Auto merge of #2738 - RalfJung:rustup, r=RalfJung

Rustup

14 files changed, 94 insertions, 109 deletions

diff --git a/compiler/rustc_mir_transform/src/check_unsafety.rs b/compiler/rustc_mir_transform/src/check_unsafety.rs
index 9c22b5df73c..adf6ae4c727 100644
--- a/compiler/rustc_mir_transform/src/check_unsafety.rs
+++ b/compiler/rustc_mir_transform/src/check_unsafety.rs
@@ -490,10 +490,10 @@ fn check_unused_unsafe(
     unused_unsafes
 }
 
-fn unsafety_check_result<'tcx>(
-    tcx: TyCtxt<'tcx>,
+fn unsafety_check_result(
+    tcx: TyCtxt<'_>,
     def: ty::WithOptConstParam<LocalDefId>,
-) -> &'tcx UnsafetyCheckResult {
+) -> &UnsafetyCheckResult {
     debug!("unsafety_violations({:?})", def);
 
     // N.B., this borrow is valid because all the consumers of
diff --git a/compiler/rustc_mir_transform/src/cleanup_post_borrowck.rs b/compiler/rustc_mir_transform/src/cleanup_post_borrowck.rs
index 3378923c22c..d435d3ee69b 100644
--- a/compiler/rustc_mir_transform/src/cleanup_post_borrowck.rs
+++ b/compiler/rustc_mir_transform/src/cleanup_post_borrowck.rs
@@ -1,39 +1,44 @@
-//! This module provides a pass to replacing the following statements with
-//! [`Nop`]s
+//! This module provides a pass that removes parts of MIR that are no longer relevant after
+//! analysis phase and borrowck. In particular, it removes false edges, user type annotations and
+//! replaces following statements with [`Nop`]s:
 //!
 //!   - [`AscribeUserType`]
 //!   - [`FakeRead`]
 //!   - [`Assign`] statements with a [`Shallow`] borrow
 //!
-//! The `CleanFakeReadsAndBorrows` "pass" is actually implemented as two
-//! traversals (aka visits) of the input MIR. The first traversal,
-//! `DeleteAndRecordFakeReads`, deletes the fake reads and finds the
-//! temporaries read by [`ForMatchGuard`] reads, and `DeleteFakeBorrows`
-//! deletes the initialization of those temporaries.
-//!
 //! [`AscribeUserType`]: rustc_middle::mir::StatementKind::AscribeUserType
-//! [`Shallow`]: rustc_middle::mir::BorrowKind::Shallow
-//! [`FakeRead`]: rustc_middle::mir::StatementKind::FakeRead
 //! [`Assign`]: rustc_middle::mir::StatementKind::Assign
-//! [`ForMatchGuard`]: rustc_middle::mir::FakeReadCause::ForMatchGuard
+//! [`FakeRead`]: rustc_middle::mir::StatementKind::FakeRead
 //! [`Nop`]: rustc_middle::mir::StatementKind::Nop
+//! [`Shallow`]: rustc_middle::mir::BorrowKind::Shallow
 
 use crate::MirPass;
-use rustc_middle::mir::visit::MutVisitor;
-use rustc_middle::mir::{Body, BorrowKind, Location, Rvalue};
-use rustc_middle::mir::{Statement, StatementKind};
+use rustc_middle::mir::{Body, BorrowKind, Rvalue, StatementKind, TerminatorKind};
 use rustc_middle::ty::TyCtxt;
 
-pub struct CleanupNonCodegenStatements;
+pub struct CleanupPostBorrowck;
 
-pub struct DeleteNonCodegenStatements<'tcx> {
-    tcx: TyCtxt<'tcx>,
-}
+impl<'tcx> MirPass<'tcx> for CleanupPostBorrowck {
+    fn run_pass(&self, _tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>) {
+        for basic_block in body.basic_blocks.as_mut() {
+            for statement in basic_block.statements.iter_mut() {
+                match statement.kind {
+                    StatementKind::AscribeUserType(..)
+                    | StatementKind::Assign(box (_, Rvalue::Ref(_, BorrowKind::Shallow, _)))
+                    | StatementKind::FakeRead(..) => statement.make_nop(),
+                    _ => (),
+                }
+            }
+            let terminator = basic_block.terminator_mut();
+            match terminator.kind {
+                TerminatorKind::FalseEdge { real_target, .. }
+                | TerminatorKind::FalseUnwind { real_target, .. } => {
+                    terminator.kind = TerminatorKind::Goto { target: real_target };
+                }
+                _ => {}
+            }
+        }
 
-impl<'tcx> MirPass<'tcx> for CleanupNonCodegenStatements {
-    fn run_pass(&self, tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>) {
-        let mut delete = DeleteNonCodegenStatements { tcx };
-        delete.visit_body_preserves_cfg(body);
         body.user_type_annotations.raw.clear();
 
         for decl in &mut body.local_decls {
@@ -41,19 +46,3 @@ impl<'tcx> MirPass<'tcx> for CleanupNonCodegenStatements {
         }
     }
 }
-
-impl<'tcx> MutVisitor<'tcx> for DeleteNonCodegenStatements<'tcx> {
-    fn tcx(&self) -> TyCtxt<'tcx> {
-        self.tcx
-    }
-
-    fn visit_statement(&mut self, statement: &mut Statement<'tcx>, location: Location) {
-        match statement.kind {
-            StatementKind::AscribeUserType(..)
-            | StatementKind::Assign(box (_, Rvalue::Ref(_, BorrowKind::Shallow, _)))
-            | StatementKind::FakeRead(..) => statement.make_nop(),
-            _ => (),
-        }
-        self.super_statement(statement, location);
-    }
-}
diff --git a/compiler/rustc_mir_transform/src/const_prop.rs b/compiler/rustc_mir_transform/src/const_prop.rs
index 044b7ce65bd..e384cfe1659 100644
--- a/compiler/rustc_mir_transform/src/const_prop.rs
+++ b/compiler/rustc_mir_transform/src/const_prop.rs
@@ -701,8 +701,8 @@ impl<'mir, 'tcx> ConstPropagator<'mir, 'tcx> {
                     BinOp::Mul if const_arg.layout.ty.is_integral() && arg_value == 0 => {
                         if let Rvalue::CheckedBinaryOp(_, _) = rvalue {
                             let val = Immediate::ScalarPair(
-                                const_arg.to_scalar().into(),
-                                Scalar::from_bool(false).into(),
+                                const_arg.to_scalar(),
+                                Scalar::from_bool(false),
                             );
                             this.ecx.write_immediate(val, &dest)
                         } else {
diff --git a/compiler/rustc_mir_transform/src/coverage/graph.rs b/compiler/rustc_mir_transform/src/coverage/graph.rs
index 782129be088..78d28f1ebab 100644
--- a/compiler/rustc_mir_transform/src/coverage/graph.rs
+++ b/compiler/rustc_mir_transform/src/coverage/graph.rs
@@ -282,9 +282,9 @@ impl graph::WithPredecessors for CoverageGraph {
 
 rustc_index::newtype_index! {
     /// A node in the control-flow graph of CoverageGraph.
+    #[debug_format = "bcb{}"]
     pub(super) struct BasicCoverageBlock {
-        DEBUG_FORMAT = "bcb{}",
-        const START_BCB = 0,
+        const START_BCB = 0;
     }
 }
 
diff --git a/compiler/rustc_mir_transform/src/coverage/mod.rs b/compiler/rustc_mir_transform/src/coverage/mod.rs
index 60481014488..1468afc6456 100644
--- a/compiler/rustc_mir_transform/src/coverage/mod.rs
+++ b/compiler/rustc_mir_transform/src/coverage/mod.rs
@@ -533,10 +533,10 @@ fn make_code_region(
     }
 }
 
-fn fn_sig_and_body<'tcx>(
-    tcx: TyCtxt<'tcx>,
+fn fn_sig_and_body(
+    tcx: TyCtxt<'_>,
     def_id: DefId,
-) -> (Option<&'tcx rustc_hir::FnSig<'tcx>>, &'tcx rustc_hir::Body<'tcx>) {
+) -> (Option<&rustc_hir::FnSig<'_>>, &rustc_hir::Body<'_>) {
     // FIXME(#79625): Consider improving MIR to provide the information needed, to avoid going back
     // to HIR for it.
     let hir_node = tcx.hir().get_if_local(def_id).expect("expected DefId is local");
diff --git a/compiler/rustc_mir_transform/src/coverage/query.rs b/compiler/rustc_mir_transform/src/coverage/query.rs
index dc1e68b253e..3bd7f31b45d 100644
--- a/compiler/rustc_mir_transform/src/coverage/query.rs
+++ b/compiler/rustc_mir_transform/src/coverage/query.rs
@@ -136,7 +136,7 @@ fn coverageinfo<'tcx>(tcx: TyCtxt<'tcx>, instance_def: ty::InstanceDef<'tcx>) ->
     coverage_visitor.info
 }
 
-fn covered_code_regions<'tcx>(tcx: TyCtxt<'tcx>, def_id: DefId) -> Vec<&'tcx CodeRegion> {
+fn covered_code_regions(tcx: TyCtxt<'_>, def_id: DefId) -> Vec<&CodeRegion> {
     let body = mir_body(tcx, def_id);
     body.basic_blocks
         .iter()
@@ -163,7 +163,7 @@ fn is_inlined(body: &Body<'_>, statement: &Statement<'_>) -> bool {
 /// This function ensures we obtain the correct MIR for the given item irrespective of
 /// whether that means const mir or runtime mir. For `const fn` this opts for runtime
 /// mir.
-fn mir_body<'tcx>(tcx: TyCtxt<'tcx>, def_id: DefId) -> &'tcx mir::Body<'tcx> {
+fn mir_body(tcx: TyCtxt<'_>, def_id: DefId) -> &mir::Body<'_> {
     let id = ty::WithOptConstParam::unknown(def_id);
     let def = ty::InstanceDef::Item(id);
     tcx.instance_mir(def)
diff --git a/compiler/rustc_mir_transform/src/coverage/tests.rs b/compiler/rustc_mir_transform/src/coverage/tests.rs
index eba6a2b34e4..fa7f22303a8 100644
--- a/compiler/rustc_mir_transform/src/coverage/tests.rs
+++ b/compiler/rustc_mir_transform/src/coverage/tests.rs
@@ -169,7 +169,7 @@ impl<'tcx> MockBlocks<'tcx> {
     }
 }
 
-fn debug_basic_blocks<'tcx>(mir_body: &Body<'tcx>) -> String {
+fn debug_basic_blocks(mir_body: &Body<'_>) -> String {
     format!(
         "{:?}",
         mir_body
diff --git a/compiler/rustc_mir_transform/src/deduce_param_attrs.rs b/compiler/rustc_mir_transform/src/deduce_param_attrs.rs
index 92f1fff6beb..ddab7bbb2e3 100644
--- a/compiler/rustc_mir_transform/src/deduce_param_attrs.rs
+++ b/compiler/rustc_mir_transform/src/deduce_param_attrs.rs
@@ -129,7 +129,7 @@ impl<'tcx> Visitor<'tcx> for DeduceReadOnly {
 }
 
 /// Returns true if values of a given type will never be passed indirectly, regardless of ABI.
-fn type_will_always_be_passed_directly<'tcx>(ty: Ty<'tcx>) -> bool {
+fn type_will_always_be_passed_directly(ty: Ty<'_>) -> bool {
     matches!(
         ty.kind(),
         ty::Bool
diff --git a/compiler/rustc_mir_transform/src/dest_prop.rs b/compiler/rustc_mir_transform/src/dest_prop.rs
index 3e45319431c..08e296a8371 100644
--- a/compiler/rustc_mir_transform/src/dest_prop.rs
+++ b/compiler/rustc_mir_transform/src/dest_prop.rs
@@ -129,6 +129,7 @@
 
 use std::collections::hash_map::{Entry, OccupiedEntry};
 
+use crate::simplify::remove_dead_blocks;
 use crate::MirPass;
 use rustc_data_structures::fx::FxHashMap;
 use rustc_index::bit_set::BitSet;
@@ -235,6 +236,12 @@ impl<'tcx> MirPass<'tcx> for DestinationPropagation {
             apply_merges(body, tcx, &merges, &merged_locals);
         }
 
+        if round_count != 0 {
+            // Merging can introduce overlap between moved arguments and/or call destination in an
+            // unreachable code, which validator considers to be ill-formed.
+            remove_dead_blocks(tcx, body);
+        }
+
         trace!(round_count);
     }
 }
@@ -651,7 +658,7 @@ impl WriteInfo {
         }
     }
 
-    fn add_place<'tcx>(&mut self, place: Place<'tcx>) {
+    fn add_place(&mut self, place: Place<'_>) {
         self.writes.push(place.local);
     }
 
diff --git a/compiler/rustc_mir_transform/src/lib.rs b/compiler/rustc_mir_transform/src/lib.rs
index 93200b28830..ae79c2290f6 100644
--- a/compiler/rustc_mir_transform/src/lib.rs
+++ b/compiler/rustc_mir_transform/src/lib.rs
@@ -77,8 +77,6 @@ mod match_branches;
 mod multiple_return_terminators;
 mod normalize_array_len;
 mod nrvo;
-// This pass is public to allow external drivers to perform MIR cleanup
-pub mod remove_false_edges;
 mod remove_noop_landing_pads;
 mod remove_storage_markers;
 mod remove_uninit_drops;
@@ -268,10 +266,7 @@ fn mir_const_qualif(tcx: TyCtxt<'_>, def: ty::WithOptConstParam<LocalDefId>) ->
 /// Make MIR ready for const evaluation. This is run on all MIR, not just on consts!
 /// FIXME(oli-obk): it's unclear whether we still need this phase (and its corresponding query).
 /// We used to have this for pre-miri MIR based const eval.
-fn mir_const<'tcx>(
-    tcx: TyCtxt<'tcx>,
-    def: ty::WithOptConstParam<LocalDefId>,
-) -> &'tcx Steal<Body<'tcx>> {
+fn mir_const(tcx: TyCtxt<'_>, def: ty::WithOptConstParam<LocalDefId>) -> &Steal<Body<'_>> {
     if let Some(def) = def.try_upgrade(tcx) {
         return tcx.mir_const(def);
     }
@@ -310,10 +305,10 @@ fn mir_const<'tcx>(
 }
 
 /// Compute the main MIR body and the list of MIR bodies of the promoteds.
-fn mir_promoted<'tcx>(
-    tcx: TyCtxt<'tcx>,
+fn mir_promoted(
+    tcx: TyCtxt<'_>,
     def: ty::WithOptConstParam<LocalDefId>,
-) -> (&'tcx Steal<Body<'tcx>>, &'tcx Steal<IndexVec<Promoted, Body<'tcx>>>) {
+) -> (&Steal<Body<'_>>, &Steal<IndexVec<Promoted, Body<'_>>>) {
     if let Some(def) = def.try_upgrade(tcx) {
         return tcx.mir_promoted(def);
     }
@@ -352,7 +347,7 @@ fn mir_promoted<'tcx>(
 }
 
 /// Compute the MIR that is used during CTFE (and thus has no optimizations run on it)
-fn mir_for_ctfe<'tcx>(tcx: TyCtxt<'tcx>, def_id: DefId) -> &'tcx Body<'tcx> {
+fn mir_for_ctfe(tcx: TyCtxt<'_>, def_id: DefId) -> &Body<'_> {
     let did = def_id.expect_local();
     if let Some(def) = ty::WithOptConstParam::try_lookup(did, tcx) {
         tcx.mir_for_ctfe_of_const_arg(def)
@@ -366,10 +361,7 @@ fn mir_for_ctfe<'tcx>(tcx: TyCtxt<'tcx>, def_id: DefId) -> &'tcx Body<'tcx> {
 /// we'd get cycle errors with `mir_for_ctfe`, because typeck would need to typeck
 /// the const parameter while type checking the main body, which in turn would try
 /// to type check the main body again.
-fn mir_for_ctfe_of_const_arg<'tcx>(
-    tcx: TyCtxt<'tcx>,
-    (did, param_did): (LocalDefId, DefId),
-) -> &'tcx Body<'tcx> {
+fn mir_for_ctfe_of_const_arg(tcx: TyCtxt<'_>, (did, param_did): (LocalDefId, DefId)) -> &Body<'_> {
     tcx.arena.alloc(inner_mir_for_ctfe(
         tcx,
         ty::WithOptConstParam { did, const_param_did: Some(param_did) },
@@ -426,10 +418,10 @@ fn inner_mir_for_ctfe(tcx: TyCtxt<'_>, def: ty::WithOptConstParam<LocalDefId>) -
 /// Obtain just the main MIR (no promoteds) and run some cleanups on it. This also runs
 /// mir borrowck *before* doing so in order to ensure that borrowck can be run and doesn't
 /// end up missing the source MIR due to stealing happening.
-fn mir_drops_elaborated_and_const_checked<'tcx>(
-    tcx: TyCtxt<'tcx>,
+fn mir_drops_elaborated_and_const_checked(
+    tcx: TyCtxt<'_>,
     def: ty::WithOptConstParam<LocalDefId>,
-) -> &'tcx Steal<Body<'tcx>> {
+) -> &Steal<Body<'_>> {
     if let Some(def) = def.try_upgrade(tcx) {
         return tcx.mir_drops_elaborated_and_const_checked(def);
     }
@@ -494,10 +486,9 @@ fn run_analysis_to_runtime_passes<'tcx>(tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>
 /// After this series of passes, no lifetime analysis based on borrowing can be done.
 fn run_analysis_cleanup_passes<'tcx>(tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>) {
     let passes: &[&dyn MirPass<'tcx>] = &[
-        &remove_false_edges::RemoveFalseEdges,
+        &cleanup_post_borrowck::CleanupPostBorrowck,
         &simplify_branches::SimplifyConstCondition::new("initial"),
         &remove_noop_landing_pads::RemoveNoopLandingPads,
-        &cleanup_post_borrowck::CleanupNonCodegenStatements,
         &simplify::SimplifyCfg::new("early-opt"),
         &deref_separator::Derefer,
     ];
@@ -600,7 +591,7 @@ fn run_optimization_passes<'tcx>(tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>) {
 }
 
 /// Optimize the MIR and prepare it for codegen.
-fn optimized_mir<'tcx>(tcx: TyCtxt<'tcx>, did: DefId) -> &'tcx Body<'tcx> {
+fn optimized_mir(tcx: TyCtxt<'_>, did: DefId) -> &Body<'_> {
     let did = did.expect_local();
     assert_eq!(ty::WithOptConstParam::try_lookup(did, tcx), None);
     tcx.arena.alloc(inner_optimized_mir(tcx, did))
@@ -637,10 +628,10 @@ fn inner_optimized_mir(tcx: TyCtxt<'_>, did: LocalDefId) -> Body<'_> {
 
 /// Fetch all the promoteds of an item and prepare their MIR bodies to be ready for
 /// constant evaluation once all substitutions become known.
-fn promoted_mir<'tcx>(
-    tcx: TyCtxt<'tcx>,
+fn promoted_mir(
+    tcx: TyCtxt<'_>,
     def: ty::WithOptConstParam<LocalDefId>,
-) -> &'tcx IndexVec<Promoted, Body<'tcx>> {
+) -> &IndexVec<Promoted, Body<'_>> {
     if tcx.is_constructor(def.did.to_def_id()) {
         return tcx.arena.alloc(IndexVec::new());
     }
diff --git a/compiler/rustc_mir_transform/src/remove_false_edges.rs b/compiler/rustc_mir_transform/src/remove_false_edges.rs
deleted file mode 100644
index 71f5ccf7e24..00000000000
--- a/compiler/rustc_mir_transform/src/remove_false_edges.rs
+++ /dev/null
@@ -1,29 +0,0 @@
-use rustc_middle::mir::{Body, TerminatorKind};
-use rustc_middle::ty::TyCtxt;
-
-use crate::MirPass;
-
-/// Removes `FalseEdge` and `FalseUnwind` terminators from the MIR.
-///
-/// These are only needed for borrow checking, and can be removed afterwards.
-///
-/// FIXME: This should probably have its own MIR phase.
-pub struct RemoveFalseEdges;
-
-impl<'tcx> MirPass<'tcx> for RemoveFalseEdges {
-    fn run_pass(&self, _: TyCtxt<'tcx>, body: &mut Body<'tcx>) {
-        for block in body.basic_blocks_mut() {
-            let terminator = block.terminator_mut();
-            terminator.kind = match terminator.kind {
-                TerminatorKind::FalseEdge { real_target, .. } => {
-                    TerminatorKind::Goto { target: real_target }
-                }
-                TerminatorKind::FalseUnwind { real_target, .. } => {
-                    TerminatorKind::Goto { target: real_target }
-                }
-
-                _ => continue,
-            }
-        }
-    }
-}
diff --git a/compiler/rustc_mir_transform/src/shim.rs b/compiler/rustc_mir_transform/src/shim.rs
index f8b55c86287..dace540fa29 100644
--- a/compiler/rustc_mir_transform/src/shim.rs
+++ b/compiler/rustc_mir_transform/src/shim.rs
@@ -174,9 +174,36 @@ fn build_drop_shim<'tcx>(tcx: TyCtxt<'tcx>, def_id: DefId, ty: Option<Ty<'tcx>>)
     let mut body =
         new_body(source, blocks, local_decls_for_sig(&sig, span), sig.inputs().len(), span);
 
+    // The first argument (index 0), but add 1 for the return value.
+    let mut dropee_ptr = Place::from(Local::new(1 + 0));
+    if tcx.sess.opts.unstable_opts.mir_emit_retag {
+        // We want to treat the function argument as if it was passed by `&mut`. As such, we
+        // generate
+        // ```
+        // temp = &mut *arg;
+        // Retag(temp, FnEntry)
+        // ```
+        // It's important that we do this first, before anything that depends on `dropee_ptr`
+        // has been put into the body.
+        let reborrow = Rvalue::Ref(
+            tcx.lifetimes.re_erased,
+            BorrowKind::Mut { allow_two_phase_borrow: false },
+            tcx.mk_place_deref(dropee_ptr),
+        );
+        let ref_ty = reborrow.ty(body.local_decls(), tcx);
+        dropee_ptr = body.local_decls.push(LocalDecl::new(ref_ty, span)).into();
+        let new_statements = [
+            StatementKind::Assign(Box::new((dropee_ptr, reborrow))),
+            StatementKind::Retag(RetagKind::FnEntry, Box::new(dropee_ptr)),
+        ];
+        for s in new_statements {
+            body.basic_blocks_mut()[START_BLOCK]
+                .statements
+                .push(Statement { source_info, kind: s });
+        }
+    }
+
     if ty.is_some() {
-        // The first argument (index 0), but add 1 for the return value.
-        let dropee_ptr = Place::from(Local::new(1 + 0));
         let patch = {
             let param_env = tcx.param_env_reveal_all_normalized(def_id);
             let mut elaborator =
diff --git a/compiler/rustc_mir_transform/src/simplify_try.rs b/compiler/rustc_mir_transform/src/simplify_try.rs
index baeb620ef24..e4f3ace9a93 100644
--- a/compiler/rustc_mir_transform/src/simplify_try.rs
+++ b/compiler/rustc_mir_transform/src/simplify_try.rs
@@ -532,7 +532,7 @@ struct VarField<'tcx> {
 }
 
 /// Match on `((_LOCAL as Variant).FIELD: TY)`.
-fn match_variant_field_place<'tcx>(place: Place<'tcx>) -> Option<(Local, VarField<'tcx>)> {
+fn match_variant_field_place(place: Place<'_>) -> Option<(Local, VarField<'_>)> {
     match place.as_ref() {
         PlaceRef {
             local,
diff --git a/compiler/rustc_mir_transform/src/sroa.rs b/compiler/rustc_mir_transform/src/sroa.rs
index 558a372fb1e..3a2bf051516 100644
--- a/compiler/rustc_mir_transform/src/sroa.rs
+++ b/compiler/rustc_mir_transform/src/sroa.rs
@@ -182,7 +182,7 @@ fn replace_flattened_locals<'tcx>(
     let mut fragments = IndexVec::new();
     for (k, v) in &replacements.fields {
         fragments.ensure_contains_elem(k.local, || Vec::new());
-        fragments[k.local].push((&k.projection[..], *v));
+        fragments[k.local].push((k.projection, *v));
     }
     debug!(?fragments);