.scope.store.value());
 
                     self.ci.ctrl = self.ci.nodes.new_node(ty::Id::VOID, Kind::Return, inps);
 
@@ -2570,9 +2553,7 @@ impl<'a> Codegen<'a> {
                     self.ci.nodes.unlock(n);
                 }
 
-                if let Some(str) = self.ci.scope.store.value().to_store() {
-                    inps.push(str);
-                }
+                inps.push(self.ci.scope.store.value());
                 self.ci.scope.loads.retain(|&load| {
                     if inps.contains(&load) {
                         return true;
@@ -2658,9 +2639,7 @@ impl<'a> Codegen<'a> {
                 }
 
                 if has_ptr_arg {
-                    if let Some(str) = self.ci.scope.store.value().to_store() {
-                        inps.push(str);
-                    }
+                    inps.push(self.ci.scope.store.value());
                     self.ci.scope.loads.retain(|&load| {
                         if inps.contains(&load) {
                             return true;
@@ -4243,7 +4222,7 @@ fn push_up(nodes: &mut Nodes) {
             return;
         }
 
-        for i in 0..nodes[node].inputs.len() {
+        for i in 1..nodes[node].inputs.len() {
             let inp = nodes[node].inputs[i];
             if !nodes[inp].kind.is_pinned() {
                 push_up_impl(inp, nodes);
@@ -4298,6 +4277,20 @@ fn push_up(nodes: &mut Nodes) {
             }
         }
     }
+
+    debug_assert_eq!(
+        nodes
+            .iter()
+            .map(|(n, _)| n)
+            .filter(|&n| !nodes.visited.get(n) && !matches!(nodes[n].kind, Kind::Arg | Kind::Mem))
+            .collect::<Vec<_>>(),
+        vec![],
+        "{:?}",
+        nodes
+            .iter()
+            .filter(|&(n, nod)| !nodes.visited.get(n) && !matches!(nod.kind, Kind::Arg | Kind::Mem))
+            .collect::<Vec<_>>()
+    );
 }
 
 fn push_down(nodes: &mut Nodes, node: Nid) {
@@ -4312,6 +4305,7 @@ fn push_down(nodes: &mut Nodes, node: Nid) {
     }
 
     fn better(nodes: &mut Nodes, is: Nid, then: Nid) -> bool {
+        debug_assert_ne!(idepth(nodes, is), idepth(nodes, then), "{is} {then}");
         loop_depth(is, nodes) < loop_depth(then, nodes)
             || idepth(nodes, is) > idepth(nodes, then)
             || nodes[then].kind == Kind::If
@@ -4321,6 +4315,12 @@ fn push_down(nodes: &mut Nodes, node: Nid) {
         return;
     }
 
+    for usage in nodes[node].outputs.clone() {
+        if is_forward_edge(usage, node, nodes) && nodes[node].kind == Kind::Stre {
+            push_down(nodes, usage);
+        }
+    }
+
     for usage in nodes[node].outputs.clone() {
         if is_forward_edge(usage, node, nodes) {
             push_down(nodes, usage);
@@ -4342,14 +4342,11 @@ fn push_down(nodes: &mut Nodes, node: Nid) {
     debug_assert!(nodes.dominates(nodes[node].inputs[0], min));
 
     let mut cursor = min;
-    loop {
+    while cursor != nodes[node].inputs[0] {
+        cursor = idom(nodes, cursor);
         if better(nodes, cursor, min) {
             min = cursor;
         }
-        if cursor == nodes[node].inputs[0] {
-            break;
-        }
-        cursor = idom(nodes, cursor);
     }
 
     if nodes[min].kind.ends_basic_block() {
@@ -4468,6 +4465,7 @@ mod tests {
         // Purely Testing Examples;
         returning_global_struct;
         small_struct_bitcast;
+        small_struct_assignment;
         wide_ret;
         comptime_min_reg_leak;
         different_types;

lang/src/vc.rs

@@ -287,7 +287,6 @@ impl BitSet {
         self.data.resize(new_len, 0);
     }
 
-    #[track_caller]
     pub fn set(&mut self, idx: Nid) -> bool {
         let idx = idx as usize;
         let data_idx = idx / Self::ELEM_SIZE;
@@ -296,4 +295,12 @@ impl BitSet {
         self.data[data_idx] |= 1 << sub_idx;
         prev == 0
     }
+
+    pub fn get(&self, idx: Nid) -> bool {
+        let idx = idx as usize;
+        let data_idx = idx / Self::ELEM_SIZE;
+        let sub_idx = idx % Self::ELEM_SIZE;
+        let prev = self.data[data_idx] & (1 << sub_idx);
+        prev != 0
+    }
 }

lang/tests/son_tests_inline.txt

@@ -1,17 +1,17 @@
 main:
     LI64 r5, 0d
     LRA r4, r0, :gb
-    LD r6, r4, 0a, 8h
-    CMPS r9, r6, r5
-    CMPUI r9, r9, 0d
-    ORI r11, r9, 0d
-    LI64 r1, 6d
-    ANDI r11, r11, 255d
-    JNE r11, r0, :0
-    CP r5, r1
+    LI64 r10, 6d
+    LD r7, r4, 0a, 8h
+    CMPS r11, r7, r5
+    CMPUI r11, r11, 0d
+    ORI r12, r11, 0d
+    ANDI r12, r12, 255d
+    JNE r12, r0, :0
+    CP r5, r10
     JMP :1
  0: LI64 r5, 1d
- 1: SUB64 r1, r5, r1
+ 1: SUB64 r1, r5, r10
     JALA r0, r31, 0a
 code size: 131
 ret: 0

lang/tests/son_tests_small_struct_bitcast.txt

@@ -1,33 +1,29 @@
 main:
-    ADDI64 r254, r254, -24d
-    ST r31, r254, 8a, 16h
+    ADDI64 r254, r254, -12d
+    ST r31, r254, 4a, 8h
     LRA r1, r0, :white
-    LD r32, r1, 0a, 4h
-    ADDI64 r5, r254, 4d
-    CP r2, r32
+    ADDI64 r4, r254, 0d
+    LD r2, r1, 0a, 4h
     JAL r31, r0, :u32_to_color
-    ST r1, r254, 4a, 4h
-    CP r2, r32
-    JAL r31, r0, :u32_to_u32
-    ADDI64 r12, r254, 0d
-    LD r11, r254, 4a, 1h
     ST r1, r254, 0a, 4h
-    LD r4, r254, 1a, 1h
-    ADD8 r7, r4, r11
-    ANDI r1, r7, 255d
-    LD r31, r254, 8a, 16h
-    ADDI64 r254, r254, 24d
+    LD r9, r254, 0a, 1h
+    ANDI r1, r9, 255d
+    LD r31, r254, 4a, 8h
+    ADDI64 r254, r254, 12d
     JALA r0, r31, 0a
 u32_to_color:
-    ADDI64 r254, r254, -4d
-    ADDI64 r3, r254, 0d
-    ST r2, r254, 0a, 4h
-    LD r1, r3, 0a, 4h
-    ADDI64 r254, r254, 4d
+    ADDI64 r254, r254, -12d
+    ST r31, r254, 4a, 8h
+    JAL r31, r0, :u32_to_u32
+    ADDI64 r5, r254, 0d
+    ST r1, r254, 0a, 4h
+    LD r1, r5, 0a, 4h
+    LD r31, r254, 4a, 8h
+    ADDI64 r254, r254, 12d
     JALA r0, r31, 0a
 u32_to_u32:
     CP r1, r2
     JALA r0, r31, 0a
-code size: 284
-ret: 254
+code size: 263
+ret: 255
 status: Ok(())