Lower stack-sized module constants to be inlined

Related to ethereum#192

crates/analyzer/src/db.rs

@@ -1,8 +1,8 @@
 use crate::context::{Analysis, FunctionBody};
 use crate::errors::TypeError;
 use crate::namespace::items::{
-    self, ContractFieldId, ContractId, EventId, FunctionId, ModuleId, StructFieldId, StructId,
-    TypeAliasId, TypeDefId,
+    self, ContractFieldId, ContractId, EventId, FunctionId, ModuleConstantId, ModuleId,
+    StructFieldId, StructId, TypeAliasId, TypeDefId,
 };
 use crate::namespace::types;
 use indexmap::IndexMap;
@@ -31,6 +31,8 @@ pub trait AnalyzerDb {
     #[salsa::interned]
     fn intern_module(&self, data: Rc<items::Module>) -> ModuleId;
     #[salsa::interned]
+    fn intern_module_const(&self, data: Rc<items::ModuleConstant>) -> ModuleConstantId;
+    #[salsa::interned]
     fn intern_struct(&self, data: Rc<items::Struct>) -> StructId;
     #[salsa::interned]
     fn intern_struct_field(&self, data: Rc<items::StructField>) -> StructFieldId;
@@ -61,6 +63,15 @@ pub trait AnalyzerDb {
     fn module_contracts(&self, module: ModuleId) -> Rc<Vec<ContractId>>;
     #[salsa::invoke(queries::module::module_structs)]
     fn module_structs(&self, module: ModuleId) -> Rc<Vec<StructId>>;
+    #[salsa::invoke(queries::module::module_constants)]
+    fn module_constants(&self, module: ModuleId) -> Rc<Vec<ModuleConstantId>>;
+
+    // Module Constant
+    #[salsa::invoke(queries::module::module_constant_type)]
+    fn module_constant_type(
+        &self,
+        id: ModuleConstantId,
+    ) -> Analysis<Result<types::Type, TypeError>>;
 
     // Contract
     #[salsa::invoke(queries::contracts::contract_all_functions)]

crates/analyzer/src/db/queries/functions.rs

@@ -154,20 +154,47 @@ pub fn function_body(db: &dyn AnalyzerDb, function: FunctionId) -> Analysis<Rc<F
         }
     }
 
+    let mut block_scope = BlockScope::new(&scope, BlockScopeType::Function);
+
+    add_module_constants_to_scope(db, &mut block_scope);
+
     // If `traverse_statements` fails, we can be confident that a diagnostic
     // has been emitted, either while analyzing this fn body or while analyzing
     // a type or fn used in this fn body, because of the `DiagnosticVoucher`
     // system. (See the definition of `FatalError`)
-    let _ = traverse_statements(
-        &mut BlockScope::new(&scope, BlockScopeType::Function),
-        &def.body,
-    );
+    let _ = traverse_statements(&mut block_scope, &def.body);
     Analysis {
         value: Rc::new(scope.body.into_inner()),
         diagnostics: Rc::new(scope.diagnostics.into_inner()),
     }
 }
 
+fn add_module_constants_to_scope(db: &dyn AnalyzerDb, scope: &mut BlockScope) {
+    for module_const in scope.root.function.module(db).all_constants(db).iter() {
+        let typ = match module_const.typ(db) {
+            Ok(typ) => typ,
+            Err(_) => {
+                // No need to report module_constant_type() already reports this
+                continue;
+            }
+        };
+
+        let const_type: FixedSize = match typ.try_into() {
+            Ok(typ) => typ,
+            Err(_) => {
+                // No need to report module_constant_type() already reports this
+                continue;
+            }
+        };
+
+        let const_name = module_const.name(db);
+        // add_var emits a msg on err; we can ignore the Result.
+        scope
+            .add_var(&const_name, const_type, module_const.span(db))
+            .ok();
+    }
+}
+
 fn all_paths_return_or_revert(block: &[Node<ast::FuncStmt>]) -> bool {
     for statement in block.iter().rev() {
         match &statement.kind {

crates/analyzer/src/db/queries/module.rs

@@ -1,11 +1,14 @@
 use crate::builtins;
-use crate::context::Analysis;
+use crate::context::{Analysis, AnalyzerContext};
 use crate::db::AnalyzerDb;
-use crate::errors;
+use crate::errors::{self, TypeError};
 use crate::namespace::items::{
-    Contract, ContractId, ModuleId, Struct, StructId, TypeAlias, TypeDefId,
+    Contract, ContractId, ModuleConstant, ModuleConstantId, ModuleId, Struct, StructId, TypeAlias,
+    TypeDefId,
 };
-use crate::namespace::types;
+use crate::namespace::scopes::ItemScope;
+use crate::namespace::types::{self, Type};
+use crate::traversal::types::type_desc;
 use fe_common::diagnostics::Label;
 use fe_parser::ast;
 use indexmap::map::{Entry, IndexMap};
@@ -131,3 +134,44 @@ pub fn module_structs(db: &dyn AnalyzerDb, module: ModuleId) -> Rc<Vec<StructId>
             .collect(),
     )
 }
+
+pub fn module_constants(db: &dyn AnalyzerDb, module: ModuleId) -> Rc<Vec<ModuleConstantId>> {
+    let ast::Module { body } = &module.data(db).ast;
+    let ids = body
+        .iter()
+        .filter_map(|stmt| match stmt {
+            ast::ModuleStmt::Constant(node) => {
+                Some(db.intern_module_const(Rc::new(ModuleConstant {
+                    ast: node.clone(),
+                    module,
+                })))
+            }
+            _ => None,
+        })
+        .collect();
+    Rc::new(ids)
+}
+
+pub fn module_constant_type(
+    db: &dyn AnalyzerDb,
+    constant: ModuleConstantId,
+) -> Analysis<Result<types::Type, TypeError>> {
+    let mut scope = ItemScope::new(db, constant.data(db).module);
+    let typ = type_desc(&mut scope, &constant.data(db).ast.kind.typ);
+
+    match &typ {
+        Ok(typ) if !matches!(typ, Type::Base(_)) => {
+            scope.error(
+                "Non-base types not yet supported for constants",
+                constant.data(db).ast.kind.typ.span,
+                &format!("this has type `{}`; expected a primitive type", typ),
+            );
+        }
+        _ => {}
+    }
+
+    Analysis {
+        value: typ,
+        diagnostics: Rc::new(scope.diagnostics),
+    }
+}

crates/analyzer/src/namespace/items.rs

@@ -7,6 +7,7 @@ use crate::traversal::pragma::check_pragma_version;
 use crate::AnalyzerDb;
 use fe_common::diagnostics::Diagnostic;
 use fe_parser::ast;
+use fe_parser::ast::Expr;
 use fe_parser::node::{Node, Span};
 use indexmap::IndexMap;
 use std::rc::Rc;
@@ -71,6 +72,19 @@ impl ModuleId {
         db.module_structs(*self)
     }
 
+    /// All constants, including duplicates
+    pub fn all_constants(&self, db: &dyn AnalyzerDb) -> Rc<Vec<ModuleConstantId>> {
+        db.module_constants(*self)
+    }
+
+    /// Get constant by name
+    pub fn lookup_constant(&self, db: &dyn AnalyzerDb, name: &str) -> Option<ModuleConstantId> {
+        self.all_constants(db)
+            .iter()
+            .cloned()
+            .find(|item| item.name(db) == name)
+    }
+
     pub fn diagnostics(&self, db: &dyn AnalyzerDb) -> Vec<Diagnostic> {
         let mut diagnostics = vec![];
         self.sink_diagnostics(db, &mut diagnostics);
@@ -89,6 +103,10 @@ impl ModuleId {
                 ast::ModuleStmt::Use(inner) => {
                     sink.push(&errors::not_yet_implemented("use", inner.span));
                 }
+                ast::ModuleStmt::Constant(_) => self
+                    .all_constants(db)
+                    .iter()
+                    .for_each(|id| id.sink_diagnostics(db, sink)),
                 _ => {} // everything else is a type def, handled below.
             }
         }
@@ -103,6 +121,58 @@ impl ModuleId {
     }
 }
 
+#[derive(Debug, PartialEq, Eq, Hash, Clone)]
+pub struct ModuleConstant {
+    pub ast: Node<ast::ConstantDecl>,
+    pub module: ModuleId,
+}
+
+#[derive(Debug, PartialEq, Eq, Hash, Copy, Clone)]
+pub struct ModuleConstantId(pub(crate) u32);
+impl_intern_key!(ModuleConstantId);
+
+impl ModuleConstantId {
+    pub fn data(&self, db: &dyn AnalyzerDb) -> Rc<ModuleConstant> {
+        db.lookup_intern_module_const(*self)
+    }
+    pub fn span(&self, db: &dyn AnalyzerDb) -> Span {
+        self.data(db).ast.span
+    }
+    pub fn typ(&self, db: &dyn AnalyzerDb) -> Result<types::Type, TypeError> {
+        db.module_constant_type(*self).value
+    }
+
+    pub fn is_base_type(&self, db: &dyn AnalyzerDb) -> bool {
+        matches!(self.typ(db), Ok(types::Type::Base(_)))
+    }
+
+    pub fn name(&self, db: &dyn AnalyzerDb) -> String {
+        self.data(db).ast.kind.name.kind.clone()
+    }
+
+    pub fn value(&self, db: &dyn AnalyzerDb) -> fe_parser::ast::Expr {
+        self.data(db).ast.kind.value.kind.clone()
+    }
+
+    pub fn sink_diagnostics(&self, db: &dyn AnalyzerDb, sink: &mut impl DiagnosticSink) {
+        db.module_constant_type(*self)
+            .diagnostics
+            .iter()
+            .for_each(|d| sink.push(d));
+
+        if !matches!(
+            self.value(db),
+            Expr::Bool(_) | Expr::Num(_) | Expr::Str(_) | Expr::Unit
+        ) {
+            sink.push(&errors::error(
+                "non-literal expressions not yet supported for constants",
+                self.data(db).ast.kind.value.span,
+                "not a literal",
+            ))
+        }
+    }
+}
+
 #[derive(Debug, PartialEq, Eq, Copy, Clone)]
 pub enum TypeDefId {
     Alias(TypeAliasId),

crates/analyzer/tests/errors.rs

@@ -219,6 +219,9 @@ test_file! { mismatch_return_type }
 test_file! { missing_return }
 test_file! { missing_return_in_else }
 test_file! { missing_return_after_if }
+test_file! { module_const_unknown_type }
+test_file! { module_const_non_base_type }
+test_file! { module_const_not_literal }
 test_file! { needs_mem_copy }
 test_file! { not_callable }
 test_file! { not_in_scope }

crates/analyzer/tests/snapshots/errors__module_const_non_base_type.snap

@@ -0,0 +1,12 @@
+---
+source: crates/analyzer/tests/errors.rs
+expression: "error_string(&path, &src)"
+
+---
+error: Non-base types not yet supported for constants
+  ┌─ compile_errors/module_const_non_base_type.fe:1:12
+  │
+1 │ const FOO: String<3> = "foo"
+  │            ^^^^^^^^^ this has type `String<3>`; expected a primitive type
+
+

crates/analyzer/tests/snapshots/errors__module_const_not_literal.snap

@@ -0,0 +1,12 @@
+---
+source: crates/analyzer/tests/errors.rs
+expression: "error_string(&path, &src)"
+
+---
+error: non-literal expressions not yet supported for constants
+  ┌─ compile_errors/module_const_not_literal.fe:1:19
+  │
+1 │ const FOO: u256 = 1 + 2
+  │                   ^^^^^ not a literal
+
+

crates/analyzer/tests/snapshots/errors__module_const_unknown_type.snap

@@ -0,0 +1,12 @@
+---
+source: crates/analyzer/tests/errors.rs
+expression: "error_string(&path, &src)"
+
+---
+error: undefined type
+  ┌─ compile_errors/module_const_unknown_type.fe:1:12
+  │
+1 │ const FOO: Bar = 1
+  │            ^^^ this type name has not been defined
+
+

crates/lowering/src/context.rs

@@ -1,4 +1,5 @@
 use fe_analyzer::context::{ExpressionAttributes, FunctionBody};
+use fe_analyzer::namespace::items::FunctionId;
 use fe_analyzer::namespace::types::{Array, FixedSize, Tuple};
 use fe_analyzer::AnalyzerDb;
 use fe_parser::ast;
@@ -52,16 +53,22 @@ impl<'a, 'db> ContractContext<'a, 'db> {
 pub struct FnContext<'a, 'b, 'db> {
     pub contract: &'a mut ContractContext<'b, 'db>,
     pub body: Rc<FunctionBody>,
+    pub id: FunctionId,
 
     /// Holds fresh id for [`FnContext::make_unique_name`]
     fresh_id: u64,
 }
 
 impl<'a, 'b, 'db> FnContext<'a, 'b, 'db> {
-    pub fn new(contract: &'a mut ContractContext<'b, 'db>, body: Rc<FunctionBody>) -> Self {
+    pub fn new(
+        id: FunctionId,
+        contract: &'a mut ContractContext<'b, 'db>,
+        body: Rc<FunctionBody>,
+    ) -> Self {
         Self {
             contract,
             body,
+            id,
             fresh_id: 0,
         }
     }

crates/lowering/src/mappers/expressions.rs

@@ -10,7 +10,7 @@ pub fn expr(context: &mut FnContext, exp: Node<fe::Expr>) -> Node<fe::Expr> {
     let span = exp.span;
 
     let lowered_kind = match exp.kind {
-        fe::Expr::Name(_) => exp.kind,
+        fe::Expr::Name(_) => expr_name(context, exp),
         fe::Expr::Num(_) => exp.kind,
         fe::Expr::Bool(_) => exp.kind,
         fe::Expr::Subscript { value, index } => fe::Expr::Subscript {
@@ -103,6 +103,27 @@ pub fn call_args(
     Node::new(lowered_args, args.span)
 }
 
+fn expr_name(context: &mut FnContext, exp: Node<fe::Expr>) -> fe::Expr {
+    let name = match &exp.kind {
+        fe::Expr::Name(name) => name,
+        _ => unreachable!(),
+    };
+
+    let db = context.db();
+
+    let module_const = context.id.module(db).lookup_constant(db, name);
+
+    // If the name maps to a base type constant we lower the code to inline
+    // the name expression to the value expression of the constant.
+    match module_const {
+        Some(val) if val.is_base_type(db) => val.value(db),
+        Some(_) => {
+            panic!("Should have been rejected at first analyzer pass")
+        }
+        None => exp.kind,
+    }
+}
+
 fn expr_tuple(context: &mut FnContext, exp: Node<fe::Expr>) -> fe::Expr {
     let typ = context
         .expression_attributes(&exp)

crates/lowering/src/mappers/functions.rs

@@ -11,7 +11,7 @@ use fe_parser::node::Node;
 
 /// Lowers a function definition.
 pub fn func_def(contract: &mut ContractContext, function: FunctionId) -> Node<fe::Function> {
-    let mut context = FnContext::new(contract, function.body(contract.db()));
+    let mut context = FnContext::new(function, contract, function.body(contract.db()));
     let node = &function.data(context.db()).ast;
     let fe::Function {
         is_pub,

crates/lowering/src/mappers/module.rs

@@ -20,6 +20,9 @@ pub fn module(db: &dyn AnalyzerDb, module: ModuleId) -> ast::Module {
         .filter_map(|stmt| match stmt {
             ast::ModuleStmt::Pragma(_) => Some(stmt.clone()),
             ast::ModuleStmt::Use(_) => Some(stmt.clone()),
+            // All name expressions referring to constants are handled at the time of lowering,
+            // which causes the constants to no longer serve a purpose.
+            ast::ModuleStmt::Constant(_) => None,
             _ => None,
         })
         .collect::<Vec<_>>();

crates/lowering/tests/lowering.rs

@@ -67,5 +67,6 @@ test_file! { nested_tuple, "lowering/nested_tuple.fe" }
 test_file! { map_tuple, "lowering/map_tuple.fe" }
 test_file! { type_alias_tuple, "lowering/type_alias_tuple.fe" }
 test_file! { tuple_destruct, "lowering/tuple_destruct.fe" }
+test_file! { module_const, "lowering/module_const.fe" }
 // TODO: the analyzer rejects lowered nested tuples.
 // test_file!(array_tuple, "lowering/array_tuple.fe");