Merge pull request #990 from rtfeldman/fuse-rc-struct

Fuse rc in structs/closures

compiler/mono/src/expand_rc.rs

@@ -157,6 +157,16 @@ impl<'a, 'i> Env<'a, 'i> {
         }
     }
 
+    fn insert_struct_info(&mut self, symbol: Symbol, fields: &'a [Layout<'a>]) {
+        self.constructor_map.insert(symbol, 0);
+        self.layout_map.insert(symbol, Layout::Struct(fields));
+    }
+
+    fn remove_struct_info(&mut self, symbol: Symbol) {
+        self.constructor_map.remove(&symbol);
+        self.layout_map.remove(&symbol);
+    }
+
     pub fn unique_symbol(&mut self) -> Symbol {
         let ident_id = self.ident_ids.gen_unique();
 
@@ -213,6 +223,10 @@ fn layout_for_constructor<'a>(
                 }
             }
         }
+        Struct(fields) => {
+            debug_assert_eq!(constructor, 0);
+            HasFields(fields)
+        }
         _ => unreachable!(),
     }
 }
@@ -322,7 +336,39 @@ enum ConstructorLayout<T> {
     Unknown,
 }
 
-pub fn expand_and_cancel<'a>(env: &mut Env<'a, '_>, stmt: &'a Stmt<'a>) -> &'a Stmt<'a> {
+pub fn expand_and_cancel_proc<'a>(
+    env: &mut Env<'a, '_>,
+    stmt: &'a Stmt<'a>,
+    arguments: &'a [(Layout<'a>, Symbol)],
+) -> &'a Stmt<'a> {
+    let mut introduced = Vec::new_in(env.arena);
+
+    for (layout, symbol) in arguments {
+        match layout {
+            Layout::Struct(fields) => {
+                env.insert_struct_info(*symbol, fields);
+
+                introduced.push(*symbol);
+            }
+            Layout::Closure(_, closure_layout, _) => {
+                if let Layout::Struct(fields) = closure_layout.layout {
+                    env.insert_struct_info(*symbol, fields);
+                }
+            }
+            _ => {}
+        }
+    }
+
+    let result = expand_and_cancel(env, stmt);
+
+    for symbol in introduced {
+        env.remove_struct_info(symbol);
+    }
+
+    result
+}
+
+fn expand_and_cancel<'a>(env: &mut Env<'a, '_>, stmt: &'a Stmt<'a>) -> &'a Stmt<'a> {
     use Stmt::*;
 
     let mut deferred_default = Deferred {
@@ -351,7 +397,7 @@ pub fn expand_and_cancel<'a>(env: &mut Env<'a, '_>, stmt: &'a Stmt<'a>) -> &'a S
                 // prevent long chains of `Let`s from blowing the stack
                 let mut literal_stack = Vec::new_in(env.arena);
 
-                while !matches!(&expr, Expr::AccessAtIndex { .. } ) {
+                while !matches!(&expr, Expr::AccessAtIndex { .. } | Expr::Struct(_)) {
                     if let Stmt::Let(symbol1, expr1, layout1, cont1) = cont {
                         literal_stack.push((symbol, expr.clone(), layout.clone()));
 
@@ -366,10 +412,10 @@ pub fn expand_and_cancel<'a>(env: &mut Env<'a, '_>, stmt: &'a Stmt<'a>) -> &'a S
 
                 let new_cont;
 
-                if let Expr::AccessAtIndex {
+                match &expr {
+                    Expr::AccessAtIndex {
                         structure, index, ..
-                } = &expr
+                    } => {
-                {
                         let entry = env
                             .alias_map
                             .entry(*structure)
@@ -383,9 +429,22 @@ pub fn expand_and_cancel<'a>(env: &mut Env<'a, '_>, stmt: &'a Stmt<'a>) -> &'a S
                         env.alias_map
                             .get_mut(structure)
                             .and_then(|map| map.remove(index));
+                    }
+                    Expr::Struct(_) => {
+                        if let Layout::Struct(fields) = layout {
+                            env.insert_struct_info(symbol, fields);
+
+                            new_cont = expand_and_cancel(env, cont);
+
+                            env.remove_struct_info(symbol);
                         } else {
                             new_cont = expand_and_cancel(env, cont);
                         }
+                    }
+                    _ => {
+                        new_cont = expand_and_cancel(env, cont);
+                    }
+                }
 
                 let stmt = Let(symbol, expr.clone(), layout.clone(), new_cont);
                 let mut stmt = &*env.arena.alloc(stmt);

compiler/mono/src/ir.rs

@@ -183,7 +183,11 @@ impl<'a> Proc<'a> {
         };
 
         for (_, proc) in procs.iter_mut() {
-            let b = expand_rc::expand_and_cancel(&mut env, arena.alloc(proc.body.clone()));
+            let b = expand_rc::expand_and_cancel_proc(
+                &mut env,
+                arena.alloc(proc.body.clone()),
+                proc.args,
+            );
             proc.body = b.clone();
         }
     }

compiler/mono/src/layout.rs

@@ -70,7 +70,9 @@ pub struct ClosureLayout<'a> {
     /// the vec is likely to be small, so linear search is fine
     captured: &'a [(TagName, &'a [Layout<'a>])],
 
-    layout: &'a Layout<'a>,
+    /// use with care; there is some stuff happening here re. unwrapping
+    /// one-element records that might cause issues
+    pub layout: &'a Layout<'a>,
 }
 
 impl<'a> ClosureLayout<'a> {

compiler/mono/tests/test_mono.rs

@@ -949,8 +949,7 @@ mod test_mono {
                     let Test.5 = 3.14f64;
                     let Test.3 = Struct {Test.4, Test.5};
                     let Test.1 = Index 0 Test.3;
-                    inc Test.1;
+                    decref Test.3;
-                    dec Test.3;
                     ret Test.1;
                 "#
             ),

compiler/reporting/tests/test_reporting.rs

@@ -4697,7 +4697,7 @@ mod test_reporting {
                 
                 I was expecting to see a private tag name.
                 
-                Hint: Private tag names start with a `@` symbol followed by an
+                Hint: Private tag names start with an `@` symbol followed by an
                 uppercase letter, like @UID or @SecretKey.
             "#
             ),