Auto merge of #44308 - eddyb:local-index, r=arielb1

[MIR] Restrict ProjectionElem::Index and Storage{Live,Dead} to Local.

(see #44285)

r? @nikomatsakis

Author: bors

src/librustc/mir/mod.rs

@@ -901,10 +901,10 @@ pub enum StatementKind<'tcx> {
     SetDiscriminant { lvalue: Lvalue<'tcx>, variant_index: usize },
 
     /// Start a live range for the storage of the local.
-    StorageLive(Lvalue<'tcx>),
+    StorageLive(Local),
 
     /// End the current live range for the storage of the local.
-    StorageDead(Lvalue<'tcx>),
+    StorageDead(Local),
 
     /// Execute a piece of inline Assembly.
     InlineAsm {
@@ -1077,12 +1077,12 @@ pub enum ProjectionElem<'tcx, V, T> {
 }
 
 /// Alias for projections as they appear in lvalues, where the base is an lvalue
-/// and the index is an operand.
-pub type LvalueProjection<'tcx> = Projection<'tcx, Lvalue<'tcx>, Operand<'tcx>, Ty<'tcx>>;
+/// and the index is a local.
+pub type LvalueProjection<'tcx> = Projection<'tcx, Lvalue<'tcx>, Local, Ty<'tcx>>;
 
 /// Alias for projections as they appear in lvalues, where the base is an lvalue
-/// and the index is an operand.
-pub type LvalueElem<'tcx> = ProjectionElem<'tcx, Operand<'tcx>, Ty<'tcx>>;
+/// and the index is a local.
+pub type LvalueElem<'tcx> = ProjectionElem<'tcx, Local, Ty<'tcx>>;
 
 newtype_index!(Field, "field");
 
@@ -1099,7 +1099,7 @@ impl<'tcx> Lvalue<'tcx> {
         self.elem(ProjectionElem::Downcast(adt_def, variant_index))
     }
 
-    pub fn index(self, index: Operand<'tcx>) -> Lvalue<'tcx> {
+    pub fn index(self, index: Local) -> Lvalue<'tcx> {
         self.elem(ProjectionElem::Index(index))
     }
 
@@ -1701,8 +1701,8 @@ impl<'tcx> TypeFoldable<'tcx> for Statement<'tcx> {
                 lvalue: lvalue.fold_with(folder),
                 variant_index,
             },
-            StorageLive(ref lval) => StorageLive(lval.fold_with(folder)),
-            StorageDead(ref lval) => StorageDead(lval.fold_with(folder)),
+            StorageLive(ref local) => StorageLive(local.fold_with(folder)),
+            StorageDead(ref local) => StorageDead(local.fold_with(folder)),
             InlineAsm { ref asm, ref outputs, ref inputs } => InlineAsm {
                 asm: asm.clone(),
                 outputs: outputs.fold_with(folder),
@@ -1732,9 +1732,9 @@ impl<'tcx> TypeFoldable<'tcx> for Statement<'tcx> {
 
         match self.kind {
             Assign(ref lval, ref rval) => { lval.visit_with(visitor) || rval.visit_with(visitor) }
-            SetDiscriminant { ref lvalue, .. } |
-            StorageLive(ref lvalue) |
-            StorageDead(ref lvalue) => lvalue.visit_with(visitor),
+            SetDiscriminant { ref lvalue, .. } => lvalue.visit_with(visitor),
+            StorageLive(ref local) |
+            StorageDead(ref local) => local.visit_with(visitor),
             InlineAsm { ref outputs, ref inputs, .. } =>
                 outputs.visit_with(visitor) || inputs.visit_with(visitor),
 

src/librustc/mir/visit.rs

@@ -256,7 +256,9 @@ macro_rules! make_mir_visitor {
             }
 
             fn visit_local(&mut self,
-                                _local: & $($mutability)* Local) {
+                            _local: & $($mutability)* Local,
+                            _context: LvalueContext<'tcx>,
+                            _location: Location) {
             }
 
             fn visit_visibility_scope(&mut self,
@@ -358,11 +360,11 @@ macro_rules! make_mir_visitor {
                     StatementKind::SetDiscriminant{ ref $($mutability)* lvalue, .. } => {
                         self.visit_lvalue(lvalue, LvalueContext::Store, location);
                     }
-                    StatementKind::StorageLive(ref $($mutability)* lvalue) => {
-                        self.visit_lvalue(lvalue, LvalueContext::StorageLive, location);
+                    StatementKind::StorageLive(ref $($mutability)* local) => {
+                        self.visit_local(local, LvalueContext::StorageLive, location);
                     }
-                    StatementKind::StorageDead(ref $($mutability)* lvalue) => {
-                        self.visit_lvalue(lvalue, LvalueContext::StorageDead, location);
+                    StatementKind::StorageDead(ref $($mutability)* local) => {
+                        self.visit_local(local, LvalueContext::StorageDead, location);
                     }
                     StatementKind::InlineAsm { ref $($mutability)* outputs,
                                                ref $($mutability)* inputs,
@@ -610,7 +612,7 @@ macro_rules! make_mir_visitor {
                             location: Location) {
                 match *lvalue {
                     Lvalue::Local(ref $($mutability)* local) => {
-                        self.visit_local(local);
+                        self.visit_local(local, context, location);
                     }
                     Lvalue::Static(ref $($mutability)* static_) => {
                         self.visit_static(static_, context, location);
@@ -662,8 +664,8 @@ macro_rules! make_mir_visitor {
                     ProjectionElem::Field(_field, ref $($mutability)* ty) => {
                         self.visit_ty(ty, Lookup::Loc(location));
                     }
-                    ProjectionElem::Index(ref $($mutability)* operand) => {
-                        self.visit_operand(operand, location);
+                    ProjectionElem::Index(ref $($mutability)* local) => {
+                        self.visit_local(local, LvalueContext::Consume, location);
                     }
                     ProjectionElem::ConstantIndex { offset: _,
                                                     min_length: _,

src/librustc/ty/structural_impls.rs

@@ -421,7 +421,7 @@ macro_rules! CopyImpls {
     }
 }
 
-CopyImpls! { (), hir::Unsafety, abi::Abi, hir::def_id::DefId }
+CopyImpls! { (), hir::Unsafety, abi::Abi, hir::def_id::DefId, ::mir::Local }
 
 impl<'tcx, T:TypeFoldable<'tcx>, U:TypeFoldable<'tcx>> TypeFoldable<'tcx> for (T, U) {
     fn super_fold_with<'gcx: 'tcx, F: TypeFolder<'gcx, 'tcx>>(&self, folder: &mut F) -> (T, U) {

src/librustc_mir/borrow_check.rs

@@ -212,11 +212,11 @@ impl<'c, 'b, 'a: 'b+'c, 'gcx, 'tcx: 'a> DataflowResultsConsumer<'b, 'gcx>
                 // ignored by borrowck
             }
 
-            StatementKind::StorageDead(ref lvalue) => {
+            StatementKind::StorageDead(local) => {
                 // causes non-drop values to be dropped.
                 self.consume_lvalue(ContextKind::StorageDead.new(location),
                                     ConsumeKind::Consume,
-                                    (lvalue, span),
+                                    (&Lvalue::Local(local), span),
                                     flow_state)
             }
         }
@@ -710,7 +710,7 @@ mod restrictions {
 
     use rustc::hir;
     use rustc::ty::{self, TyCtxt};
-    use rustc::mir::{Lvalue, Mir, Operand, ProjectionElem};
+    use rustc::mir::{Lvalue, Mir, ProjectionElem};
 
     pub(super) struct Restrictions<'c, 'tcx: 'c> {
         mir: &'c Mir<'tcx>,
@@ -809,12 +809,7 @@ mod restrictions {
                         ProjectionElem::Downcast(..) |
                         ProjectionElem::Subslice { .. } |
                         ProjectionElem::ConstantIndex { .. } |
-                        ProjectionElem::Index(Operand::Constant(..)) => {
-                            cursor = &proj.base;
-                            continue 'cursor;
-                        }
-                        ProjectionElem::Index(Operand::Consume(ref index)) => {
-                            self.lvalue_stack.push(index); // FIXME: did old borrowck do this?
+                        ProjectionElem::Index(_) => {
                             cursor = &proj.base;
                             continue 'cursor;
                         }
@@ -1004,7 +999,7 @@ impl<'c, 'b, 'a: 'b+'c, 'gcx, 'tcx: 'a> MirBorrowckCtxt<'c, 'b, 'a, 'gcx, 'tcx>
                         ("",   format!(""), None), // (dont emit downcast info)
                     ProjectionElem::Field(field, _ty) =>
                         ("",   format!(".{}", field.index()), None),
-                    ProjectionElem::Index(ref index) =>
+                    ProjectionElem::Index(index) =>
                         ("",   format!(""), Some(index)),
                     ProjectionElem::ConstantIndex { offset, min_length, from_end: true } =>
                         ("",   format!("[{} of {}]", offset, min_length), None),
@@ -1021,23 +1016,11 @@ impl<'c, 'b, 'a: 'b+'c, 'gcx, 'tcx: 'a> MirBorrowckCtxt<'c, 'b, 'a, 'gcx, 'tcx>
                 self.append_lvalue_to_string(&proj.base, buf);
                 if let Some(index) = index_operand {
                     buf.push_str("[");
-                    self.append_operand_to_string(index, buf);
+                    self.append_lvalue_to_string(&Lvalue::Local(index), buf);
                     buf.push_str("]");
                 } else {
                     buf.push_str(&suffix);
                 }
-
-            }
-        }
-    }
-
-    fn append_operand_to_string(&self, operand: &Operand, buf: &mut String) {
-        match *operand {
-            Operand::Consume(ref lvalue) => {
-                self.append_lvalue_to_string(lvalue, buf);
-            }
-            Operand::Constant(ref constant) => {
-                buf.push_str(&format!("{:?}", constant));
             }
         }
     }

src/librustc_mir/build/expr/as_lvalue.rs

@@ -61,7 +61,7 @@ impl<'a, 'gcx, 'tcx> Builder<'a, 'gcx, 'tcx> {
                 // region_scope=None so lvalue indexes live forever. They are scalars so they
                 // do not need storage annotations, and they are often copied between
                 // places.
-                let idx = unpack!(block = this.as_operand(block, None, index));
+                let idx = unpack!(block = this.as_temp(block, None, index));
 
                 // bounds check:
                 let (len, lt) = (this.temp(usize_ty.clone(), expr_span),
@@ -70,12 +70,12 @@ impl<'a, 'gcx, 'tcx> Builder<'a, 'gcx, 'tcx> {
                                      &len, Rvalue::Len(slice.clone()));
                 this.cfg.push_assign(block, source_info, // lt = idx < len
                                      &lt, Rvalue::BinaryOp(BinOp::Lt,
-                                                           idx.clone(),
+                                                           Operand::Consume(Lvalue::Local(idx)),
                                                            Operand::Consume(len.clone())));
 
                 let msg = AssertMessage::BoundsCheck {
                     len: Operand::Consume(len),
-                    index: idx.clone()
+                    index: Operand::Consume(Lvalue::Local(idx))
                 };
                 let success = this.assert(block, Operand::Consume(lt), true,
                                           msg, expr_span);
@@ -127,7 +127,8 @@ impl<'a, 'gcx, 'tcx> Builder<'a, 'gcx, 'tcx> {
                     Some(Category::Lvalue) => false,
                     _ => true,
                 });
-                this.as_temp(block, expr.temp_lifetime, expr)
+                let temp = unpack!(block = this.as_temp(block, expr.temp_lifetime, expr));
+                block.and(Lvalue::Local(temp))
             }
         }
     }

src/librustc_mir/build/expr/as_operand.rs

@@ -74,7 +74,7 @@ impl<'a, 'gcx, 'tcx> Builder<'a, 'gcx, 'tcx> {
             Category::Rvalue(..) => {
                 let operand =
                     unpack!(block = this.as_temp(block, scope, expr));
-                block.and(Operand::Consume(operand))
+                block.and(Operand::Consume(Lvalue::Local(operand)))
             }
         }
     }

src/librustc_mir/build/expr/as_rvalue.rs

@@ -96,23 +96,23 @@ impl<'a, 'gcx, 'tcx> Builder<'a, 'gcx, 'tcx> {
             }
             ExprKind::Box { value } => {
                 let value = this.hir.mirror(value);
-                let result = this.temp(expr.ty, expr_span);
+                let result = this.local_decls.push(LocalDecl::new_temp(expr.ty, expr_span));
                 this.cfg.push(block, Statement {
                     source_info,
-                    kind: StatementKind::StorageLive(result.clone())
+                    kind: StatementKind::StorageLive(result)
                 });
                 if let Some(scope) = scope {
                     // schedule a shallow free of that memory, lest we unwind:
-                    this.schedule_drop(expr_span, scope, &result, value.ty);
+                    this.schedule_drop(expr_span, scope, &Lvalue::Local(result), value.ty);
                 }
 
                 // malloc some memory of suitable type (thus far, uninitialized):
                 let box_ = Rvalue::NullaryOp(NullOp::Box, value.ty);
-                this.cfg.push_assign(block, source_info, &result, box_);
+                this.cfg.push_assign(block, source_info, &Lvalue::Local(result), box_);
 
                 // initialize the box contents:
-                unpack!(block = this.into(&result.clone().deref(), block, value));
-                block.and(Rvalue::Use(Operand::Consume(result)))
+                unpack!(block = this.into(&Lvalue::Local(result).deref(), block, value));
+                block.and(Rvalue::Use(Operand::Consume(Lvalue::Local(result))))
             }
             ExprKind::Cast { source } => {
                 let source = this.hir.mirror(source);

src/librustc_mir/build/expr/as_temp.rs

@@ -23,7 +23,7 @@ impl<'a, 'gcx, 'tcx> Builder<'a, 'gcx, 'tcx> {
                       block: BasicBlock,
                       temp_lifetime: Option<region::Scope>,
                       expr: M)
-                      -> BlockAnd<Lvalue<'tcx>>
+                      -> BlockAnd<Local>
         where M: Mirror<'tcx, Output = Expr<'tcx>>
     {
         let expr = self.hir.mirror(expr);
@@ -34,7 +34,7 @@ impl<'a, 'gcx, 'tcx> Builder<'a, 'gcx, 'tcx> {
                     mut block: BasicBlock,
                     temp_lifetime: Option<region::Scope>,
                     expr: Expr<'tcx>)
-                    -> BlockAnd<Lvalue<'tcx>> {
+                    -> BlockAnd<Local> {
         debug!("expr_as_temp(block={:?}, temp_lifetime={:?}, expr={:?})",
                block, temp_lifetime, expr);
         let this = self;
@@ -47,13 +47,13 @@ impl<'a, 'gcx, 'tcx> Builder<'a, 'gcx, 'tcx> {
             });
         }
 
-        let expr_ty = expr.ty.clone();
-        let temp = this.temp(expr_ty.clone(), expr_span);
+        let expr_ty = expr.ty;
+        let temp = this.local_decls.push(LocalDecl::new_temp(expr_ty, expr_span));
 
         if !expr_ty.is_never() {
             this.cfg.push(block, Statement {
                 source_info,
-                kind: StatementKind::StorageLive(temp.clone())
+                kind: StatementKind::StorageLive(temp)
             });
         }
 
@@ -68,18 +68,18 @@ impl<'a, 'gcx, 'tcx> Builder<'a, 'gcx, 'tcx> {
             Category::Lvalue => {
                 let lvalue = unpack!(block = this.as_lvalue(block, expr));
                 let rvalue = Rvalue::Use(Operand::Consume(lvalue));
-                this.cfg.push_assign(block, source_info, &temp, rvalue);
+                this.cfg.push_assign(block, source_info, &Lvalue::Local(temp), rvalue);
             }
             _ => {
-                unpack!(block = this.into(&temp, block, expr));
+                unpack!(block = this.into(&Lvalue::Local(temp), block, expr));
             }
         }
 
         // In constants, temp_lifetime is None. We should not need to drop
         // anything because no values with a destructor can be created in
         // a constant at this time, even if the type may need dropping.
         if let Some(temp_lifetime) = temp_lifetime {
-            this.schedule_drop(expr_span, temp_lifetime, &temp, expr_ty);
+            this.schedule_drop(expr_span, temp_lifetime, &Lvalue::Local(temp), expr_ty);
         }
 
         block.and(temp)

src/librustc_mir/build/expr/into.rs

@@ -229,7 +229,7 @@ impl<'a, 'gcx, 'tcx> Builder<'a, 'gcx, 'tcx> {
 
                     let topmost_scope = this.topmost_scope();
                     let ptr = unpack!(block = this.as_temp(block, Some(topmost_scope), ptr));
-                    this.into(&ptr.deref(), block, val)
+                    this.into(&Lvalue::Local(ptr).deref(), block, val)
                 } else {
                     let args: Vec<_> =
                         args.into_iter()

src/librustc_mir/build/matches/mod.rs

@@ -194,7 +194,7 @@ impl<'a, 'gcx, 'tcx> Builder<'a, 'gcx, 'tcx> {
         let source_info = self.source_info(span);
         self.cfg.push(block, Statement {
             source_info,
-            kind: StatementKind::StorageLive(Lvalue::Local(local_id))
+            kind: StatementKind::StorageLive(local_id)
         });
         Lvalue::Local(local_id)
     }