convert constant promotion into a query

Author: nikomatsakis

src/librustc/dep_graph/dep_node.rs

@@ -553,6 +553,7 @@ define_dep_nodes!( <'tcx>
     [] LookupDeprecationEntry(DefId),
     [] ItemBodyNestedBodies(DefId),
     [] ConstIsRvaluePromotableToStatic(DefId),
+    [] RvaluePromotableMap(DefId),
     [] ImplParent(DefId),
     [] TraitOfItem(DefId),
     [] IsExportedSymbol(DefId),

src/librustc/middle/expr_use_visitor.rs

@@ -27,10 +27,11 @@ use middle::region;
 use ty::{self, TyCtxt, adjustment};
 
 use hir::{self, PatKind};
-
+use std::rc::Rc;
 use syntax::ast;
 use syntax::ptr::P;
 use syntax_pos::Span;
+use util::nodemap::ItemLocalMap;
 
 ///////////////////////////////////////////////////////////////////////////
 // The Delegate trait
@@ -262,15 +263,30 @@ macro_rules! return_if_err {
 }
 
 impl<'a, 'tcx> ExprUseVisitor<'a, 'tcx, 'tcx> {
+    /// Creates the ExprUseVisitor, configuring it with the various options provided:
+    ///
+    /// - `delegate` -- who receives the callbacks
+    /// - `param_env` --- parameter environment for trait lookups (esp. pertaining to `Copy`)
+    /// - `region_scope_tree` --- region scope tree for the code being analyzed
+    /// - `tables` --- typeck results for the code being analyzed
+    /// - `rvalue_promotable_map` --- if you care about rvalue promotion, then provide
+    ///   the map here (it can be computed with `tcx.rvalue_promotable_map(def_id)`).
+    ///   `None` means that rvalues will be given more conservative lifetimes.
+    ///
+    /// See also `with_infer`, which is used *during* typeck.
     pub fn new(delegate: &'a mut (Delegate<'tcx>+'a),
                tcx: TyCtxt<'a, 'tcx, 'tcx>,
                param_env: ty::ParamEnv<'tcx>,
                region_scope_tree: &'a region::ScopeTree,
-               tables: &'a ty::TypeckTables<'tcx>)
+               tables: &'a ty::TypeckTables<'tcx>,
+               rvalue_promotable_map: Option<Rc<ItemLocalMap<bool>>>)
                -> Self
     {
         ExprUseVisitor {
-            mc: mc::MemCategorizationContext::new(tcx, region_scope_tree, tables),
+            mc: mc::MemCategorizationContext::new(tcx,
+                                                  region_scope_tree,
+                                                  tables,
+                                                  rvalue_promotable_map),
             delegate,
             param_env,
         }

src/librustc/middle/mem_categorization.rs

@@ -86,6 +86,7 @@ use syntax_pos::Span;
 
 use std::fmt;
 use std::rc::Rc;
+use util::nodemap::ItemLocalMap;
 
 #[derive(Clone, PartialEq)]
 pub enum Categorization<'tcx> {
@@ -285,6 +286,7 @@ pub struct MemCategorizationContext<'a, 'gcx: 'a+'tcx, 'tcx: 'a> {
     pub tcx: TyCtxt<'a, 'gcx, 'tcx>,
     pub region_scope_tree: &'a region::ScopeTree,
     pub tables: &'a ty::TypeckTables<'tcx>,
+    rvalue_promotable_map: Option<Rc<ItemLocalMap<bool>>>,
     infcx: Option<&'a InferCtxt<'a, 'gcx, 'tcx>>,
 }
 
@@ -392,21 +394,46 @@ impl MutabilityCategory {
 impl<'a, 'tcx> MemCategorizationContext<'a, 'tcx, 'tcx> {
     pub fn new(tcx: TyCtxt<'a, 'tcx, 'tcx>,
                region_scope_tree: &'a region::ScopeTree,
-               tables: &'a ty::TypeckTables<'tcx>)
+               tables: &'a ty::TypeckTables<'tcx>,
+               rvalue_promotable_map: Option<Rc<ItemLocalMap<bool>>>)
                -> MemCategorizationContext<'a, 'tcx, 'tcx> {
-        MemCategorizationContext { tcx, region_scope_tree, tables, infcx: None }
+        MemCategorizationContext {
+            tcx,
+            region_scope_tree,
+            tables,
+            rvalue_promotable_map,
+            infcx: None
+        }
     }
 }
 
 impl<'a, 'gcx, 'tcx> MemCategorizationContext<'a, 'gcx, 'tcx> {
+    /// Creates a `MemCategorizationContext` during type inference.
+    /// This is used during upvar analysis and a few other places.
+    /// Because the typeck tables are not yet complete, the results
+    /// from the analysis must be used with caution:
+    ///
+    /// - rvalue promotions are not known, so the lifetimes of
+    ///   temporaries may be overly conservative;
+    /// - similarly, as the results of upvar analysis are not yet
+    ///   known, the results around upvar accesses may be incorrect.
     pub fn with_infer(infcx: &'a InferCtxt<'a, 'gcx, 'tcx>,
                       region_scope_tree: &'a region::ScopeTree,
                       tables: &'a ty::TypeckTables<'tcx>)
                       -> MemCategorizationContext<'a, 'gcx, 'tcx> {
+        let tcx = infcx.tcx;
+
+        // Subtle: we can't do rvalue promotion analysis until the
+        // typeck false is complete, which means that you can't trust
+        // the rvalue lifetimes that result, but that's ok, since we
+        // don't need to know those during type inference.
+        let rvalue_promotable_map = None;
+
         MemCategorizationContext {
-            tcx: infcx.tcx,
+            tcx,
             region_scope_tree,
             tables,
+            rvalue_promotable_map,
             infcx: Some(infcx),
         }
     }
@@ -871,8 +898,9 @@ impl<'a, 'gcx, 'tcx> MemCategorizationContext<'a, 'gcx, 'tcx> {
                            span: Span,
                            expr_ty: Ty<'tcx>)
                            -> cmt<'tcx> {
-        let promotable = self.tcx.rvalue_promotable_to_static.borrow().get(&id).cloned()
-                                   .unwrap_or(false);
+        let hir_id = self.tcx.hir.node_to_hir_id(id);
+        let promotable = self.rvalue_promotable_map.as_ref().map(|m| m[&hir_id.local_id])
+                                                            .unwrap_or(false);
 
         // Always promote `[T; 0]` (even when e.g. borrowed mutably).
         let promotable = match expr_ty.sty {
@@ -887,7 +915,7 @@ impl<'a, 'gcx, 'tcx> MemCategorizationContext<'a, 'gcx, 'tcx> {
         let re = if promotable {
             self.tcx.types.re_static
         } else {
-            self.temporary_scope(self.tcx.hir.node_to_hir_id(id).local_id)
+            self.temporary_scope(hir_id.local_id)
         };
         let ret = self.cat_rvalue(id, span, re, expr_ty);
         debug!("cat_rvalue_node ret {:?}", ret);

src/librustc/ty/context.rs

@@ -904,9 +904,6 @@ pub struct GlobalCtxt<'tcx> {
     /// Merge this with `selection_cache`?
     pub evaluation_cache: traits::EvaluationCache<'tcx>,
 
-    /// Maps Expr NodeId's to `true` iff `&expr` can have 'static lifetime.
-    pub rvalue_promotable_to_static: RefCell<NodeMap<bool>>,
-
     /// The definite name of the current crate after taking into account
     /// attributes, commandline parameters, etc.
     pub crate_name: Symbol,
@@ -1178,7 +1175,6 @@ impl<'a, 'gcx, 'tcx> TyCtxt<'a, 'gcx, 'tcx> {
             normalized_cache: RefCell::new(FxHashMap()),
             selection_cache: traits::SelectionCache::new(),
             evaluation_cache: traits::EvaluationCache::new(),
-            rvalue_promotable_to_static: RefCell::new(NodeMap()),
             crate_name: Symbol::intern(crate_name),
             data_layout,
             layout_interner: RefCell::new(FxHashSet()),

src/librustc/ty/maps/config.rs

@@ -29,7 +29,12 @@ pub(super) trait QueryDescription: QueryConfig {
 
 impl<M: QueryConfig<Key=DefId>> QueryDescription for M {
     default fn describe(tcx: TyCtxt, def_id: DefId) -> String {
-        format!("processing `{}`", tcx.item_path_str(def_id))
+        if !tcx.sess.verbose() {
+            format!("processing `{}`", tcx.item_path_str(def_id))
+        } else {
+            let name = unsafe { ::std::intrinsics::type_name::<M>() };
+            format!("processing `{}` applied to `{:?}`", name, def_id)
+        }
     }
 }
 
@@ -214,6 +219,13 @@ impl<'tcx> QueryDescription for queries::const_is_rvalue_promotable_to_static<'t
     }
 }
 
+impl<'tcx> QueryDescription for queries::rvalue_promotable_map<'tcx> {
+    fn describe(tcx: TyCtxt, def_id: DefId) -> String {
+        format!("checking which parts of `{}` are promotable to static",
+                tcx.item_path_str(def_id))
+    }
+}
+
 impl<'tcx> QueryDescription for queries::is_mir_available<'tcx> {
     fn describe(tcx: TyCtxt, def_id: DefId) -> String {
         format!("checking if item is mir available: `{}`",

src/librustc/ty/maps/mod.rs

@@ -37,7 +37,7 @@ use ty::{self, CrateInherentImpls, Ty, TyCtxt};
 use ty::layout::{Layout, LayoutError};
 use ty::steal::Steal;
 use ty::subst::Substs;
-use util::nodemap::{DefIdSet, DefIdMap};
+use util::nodemap::{DefIdSet, DefIdMap, ItemLocalMap};
 use util::common::{profq_msg, ProfileQueriesMsg};
 
 use rustc_data_structures::indexed_set::IdxSetBuf;
@@ -228,6 +228,7 @@ define_maps! { <'tcx>
     [] fn is_exported_symbol: IsExportedSymbol(DefId) -> bool,
     [] fn item_body_nested_bodies: ItemBodyNestedBodies(DefId) -> ExternBodyNestedBodies,
     [] fn const_is_rvalue_promotable_to_static: ConstIsRvaluePromotableToStatic(DefId) -> bool,
+    [] fn rvalue_promotable_map: RvaluePromotableMap(DefId) -> Rc<ItemLocalMap<bool>>,
     [] fn is_mir_available: IsMirAvailable(DefId) -> bool,
     [] fn vtable_methods: vtable_methods_node(ty::PolyTraitRef<'tcx>)
                           -> Rc<Vec<Option<(DefId, &'tcx Substs<'tcx>)>>>,

src/librustc_borrowck/borrowck/check_loans.rs

@@ -206,7 +206,13 @@ pub fn check_loans<'a, 'b, 'c, 'tcx>(bccx: &BorrowckCtxt<'a, 'tcx>,
         all_loans,
         param_env,
     };
-    euv::ExprUseVisitor::new(&mut clcx, bccx.tcx, param_env, &bccx.region_scope_tree, bccx.tables)
+    let rvalue_promotable_map = bccx.tcx.rvalue_promotable_map(def_id);
+    euv::ExprUseVisitor::new(&mut clcx,
+                             bccx.tcx,
+                             param_env,
+                             &bccx.region_scope_tree,
+                             bccx.tables,
+                             Some(rvalue_promotable_map))
         .consume_body(body);
 }
 

src/librustc_borrowck/borrowck/gather_loans/mod.rs

@@ -48,7 +48,13 @@ pub fn gather_loans_in_fn<'a, 'tcx>(bccx: &BorrowckCtxt<'a, 'tcx>,
         move_error_collector: move_error::MoveErrorCollector::new(),
     };
 
-    euv::ExprUseVisitor::new(&mut glcx, bccx.tcx, param_env, &bccx.region_scope_tree, bccx.tables)
+    let rvalue_promotable_map = bccx.tcx.rvalue_promotable_map(def_id);
+    euv::ExprUseVisitor::new(&mut glcx,
+                             bccx.tcx,
+                             param_env,
+                             &bccx.region_scope_tree,
+                             bccx.tables,
+                             Some(rvalue_promotable_map))
         .consume_body(bccx.body);
 
     glcx.report_potential_errors();

src/librustc_const_eval/check_match.rs

@@ -526,7 +526,7 @@ fn check_for_mutation_in_guard(cx: &MatchVisitor, guard: &hir::Expr) {
     let mut checker = MutationChecker {
         cx,
     };
-    ExprUseVisitor::new(&mut checker, cx.tcx, cx.param_env, cx.region_scope_tree, cx.tables)
+    ExprUseVisitor::new(&mut checker, cx.tcx, cx.param_env, cx.region_scope_tree, cx.tables, None)
         .walk_expr(guard);
 }
 

src/librustc_driver/driver.rs

@@ -38,7 +38,7 @@ use rustc_typeck as typeck;
 use rustc_privacy;
 use rustc_plugin::registry::Registry;
 use rustc_plugin as plugin;
-use rustc_passes::{ast_validation, no_asm, loops, consts, static_recursion, hir_stats};
+use rustc_passes::{self, ast_validation, no_asm, loops, consts, static_recursion, hir_stats};
 use rustc_const_eval::{self, check_match};
 use super::Compilation;
 use ::DefaultTransCrate;
@@ -973,6 +973,7 @@ pub fn phase_3_run_analysis_passes<'tcx, F, R>(sess: &'tcx Session,
     traits::provide(&mut local_providers);
     reachable::provide(&mut local_providers);
     rustc_const_eval::provide(&mut local_providers);
+    rustc_passes::provide(&mut local_providers);
     middle::region::provide(&mut local_providers);
     cstore::provide_local(&mut local_providers);
     lint::provide(&mut local_providers);

src/librustc_metadata/astencode.rs

@@ -56,7 +56,8 @@ impl<'a, 'b, 'tcx> IsolatedEncoder<'a, 'b, 'tcx> {
         };
 
         let lazy_body = self.lazy(body);
-        let tables = self.tcx.body_tables(body_id);
+        let body_owner_def_id = self.tcx.hir.body_owner_def_id(body_id);
+        let tables = self.tcx.typeck_tables_of(body_owner_def_id);
         let lazy_tables = self.lazy(tables);
 
         let mut visitor = NestedBodyCollector {
@@ -67,7 +68,7 @@ impl<'a, 'b, 'tcx> IsolatedEncoder<'a, 'b, 'tcx> {
         let lazy_nested_bodies = self.lazy_seq_ref_from_slice(&visitor.bodies_found);
 
         let rvalue_promotable_to_static =
-            self.tcx.rvalue_promotable_to_static.borrow()[&body.value.id];
+            self.tcx.const_is_rvalue_promotable_to_static(body_owner_def_id);
 
         self.lazy(&Ast {
             body: lazy_body,