Auto merge of #41917 - arielb1:mir-array, r=nagisa

Translate array drop glue using MIR

I was a bit lazy here and used a usize-based index instead of a pointer iteration. Do you think this is important @eddyb?

r? @eddyb

src/librustc/ich/impls_mir.rs

@@ -315,7 +315,8 @@ impl<'a, 'tcx> HashStable<StableHashingContext<'a, 'tcx>> for mir::Rvalue<'tcx>
             mir::Rvalue::Discriminant(ref lvalue) => {
                 lvalue.hash_stable(hcx, hasher);
             }
-            mir::Rvalue::Box(ty) => {
+            mir::Rvalue::NullaryOp(op, ty) => {
+                op.hash_stable(hcx, hasher);
                 ty.hash_stable(hcx, hasher);
             }
             mir::Rvalue::Aggregate(ref kind, ref operands) => {
@@ -374,14 +375,19 @@ impl_stable_hash_for!(enum mir::BinOp {
     Le,
     Ne,
     Ge,
-    Gt
+    Gt,
+    Offset
 });
 
 impl_stable_hash_for!(enum mir::UnOp {
     Not,
     Neg
 });
 
+impl_stable_hash_for!(enum mir::NullOp {
+    Box,
+    SizeOf
+});
 
 impl_stable_hash_for!(struct mir::Constant<'tcx> { span, ty, literal });
 

src/librustc/lib.rs

@@ -47,7 +47,7 @@
 #![cfg_attr(stage0, feature(staged_api))]
 #![cfg_attr(stage0, feature(loop_break_value))]
 
-#![recursion_limit="128"]
+#![recursion_limit="192"]
 
 extern crate arena;
 extern crate core;

src/librustc/middle/cstore.rs

@@ -245,7 +245,6 @@ pub trait CrateStore {
 
     // flags
     fn is_const_fn(&self, did: DefId) -> bool;
-    fn is_default_impl(&self, impl_did: DefId) -> bool;
     fn is_dllimport_foreign_item(&self, def: DefId) -> bool;
     fn is_statically_included_foreign_item(&self, def_id: DefId) -> bool;
 
@@ -364,7 +363,6 @@ impl CrateStore for DummyCrateStore {
 
     // flags
     fn is_const_fn(&self, did: DefId) -> bool { bug!("is_const_fn") }
-    fn is_default_impl(&self, impl_did: DefId) -> bool { bug!("is_default_impl") }
     fn is_dllimport_foreign_item(&self, id: DefId) -> bool { false }
     fn is_statically_included_foreign_item(&self, def_id: DefId) -> bool { false }
 

src/librustc/mir/mod.rs

@@ -1046,6 +1046,7 @@ pub enum Rvalue<'tcx> {
     BinaryOp(BinOp, Operand<'tcx>, Operand<'tcx>),
     CheckedBinaryOp(BinOp, Operand<'tcx>, Operand<'tcx>),
 
+    NullaryOp(NullOp, Ty<'tcx>),
     UnaryOp(UnOp, Operand<'tcx>),
 
     /// Read the discriminant of an ADT.
@@ -1054,9 +1055,6 @@ pub enum Rvalue<'tcx> {
     /// be defined to return, say, a 0) if ADT is not an enum.
     Discriminant(Lvalue<'tcx>),
 
-    /// Creates an *uninitialized* Box
-    Box(Ty<'tcx>),
-
     /// Create an aggregate value, like a tuple or struct.  This is
     /// only needed because we want to distinguish `dest = Foo { x:
     /// ..., y: ... }` from `dest.x = ...; dest.y = ...;` in the case
@@ -1132,6 +1130,8 @@ pub enum BinOp {
     Ge,
     /// The `>` operator (greater than)
     Gt,
+    /// The `ptr.offset` operator
+    Offset,
 }
 
 impl BinOp {
@@ -1144,6 +1144,14 @@ impl BinOp {
     }
 }
 
+#[derive(Copy, Clone, Debug, PartialEq, Eq, RustcEncodable, RustcDecodable)]
+pub enum NullOp {
+    /// Return the size of a value of that type
+    SizeOf,
+    /// Create a new uninitialized box for a value of that type
+    Box,
+}
+
 #[derive(Copy, Clone, Debug, PartialEq, Eq, RustcEncodable, RustcDecodable)]
 pub enum UnOp {
     /// The `!` operator for logical inversion
@@ -1167,7 +1175,7 @@ impl<'tcx> Debug for Rvalue<'tcx> {
             }
             UnaryOp(ref op, ref a) => write!(fmt, "{:?}({:?})", op, a),
             Discriminant(ref lval) => write!(fmt, "discriminant({:?})", lval),
-            Box(ref t) => write!(fmt, "Box({:?})", t),
+            NullaryOp(ref op, ref t) => write!(fmt, "{:?}({:?})", op, t),
             Ref(_, borrow_kind, ref lv) => {
                 let kind_str = match borrow_kind {
                     BorrowKind::Shared => "",
@@ -1601,7 +1609,7 @@ impl<'tcx> TypeFoldable<'tcx> for Rvalue<'tcx> {
                 CheckedBinaryOp(op, rhs.fold_with(folder), lhs.fold_with(folder)),
             UnaryOp(op, ref val) => UnaryOp(op, val.fold_with(folder)),
             Discriminant(ref lval) => Discriminant(lval.fold_with(folder)),
-            Box(ty) => Box(ty.fold_with(folder)),
+            NullaryOp(op, ty) => NullaryOp(op, ty.fold_with(folder)),
             Aggregate(ref kind, ref fields) => {
                 let kind = box match **kind {
                     AggregateKind::Array(ty) => AggregateKind::Array(ty.fold_with(folder)),
@@ -1629,7 +1637,7 @@ impl<'tcx> TypeFoldable<'tcx> for Rvalue<'tcx> {
                 rhs.visit_with(visitor) || lhs.visit_with(visitor),
             UnaryOp(_, ref val) => val.visit_with(visitor),
             Discriminant(ref lval) => lval.visit_with(visitor),
-            Box(ty) => ty.visit_with(visitor),
+            NullaryOp(_, ty) => ty.visit_with(visitor),
             Aggregate(ref kind, ref fields) => {
                 (match **kind {
                     AggregateKind::Array(ty) => ty.visit_with(visitor),

src/librustc/mir/tcx.rs

@@ -166,7 +166,8 @@ impl<'tcx> Rvalue<'tcx> {
                 let ty = op.ty(tcx, lhs_ty, rhs_ty);
                 tcx.intern_tup(&[ty, tcx.types.bool], false)
             }
-            Rvalue::UnaryOp(_, ref operand) => {
+            Rvalue::UnaryOp(UnOp::Not, ref operand) |
+            Rvalue::UnaryOp(UnOp::Neg, ref operand) => {
                 operand.ty(mir, tcx)
             }
             Rvalue::Discriminant(ref lval) => {
@@ -179,9 +180,8 @@ impl<'tcx> Rvalue<'tcx> {
                     bug!("Rvalue::Discriminant on Lvalue of type {:?}", ty);
                 }
             }
-            Rvalue::Box(t) => {
-                tcx.mk_box(t)
-            }
+            Rvalue::NullaryOp(NullOp::Box, t) => tcx.mk_box(t),
+            Rvalue::NullaryOp(NullOp::SizeOf, _) => tcx.types.usize,
             Rvalue::Aggregate(ref ak, ref ops) => {
                 match **ak {
                     AggregateKind::Array(ty) => {
@@ -227,7 +227,7 @@ impl<'tcx> BinOp {
                 assert_eq!(lhs_ty, rhs_ty);
                 lhs_ty
             }
-            &BinOp::Shl | &BinOp::Shr => {
+            &BinOp::Shl | &BinOp::Shr | &BinOp::Offset => {
                 lhs_ty // lhs_ty can be != rhs_ty
             }
             &BinOp::Eq | &BinOp::Lt | &BinOp::Le |
@@ -270,7 +270,8 @@ impl BinOp {
             BinOp::Lt => hir::BinOp_::BiLt,
             BinOp::Gt => hir::BinOp_::BiGt,
             BinOp::Le => hir::BinOp_::BiLe,
-            BinOp::Ge => hir::BinOp_::BiGe
+            BinOp::Ge => hir::BinOp_::BiGe,
+            BinOp::Offset => unreachable!()
         }
     }
 }

src/librustc/mir/visit.rs

@@ -509,7 +509,7 @@ macro_rules! make_mir_visitor {
                         self.visit_lvalue(lvalue, LvalueContext::Inspect, location);
                     }
 
-                    Rvalue::Box(ref $($mutability)* ty) => {
+                    Rvalue::NullaryOp(_op, ref $($mutability)* ty) => {
                         self.visit_ty(ty);
                     }
 

src/librustc/ty/item_path.rs

@@ -218,15 +218,15 @@ impl<'a, 'gcx, 'tcx> TyCtxt<'a, 'gcx, 'tcx> {
 
         // Always use types for non-local impls, where types are always
         // available, and filename/line-number is mostly uninteresting.
-        let use_types = !impl_def_id.is_local() || {
+        let use_types = !self.is_default_impl(impl_def_id) && (!impl_def_id.is_local() || {
             // Otherwise, use filename/line-number if forced.
             let force_no_types = FORCE_IMPL_FILENAME_LINE.with(|f| f.get());
             !force_no_types && {
                 // Otherwise, use types if we can query them without inducing a cycle.
                 ty::queries::impl_trait_ref::try_get(self, DUMMY_SP, impl_def_id).is_ok() &&
                     ty::queries::type_of::try_get(self, DUMMY_SP, impl_def_id).is_ok()
             }
-        };
+        });
 
         if !use_types {
             return self.push_impl_path_fallback(buffer, impl_def_id);

src/librustc/ty/maps.rs

@@ -774,6 +774,9 @@ define_maps! { <'tcx>
     /// True if this is a foreign item (i.e., linked via `extern { ... }`).
     [] is_foreign_item: IsForeignItem(DefId) -> bool,
 
+    /// True if this is a default impl (aka impl Foo for ..)
+    [] is_default_impl: ItemSignature(DefId) -> bool,
+
     /// Get a map with the variance of every item; use `item_variance`
     /// instead.
     [] crate_variances: crate_variances(CrateNum) -> Rc<ty::CrateVariancesMap>,

src/librustc/ty/util.rs

@@ -600,6 +600,15 @@ impl<'a, 'gcx, 'tcx> TyCtxt<'a, 'gcx, 'tcx> {
             bug!("empty_substs_for_def_id: {:?} has type parameters", item_def_id)
         })
     }
+
+    pub fn const_usize(&self, val: u16) -> ConstInt {
+        match self.sess.target.uint_type {
+            ast::UintTy::U16 => ConstInt::Usize(ConstUsize::Us16(val as u16)),
+            ast::UintTy::U32 => ConstInt::Usize(ConstUsize::Us32(val as u32)),
+            ast::UintTy::U64 => ConstInt::Usize(ConstUsize::Us64(val as u64)),
+            _ => bug!(),
+        }
+    }
 }
 
 pub struct TypeIdHasher<'a, 'gcx: 'a+'tcx, 'tcx: 'a, W> {

src/librustc_borrowck/borrowck/mir/elaborate_drops.rs

@@ -22,7 +22,7 @@ use rustc::util::nodemap::FxHashMap;
 use rustc_data_structures::indexed_set::IdxSetBuf;
 use rustc_data_structures::indexed_vec::Idx;
 use rustc_mir::util::patch::MirPatch;
-use rustc_mir::util::elaborate_drops::{DropFlagState, elaborate_drop};
+use rustc_mir::util::elaborate_drops::{DropFlagState, Unwind, elaborate_drop};
 use rustc_mir::util::elaborate_drops::{DropElaborator, DropStyle, DropFlagMode};
 use syntax::ast;
 use syntax_pos::Span;
@@ -399,14 +399,13 @@ impl<'b, 'tcx> ElaborateDropsCtxt<'b, 'tcx> {
                                     ctxt: self
                                 },
                                 terminator.source_info,
-                                data.is_cleanup,
                                 location,
                                 path,
                                 target,
                                 if data.is_cleanup {
-                                    None
+                                    Unwind::InCleanup
                                 } else {
-                                    Some(Option::unwrap_or(unwind, resume_block))
+                                    Unwind::To(Option::unwrap_or(unwind, resume_block))
                                 },
                                 bb)
                         }
@@ -455,6 +454,7 @@ impl<'b, 'tcx> ElaborateDropsCtxt<'b, 'tcx> {
         let bb = loc.block;
         let data = &self.mir[bb];
         let terminator = data.terminator();
+        assert!(!data.is_cleanup, "DropAndReplace in unwind path not supported");
 
         let assign = Statement {
             kind: StatementKind::Assign(location.clone(), Rvalue::Use(value.clone())),
@@ -477,7 +477,7 @@ impl<'b, 'tcx> ElaborateDropsCtxt<'b, 'tcx> {
                 kind: TerminatorKind::Goto { target: target },
                 ..*terminator
             }),
-            is_cleanup: data.is_cleanup,
+            is_cleanup: false,
         });
 
         match self.move_data().rev_lookup.find(location) {
@@ -491,11 +491,10 @@ impl<'b, 'tcx> ElaborateDropsCtxt<'b, 'tcx> {
                         ctxt: self
                     },
                     terminator.source_info,
-                    data.is_cleanup,
                     location,
                     path,
                     target,
-                    Some(unwind),
+                    Unwind::To(unwind),
                     bb);
                 on_all_children_bits(self.tcx, self.mir, self.move_data(), path, |child| {
                     self.set_drop_flag(Location { block: target, statement_index: 0 },

src/librustc_borrowck/borrowck/mir/gather_moves.rs

@@ -438,7 +438,8 @@ impl<'a, 'tcx> MoveDataBuilder<'a, 'tcx> {
             Rvalue::Ref(..) |
             Rvalue::Discriminant(..) |
             Rvalue::Len(..) |
-            Rvalue::Box(..) => {
+            Rvalue::NullaryOp(NullOp::SizeOf, _) |
+            Rvalue::NullaryOp(NullOp::Box, _) => {
                 // This returns an rvalue with uninitialized contents. We can't
                 // move out of it here because it is an rvalue - assignments always
                 // completely initialize their lvalue.

src/librustc_borrowck/borrowck/mir/mod.rs

@@ -59,7 +59,7 @@ pub fn borrowck_mir(bcx: &mut BorrowckCtxt,
                     attributes: &[ast::Attribute]) {
     let tcx = bcx.tcx;
     let def_id = tcx.hir.local_def_id(id);
-    debug!("borrowck_mir({}) UNIMPLEMENTED", tcx.item_path_str(def_id));
+    debug!("borrowck_mir({:?}) UNIMPLEMENTED", def_id);
 
     // It is safe for us to borrow `mir_validated()`: `optimized_mir`
     // steals it, but it forces the `borrowck` query.

src/librustc_data_structures/indexed_vec.rs

@@ -212,6 +212,13 @@ impl<I: Idx, T> IndexMut<I> for IndexVec<I, T> {
     }
 }
 
+impl<I: Idx, T> Default for IndexVec<I, T> {
+    #[inline]
+    fn default() -> Self {
+        Self::new()
+    }
+}
+
 impl<I: Idx, T> Extend<T> for IndexVec<I, T> {
     #[inline]
     fn extend<J: IntoIterator<Item = T>>(&mut self, iter: J) {

src/librustc_metadata/cstore_impl.rs

@@ -106,6 +106,7 @@ provide! { <'tcx> tcx, def_id, cdata
     closure_type => { cdata.closure_ty(def_id.index, tcx) }
     inherent_impls => { Rc::new(cdata.get_inherent_implementations_for_type(def_id.index)) }
     is_foreign_item => { cdata.is_foreign_item(def_id.index) }
+    is_default_impl => { cdata.is_default_impl(def_id.index) }
     describe_def => { cdata.get_def(def_id.index) }
     def_span => { cdata.get_span(def_id.index, &tcx.sess) }
     stability => { cdata.get_stability(def_id.index) }
@@ -176,11 +177,6 @@ impl CrateStore for cstore::CStore {
         self.get_crate_data(did.krate).is_const_fn(did.index)
     }
 
-    fn is_default_impl(&self, impl_did: DefId) -> bool {
-        self.dep_graph.read(DepNode::MetaData(impl_did));
-        self.get_crate_data(impl_did.krate).is_default_impl(impl_did.index)
-    }
-
     fn is_statically_included_foreign_item(&self, def_id: DefId) -> bool
     {
         self.do_is_statically_included_foreign_item(def_id)
@@ -403,7 +399,7 @@ impl CrateStore for cstore::CStore {
         }
 
         self.dep_graph.read(DepNode::MetaData(def_id));
-        debug!("item_body({}): inlining item", tcx.item_path_str(def_id));
+        debug!("item_body({:?}): inlining item", def_id);
 
         self.get_crate_data(def_id.krate).item_body(tcx, def_id.index)
     }
@@ -515,4 +511,4 @@ impl CrateStore for cstore::CStore {
         drop(visible_parent_map);
         self.visible_parent_map.borrow()
     }
-}
+}

src/librustc_mir/build/expr/as_rvalue.rs

@@ -97,7 +97,8 @@ impl<'a, 'gcx, 'tcx> Builder<'a, 'gcx, 'tcx> {
                 let value = this.hir.mirror(value);
                 let result = this.temp(expr.ty, expr_span);
                 // to start, malloc some memory of suitable type (thus far, uninitialized):
-                this.cfg.push_assign(block, source_info, &result, Rvalue::Box(value.ty));
+                let box_ = Rvalue::NullaryOp(NullOp::Box, value.ty);
+                this.cfg.push_assign(block, source_info, &result, box_);
                 this.in_scope(value_extents, block, |this| {
                     // schedule a shallow free of that memory, lest we unwind:
                     this.schedule_box_free(expr_span, value_extents, &result, value.ty);

src/librustc_mir/shim.rs

@@ -198,11 +198,10 @@ fn build_drop_shim<'a, 'tcx>(tcx: ty::TyCtxt<'a, 'tcx, 'tcx>,
             elaborate_drops::elaborate_drop(
                 &mut elaborator,
                 source_info,
-                false,
                 &dropee,
                 (),
                 return_block,
-                Some(resume_block),
+                elaborate_drops::Unwind::To(resume_block),
                 START_BLOCK
             );
             elaborator.patch

src/librustc_mir/transform/erase_regions.rs

@@ -53,7 +53,7 @@ impl<'a, 'tcx> MutVisitor<'tcx> for EraseRegionsVisitor<'a, 'tcx> {
             Rvalue::CheckedBinaryOp(..) |
             Rvalue::UnaryOp(..) |
             Rvalue::Discriminant(..) |
-            Rvalue::Box(..) |
+            Rvalue::NullaryOp(..) |
             Rvalue::Aggregate(..) => {
                 // These variants don't contain regions.
             }