Rollup of 14 pull requests

.gitattributes

@@ -5,6 +5,7 @@
 *.h rust
 *.rs rust diff=rust
 *.fixed linguist-language=Rust
+*.mir linguist-language=Rust
 src/etc/installer/gfx/* binary
 *.woff binary
 src/vendor/** -text

compiler/rustc_ast_passes/src/ast_validation.rs

@@ -522,7 +522,7 @@ impl<'a> AstValidator<'a> {
             self.err_handler()
                 .struct_span_err(ident.span, "functions in `extern` blocks cannot have qualifiers")
                 .span_label(self.current_extern_span(), "in this `extern` block")
-                .span_suggestion(
+                .span_suggestion_verbose(
                     span.until(ident.span.shrink_to_lo()),
                     "remove the qualifiers",
                     "fn ".to_string(),

compiler/rustc_mir/src/transform/const_prop.rs

@@ -800,7 +800,7 @@ impl<'mir, 'tcx> ConstPropagator<'mir, 'tcx> {
             }
         }
 
-        trace!("attepting to replace {:?} with {:?}", rval, value);
+        trace!("attempting to replace {:?} with {:?}", rval, value);
         if let Err(e) = self.ecx.const_validate_operand(
             value,
             vec![],
@@ -890,6 +890,10 @@ impl<'mir, 'tcx> ConstPropagator<'mir, 'tcx> {
             return false;
         }
 
+        if !self.tcx.consider_optimizing(|| format!("ConstantPropagation - OpTy: {:?}", op)) {
+            return false;
+        }
+
         match *op {
             interpret::Operand::Immediate(Immediate::Scalar(ScalarMaybeUninit::Scalar(s))) => {
                 s.is_bits()

compiler/rustc_mir/src/transform/early_otherwise_branch.rs

@@ -46,6 +46,10 @@ impl<'tcx> MirPass<'tcx> for EarlyOtherwiseBranch {
         let should_cleanup = !opts_to_apply.is_empty();
 
         for opt_to_apply in opts_to_apply {
+            if !tcx.consider_optimizing(|| format!("EarlyOtherwiseBranch {:?}", &opt_to_apply)) {
+                break;
+            }
+
             trace!("SUCCESS: found optimization possibility to apply: {:?}", &opt_to_apply);
 
             let statements_before =

compiler/rustc_mir/src/transform/instcombine.rs

@@ -39,13 +39,21 @@ pub struct InstCombineVisitor<'tcx> {
     tcx: TyCtxt<'tcx>,
 }
 
+impl<'tcx> InstCombineVisitor<'tcx> {
+    fn should_combine(&self, rvalue: &Rvalue<'tcx>, location: Location) -> bool {
+        self.tcx.consider_optimizing(|| {
+            format!("InstCombine - Rvalue: {:?} Location: {:?}", rvalue, location)
+        })
+    }
+}
+
 impl<'tcx> MutVisitor<'tcx> for InstCombineVisitor<'tcx> {
     fn tcx(&self) -> TyCtxt<'tcx> {
         self.tcx
     }
 
     fn visit_rvalue(&mut self, rvalue: &mut Rvalue<'tcx>, location: Location) {
-        if self.optimizations.and_stars.remove(&location) {
+        if self.optimizations.and_stars.remove(&location) && self.should_combine(rvalue, location) {
             debug!("replacing `&*`: {:?}", rvalue);
             let new_place = match rvalue {
                 Rvalue::Ref(_, _, place) => {
@@ -67,18 +75,24 @@ impl<'tcx> MutVisitor<'tcx> for InstCombineVisitor<'tcx> {
         }
 
         if let Some(constant) = self.optimizations.arrays_lengths.remove(&location) {
-            debug!("replacing `Len([_; N])`: {:?}", rvalue);
-            *rvalue = Rvalue::Use(Operand::Constant(box constant));
+            if self.should_combine(rvalue, location) {
+                debug!("replacing `Len([_; N])`: {:?}", rvalue);
+                *rvalue = Rvalue::Use(Operand::Constant(box constant));
+            }
         }
 
         if let Some(operand) = self.optimizations.unneeded_equality_comparison.remove(&location) {
-            debug!("replacing {:?} with {:?}", rvalue, operand);
-            *rvalue = Rvalue::Use(operand);
+            if self.should_combine(rvalue, location) {
+                debug!("replacing {:?} with {:?}", rvalue, operand);
+                *rvalue = Rvalue::Use(operand);
+            }
         }
 
         if let Some(place) = self.optimizations.unneeded_deref.remove(&location) {
-            debug!("unneeded_deref: replacing {:?} with {:?}", rvalue, place);
-            *rvalue = Rvalue::Use(Operand::Copy(place));
+            if self.should_combine(rvalue, location) {
+                debug!("unneeded_deref: replacing {:?} with {:?}", rvalue, place);
+                *rvalue = Rvalue::Use(Operand::Copy(place));
+            }
         }
 
         self.super_rvalue(rvalue, location)

compiler/rustc_mir/src/transform/lower_intrinsics.rs

@@ -11,15 +11,11 @@ pub struct LowerIntrinsics;
 
 impl<'tcx> MirPass<'tcx> for LowerIntrinsics {
     fn run_pass(&self, tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>) {
-        for block in body.basic_blocks_mut() {
+        let (basic_blocks, local_decls) = body.basic_blocks_and_local_decls_mut();
+        for block in basic_blocks {
             let terminator = block.terminator.as_mut().unwrap();
-            if let TerminatorKind::Call {
-                func: Operand::Constant(box Constant { literal: ty::Const { ty: func_ty, .. }, .. }),
-                args,
-                destination,
-                ..
-            } = &mut terminator.kind
-            {
+            if let TerminatorKind::Call { func, args, destination, .. } = &mut terminator.kind {
+                let func_ty = func.ty(local_decls, tcx);
                 let (intrinsic_name, substs) = match resolve_rust_intrinsic(tcx, func_ty) {
                     None => continue,
                     Some(it) => it,

compiler/rustc_mir/src/transform/match_branches.rs

@@ -43,8 +43,13 @@ impl<'tcx> MirPass<'tcx> for MatchBranchSimplification {
         }
 
         let param_env = tcx.param_env(body.source.def_id());
+        let def_id = body.source.def_id();
         let (bbs, local_decls) = body.basic_blocks_and_local_decls_mut();
         'outer: for bb_idx in bbs.indices() {
+            if !tcx.consider_optimizing(|| format!("MatchBranchSimplification {:?} ", def_id)) {
+                continue;
+            }
+
             let (discr, val, switch_ty, first, second) = match bbs[bb_idx].terminator().kind {
                 TerminatorKind::SwitchInt {
                     discr: ref discr @ (Operand::Copy(_) | Operand::Move(_)),

compiler/rustc_mir/src/transform/multiple_return_terminators.rs

@@ -16,6 +16,7 @@ impl<'tcx> MirPass<'tcx> for MultipleReturnTerminators {
 
         // find basic blocks with no statement and a return terminator
         let mut bbs_simple_returns = BitSet::new_empty(body.basic_blocks().len());
+        let def_id = body.source.def_id();
         let bbs = body.basic_blocks_mut();
         for idx in bbs.indices() {
             if bbs[idx].statements.is_empty()
@@ -26,6 +27,10 @@ impl<'tcx> MirPass<'tcx> for MultipleReturnTerminators {
         }
 
         for bb in bbs {
+            if !tcx.consider_optimizing(|| format!("MultipleReturnTerminators {:?} ", def_id)) {
+                break;
+            }
+
             if let TerminatorKind::Goto { target } = bb.terminator().kind {
                 if bbs_simple_returns.contains(target) {
                     bb.terminator_mut().kind = TerminatorKind::Return;

compiler/rustc_mir/src/transform/nrvo.rs

@@ -38,18 +38,22 @@ impl<'tcx> MirPass<'tcx> for RenameReturnPlace {
             return;
         }
 
+        let def_id = body.source.def_id();
         let returned_local = match local_eligible_for_nrvo(body) {
             Some(l) => l,
             None => {
-                debug!("`{:?}` was ineligible for NRVO", body.source.def_id());
+                debug!("`{:?}` was ineligible for NRVO", def_id);
                 return;
             }
         };
 
+        if !tcx.consider_optimizing(|| format!("RenameReturnPlace {:?}", def_id)) {
+            return;
+        }
+
         debug!(
             "`{:?}` was eligible for NRVO, making {:?} the return place",
-            body.source.def_id(),
-            returned_local
+            def_id, returned_local
         );
 
         RenameToReturnPlace { tcx, to_rename: returned_local }.visit_body(body);

compiler/rustc_mir/src/transform/remove_unneeded_drops.rs

@@ -21,6 +21,12 @@ impl<'tcx> MirPass<'tcx> for RemoveUnneededDrops {
         opt_finder.visit_body(body);
         let should_simplify = !opt_finder.optimizations.is_empty();
         for (loc, target) in opt_finder.optimizations {
+            if !tcx
+                .consider_optimizing(|| format!("RemoveUnneededDrops {:?} ", body.source.def_id()))
+            {
+                break;
+            }
+
             let terminator = body.basic_blocks_mut()[loc.block].terminator_mut();
             debug!("SUCCESS: replacing `drop` with goto({:?})", target);
             terminator.kind = TerminatorKind::Goto { target };

compiler/rustc_mir/src/transform/unreachable_prop.rs

@@ -50,6 +50,12 @@ impl MirPass<'_> for UnreachablePropagation {
 
         let replaced = !replacements.is_empty();
         for (bb, terminator_kind) in replacements {
+            if !tcx.consider_optimizing(|| {
+                format!("UnreachablePropagation {:?} ", body.source.def_id())
+            }) {
+                break;
+            }
+
             body.basic_blocks_mut()[bb].terminator_mut().kind = terminator_kind;
         }
 

compiler/rustc_mir_build/src/build/expr/as_place.rs

@@ -160,7 +160,30 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
                 expr_span,
                 source_info,
             ),
-            ExprKind::SelfRef => block.and(PlaceBuilder::from(Local::new(1))),
+            ExprKind::UpvarRef { closure_def_id, var_hir_id } => {
+                let capture = this
+                    .hir
+                    .typeck_results
+                    .closure_captures
+                    .get(&closure_def_id)
+                    .and_then(|captures| captures.get_full(&var_hir_id));
+
+                if capture.is_none() {
+                    if !this.hir.tcx().features().capture_disjoint_fields {
+                        bug!(
+                            "No associated capture found for {:?} even though \
+                            capture_disjoint_fields isn't enabled",
+                            expr.kind
+                        )
+                    }
+                    // FIXME(project-rfc-2229#24): Handle this case properly
+                }
+
+                // Unwrap until the FIXME has been resolved
+                let (capture_index, _, upvar_id) = capture.unwrap();
+                this.lower_closure_capture(block, capture_index, *upvar_id)
+            }
+
             ExprKind::VarRef { id } => {
                 let place_builder = if this.is_bound_var_in_guard(id) {
                     let index = this.var_local_id(id, RefWithinGuard);
@@ -270,6 +293,61 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
         }
     }
 
+    /// Lower a closure/generator capture by representing it as a field
+    /// access within the desugared closure/generator.
+    ///
+    /// `capture_index` is the index of the capture within the desugared
+    /// closure/generator.
+    fn lower_closure_capture(
+        &mut self,
+        block: BasicBlock,
+        capture_index: usize,
+        upvar_id: ty::UpvarId,
+    )  -> BlockAnd<PlaceBuilder<'tcx>> {
+        let closure_ty = self
+            .hir
+            .typeck_results()
+            .node_type(self.hir.tcx().hir().local_def_id_to_hir_id(upvar_id.closure_expr_id));
+
+        // Captures are represented using fields inside a structure.
+        // This represents accessing self in the closure structure
+        let mut place_builder = PlaceBuilder::from(Local::new(1));
+
+        // In case of Fn/FnMut closures we must deref to access the fields
+        // Generators are considered FnOnce, so we ignore this step for them.
+        if let ty::Closure(_, closure_substs) = closure_ty.kind() {
+            match self.hir.infcx().closure_kind(closure_substs).unwrap() {
+                ty::ClosureKind::Fn | ty::ClosureKind::FnMut => {
+                    place_builder = place_builder.deref();
+                }
+                ty::ClosureKind::FnOnce => {}
+            }
+        }
+
+        let substs = match closure_ty.kind() {
+            ty::Closure(_, substs) => ty::UpvarSubsts::Closure(substs),
+            ty::Generator(_, substs, _) => ty::UpvarSubsts::Generator(substs),
+            _ => bug!("Lowering capture for non-closure type {:?}", closure_ty)
+        };
+
+        // Access the capture by accessing the field within the Closure struct.
+        //
+        // We must have inferred the capture types since we are building MIR, therefore
+        // it's safe to call `upvar_tys` and we can unwrap here because
+        // we know that the capture exists and is the `capture_index`-th capture.
+        let var_ty = substs.upvar_tys().nth(capture_index).unwrap();
+        place_builder = place_builder.field(Field::new(capture_index), var_ty);
+
+        // If the variable is captured via ByRef(Immutable/Mutable) Borrow,
+        // we need to deref it
+        match self.hir.typeck_results.upvar_capture(upvar_id) {
+            ty::UpvarCapture::ByRef(_) => {
+                block.and(place_builder.deref())
+            }
+            ty::UpvarCapture::ByValue(_) => block.and(place_builder),
+        }
+    }
+
     /// Lower an index expression
     ///
     /// This has two complications;

compiler/rustc_mir_build/src/build/expr/as_rvalue.rs

@@ -250,7 +250,7 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
             | ExprKind::Deref { .. }
             | ExprKind::Index { .. }
             | ExprKind::VarRef { .. }
-            | ExprKind::SelfRef
+            | ExprKind::UpvarRef { .. }
             | ExprKind::Break { .. }
             | ExprKind::Continue { .. }
             | ExprKind::Return { .. }

compiler/rustc_mir_build/src/build/expr/category.rs

@@ -38,7 +38,7 @@ impl Category {
             ExprKind::Field { .. }
             | ExprKind::Deref { .. }
             | ExprKind::Index { .. }
-            | ExprKind::SelfRef
+            | ExprKind::UpvarRef { .. }
             | ExprKind::VarRef { .. }
             | ExprKind::PlaceTypeAscription { .. }
             | ExprKind::ValueTypeAscription { .. } => Some(Category::Place),

compiler/rustc_mir_build/src/build/expr/into.rs

@@ -400,7 +400,7 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
 
             // Avoid creating a temporary
             ExprKind::VarRef { .. }
-            | ExprKind::SelfRef
+            | ExprKind::UpvarRef { .. }
             | ExprKind::PlaceTypeAscription { .. }
             | ExprKind::ValueTypeAscription { .. } => {
                 debug_assert!(Category::of(&expr.kind) == Some(Category::Place));