Merge #148

148: Modal harmony r=nikomatsakis a=nikomatsakis

This branch implements #143. It's not quite where I want it to be yet, but close enough I figured I'd open it up so that there's a preview + playground etc.

Here is a list of things I have done and have yet to do (will update as I go, this is off the top of my head):

* [x] Add specifiers `my`, `our`, etc
* [x] Change leasing an `our` value to yield another `our` value, instead of `our leased` (preserves all invariants, more convenient overall)
* [x] Check that values assigned to a `my` etc location meet the requirements
* [x] Change the default specifier from `any` to `our leased`
* [x] Ensure that when unique things are stored in shared locations, they are shared ([example where it goes wrong today](https://deploy-preview-148--dada-lang.netlify.app/playground/?code=class+Point%28x%2C+y%29%0A%0Aasync+fn+main%28%29+%7B%0A++++our+s+%3D+%22foo%22%0A++++our+t+%3D+foo%28s%29%0A++++p+%3D+Point%28s%2C+t%29%0A++++q+%3D+p%0A++++print%28p%29.await%0A%7D%0A%0Afn+foo%28our+s%29+%7B%0A++++s%0A%7D%0A))

Co-authored-by: Niko Matsakis <[email protected]>

components/dada-brew/src/brew.rs

@@ -4,7 +4,7 @@ use dada_ir::{
         bir::{self, BirData},
         validated::{self, ExprOrigin},
     },
-    storage_mode::Atomic,
+    storage::Atomic,
 };
 use salsa::DebugWithDb;
 
@@ -85,7 +85,7 @@ impl Cursor {
             validated::ExprData::Continue(from_expr) => {
                 self.push_breakpoint_start(brewery, origin);
                 let loop_context = brewery.loop_context(*from_expr);
-                self.push_breakpoint_end(brewery, None, origin);
+                self.push_breakpoint_end(brewery, None::<bir::Place>, origin);
                 self.terminate_and_goto(brewery, loop_context.continue_block, origin);
             }
 
@@ -103,22 +103,49 @@ impl Cursor {
 
             validated::ExprData::Error => {
                 self.push_breakpoint_start(brewery, origin);
-                self.push_breakpoint_end(brewery, None, origin);
+                self.push_breakpoint_end(brewery, None::<bir::Place>, origin);
                 self.terminate_and_diverge(brewery, bir::TerminatorData::Error, origin)
             }
 
-            validated::ExprData::Assign(place, value_expr) => {
+            validated::ExprData::AssignTemporary(place, value_expr) => {
+                // temporaries are always created with "any" specifier, which ensures
+                // that we will never have to apply specifier to `value_expr`
+                assert_eq!(brewery.validated_tables()[*place].specifier, None);
+
+                // we only ever use this for temporaries, user-created values use `AssignFromPlace`
+                assert!(matches!(
+                    brewery.origin(*place),
+                    validated::LocalVariableOrigin::Temporary(_)
+                ));
+
                 self.push_breakpoint_start(brewery, origin);
-                let (place, origins) = self.brew_place(brewery, *place);
+                let place = self.brew_target_variable(brewery, *place, origin);
                 self.brew_expr_and_assign_to(brewery, place, *value_expr);
-                self.push_breakpoint_ends(brewery, None, origins, origin)
+                self.push_breakpoint_end(brewery, None::<bir::Place>, origin)
+            }
+
+            validated::ExprData::AssignFromPlace(target_place, source_place) => {
+                let (target_place, target_origins) = self.brew_target_place(brewery, *target_place);
+                let (source_place, source_origins) = self.brew_place(brewery, *source_place);
+                self.push_breakpoint_starts(
+                    brewery,
+                    target_origins.iter().chain(source_origins.iter()).copied(),
+                    origin,
+                );
+                self.push_assignment_from_place(brewery, target_place, source_place, origin);
+                self.push_breakpoint_ends(
+                    brewery,
+                    None::<bir::Place>,
+                    target_origins.into_iter().chain(source_origins),
+                    origin,
+                )
             }
 
             validated::ExprData::Declare(vars, subexpr) => {
                 self.push_breakpoint_start(brewery, origin);
                 self.brew_expr_for_side_effects(brewery, *subexpr);
                 self.pop_declared_variables(brewery, vars, origin);
-                self.push_breakpoint_end(brewery, None, origin);
+                self.push_breakpoint_end(brewery, None::<bir::Place>, origin);
             }
 
             validated::ExprData::Await(_)
@@ -134,6 +161,7 @@ impl Cursor {
             | validated::ExprData::FloatLiteral(_)
             | validated::ExprData::StringLiteral(_)
             | validated::ExprData::Call(_, _)
+            | validated::ExprData::Reserve(_)
             | validated::ExprData::Share(_)
             | validated::ExprData::Lease(_)
             | validated::ExprData::Give(_)
@@ -145,6 +173,8 @@ impl Cursor {
         self.pop_temporary_scope(brewery, temporary_scope);
     }
 
+    /// Compiles expr into a temporary `t` and returns `Some(t)`.
+    /// Returns `None` if this is dead code.
     pub(crate) fn brew_expr_to_temporary(
         &mut self,
         brewery: &mut Brewery<'_>,
@@ -154,7 +184,7 @@ impl Cursor {
         // Spill into a temporary
         let temp_place = add_temporary_place(brewery, origin);
         self.brew_expr_and_assign_to(brewery, temp_place, expr);
-        Some(temp_place)
+        Some(brewery.place_from_target_place(temp_place))
     }
 
     /// Compiles an expression down to the value it produces.
@@ -164,7 +194,7 @@ impl Cursor {
     pub(crate) fn brew_expr_and_assign_to(
         &mut self,
         brewery: &mut Brewery<'_>,
-        target: bir::Place,
+        target: bir::TargetPlace,
         expr: validated::Expr,
     ) {
         let origin = brewery.origin(expr);
@@ -238,10 +268,18 @@ impl Cursor {
                 );
             }
 
-            validated::ExprData::Share(place) => {
+            validated::ExprData::Share(operand) => {
+                if let Some(temp) = self.brew_expr_to_temporary(brewery, *operand) {
+                    self.push_breakpoint_start(brewery, origin);
+                    self.push_assignment(brewery, target, bir::ExprData::Share(temp), origin);
+                    self.push_breakpoint_end(brewery, Some(target), origin);
+                }
+            }
+
+            validated::ExprData::Reserve(place) => {
                 let (place, origins) = self.brew_place(brewery, *place);
                 self.push_breakpoint_starts(brewery, origins.iter().copied(), origin);
-                self.push_assignment(brewery, target, bir::ExprData::GiveShare(place), origin);
+                self.push_assignment(brewery, target, bir::ExprData::Reserve(place), origin);
                 self.push_breakpoint_ends(brewery, Some(target), origins, origin);
             }
 
@@ -375,8 +413,7 @@ impl Cursor {
                 }
             }
 
-            validated::ExprData::Assign(_, _) => {
-                self.push_breakpoint_start(brewery, origin);
+            validated::ExprData::AssignTemporary(..) | validated::ExprData::AssignFromPlace(..) => {
                 self.brew_expr_for_side_effects(brewery, expr);
                 self.push_assignment(brewery, target, bir::ExprData::Unit, origin);
             }
@@ -429,7 +466,7 @@ impl Cursor {
                 self.push_breakpoint_start(brewery, origin);
                 self.brew_expr_and_assign_to(brewery, target, *subexpr);
                 self.pop_declared_variables(brewery, vars, origin);
-                self.push_breakpoint_end(brewery, None, origin);
+                self.push_breakpoint_end(brewery, None::<bir::Place>, origin);
             }
 
             validated::ExprData::Error
@@ -485,21 +522,52 @@ impl Cursor {
             }
         }
     }
+
+    pub(crate) fn brew_target_place(
+        &mut self,
+        brewery: &mut Brewery<'_>,
+        place: validated::TargetPlace,
+    ) -> (bir::TargetPlace, Vec<ExprOrigin>) {
+        let origin = brewery.origin(place);
+        match brewery.validated_tables()[place] {
+            validated::TargetPlaceData::LocalVariable(validated_var) => {
+                let place = self.brew_target_variable(brewery, validated_var, origin);
+                (place, vec![origin])
+            }
+            validated::TargetPlaceData::Dot(base, field) => {
+                let (base, mut origins) = self.brew_place(brewery, base);
+                let place = brewery.add(bir::TargetPlaceData::Dot(base, field), origin);
+                origins.push(origin);
+                (place, origins)
+            }
+        }
+    }
+    pub(crate) fn brew_target_variable(
+        &mut self,
+        brewery: &mut Brewery<'_>,
+        validated_var: validated::LocalVariable,
+        origin: ExprOrigin,
+    ) -> bir::TargetPlace {
+        let bir_var = brewery.variable(validated_var);
+        brewery.add(bir::TargetPlaceData::LocalVariable(bir_var), origin)
+    }
 }
 
 fn add_temporary(brewery: &mut Brewery, origin: ExprOrigin) -> bir::LocalVariable {
     let temporary = brewery.add(
         bir::LocalVariableData {
             name: None,
+            specifier: None,
             atomic: Atomic::No,
         },
         validated::LocalVariableOrigin::Temporary(origin.into()),
     );
+    tracing::debug!("created temporary: temp{{{:?}}}", u32::from(temporary));
     brewery.push_temporary(temporary);
     temporary
 }
 
-fn add_temporary_place(brewery: &mut Brewery, origin: ExprOrigin) -> bir::Place {
+fn add_temporary_place(brewery: &mut Brewery, origin: ExprOrigin) -> bir::TargetPlace {
     let temporary_var = add_temporary(brewery, origin);
-    brewery.add(bir::PlaceData::LocalVariable(temporary_var), origin)
+    brewery.add(bir::TargetPlaceData::LocalVariable(temporary_var), origin)
 }

components/dada-brew/src/brewery.rs

@@ -14,7 +14,7 @@ use dada_ir::{
 pub struct Brewery<'me> {
     db: &'me dyn crate::Db,
     code: Code,
-    breakpoints: &'me [syntax::Expr],
+    pub(crate) breakpoints: &'me [syntax::Expr],
     validated_tree_data: &'me validated::TreeData,
     validated_origins: &'me validated::Origins,
     tables: &'me mut bir::Tables,
@@ -43,7 +43,7 @@ pub struct Brewery<'me> {
 pub struct LoopContext {
     pub continue_block: bir::BasicBlock,
     pub break_block: bir::BasicBlock,
-    pub loop_value: bir::Place,
+    pub loop_value: bir::TargetPlace,
 }
 
 impl<'me> Brewery<'me> {
@@ -154,6 +154,18 @@ impl<'me> Brewery<'me> {
         add(self.tables, self.origins, data, origin)
     }
 
+    /// Converts a target-place into a place.
+    pub fn place_from_target_place(&mut self, place: bir::TargetPlace) -> bir::Place {
+        match self.tables[place] {
+            bir::TargetPlaceData::LocalVariable(lv) => {
+                self.add(bir::PlaceData::LocalVariable(lv), self.origins[place])
+            }
+            bir::TargetPlaceData::Dot(owner_place, name) => {
+                self.add(bir::PlaceData::Dot(owner_place, name), self.origins[place])
+            }
+        }
+    }
+
     /// Find the loop context for a given loop expression.
     ///
     /// Panics if that loop context has not been pushed.
@@ -185,6 +197,7 @@ impl<'me> Brewery<'me> {
     ///
     /// See the comments on the `temporaries` field for more information.
     pub fn push_temporary(&mut self, lv: bir::LocalVariable) {
+        tracing::debug!("pushing temporary: {:?}", lv);
         self.temporaries.push(lv);
     }
 
@@ -217,6 +230,7 @@ fn map_variables(
                 origins,
                 bir::LocalVariableData {
                     name: validated_var_data.name,
+                    specifier: validated_var_data.specifier,
                     atomic: validated_var_data.atomic,
                 },
                 validated_var_origin,

components/dada-brew/src/cursor.rs

@@ -140,13 +140,26 @@ impl Cursor {
     pub(crate) fn push_assignment(
         &mut self,
         brewery: &mut Brewery<'_>,
-        target: bir::Place,
+        target: bir::TargetPlace,
         value: bir::ExprData,
         origin: ExprOrigin,
     ) {
         if self.end_block.is_some() {
             let value = brewery.add(value, origin);
-            let statement = brewery.add(bir::StatementData::Assign(target, value), origin);
+            let statement = brewery.add(bir::StatementData::AssignExpr(target, value), origin);
+            self.push_statement(brewery, statement);
+        }
+    }
+
+    pub(crate) fn push_assignment_from_place(
+        &mut self,
+        brewery: &mut Brewery<'_>,
+        target: bir::TargetPlace,
+        source: bir::Place,
+        origin: ExprOrigin,
+    ) {
+        if self.end_block.is_some() {
+            let statement = brewery.add(bir::StatementData::AssignPlace(target, source), origin);
             self.push_statement(brewery, statement);
         }
     }
@@ -167,6 +180,11 @@ impl Cursor {
     /// If `origin` is a breakpoint expression, push a "breakpoint-start"
     /// statement onto the current basic block.
     pub(crate) fn push_breakpoint_start(&mut self, brewery: &mut Brewery<'_>, origin: ExprOrigin) {
+        tracing::debug!(
+            "push_breakpoint_start: origin={:?} breakpoints={:?}",
+            origin,
+            brewery.breakpoints
+        );
         if !origin.synthesized && self.end_block.is_some() {
             if let Some(breakpoint_index) = brewery.expr_is_breakpoint(origin.syntax_expr) {
                 let filename = brewery.code().filename(brewery.db());
@@ -186,10 +204,11 @@ impl Cursor {
     pub(crate) fn push_breakpoint_ends(
         &mut self,
         brewery: &mut Brewery<'_>,
-        place: Option<bir::Place>,
+        place: Option<impl AnyPlace>,
         origins: impl IntoIterator<Item = ExprOrigin>,
         origin: ExprOrigin,
     ) {
+        let place = place.map(|p| p.into_place(brewery));
         for o in origins.into_iter().chain(Some(origin)) {
             self.push_breakpoint_end_with_distinct_origin(brewery, origin.syntax_expr, place, o);
         }
@@ -200,9 +219,10 @@ impl Cursor {
     pub(crate) fn push_breakpoint_end(
         &mut self,
         brewery: &mut Brewery<'_>,
-        place: Option<bir::Place>,
+        place: Option<impl AnyPlace>,
         origin: ExprOrigin,
     ) {
+        let place = place.map(|p| p.into_place(brewery));
         self.push_breakpoint_end_with_distinct_origin(brewery, origin.syntax_expr, place, origin);
     }
 
@@ -245,3 +265,19 @@ impl Cursor {
         Some((place, *name))
     }
 }
+
+pub(crate) trait AnyPlace {
+    fn into_place(self, brewery: &mut Brewery<'_>) -> bir::Place;
+}
+
+impl AnyPlace for bir::Place {
+    fn into_place(self, _brewery: &mut Brewery<'_>) -> bir::Place {
+        self
+    }
+}
+
+impl AnyPlace for bir::TargetPlace {
+    fn into_place(self, brewery: &mut Brewery<'_>) -> bir::Place {
+        brewery.place_from_target_place(self)
+    }
+}

components/dada-db/src/lib.rs

@@ -66,7 +66,7 @@ impl Db {
         for item in filename.items(self) {
             if let Item::Function(function) = item {
                 let function_name = function.name(self);
-                if name == function_name {
+                if name == function_name.word(self) {
                     return Some(*function);
                 }
             }