Auto merge of #12827 - Veykril:be-lazy, r=Veykril

internal: Construct fewer `AstIdMap`s in lowering

4 files changed, 37 insertions, 49 deletions

diff --git a/crates/hir-def/src/body.rs b/crates/hir-def/src/body.rs
index 33851d90a2f..080a307b1f8 100644
--- a/crates/hir-def/src/body.rs
+++ b/crates/hir-def/src/body.rs
@@ -5,21 +5,18 @@ mod lower;
 mod tests;
 pub mod scope;
 
-use std::{mem, ops::Index, sync::Arc};
+use std::{ops::Index, sync::Arc};
 
 use base_db::CrateId;
 use cfg::{CfgExpr, CfgOptions};
 use drop_bomb::DropBomb;
 use either::Either;
-use hir_expand::{
-    ast_id_map::AstIdMap, hygiene::Hygiene, AstId, ExpandError, ExpandResult, HirFileId, InFile,
-    MacroCallId,
-};
+use hir_expand::{hygiene::Hygiene, ExpandError, ExpandResult, HirFileId, InFile, MacroCallId};
 use la_arena::{Arena, ArenaMap};
 use limit::Limit;
 use profile::Count;
 use rustc_hash::FxHashMap;
-use syntax::{ast, AstNode, AstPtr, SyntaxNodePtr};
+use syntax::{ast, AstPtr, SyntaxNodePtr};
 
 use crate::{
     attr::{Attrs, RawAttrs},
@@ -50,7 +47,6 @@ pub struct Expander {
     cfg_expander: CfgExpander,
     def_map: Arc<DefMap>,
     current_file_id: HirFileId,
-    ast_id_map: Arc<AstIdMap>,
     module: LocalModuleId,
     recursion_limit: usize,
 }
@@ -80,12 +76,10 @@ impl Expander {
     pub fn new(db: &dyn DefDatabase, current_file_id: HirFileId, module: ModuleId) -> Expander {
         let cfg_expander = CfgExpander::new(db, current_file_id, module.krate);
         let def_map = module.def_map(db);
-        let ast_id_map = db.ast_id_map(current_file_id);
         Expander {
             cfg_expander,
             def_map,
             current_file_id,
-            ast_id_map,
             module: module.local_id,
             recursion_limit: 0,
         }
@@ -168,14 +162,10 @@ impl Expander {
         tracing::debug!("macro expansion {:#?}", node.syntax());
 
         self.recursion_limit += 1;
-        let mark = Mark {
-            file_id: self.current_file_id,
-            ast_id_map: mem::take(&mut self.ast_id_map),
-            bomb: DropBomb::new("expansion mark dropped"),
-        };
+        let mark =
+            Mark { file_id: self.current_file_id, bomb: DropBomb::new("expansion mark dropped") };
         self.cfg_expander.hygiene = Hygiene::new(db.upcast(), file_id);
         self.current_file_id = file_id;
-        self.ast_id_map = db.ast_id_map(file_id);
 
         ExpandResult { value: Some((mark, node)), err }
     }
@@ -183,7 +173,6 @@ impl Expander {
     pub fn exit(&mut self, db: &dyn DefDatabase, mut mark: Mark) {
         self.cfg_expander.hygiene = Hygiene::new(db.upcast(), mark.file_id);
         self.current_file_id = mark.file_id;
-        self.ast_id_map = mem::take(&mut mark.ast_id_map);
         self.recursion_limit -= 1;
         mark.bomb.defuse();
     }
@@ -213,11 +202,6 @@ impl Expander {
         self.def_map.resolve_path(db, self.module, path, BuiltinShadowMode::Other).0.take_macros()
     }
 
-    fn ast_id<N: AstNode>(&self, item: &N) -> AstId<N> {
-        let file_local_id = self.ast_id_map.ast_id(item);
-        AstId::new(self.current_file_id, file_local_id)
-    }
-
     fn recursion_limit(&self, db: &dyn DefDatabase) -> Limit {
         let limit = db.crate_limits(self.cfg_expander.krate).recursion_limit as _;
 
@@ -233,7 +217,6 @@ impl Expander {
 #[derive(Debug)]
 pub struct Mark {
     file_id: HirFileId,
-    ast_id_map: Arc<AstIdMap>,
     bomb: DropBomb,
 }
 
diff --git a/crates/hir-def/src/body/lower.rs b/crates/hir-def/src/body/lower.rs
index 049afa82279..c3f26112278 100644
--- a/crates/hir-def/src/body/lower.rs
+++ b/crates/hir-def/src/body/lower.rs
@@ -5,12 +5,13 @@ use std::{mem, sync::Arc};
 
 use either::Either;
 use hir_expand::{
-    ast_id_map::{AstIdMap, FileAstId},
+    ast_id_map::AstIdMap,
     hygiene::Hygiene,
     name::{name, AsName, Name},
-    ExpandError, HirFileId, InFile,
+    AstId, ExpandError, HirFileId, InFile,
 };
 use la_arena::Arena;
+use once_cell::unsync::OnceCell;
 use profile::Count;
 use rustc_hash::FxHashMap;
 use syntax::{
@@ -41,8 +42,7 @@ use crate::{
 pub struct LowerCtx<'a> {
     pub db: &'a dyn DefDatabase,
     hygiene: Hygiene,
-    file_id: Option<HirFileId>,
-    source_ast_id_map: Option<Arc<AstIdMap>>,
+    ast_id_map: Option<(HirFileId, OnceCell<Arc<AstIdMap>>)>,
 }
 
 impl<'a> LowerCtx<'a> {
@@ -50,29 +50,26 @@ impl<'a> LowerCtx<'a> {
         LowerCtx {
             db,
             hygiene: Hygiene::new(db.upcast(), file_id),
-            file_id: Some(file_id),
-            source_ast_id_map: Some(db.ast_id_map(file_id)),
+            ast_id_map: Some((file_id, OnceCell::new())),
         }
     }
 
     pub fn with_hygiene(db: &'a dyn DefDatabase, hygiene: &Hygiene) -> Self {
-        LowerCtx { db, hygiene: hygiene.clone(), file_id: None, source_ast_id_map: None }
+        LowerCtx { db, hygiene: hygiene.clone(), ast_id_map: None }
     }
 
     pub(crate) fn hygiene(&self) -> &Hygiene {
         &self.hygiene
     }
 
-    pub(crate) fn file_id(&self) -> HirFileId {
-        self.file_id.unwrap()
-    }
-
     pub(crate) fn lower_path(&self, ast: ast::Path) -> Option<Path> {
         Path::from_src(ast, self)
     }
 
-    pub(crate) fn ast_id<N: AstNode>(&self, item: &N) -> Option<FileAstId<N>> {
-        self.source_ast_id_map.as_ref().map(|ast_id_map| ast_id_map.ast_id(item))
+    pub(crate) fn ast_id<N: AstNode>(&self, db: &dyn DefDatabase, item: &N) -> Option<AstId<N>> {
+        let &(file_id, ref ast_id_map) = self.ast_id_map.as_ref()?;
+        let ast_id_map = ast_id_map.get_or_init(|| db.ast_id_map(file_id));
+        Some(InFile::new(file_id, ast_id_map.ast_id(item)))
     }
 }
 
@@ -85,6 +82,7 @@ pub(super) fn lower(
     ExprCollector {
         db,
         source_map: BodySourceMap::default(),
+        ast_id_map: db.ast_id_map(expander.current_file_id),
         body: Body {
             exprs: Arena::default(),
             pats: Arena::default(),
@@ -105,6 +103,7 @@ pub(super) fn lower(
 struct ExprCollector<'a> {
     db: &'a dyn DefDatabase,
     expander: Expander,
+    ast_id_map: Arc<AstIdMap>,
     body: Body,
     source_map: BodySourceMap,
     // a poor-mans union-find?
@@ -586,8 +585,13 @@ impl ExprCollector<'_> {
         match res.value {
             Some((mark, expansion)) => {
                 self.source_map.expansions.insert(macro_call_ptr, self.expander.current_file_id);
+                let prev_ast_id_map = mem::replace(
+                    &mut self.ast_id_map,
+                    self.db.ast_id_map(self.expander.current_file_id),
+                );
 
                 let id = collector(self, Some(expansion));
+                self.ast_id_map = prev_ast_id_map;
                 self.expander.exit(self.db, mark);
                 id
             }
@@ -675,7 +679,8 @@ impl ExprCollector<'_> {
     }
 
     fn collect_block(&mut self, block: ast::BlockExpr) -> ExprId {
-        let ast_id = self.expander.ast_id(&block);
+        let file_local_id = self.ast_id_map.ast_id(&block);
+        let ast_id = AstId::new(self.expander.current_file_id, file_local_id);
         let block_loc =
             BlockLoc { ast_id, module: self.expander.def_map.module_id(self.expander.module) };
         let block_id = self.db.intern_block(block_loc);
diff --git a/crates/hir-def/src/data.rs b/crates/hir-def/src/data.rs
index 8e8b5c322f9..ca15e7c4100 100644
--- a/crates/hir-def/src/data.rs
+++ b/crates/hir-def/src/data.rs
@@ -550,14 +550,17 @@ impl<'a> AssocItemCollector<'a> {
                 AssocItem::MacroCall(call) => {
                     let call = &item_tree[call];
                     let ast_id_map = self.db.ast_id_map(self.expander.current_file_id());
-                    let root = self.db.parse_or_expand(self.expander.current_file_id()).unwrap();
-                    let call = ast_id_map.get(call.ast_id).to_node(&root);
-                    let _cx =
-                        stdx::panic_context::enter(format!("collect_items MacroCall: {}", call));
-                    let res = self.expander.enter_expand(self.db, call);
-
-                    if let Ok(ExpandResult { value: Some((mark, mac)), .. }) = res {
-                        self.collect_macro_items(mark, mac);
+                    if let Some(root) = self.db.parse_or_expand(self.expander.current_file_id()) {
+                        let call = ast_id_map.get(call.ast_id).to_node(&root);
+                        let _cx = stdx::panic_context::enter(format!(
+                            "collect_items MacroCall: {}",
+                            call
+                        ));
+                        let res = self.expander.enter_expand(self.db, call);
+
+                        if let Ok(ExpandResult { value: Some((mark, mac)), .. }) = res {
+                            self.collect_macro_items(mark, mac);
+                        }
                     }
                 }
             }
diff --git a/crates/hir-def/src/type_ref.rs b/crates/hir-def/src/type_ref.rs
index 97aeed819af..9248059627d 100644
--- a/crates/hir-def/src/type_ref.rs
+++ b/crates/hir-def/src/type_ref.rs
@@ -5,7 +5,7 @@ use std::fmt::Write;
 
 use hir_expand::{
     name::{AsName, Name},
-    AstId, InFile,
+    AstId,
 };
 use syntax::ast::{self, HasName};
 
@@ -236,10 +236,7 @@ impl TypeRef {
                 TypeRef::DynTrait(type_bounds_from_ast(ctx, inner.type_bound_list()))
             }
             ast::Type::MacroType(mt) => match mt.macro_call() {
-                Some(mc) => ctx
-                    .ast_id(&mc)
-                    .map(|mc| TypeRef::Macro(InFile::new(ctx.file_id(), mc)))
-                    .unwrap_or(TypeRef::Error),
+                Some(mc) => ctx.ast_id(ctx.db, &mc).map(TypeRef::Macro).unwrap_or(TypeRef::Error),
                 None => TypeRef::Error,
             },
         }