Auto merge of #83177 - erikdesjardins:zstassign, r=oli-obk

Remove assignments to ZST places instead of marking ZST return place as unused

partially reverts #83118

requested by `@tmiasko` in https://github.com/rust-lang/rust/pull/83118#issuecomment-799692574

r? `@oli-obk`

compiler/rustc_mir/src/transform/mod.rs

@@ -44,6 +44,7 @@
 pub mod remove_noop_landing_pads;
 pub mod remove_storage_markers;
 pub mod remove_unneeded_drops;
+pub mod remove_zsts;
 pub mod required_consts;
 pub mod rustc_peek;
 pub mod simplify;
@@ -494,6 +495,7 @@ fn run_optimization_passes<'tcx>(tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>) {
     // The main optimizations that we do on MIR.
     let optimizations: &[&dyn MirPass<'tcx>] = &[
         &remove_storage_markers::RemoveStorageMarkers,
+        &remove_zsts::RemoveZsts,
         &const_goto::ConstGoto,
         &remove_unneeded_drops::RemoveUnneededDrops,
         &match_branches::MatchBranchSimplification,

compiler/rustc_mir/src/transform/remove_zsts.rs

+//! Removes assignments to ZST places.
+
+use crate::transform::MirPass;
+use rustc_middle::mir::{Body, StatementKind};
+use rustc_middle::ty::{self, Ty, TyCtxt};
+
+pub struct RemoveZsts;
+
+impl<'tcx> MirPass<'tcx> for RemoveZsts {
+    fn run_pass(&self, tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>) {
+        if tcx.sess.mir_opt_level() < 3 {
+            return;
+        }
+        let param_env = tcx.param_env(body.source.def_id());
+        let (basic_blocks, local_decls) = body.basic_blocks_and_local_decls_mut();
+        for block in basic_blocks.iter_mut() {
+            for statement in block.statements.iter_mut() {
+                match statement.kind {
+                    StatementKind::Assign(box (place, _)) => {
+                        let place_ty = place.ty(local_decls, tcx).ty;
+                        if !maybe_zst(place_ty) {
+                            continue;
+                        }
+                        let layout = match tcx.layout_of(param_env.and(place_ty)) {
+                            Ok(layout) => layout,
+                            Err(_) => continue,
+                        };
+                        if !layout.is_zst() {
+                            continue;
+                        }
+                        if tcx.consider_optimizing(|| {
+                            format!(
+                                "RemoveZsts - Place: {:?} SourceInfo: {:?}",
+                                place, statement.source_info
+                            )
+                        }) {
+                            statement.make_nop();
+                        }
+                    }
+                    _ => {}
+                }
+            }
+        }
+    }
+}
+
+/// A cheap, approximate check to avoid unnecessary `layout_of` calls.
+fn maybe_zst(ty: Ty<'_>) -> bool {
+    match ty.kind() {
+        // maybe ZST (could be more precise)
+        ty::Adt(..) | ty::Array(..) | ty::Closure(..) | ty::Tuple(..) | ty::Opaque(..) => true,
+        // definitely ZST
+        ty::FnDef(..) | ty::Never => true,
+        // unreachable or can't be ZST
+        _ => false,
+    }
+}

compiler/rustc_mir/src/transform/simplify.rs

@@ -31,10 +31,10 @@
 use rustc_index::vec::{Idx, IndexVec};
 use rustc_middle::mir::visit::{MutVisitor, MutatingUseContext, PlaceContext, Visitor};
 use rustc_middle::mir::*;
-use rustc_middle::ty::ParamEnv;
 use rustc_middle::ty::TyCtxt;
 use smallvec::SmallVec;
-use std::{borrow::Cow, convert::TryInto};
+use std::borrow::Cow;
+use std::convert::TryInto;
 
 pub struct SimplifyCfg {
     label: String,
@@ -326,7 +326,7 @@ fn run_pass(&self, tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>) {
 
 pub fn simplify_locals<'tcx>(body: &mut Body<'tcx>, tcx: TyCtxt<'tcx>) {
     // First, we're going to get a count of *actual* uses for every `Local`.
-    let mut used_locals = UsedLocals::new(body, tcx);
+    let mut used_locals = UsedLocals::new(body);
 
     // Next, we're going to remove any `Local` with zero actual uses. When we remove those
     // `Locals`, we're also going to subtract any uses of other `Locals` from the `used_locals`
@@ -336,8 +336,7 @@ pub fn simplify_locals<'tcx>(body: &mut Body<'tcx>, tcx: TyCtxt<'tcx>) {
     remove_unused_definitions(&mut used_locals, body);
 
     // Finally, we'll actually do the work of shrinking `body.local_decls` and remapping the `Local`s.
-    let arg_count = body.arg_count.try_into().unwrap();
-    let map = make_local_map(&mut body.local_decls, &used_locals, arg_count);
+    let map = make_local_map(&mut body.local_decls, &used_locals);
 
     // Only bother running the `LocalUpdater` if we actually found locals to remove.
     if map.iter().any(Option::is_none) {
@@ -350,61 +349,54 @@ pub fn simplify_locals<'tcx>(body: &mut Body<'tcx>, tcx: TyCtxt<'tcx>) {
 }
 
 /// Construct the mapping while swapping out unused stuff out from the `vec`.
-fn make_local_map<'tcx, V>(
+fn make_local_map<V>(
     local_decls: &mut IndexVec<Local, V>,
-    used_locals: &UsedLocals<'tcx>,
-    arg_count: u32,
+    used_locals: &UsedLocals,
 ) -> IndexVec<Local, Option<Local>> {
-    let mut map: IndexVec<Local, Option<Local>> = IndexVec::from_elem(None, local_decls);
+    let mut map: IndexVec<Local, Option<Local>> = IndexVec::from_elem(None, &*local_decls);
     let mut used = Local::new(0);
 
     for alive_index in local_decls.indices() {
-        // When creating the local map treat the `RETURN_PLACE` and arguments as used.
-        if alive_index.as_u32() <= arg_count || used_locals.is_used(alive_index) {
-            map[alive_index] = Some(used);
-            if alive_index != used {
-                local_decls.swap(alive_index, used);
-            }
-            used.increment_by(1);
+        // `is_used` treats the `RETURN_PLACE` and arguments as used.
+        if !used_locals.is_used(alive_index) {
+            continue;
         }
+
+        map[alive_index] = Some(used);
+        if alive_index != used {
+            local_decls.swap(alive_index, used);
+        }
+        used.increment_by(1);
     }
     local_decls.truncate(used.index());
     map
 }
 
 /// Keeps track of used & unused locals.
-struct UsedLocals<'tcx> {
+struct UsedLocals {
     increment: bool,
+    arg_count: u32,
     use_count: IndexVec<Local, u32>,
-    is_static: bool,
-    local_decls: IndexVec<Local, LocalDecl<'tcx>>,
-    param_env: ParamEnv<'tcx>,
-    tcx: TyCtxt<'tcx>,
 }
 
-impl UsedLocals<'tcx> {
+impl UsedLocals {
     /// Determines which locals are used & unused in the given body.
-    fn new(body: &Body<'tcx>, tcx: TyCtxt<'tcx>) -> Self {
-        let def_id = body.source.def_id();
-        let is_static = tcx.is_static(def_id);
-        let param_env = tcx.param_env(def_id);
-        let local_decls = body.local_decls.clone();
+    fn new(body: &Body<'_>) -> Self {
         let mut this = Self {
             increment: true,
+            arg_count: body.arg_count.try_into().unwrap(),
             use_count: IndexVec::from_elem(0, &body.local_decls),
-            is_static,
-            local_decls,
-            param_env,
-            tcx,
         };
         this.visit_body(body);
         this
     }
 
     /// Checks if local is used.
+    ///
+    /// Return place and arguments are always considered used.
     fn is_used(&self, local: Local) -> bool {
         trace!("is_used({:?}): use_count: {:?}", local, self.use_count[local]);
-        self.use_count[local] != 0
+        local.as_u32() <= self.arg_count || self.use_count[local] != 0
     }
 
     /// Updates the use counts to reflect the removal of given statement.
@@ -434,7 +426,7 @@ fn visit_lhs(&mut self, place: &Place<'tcx>, location: Location) {
     }
 }
 
-impl Visitor<'tcx> for UsedLocals<'tcx> {
+impl Visitor<'_> for UsedLocals {
     fn visit_statement(&mut self, statement: &Statement<'tcx>, location: Location) {
         match statement.kind {
             StatementKind::LlvmInlineAsm(..)
@@ -461,21 +453,7 @@ fn visit_statement(&mut self, statement: &Statement<'tcx>, location: Location) {
         }
     }
 
-    fn visit_local(&mut self, local: &Local, ctx: PlaceContext, _location: Location) {
-        debug!("local: {:?} is_static: {:?}, ctx: {:?}", local, self.is_static, ctx);
-        // Do not count _0 as a used in `return;` if it is a ZST.
-        let return_place = *local == RETURN_PLACE
-            && matches!(ctx, PlaceContext::NonMutatingUse(visit::NonMutatingUseContext::Move));
-        if !self.is_static && return_place {
-            let ty = self.local_decls[*local].ty;
-            let param_env_and = self.param_env.and(ty);
-            if let Ok(layout) = self.tcx.layout_of(param_env_and) {
-                debug!("layout.is_zst: {:?}", layout.is_zst());
-                if layout.is_zst() {
-                    return;
-                }
-            }
-        }
+    fn visit_local(&mut self, local: &Local, _ctx: PlaceContext, _location: Location) {
         if self.increment {
             self.use_count[*local] += 1;
         } else {
@@ -486,10 +464,7 @@ fn visit_local(&mut self, local: &Local, ctx: PlaceContext, _location: Location)
 }
 
 /// Removes unused definitions. Updates the used locals to reflect the changes made.
-fn remove_unused_definitions<'a, 'tcx>(
-    used_locals: &'a mut UsedLocals<'tcx>,
-    body: &mut Body<'tcx>,
-) {
+fn remove_unused_definitions<'a, 'tcx>(used_locals: &'a mut UsedLocals, body: &mut Body<'tcx>) {
     // The use counts are updated as we remove the statements. A local might become unused
     // during the retain operation, leading to a temporary inconsistency (storage statements or
     // definitions referencing the local might remain). For correctness it is crucial that this

src/test/mir-opt/const_allocation.main.ConstProp.after.32bit.mir

@@ -18,7 +18,7 @@ fn main() -> () {
         _1 = (*_2);                      // scope 0 at $DIR/const_allocation.rs:8:5: 8:8
         StorageDead(_2);                 // scope 0 at $DIR/const_allocation.rs:8:8: 8:9
         StorageDead(_1);                 // scope 0 at $DIR/const_allocation.rs:8:8: 8:9
-        _0 = const ();                   // scope 0 at $DIR/const_allocation.rs:7:11: 9:2
+        nop;                             // scope 0 at $DIR/const_allocation.rs:7:11: 9:2
         return;                          // scope 0 at $DIR/const_allocation.rs:9:2: 9:2
     }
 }

src/test/mir-opt/const_allocation.main.ConstProp.after.64bit.mir

@@ -18,7 +18,7 @@ fn main() -> () {
         _1 = (*_2);                      // scope 0 at $DIR/const_allocation.rs:8:5: 8:8
         StorageDead(_2);                 // scope 0 at $DIR/const_allocation.rs:8:8: 8:9
         StorageDead(_1);                 // scope 0 at $DIR/const_allocation.rs:8:8: 8:9
-        _0 = const ();                   // scope 0 at $DIR/const_allocation.rs:7:11: 9:2
+        nop;                             // scope 0 at $DIR/const_allocation.rs:7:11: 9:2
         return;                          // scope 0 at $DIR/const_allocation.rs:9:2: 9:2
     }
 }

src/test/mir-opt/const_allocation2.main.ConstProp.after.32bit.mir

@@ -18,7 +18,7 @@ fn main() -> () {
         _1 = (*_2);                      // scope 0 at $DIR/const_allocation2.rs:5:5: 5:8
         StorageDead(_2);                 // scope 0 at $DIR/const_allocation2.rs:5:8: 5:9
         StorageDead(_1);                 // scope 0 at $DIR/const_allocation2.rs:5:8: 5:9
-        _0 = const ();                   // scope 0 at $DIR/const_allocation2.rs:4:11: 6:2
+        nop;                             // scope 0 at $DIR/const_allocation2.rs:4:11: 6:2
         return;                          // scope 0 at $DIR/const_allocation2.rs:6:2: 6:2
     }
 }

src/test/mir-opt/const_allocation2.main.ConstProp.after.64bit.mir

@@ -18,7 +18,7 @@ fn main() -> () {
         _1 = (*_2);                      // scope 0 at $DIR/const_allocation2.rs:5:5: 5:8
         StorageDead(_2);                 // scope 0 at $DIR/const_allocation2.rs:5:8: 5:9
         StorageDead(_1);                 // scope 0 at $DIR/const_allocation2.rs:5:8: 5:9
-        _0 = const ();                   // scope 0 at $DIR/const_allocation2.rs:4:11: 6:2
+        nop;                             // scope 0 at $DIR/const_allocation2.rs:4:11: 6:2
         return;                          // scope 0 at $DIR/const_allocation2.rs:6:2: 6:2
     }
 }

src/test/mir-opt/const_allocation3.main.ConstProp.after.32bit.mir

@@ -18,7 +18,7 @@ fn main() -> () {
         _1 = (*_2);                      // scope 0 at $DIR/const_allocation3.rs:5:5: 5:8
         StorageDead(_2);                 // scope 0 at $DIR/const_allocation3.rs:5:8: 5:9
         StorageDead(_1);                 // scope 0 at $DIR/const_allocation3.rs:5:8: 5:9
-        _0 = const ();                   // scope 0 at $DIR/const_allocation3.rs:4:11: 6:2
+        nop;                             // scope 0 at $DIR/const_allocation3.rs:4:11: 6:2
         return;                          // scope 0 at $DIR/const_allocation3.rs:6:2: 6:2
     }
 }

src/test/mir-opt/const_allocation3.main.ConstProp.after.64bit.mir

@@ -18,7 +18,7 @@ fn main() -> () {
         _1 = (*_2);                      // scope 0 at $DIR/const_allocation3.rs:5:5: 5:8
         StorageDead(_2);                 // scope 0 at $DIR/const_allocation3.rs:5:8: 5:9
         StorageDead(_1);                 // scope 0 at $DIR/const_allocation3.rs:5:8: 5:9
-        _0 = const ();                   // scope 0 at $DIR/const_allocation3.rs:4:11: 6:2
+        nop;                             // scope 0 at $DIR/const_allocation3.rs:4:11: 6:2
         return;                          // scope 0 at $DIR/const_allocation3.rs:6:2: 6:2
     }
 }

src/test/mir-opt/const_debuginfo.main.ConstDebugInfo.diff

@@ -99,7 +99,6 @@
           _13 = const 64_u32;              // scope 8 at $DIR/const_debuginfo.rs:21:13: 21:22
           StorageDead(_15);                // scope 8 at $DIR/const_debuginfo.rs:21:21: 21:22
           StorageDead(_14);                // scope 8 at $DIR/const_debuginfo.rs:21:21: 21:22
-          _0 = const ();                   // scope 0 at $DIR/const_debuginfo.rs:8:11: 22:2
           StorageDead(_13);                // scope 8 at $DIR/const_debuginfo.rs:22:1: 22:2
           StorageDead(_12);                // scope 7 at $DIR/const_debuginfo.rs:22:1: 22:2
           StorageDead(_11);                // scope 6 at $DIR/const_debuginfo.rs:22:1: 22:2

src/test/mir-opt/const_prop/aggregate.main.ConstProp.diff

@@ -23,7 +23,7 @@
 +         _1 = const 1_i32;                // scope 0 at $DIR/aggregate.rs:5:13: 5:28
           StorageDead(_2);                 // scope 0 at $DIR/aggregate.rs:5:27: 5:28
           StorageDead(_3);                 // scope 0 at $DIR/aggregate.rs:5:28: 5:29
-          _0 = const ();                   // scope 0 at $DIR/aggregate.rs:4:11: 6:2
+          nop;                             // scope 0 at $DIR/aggregate.rs:4:11: 6:2
           StorageDead(_1);                 // scope 0 at $DIR/aggregate.rs:6:1: 6:2
           return;                          // scope 0 at $DIR/aggregate.rs:6:2: 6:2
       }

src/test/mir-opt/const_prop/array_index.main.ConstProp.32bit.diff

@@ -30,7 +30,7 @@
 +         _1 = const 2_u32;                // scope 0 at $DIR/array_index.rs:5:18: 5:33
           StorageDead(_3);                 // scope 0 at $DIR/array_index.rs:5:33: 5:34
           StorageDead(_2);                 // scope 0 at $DIR/array_index.rs:5:33: 5:34
-          _0 = const ();                   // scope 0 at $DIR/array_index.rs:4:11: 6:2
+          nop;                             // scope 0 at $DIR/array_index.rs:4:11: 6:2
           StorageDead(_1);                 // scope 0 at $DIR/array_index.rs:6:1: 6:2
           return;                          // scope 0 at $DIR/array_index.rs:6:2: 6:2
       }

src/test/mir-opt/const_prop/array_index.main.ConstProp.64bit.diff

@@ -30,7 +30,7 @@
 +         _1 = const 2_u32;                // scope 0 at $DIR/array_index.rs:5:18: 5:33
           StorageDead(_3);                 // scope 0 at $DIR/array_index.rs:5:33: 5:34
           StorageDead(_2);                 // scope 0 at $DIR/array_index.rs:5:33: 5:34
-          _0 = const ();                   // scope 0 at $DIR/array_index.rs:4:11: 6:2
+          nop;                             // scope 0 at $DIR/array_index.rs:4:11: 6:2
           StorageDead(_1);                 // scope 0 at $DIR/array_index.rs:6:1: 6:2
           return;                          // scope 0 at $DIR/array_index.rs:6:2: 6:2
       }

src/test/mir-opt/const_prop/bad_op_div_by_zero.main.ConstProp.diff

@@ -45,7 +45,7 @@
 -         _2 = Div(const 1_i32, move _3);  // scope 1 at $DIR/bad_op_div_by_zero.rs:5:14: 5:19
 +         _2 = Div(const 1_i32, const 0_i32); // scope 1 at $DIR/bad_op_div_by_zero.rs:5:14: 5:19
           StorageDead(_3);                 // scope 1 at $DIR/bad_op_div_by_zero.rs:5:18: 5:19
-          _0 = const ();                   // scope 0 at $DIR/bad_op_div_by_zero.rs:3:11: 6:2
+          nop;                             // scope 0 at $DIR/bad_op_div_by_zero.rs:3:11: 6:2
           StorageDead(_2);                 // scope 1 at $DIR/bad_op_div_by_zero.rs:6:1: 6:2
           StorageDead(_1);                 // scope 0 at $DIR/bad_op_div_by_zero.rs:6:1: 6:2
           return;                          // scope 0 at $DIR/bad_op_div_by_zero.rs:6:2: 6:2

src/test/mir-opt/const_prop/bad_op_mod_by_zero.main.ConstProp.diff

@@ -45,7 +45,7 @@
 -         _2 = Rem(const 1_i32, move _3);  // scope 1 at $DIR/bad_op_mod_by_zero.rs:5:14: 5:19
 +         _2 = Rem(const 1_i32, const 0_i32); // scope 1 at $DIR/bad_op_mod_by_zero.rs:5:14: 5:19
           StorageDead(_3);                 // scope 1 at $DIR/bad_op_mod_by_zero.rs:5:18: 5:19
-          _0 = const ();                   // scope 0 at $DIR/bad_op_mod_by_zero.rs:3:11: 6:2
+          nop;                             // scope 0 at $DIR/bad_op_mod_by_zero.rs:3:11: 6:2
           StorageDead(_2);                 // scope 1 at $DIR/bad_op_mod_by_zero.rs:6:1: 6:2
           StorageDead(_1);                 // scope 0 at $DIR/bad_op_mod_by_zero.rs:6:1: 6:2
           return;                          // scope 0 at $DIR/bad_op_mod_by_zero.rs:6:2: 6:2

src/test/mir-opt/const_prop/bad_op_unsafe_oob_for_slices.main.ConstProp.32bit.diff

@@ -50,7 +50,7 @@
       bb1: {
           _5 = (*_1)[_6];                  // scope 2 at $DIR/bad_op_unsafe_oob_for_slices.rs:7:18: 7:25
           StorageDead(_6);                 // scope 2 at $DIR/bad_op_unsafe_oob_for_slices.rs:7:25: 7:26
-          _0 = const ();                   // scope 2 at $DIR/bad_op_unsafe_oob_for_slices.rs:6:5: 8:6
+          nop;                             // scope 2 at $DIR/bad_op_unsafe_oob_for_slices.rs:6:5: 8:6
           StorageDead(_5);                 // scope 2 at $DIR/bad_op_unsafe_oob_for_slices.rs:8:5: 8:6
           StorageDead(_1);                 // scope 0 at $DIR/bad_op_unsafe_oob_for_slices.rs:9:1: 9:2
           return;                          // scope 0 at $DIR/bad_op_unsafe_oob_for_slices.rs:9:2: 9:2

src/test/mir-opt/const_prop/bad_op_unsafe_oob_for_slices.main.ConstProp.64bit.diff

@@ -50,7 +50,7 @@
       bb1: {
           _5 = (*_1)[_6];                  // scope 2 at $DIR/bad_op_unsafe_oob_for_slices.rs:7:18: 7:25
           StorageDead(_6);                 // scope 2 at $DIR/bad_op_unsafe_oob_for_slices.rs:7:25: 7:26
-          _0 = const ();                   // scope 2 at $DIR/bad_op_unsafe_oob_for_slices.rs:6:5: 8:6
+          nop;                             // scope 2 at $DIR/bad_op_unsafe_oob_for_slices.rs:6:5: 8:6
           StorageDead(_5);                 // scope 2 at $DIR/bad_op_unsafe_oob_for_slices.rs:8:5: 8:6
           StorageDead(_1);                 // scope 0 at $DIR/bad_op_unsafe_oob_for_slices.rs:9:1: 9:2
           return;                          // scope 0 at $DIR/bad_op_unsafe_oob_for_slices.rs:9:2: 9:2

src/test/mir-opt/const_prop/boxes.main.ConstProp.diff

@@ -28,7 +28,7 @@
   
       bb1: {
           StorageDead(_3);                 // scope 0 at $DIR/boxes.rs:12:26: 12:27
-          _0 = const ();                   // scope 0 at $DIR/boxes.rs:11:11: 13:2
+          nop;                             // scope 0 at $DIR/boxes.rs:11:11: 13:2
           StorageDead(_1);                 // scope 0 at $DIR/boxes.rs:13:1: 13:2
           return;                          // scope 0 at $DIR/boxes.rs:13:2: 13:2
       }

src/test/mir-opt/const_prop/cast.main.ConstProp.diff

@@ -19,7 +19,7 @@
           StorageLive(_2);                 // scope 1 at $DIR/cast.rs:6:9: 6:10
 -         _2 = const 42_u32 as u8 (Misc);  // scope 1 at $DIR/cast.rs:6:13: 6:24
 +         _2 = const 42_u8;                // scope 1 at $DIR/cast.rs:6:13: 6:24
-          _0 = const ();                   // scope 0 at $DIR/cast.rs:3:11: 7:2
+          nop;                             // scope 0 at $DIR/cast.rs:3:11: 7:2
           StorageDead(_2);                 // scope 1 at $DIR/cast.rs:7:1: 7:2
           StorageDead(_1);                 // scope 0 at $DIR/cast.rs:7:1: 7:2
           return;                          // scope 0 at $DIR/cast.rs:7:2: 7:2

src/test/mir-opt/const_prop/checked_add.main.ConstProp.diff

@@ -23,7 +23,7 @@
       bb1: {
 -         _1 = move (_2.0: u32);           // scope 0 at $DIR/checked_add.rs:5:18: 5:23
 +         _1 = const 2_u32;                // scope 0 at $DIR/checked_add.rs:5:18: 5:23
-          _0 = const ();                   // scope 0 at $DIR/checked_add.rs:4:11: 6:2
+          nop;                             // scope 0 at $DIR/checked_add.rs:4:11: 6:2
           StorageDead(_1);                 // scope 0 at $DIR/checked_add.rs:6:1: 6:2
           return;                          // scope 0 at $DIR/checked_add.rs:6:2: 6:2
       }

src/test/mir-opt/const_prop/const_prop_fails_gracefully.main.ConstProp.diff

@@ -39,7 +39,7 @@
       bb1: {
           StorageDead(_5);                 // scope 1 at $DIR/const_prop_fails_gracefully.rs:8:11: 8:12
           StorageDead(_4);                 // scope 1 at $DIR/const_prop_fails_gracefully.rs:8:12: 8:13
-          _0 = const ();                   // scope 0 at $DIR/const_prop_fails_gracefully.rs:5:11: 9:2
+          nop;                             // scope 0 at $DIR/const_prop_fails_gracefully.rs:5:11: 9:2
           StorageDead(_1);                 // scope 0 at $DIR/const_prop_fails_gracefully.rs:9:1: 9:2
           return;                          // scope 0 at $DIR/const_prop_fails_gracefully.rs:9:2: 9:2
       }

src/test/mir-opt/const_prop/control_flow_simplification.hello.PreCodegen.before.mir

@@ -4,6 +4,7 @@ fn hello() -> () {
     let mut _0: ();                      // return place in scope 0 at $DIR/control-flow-simplification.rs:11:14: 11:14
 
     bb0: {
+        _0 = const ();                   // scope 0 at $DIR/control-flow-simplification.rs:14:6: 14:6
         return;                          // scope 0 at $DIR/control-flow-simplification.rs:15:2: 15:2
     }
 }

src/test/mir-opt/const_prop/discriminant.main.ConstProp.32bit.diff

@@ -41,7 +41,7 @@
           _1 = Add(move _2, const 0_i32);  // scope 0 at $DIR/discriminant.rs:11:13: 11:68
           StorageDead(_2);                 // scope 0 at $DIR/discriminant.rs:11:67: 11:68
           StorageDead(_3);                 // scope 0 at $DIR/discriminant.rs:11:68: 11:69
-          _0 = const ();                   // scope 0 at $DIR/discriminant.rs:10:11: 12:2
+          nop;                             // scope 0 at $DIR/discriminant.rs:10:11: 12:2
           StorageDead(_1);                 // scope 0 at $DIR/discriminant.rs:12:1: 12:2
           return;                          // scope 0 at $DIR/discriminant.rs:12:2: 12:2
       }

src/test/mir-opt/const_prop/discriminant.main.ConstProp.64bit.diff

@@ -41,7 +41,7 @@
           _1 = Add(move _2, const 0_i32);  // scope 0 at $DIR/discriminant.rs:11:13: 11:68
           StorageDead(_2);                 // scope 0 at $DIR/discriminant.rs:11:67: 11:68
           StorageDead(_3);                 // scope 0 at $DIR/discriminant.rs:11:68: 11:69
-          _0 = const ();                   // scope 0 at $DIR/discriminant.rs:10:11: 12:2
+          nop;                             // scope 0 at $DIR/discriminant.rs:10:11: 12:2
           StorageDead(_1);                 // scope 0 at $DIR/discriminant.rs:12:1: 12:2
           return;                          // scope 0 at $DIR/discriminant.rs:12:2: 12:2
       }

src/test/mir-opt/const_prop/indirect.main.ConstProp.diff

@@ -28,7 +28,7 @@
 -         _1 = move (_3.0: u8);            // scope 0 at $DIR/indirect.rs:5:13: 5:29
 +         _1 = const 3_u8;                 // scope 0 at $DIR/indirect.rs:5:13: 5:29
           StorageDead(_2);                 // scope 0 at $DIR/indirect.rs:5:28: 5:29
-          _0 = const ();                   // scope 0 at $DIR/indirect.rs:4:11: 6:2
+          nop;                             // scope 0 at $DIR/indirect.rs:4:11: 6:2
           StorageDead(_1);                 // scope 0 at $DIR/indirect.rs:6:1: 6:2
           return;                          // scope 0 at $DIR/indirect.rs:6:2: 6:2
       }

src/test/mir-opt/const_prop/issue_66971.main.ConstProp.diff

@@ -11,8 +11,7 @@
           StorageLive(_1);                 // scope 0 at $DIR/issue-66971.rs:16:5: 16:23
           StorageLive(_2);                 // scope 0 at $DIR/issue-66971.rs:16:12: 16:22
           StorageLive(_3);                 // scope 0 at $DIR/issue-66971.rs:16:13: 16:15
--         (_2.0: ()) = move _3;            // scope 0 at $DIR/issue-66971.rs:16:12: 16:22
-+         (_2.0: ()) = const ();           // scope 0 at $DIR/issue-66971.rs:16:12: 16:22
+          nop;                             // scope 0 at $DIR/issue-66971.rs:16:12: 16:22
           (_2.1: u8) = const 0_u8;         // scope 0 at $DIR/issue-66971.rs:16:12: 16:22
           (_2.2: u8) = const 0_u8;         // scope 0 at $DIR/issue-66971.rs:16:12: 16:22
           StorageDead(_3);                 // scope 0 at $DIR/issue-66971.rs:16:21: 16:22
@@ -25,7 +24,7 @@
       bb1: {
           StorageDead(_2);                 // scope 0 at $DIR/issue-66971.rs:16:22: 16:23
           StorageDead(_1);                 // scope 0 at $DIR/issue-66971.rs:16:23: 16:24
-          _0 = const ();                   // scope 0 at $DIR/issue-66971.rs:15:11: 17:2
+          nop;                             // scope 0 at $DIR/issue-66971.rs:15:11: 17:2
           return;                          // scope 0 at $DIR/issue-66971.rs:17:2: 17:2
       }
   }

src/test/mir-opt/const_prop/issue_67019.main.ConstProp.diff

@@ -28,7 +28,7 @@
       bb1: {
           StorageDead(_2);                 // scope 0 at $DIR/issue-67019.rs:11:19: 11:20
           StorageDead(_1);                 // scope 0 at $DIR/issue-67019.rs:11:20: 11:21
-          _0 = const ();                   // scope 0 at $DIR/issue-67019.rs:10:11: 12:2
+          nop;                             // scope 0 at $DIR/issue-67019.rs:10:11: 12:2
           return;                          // scope 0 at $DIR/issue-67019.rs:12:2: 12:2
       }
   }

src/test/mir-opt/const_prop/large_array_index.main.ConstProp.32bit.diff

@@ -29,7 +29,7 @@
           _1 = _2[_3];                     // scope 0 at $DIR/large_array_index.rs:6:17: 6:32
           StorageDead(_3);                 // scope 0 at $DIR/large_array_index.rs:6:32: 6:33
           StorageDead(_2);                 // scope 0 at $DIR/large_array_index.rs:6:32: 6:33
-          _0 = const ();                   // scope 0 at $DIR/large_array_index.rs:4:11: 7:2
+          nop;                             // scope 0 at $DIR/large_array_index.rs:4:11: 7:2
           StorageDead(_1);                 // scope 0 at $DIR/large_array_index.rs:7:1: 7:2
           return;                          // scope 0 at $DIR/large_array_index.rs:7:2: 7:2
       }

src/test/mir-opt/const_prop/large_array_index.main.ConstProp.64bit.diff

@@ -29,7 +29,7 @@
           _1 = _2[_3];                     // scope 0 at $DIR/large_array_index.rs:6:17: 6:32
           StorageDead(_3);                 // scope 0 at $DIR/large_array_index.rs:6:32: 6:33
           StorageDead(_2);                 // scope 0 at $DIR/large_array_index.rs:6:32: 6:33
-          _0 = const ();                   // scope 0 at $DIR/large_array_index.rs:4:11: 7:2
+          nop;                             // scope 0 at $DIR/large_array_index.rs:4:11: 7:2
           StorageDead(_1);                 // scope 0 at $DIR/large_array_index.rs:7:1: 7:2
           return;                          // scope 0 at $DIR/large_array_index.rs:7:2: 7:2
       }

src/test/mir-opt/const_prop/mutable_variable.main.ConstProp.diff

@@ -19,7 +19,7 @@
           StorageLive(_2);                 // scope 1 at $DIR/mutable_variable.rs:7:9: 7:10
 -         _2 = _1;                         // scope 1 at $DIR/mutable_variable.rs:7:13: 7:14
 +         _2 = const 99_i32;               // scope 1 at $DIR/mutable_variable.rs:7:13: 7:14
-          _0 = const ();                   // scope 0 at $DIR/mutable_variable.rs:4:11: 8:2
+          nop;                             // scope 0 at $DIR/mutable_variable.rs:4:11: 8:2
           StorageDead(_2);                 // scope 1 at $DIR/mutable_variable.rs:8:1: 8:2
           StorageDead(_1);                 // scope 0 at $DIR/mutable_variable.rs:8:1: 8:2
           return;                          // scope 0 at $DIR/mutable_variable.rs:8:2: 8:2

src/test/mir-opt/const_prop/mutable_variable_aggregate.main.ConstProp.diff

@@ -23,7 +23,7 @@
 +                                          // mir::Constant
 +                                          // + span: $DIR/mutable_variable_aggregate.rs:7:13: 7:14
 +                                          // + literal: Const { ty: (i32, i32), val: Value(ByRef { alloc: Allocation { bytes: [42, 0, 0, 0, 99, 0, 0, 0], relocations: Relocations(SortedMap { data: [] }), init_mask: InitMask { blocks: [255], len: Size { raw: 8 } }, size: Size { raw: 8 }, align: Align { pow2: 2 }, mutability: Not, extra: () }, offset: Size { raw: 0 } }) }
-          _0 = const ();                   // scope 0 at $DIR/mutable_variable_aggregate.rs:4:11: 8:2
+          nop;                             // scope 0 at $DIR/mutable_variable_aggregate.rs:4:11: 8:2
           StorageDead(_2);                 // scope 1 at $DIR/mutable_variable_aggregate.rs:8:1: 8:2
           StorageDead(_1);                 // scope 0 at $DIR/mutable_variable_aggregate.rs:8:1: 8:2
           return;                          // scope 0 at $DIR/mutable_variable_aggregate.rs:8:2: 8:2

src/test/mir-opt/const_prop/mutable_variable_aggregate_mut_ref.main.ConstProp.diff

@@ -25,7 +25,7 @@
           ((*_2).1: i32) = const 99_i32;   // scope 2 at $DIR/mutable_variable_aggregate_mut_ref.rs:7:5: 7:13
           StorageLive(_3);                 // scope 2 at $DIR/mutable_variable_aggregate_mut_ref.rs:8:9: 8:10
           _3 = _1;                         // scope 2 at $DIR/mutable_variable_aggregate_mut_ref.rs:8:13: 8:14
-          _0 = const ();                   // scope 0 at $DIR/mutable_variable_aggregate_mut_ref.rs:4:11: 9:2
+          nop;                             // scope 0 at $DIR/mutable_variable_aggregate_mut_ref.rs:4:11: 9:2
           StorageDead(_3);                 // scope 2 at $DIR/mutable_variable_aggregate_mut_ref.rs:9:1: 9:2
           StorageDead(_2);                 // scope 1 at $DIR/mutable_variable_aggregate_mut_ref.rs:9:1: 9:2
           StorageDead(_1);                 // scope 0 at $DIR/mutable_variable_aggregate_mut_ref.rs:9:1: 9:2

src/test/mir-opt/const_prop/mutable_variable_aggregate_partial_read.main.ConstProp.diff

@@ -26,7 +26,7 @@
           StorageLive(_2);                 // scope 1 at $DIR/mutable_variable_aggregate_partial_read.rs:8:9: 8:10
 -         _2 = (_1.1: i32);                // scope 1 at $DIR/mutable_variable_aggregate_partial_read.rs:8:13: 8:16
 +         _2 = const 99_i32;               // scope 1 at $DIR/mutable_variable_aggregate_partial_read.rs:8:13: 8:16
-          _0 = const ();                   // scope 0 at $DIR/mutable_variable_aggregate_partial_read.rs:4:11: 9:2
+          nop;                             // scope 0 at $DIR/mutable_variable_aggregate_partial_read.rs:4:11: 9:2
           StorageDead(_2);                 // scope 1 at $DIR/mutable_variable_aggregate_partial_read.rs:9:1: 9:2
           StorageDead(_1);                 // scope 0 at $DIR/mutable_variable_aggregate_partial_read.rs:9:1: 9:2
           return;                          // scope 0 at $DIR/mutable_variable_aggregate_partial_read.rs:9:2: 9:2

src/test/mir-opt/const_prop/mutable_variable_no_prop.main.ConstProp.diff

@@ -34,11 +34,11 @@
           _1 = move _3;                    // scope 2 at $DIR/mutable_variable_no_prop.rs:9:9: 9:19
           StorageDead(_3);                 // scope 2 at $DIR/mutable_variable_no_prop.rs:9:18: 9:19
           StorageDead(_4);                 // scope 2 at $DIR/mutable_variable_no_prop.rs:9:19: 9:20
-          _2 = const ();                   // scope 2 at $DIR/mutable_variable_no_prop.rs:8:5: 10:6
+          nop;                             // scope 2 at $DIR/mutable_variable_no_prop.rs:8:5: 10:6
           StorageDead(_2);                 // scope 1 at $DIR/mutable_variable_no_prop.rs:10:5: 10:6
           StorageLive(_5);                 // scope 1 at $DIR/mutable_variable_no_prop.rs:11:9: 11:10
           _5 = _1;                         // scope 1 at $DIR/mutable_variable_no_prop.rs:11:13: 11:14
-          _0 = const ();                   // scope 0 at $DIR/mutable_variable_no_prop.rs:6:11: 12:2
+          nop;                             // scope 0 at $DIR/mutable_variable_no_prop.rs:6:11: 12:2
           StorageDead(_5);                 // scope 1 at $DIR/mutable_variable_no_prop.rs:12:1: 12:2
           StorageDead(_1);                 // scope 0 at $DIR/mutable_variable_no_prop.rs:12:1: 12:2
           return;                          // scope 0 at $DIR/mutable_variable_no_prop.rs:12:2: 12:2

src/test/mir-opt/const_prop/mutable_variable_unprop_assign.main.ConstProp.diff

@@ -41,7 +41,7 @@
           _4 = (_2.1: i32);                // scope 2 at $DIR/mutable_variable_unprop_assign.rs:8:13: 8:16
           StorageLive(_5);                 // scope 3 at $DIR/mutable_variable_unprop_assign.rs:9:9: 9:10
           _5 = (_2.0: i32);                // scope 3 at $DIR/mutable_variable_unprop_assign.rs:9:13: 9:16
-          _0 = const ();                   // scope 0 at $DIR/mutable_variable_unprop_assign.rs:4:11: 10:2
+          nop;                             // scope 0 at $DIR/mutable_variable_unprop_assign.rs:4:11: 10:2
           StorageDead(_5);                 // scope 3 at $DIR/mutable_variable_unprop_assign.rs:10:1: 10:2
           StorageDead(_4);                 // scope 2 at $DIR/mutable_variable_unprop_assign.rs:10:1: 10:2
           StorageDead(_2);                 // scope 1 at $DIR/mutable_variable_unprop_assign.rs:10:1: 10:2

src/test/mir-opt/const_prop/optimizes_into_variable.main.ConstProp.32bit.diff

@@ -60,7 +60,7 @@
 -         _8 = (_9.1: u32);                // scope 2 at $DIR/optimizes_into_variable.rs:14:13: 14:38
 +         _8 = const 42_u32;               // scope 2 at $DIR/optimizes_into_variable.rs:14:13: 14:38
           StorageDead(_9);                 // scope 2 at $DIR/optimizes_into_variable.rs:14:38: 14:39
-          _0 = const ();                   // scope 0 at $DIR/optimizes_into_variable.rs:11:11: 15:2
+          nop;                             // scope 0 at $DIR/optimizes_into_variable.rs:11:11: 15:2
           StorageDead(_8);                 // scope 2 at $DIR/optimizes_into_variable.rs:15:1: 15:2
           StorageDead(_3);                 // scope 1 at $DIR/optimizes_into_variable.rs:15:1: 15:2
           StorageDead(_1);                 // scope 0 at $DIR/optimizes_into_variable.rs:15:1: 15:2

src/test/mir-opt/const_prop/optimizes_into_variable.main.ConstProp.64bit.diff

@@ -60,7 +60,7 @@
 -         _8 = (_9.1: u32);                // scope 2 at $DIR/optimizes_into_variable.rs:14:13: 14:38
 +         _8 = const 42_u32;               // scope 2 at $DIR/optimizes_into_variable.rs:14:13: 14:38
           StorageDead(_9);                 // scope 2 at $DIR/optimizes_into_variable.rs:14:38: 14:39
-          _0 = const ();                   // scope 0 at $DIR/optimizes_into_variable.rs:11:11: 15:2
+          nop;                             // scope 0 at $DIR/optimizes_into_variable.rs:11:11: 15:2
           StorageDead(_8);                 // scope 2 at $DIR/optimizes_into_variable.rs:15:1: 15:2
           StorageDead(_3);                 // scope 1 at $DIR/optimizes_into_variable.rs:15:1: 15:2
           StorageDead(_1);                 // scope 0 at $DIR/optimizes_into_variable.rs:15:1: 15:2

src/test/mir-opt/const_prop/read_immutable_static.main.ConstProp.diff

@@ -42,7 +42,7 @@
           StorageDead(_2);                 // scope 0 at $DIR/read_immutable_static.rs:7:21: 7:22
           StorageDead(_5);                 // scope 0 at $DIR/read_immutable_static.rs:7:22: 7:23
           StorageDead(_3);                 // scope 0 at $DIR/read_immutable_static.rs:7:22: 7:23
-          _0 = const ();                   // scope 0 at $DIR/read_immutable_static.rs:6:11: 8:2
+          nop;                             // scope 0 at $DIR/read_immutable_static.rs:6:11: 8:2
           StorageDead(_1);                 // scope 0 at $DIR/read_immutable_static.rs:8:1: 8:2
           return;                          // scope 0 at $DIR/read_immutable_static.rs:8:2: 8:2
       }

src/test/mir-opt/const_prop/ref_deref.main.ConstProp.diff

@@ -23,7 +23,7 @@
 +         _1 = const 4_i32;                // scope 0 at $DIR/ref_deref.rs:5:5: 5:10
           StorageDead(_2);                 // scope 0 at $DIR/ref_deref.rs:5:10: 5:11
           StorageDead(_1);                 // scope 0 at $DIR/ref_deref.rs:5:10: 5:11
-          _0 = const ();                   // scope 0 at $DIR/ref_deref.rs:4:11: 6:2
+          nop;                             // scope 0 at $DIR/ref_deref.rs:4:11: 6:2
           return;                          // scope 0 at $DIR/ref_deref.rs:6:2: 6:2
       }
   }

src/test/mir-opt/const_prop/ref_deref_project.main.ConstProp.diff

@@ -22,7 +22,7 @@
           _1 = (*_2);                      // scope 0 at $DIR/ref_deref_project.rs:5:5: 5:17
           StorageDead(_2);                 // scope 0 at $DIR/ref_deref_project.rs:5:17: 5:18
           StorageDead(_1);                 // scope 0 at $DIR/ref_deref_project.rs:5:17: 5:18
-          _0 = const ();                   // scope 0 at $DIR/ref_deref_project.rs:4:11: 6:2
+          nop;                             // scope 0 at $DIR/ref_deref_project.rs:4:11: 6:2
           return;                          // scope 0 at $DIR/ref_deref_project.rs:6:2: 6:2
       }
   }

src/test/mir-opt/const_prop/reify_fn_ptr.main.ConstProp.diff

@@ -22,7 +22,7 @@
           _1 = move _2 as *const fn() (Misc); // scope 0 at $DIR/reify_fn_ptr.rs:4:13: 4:41
           StorageDead(_2);                 // scope 0 at $DIR/reify_fn_ptr.rs:4:40: 4:41
           StorageDead(_1);                 // scope 0 at $DIR/reify_fn_ptr.rs:4:41: 4:42
-          _0 = const ();                   // scope 0 at $DIR/reify_fn_ptr.rs:3:11: 5:2
+          nop;                             // scope 0 at $DIR/reify_fn_ptr.rs:3:11: 5:2
           return;                          // scope 0 at $DIR/reify_fn_ptr.rs:5:2: 5:2
       }
   }

src/test/mir-opt/const_prop/repeat.main.ConstProp.32bit.diff

@@ -35,7 +35,7 @@
           StorageDead(_2);                 // scope 0 at $DIR/repeat.rs:6:31: 6:32
           StorageDead(_4);                 // scope 0 at $DIR/repeat.rs:6:32: 6:33
           StorageDead(_3);                 // scope 0 at $DIR/repeat.rs:6:32: 6:33
-          _0 = const ();                   // scope 0 at $DIR/repeat.rs:5:11: 7:2
+          nop;                             // scope 0 at $DIR/repeat.rs:5:11: 7:2
           StorageDead(_1);                 // scope 0 at $DIR/repeat.rs:7:1: 7:2
           return;                          // scope 0 at $DIR/repeat.rs:7:2: 7:2
       }

src/test/mir-opt/const_prop/repeat.main.ConstProp.64bit.diff

@@ -35,7 +35,7 @@
           StorageDead(_2);                 // scope 0 at $DIR/repeat.rs:6:31: 6:32
           StorageDead(_4);                 // scope 0 at $DIR/repeat.rs:6:32: 6:33
           StorageDead(_3);                 // scope 0 at $DIR/repeat.rs:6:32: 6:33
-          _0 = const ();                   // scope 0 at $DIR/repeat.rs:5:11: 7:2
+          nop;                             // scope 0 at $DIR/repeat.rs:5:11: 7:2
           StorageDead(_1);                 // scope 0 at $DIR/repeat.rs:7:1: 7:2
           return;                          // scope 0 at $DIR/repeat.rs:7:2: 7:2
       }

src/test/mir-opt/const_prop/scalar_literal_propagation.main.ConstProp.diff

@@ -27,7 +27,7 @@
       bb1: {
           StorageDead(_3);                 // scope 1 at $DIR/scalar_literal_propagation.rs:4:14: 4:15
           StorageDead(_2);                 // scope 1 at $DIR/scalar_literal_propagation.rs:4:15: 4:16
-          _0 = const ();                   // scope 0 at $DIR/scalar_literal_propagation.rs:2:11: 5:2
+          nop;                             // scope 0 at $DIR/scalar_literal_propagation.rs:2:11: 5:2
           StorageDead(_1);                 // scope 0 at $DIR/scalar_literal_propagation.rs:5:1: 5:2
           return;                          // scope 0 at $DIR/scalar_literal_propagation.rs:5:2: 5:2
       }

src/test/mir-opt/const_prop/slice_len.main.ConstProp.32bit.diff

@@ -46,7 +46,7 @@
           StorageDead(_4);                 // scope 0 at $DIR/slice_len.rs:5:33: 5:34
           StorageDead(_2);                 // scope 0 at $DIR/slice_len.rs:5:33: 5:34
           StorageDead(_1);                 // scope 0 at $DIR/slice_len.rs:5:33: 5:34
-          _0 = const ();                   // scope 0 at $DIR/slice_len.rs:4:11: 6:2
+          nop;                             // scope 0 at $DIR/slice_len.rs:4:11: 6:2
           return;                          // scope 0 at $DIR/slice_len.rs:6:2: 6:2
       }
   }

src/test/mir-opt/const_prop/slice_len.main.ConstProp.64bit.diff

@@ -46,7 +46,7 @@
           StorageDead(_4);                 // scope 0 at $DIR/slice_len.rs:5:33: 5:34
           StorageDead(_2);                 // scope 0 at $DIR/slice_len.rs:5:33: 5:34
           StorageDead(_1);                 // scope 0 at $DIR/slice_len.rs:5:33: 5:34
-          _0 = const ();                   // scope 0 at $DIR/slice_len.rs:4:11: 6:2
+          nop;                             // scope 0 at $DIR/slice_len.rs:4:11: 6:2
           return;                          // scope 0 at $DIR/slice_len.rs:6:2: 6:2
       }
   }

src/test/mir-opt/const_prop/tuple_literal_propagation.main.ConstProp.diff

@@ -30,7 +30,7 @@
       bb1: {
           StorageDead(_3);                 // scope 1 at $DIR/tuple_literal_propagation.rs:5:14: 5:15
           StorageDead(_2);                 // scope 1 at $DIR/tuple_literal_propagation.rs:5:15: 5:16
-          _0 = const ();                   // scope 0 at $DIR/tuple_literal_propagation.rs:2:11: 6:2
+          nop;                             // scope 0 at $DIR/tuple_literal_propagation.rs:2:11: 6:2
           StorageDead(_1);                 // scope 0 at $DIR/tuple_literal_propagation.rs:6:1: 6:2
           return;                          // scope 0 at $DIR/tuple_literal_propagation.rs:6:2: 6:2
       }

src/test/mir-opt/const_prop_miscompile.bar.ConstProp.diff

@@ -25,14 +25,14 @@
           _3 = &raw mut (_1.0: i32);       // scope 2 at $DIR/const_prop_miscompile.rs:14:10: 14:22
           (*_3) = const 5_i32;             // scope 2 at $DIR/const_prop_miscompile.rs:14:9: 14:26
           StorageDead(_3);                 // scope 2 at $DIR/const_prop_miscompile.rs:14:26: 14:27
-          _2 = const ();                   // scope 2 at $DIR/const_prop_miscompile.rs:13:5: 15:6
+          nop;                             // scope 2 at $DIR/const_prop_miscompile.rs:13:5: 15:6
           StorageDead(_2);                 // scope 1 at $DIR/const_prop_miscompile.rs:15:5: 15:6
           StorageLive(_4);                 // scope 1 at $DIR/const_prop_miscompile.rs:16:9: 16:10
           StorageLive(_5);                 // scope 1 at $DIR/const_prop_miscompile.rs:16:13: 16:20
           _5 = (_1.0: i32);                // scope 1 at $DIR/const_prop_miscompile.rs:16:15: 16:18
           _4 = Eq(move _5, const 5_i32);   // scope 1 at $DIR/const_prop_miscompile.rs:16:13: 16:25
           StorageDead(_5);                 // scope 1 at $DIR/const_prop_miscompile.rs:16:24: 16:25
-          _0 = const ();                   // scope 0 at $DIR/const_prop_miscompile.rs:11:10: 17:2
+          nop;                             // scope 0 at $DIR/const_prop_miscompile.rs:11:10: 17:2
           StorageDead(_4);                 // scope 1 at $DIR/const_prop_miscompile.rs:17:1: 17:2
           StorageDead(_1);                 // scope 0 at $DIR/const_prop_miscompile.rs:17:1: 17:2
           return;                          // scope 0 at $DIR/const_prop_miscompile.rs:17:2: 17:2

src/test/mir-opt/const_prop_miscompile.foo.ConstProp.diff

@@ -26,7 +26,7 @@
           _4 = (_1.0: i32);                // scope 1 at $DIR/const_prop_miscompile.rs:7:15: 7:18
           _3 = Eq(move _4, const 5_i32);   // scope 1 at $DIR/const_prop_miscompile.rs:7:13: 7:25
           StorageDead(_4);                 // scope 1 at $DIR/const_prop_miscompile.rs:7:24: 7:25
-          _0 = const ();                   // scope 0 at $DIR/const_prop_miscompile.rs:4:10: 8:2
+          nop;                             // scope 0 at $DIR/const_prop_miscompile.rs:4:10: 8:2
           StorageDead(_3);                 // scope 1 at $DIR/const_prop_miscompile.rs:8:1: 8:2
           StorageDead(_1);                 // scope 0 at $DIR/const_prop_miscompile.rs:8:1: 8:2
           return;                          // scope 0 at $DIR/const_prop_miscompile.rs:8:2: 8:2

src/test/mir-opt/dest-prop/branch.main.DestinationPropagation.diff

@@ -62,7 +62,7 @@
   
       bb6: {
           StorageDead(_3);                 // scope 1 at $DIR/branch.rs:20:5: 20:6
-          _0 = const ();                   // scope 0 at $DIR/branch.rs:12:11: 21:2
+          nop;                             // scope 0 at $DIR/branch.rs:12:11: 21:2
 -         StorageDead(_2);                 // scope 1 at $DIR/branch.rs:21:1: 21:2
 -         StorageDead(_1);                 // scope 0 at $DIR/branch.rs:21:1: 21:2
 +         nop;                             // scope 1 at $DIR/branch.rs:21:1: 21:2

src/test/mir-opt/dest-prop/copy_propagation_arg.bar.DestinationPropagation.diff

@@ -21,7 +21,7 @@
           StorageDead(_3);                 // scope 0 at $DIR/copy_propagation_arg.rs:16:12: 16:13
           StorageDead(_2);                 // scope 0 at $DIR/copy_propagation_arg.rs:16:13: 16:14
           _1 = const 5_u8;                 // scope 0 at $DIR/copy_propagation_arg.rs:17:5: 17:10
-          _0 = const ();                   // scope 0 at $DIR/copy_propagation_arg.rs:15:19: 18:2
+          nop;                             // scope 0 at $DIR/copy_propagation_arg.rs:15:19: 18:2
           return;                          // scope 0 at $DIR/copy_propagation_arg.rs:18:2: 18:2
       }
   }

src/test/mir-opt/dest-prop/copy_propagation_arg.baz.DestinationPropagation.diff

@@ -15,7 +15,7 @@
 +         nop;                             // scope 0 at $DIR/copy_propagation_arg.rs:23:9: 23:10
 +         nop;                             // scope 0 at $DIR/copy_propagation_arg.rs:23:5: 23:10
 +         nop;                             // scope 0 at $DIR/copy_propagation_arg.rs:23:9: 23:10
-          _0 = const ();                   // scope 0 at $DIR/copy_propagation_arg.rs:21:20: 24:2
+          nop;                             // scope 0 at $DIR/copy_propagation_arg.rs:21:20: 24:2
           return;                          // scope 0 at $DIR/copy_propagation_arg.rs:24:2: 24:2
       }
   }

src/test/mir-opt/dest-prop/copy_propagation_arg.foo.DestinationPropagation.diff

@@ -25,7 +25,7 @@
 -         StorageDead(_2);                 // scope 0 at $DIR/copy_propagation_arg.rs:11:16: 11:17
 +         nop;                             // scope 0 at $DIR/copy_propagation_arg.rs:11:5: 11:17
 +         nop;                             // scope 0 at $DIR/copy_propagation_arg.rs:11:16: 11:17
-          _0 = const ();                   // scope 0 at $DIR/copy_propagation_arg.rs:9:19: 12:2
+          nop;                             // scope 0 at $DIR/copy_propagation_arg.rs:9:19: 12:2
           return;                          // scope 0 at $DIR/copy_propagation_arg.rs:12:2: 12:2
       }
   }

src/test/mir-opt/dest-prop/cycle.main.DestinationPropagation.diff

@@ -58,7 +58,6 @@
 +         _6 = _4;                         // scope 3 at $DIR/cycle.rs:14:10: 14:11
           StorageDead(_6);                 // scope 3 at $DIR/cycle.rs:14:11: 14:12
           StorageDead(_5);                 // scope 3 at $DIR/cycle.rs:14:12: 14:13
-          _0 = const ();                   // scope 0 at $DIR/cycle.rs:8:11: 15:2
 -         StorageDead(_3);                 // scope 2 at $DIR/cycle.rs:15:1: 15:2
 -         StorageDead(_2);                 // scope 1 at $DIR/cycle.rs:15:1: 15:2
 -         StorageDead(_1);                 // scope 0 at $DIR/cycle.rs:15:1: 15:2

src/test/mir-opt/dest-prop/union.main.DestinationPropagation.diff

@@ -33,7 +33,6 @@
           _4 = (_1.0: u32);                // scope 2 at $DIR/union.rs:15:19: 15:24
           StorageDead(_4);                 // scope 1 at $DIR/union.rs:15:26: 15:27
           StorageDead(_3);                 // scope 1 at $DIR/union.rs:15:27: 15:28
-          _0 = const ();                   // scope 0 at $DIR/union.rs:8:11: 16:2
           StorageDead(_1);                 // scope 0 at $DIR/union.rs:16:1: 16:2
           return;                          // scope 0 at $DIR/union.rs:16:2: 16:2
       }

src/test/mir-opt/early_otherwise_branch_68867.try_sum.EarlyOtherwiseBranch.before-SimplifyBranches-final.after.diff

@@ -98,7 +98,7 @@
 -     bb2: {
 +         StorageDead(_35);                // scope 0 at $DIR/early_otherwise_branch_68867.rs:27:25: 27:27
           StorageLive(_33);                // scope 0 at $DIR/early_otherwise_branch_68867.rs:27:25: 27:27
-          ((_0 as Err).0: ()) = const ();  // scope 0 at $DIR/early_otherwise_branch_68867.rs:27:21: 27:28
+-         nop;                             // scope 0 at $DIR/early_otherwise_branch_68867.rs:27:21: 27:28
           discriminant(_0) = 1;            // scope 0 at $DIR/early_otherwise_branch_68867.rs:27:21: 27:28
           StorageDead(_33);                // scope 0 at $DIR/early_otherwise_branch_68867.rs:27:27: 27:28
 -         StorageDead(_3);                 // scope 0 at $DIR/early_otherwise_branch_68867.rs:28:6: 28:7

src/test/mir-opt/early_otherwise_branch_68867.try_sum.EarlyOtherwiseBranch.diff

@@ -84,7 +84,7 @@
 -     bb2: {
 +         StorageDead(_35);                // scope 0 at $DIR/early_otherwise_branch_68867.rs:27:25: 27:27
           StorageLive(_33);                // scope 0 at $DIR/early_otherwise_branch_68867.rs:27:25: 27:27
-          ((_0 as Err).0: ()) = const ();  // scope 0 at $DIR/early_otherwise_branch_68867.rs:27:21: 27:28
+-         nop;                             // scope 0 at $DIR/early_otherwise_branch_68867.rs:27:21: 27:28
           discriminant(_0) = 1;            // scope 0 at $DIR/early_otherwise_branch_68867.rs:27:21: 27:28
           StorageDead(_33);                // scope 0 at $DIR/early_otherwise_branch_68867.rs:27:27: 27:28
           StorageDead(_3);                 // scope 0 at $DIR/early_otherwise_branch_68867.rs:28:6: 28:7

src/test/mir-opt/inline/issue_76997_inline_scopes_parenting.main.Inline.after.mir

@@ -28,7 +28,6 @@ fn main() -> () {
         StorageLive(_5);                 // scope 1 at $DIR/issue-76997-inline-scopes-parenting.rs:6:5: 6:10
         _5 = move (_3.0: ());            // scope 1 at $DIR/issue-76997-inline-scopes-parenting.rs:6:5: 6:10
         StorageLive(_6);                 // scope 2 at $DIR/issue-76997-inline-scopes-parenting.rs:6:5: 6:10
-        _6 = const ();                   // scope 2 at $DIR/issue-76997-inline-scopes-parenting.rs:6:5: 6:10
         StorageDead(_6);                 // scope 2 at $DIR/issue-76997-inline-scopes-parenting.rs:6:5: 6:10
         StorageDead(_5);                 // scope 1 at $DIR/issue-76997-inline-scopes-parenting.rs:6:5: 6:10
         StorageDead(_4);                 // scope 1 at $DIR/issue-76997-inline-scopes-parenting.rs:6:9: 6:10

src/test/mir-opt/issue_73223.main.SimplifyArmIdentity.32bit.diff

@@ -58,7 +58,7 @@
       }
   
       bb1: {
-          _0 = const ();                   // scope 0 at $DIR/issue-73223.rs:4:17: 4:23
+          nop;                             // scope 0 at $DIR/issue-73223.rs:4:17: 4:23
           StorageDead(_2);                 // scope 0 at $DIR/issue-73223.rs:5:6: 5:7
           StorageDead(_1);                 // scope 0 at $DIR/issue-73223.rs:9:1: 9:2
           return;                          // scope 0 at $DIR/issue-73223.rs:9:2: 9:2
@@ -146,13 +146,13 @@
       }
   
       bb4: {
-          _8 = const ();                   // scope 4 at $SRC_DIR/core/src/macros/mod.rs:LL:COL
+          nop;                             // scope 4 at $SRC_DIR/core/src/macros/mod.rs:LL:COL
           StorageDead(_15);                // scope 4 at $SRC_DIR/core/src/macros/mod.rs:LL:COL
           StorageDead(_14);                // scope 3 at $SRC_DIR/core/src/macros/mod.rs:LL:COL
           StorageDead(_13);                // scope 3 at $SRC_DIR/core/src/macros/mod.rs:LL:COL
           StorageDead(_9);                 // scope 3 at $SRC_DIR/core/src/macros/mod.rs:LL:COL
           StorageDead(_8);                 // scope 3 at $SRC_DIR/core/src/macros/mod.rs:LL:COL
-          _0 = const ();                   // scope 0 at $DIR/issue-73223.rs:1:11: 9:2
+          nop;                             // scope 0 at $DIR/issue-73223.rs:1:11: 9:2
           StorageDead(_6);                 // scope 1 at $DIR/issue-73223.rs:9:1: 9:2
           StorageDead(_1);                 // scope 0 at $DIR/issue-73223.rs:9:1: 9:2
           return;                          // scope 0 at $DIR/issue-73223.rs:9:2: 9:2

src/test/mir-opt/issue_73223.main.SimplifyArmIdentity.64bit.diff

@@ -58,7 +58,7 @@
       }
   
       bb1: {
-          _0 = const ();                   // scope 0 at $DIR/issue-73223.rs:4:17: 4:23
+          nop;                             // scope 0 at $DIR/issue-73223.rs:4:17: 4:23
           StorageDead(_2);                 // scope 0 at $DIR/issue-73223.rs:5:6: 5:7
           StorageDead(_1);                 // scope 0 at $DIR/issue-73223.rs:9:1: 9:2
           return;                          // scope 0 at $DIR/issue-73223.rs:9:2: 9:2
@@ -146,13 +146,13 @@
       }
   
       bb4: {
-          _8 = const ();                   // scope 4 at $SRC_DIR/core/src/macros/mod.rs:LL:COL
+          nop;                             // scope 4 at $SRC_DIR/core/src/macros/mod.rs:LL:COL
           StorageDead(_15);                // scope 4 at $SRC_DIR/core/src/macros/mod.rs:LL:COL
           StorageDead(_14);                // scope 3 at $SRC_DIR/core/src/macros/mod.rs:LL:COL
           StorageDead(_13);                // scope 3 at $SRC_DIR/core/src/macros/mod.rs:LL:COL
           StorageDead(_9);                 // scope 3 at $SRC_DIR/core/src/macros/mod.rs:LL:COL
           StorageDead(_8);                 // scope 3 at $SRC_DIR/core/src/macros/mod.rs:LL:COL
-          _0 = const ();                   // scope 0 at $DIR/issue-73223.rs:1:11: 9:2
+          nop;                             // scope 0 at $DIR/issue-73223.rs:1:11: 9:2
           StorageDead(_6);                 // scope 1 at $DIR/issue-73223.rs:9:1: 9:2
           StorageDead(_1);                 // scope 0 at $DIR/issue-73223.rs:9:1: 9:2
           return;                          // scope 0 at $DIR/issue-73223.rs:9:2: 9:2

src/test/mir-opt/issue_76432.test.SimplifyComparisonIntegral.diff

@@ -107,7 +107,7 @@
           StorageDead(_14);                // scope 1 at $DIR/issue_76432.rs:9:84: 9:85
           StorageDead(_13);                // scope 1 at $DIR/issue_76432.rs:9:84: 9:85
           StorageDead(_9);                 // scope 1 at $DIR/issue_76432.rs:11:6: 11:7
-          _0 = const ();                   // scope 0 at $DIR/issue_76432.rs:6:44: 12:2
+          nop;                             // scope 0 at $DIR/issue_76432.rs:6:44: 12:2
           StorageDead(_5);                 // scope 0 at $DIR/issue_76432.rs:12:1: 12:2
           StorageDead(_2);                 // scope 0 at $DIR/issue_76432.rs:12:1: 12:2
           return;                          // scope 0 at $DIR/issue_76432.rs:12:2: 12:2

src/test/mir-opt/matches_reduce_branches.foo.MatchBranchSimplification.32bit.diff

@@ -13,7 +13,7 @@
 -     }
 - 
 -     bb1: {
--         goto -> bb3;                     // scope 0 at $DIR/matches_reduce_branches.rs:8:5: 10:6
+-         goto -> bb3;                     // scope 0 at $SRC_DIR/core/src/macros/mod.rs:LL:COL
 -     }
 - 
 -     bb2: {

src/test/mir-opt/matches_reduce_branches.foo.MatchBranchSimplification.64bit.diff

@@ -13,7 +13,7 @@
 -     }
 - 
 -     bb1: {
--         goto -> bb3;                     // scope 0 at $DIR/matches_reduce_branches.rs:8:5: 10:6
+-         goto -> bb3;                     // scope 0 at $SRC_DIR/core/src/macros/mod.rs:LL:COL
 -     }
 - 
 -     bb2: {

src/test/mir-opt/multiple_return_terminators.test.MultipleReturnTerminators.diff

@@ -4,24 +4,8 @@
   fn test(_1: bool) -> () {
       debug x => _1;                       // in scope 0 at $DIR/multiple_return_terminators.rs:4:9: 4:10
       let mut _0: ();                      // return place in scope 0 at $DIR/multiple_return_terminators.rs:4:18: 4:18
-      let mut _2: bool;                    // in scope 0 at $DIR/multiple_return_terminators.rs:5:8: 5:9
   
       bb0: {
-          StorageLive(_2);                 // scope 0 at $DIR/multiple_return_terminators.rs:5:8: 5:9
-          _2 = _1;                         // scope 0 at $DIR/multiple_return_terminators.rs:5:8: 5:9
-          switchInt(move _2) -> [false: bb2, otherwise: bb1]; // scope 0 at $DIR/multiple_return_terminators.rs:5:5: 9:6
-      }
-  
-      bb1: {
-          goto -> bb3;                     // scope 0 at $DIR/multiple_return_terminators.rs:5:5: 9:6
-      }
-  
-      bb2: {
-          goto -> bb3;                     // scope 0 at $DIR/multiple_return_terminators.rs:5:5: 9:6
-      }
-  
-      bb3: {
-          StorageDead(_2);                 // scope 0 at $DIR/multiple_return_terminators.rs:9:5: 9:6
           return;                          // scope 0 at $DIR/multiple_return_terminators.rs:10:2: 10:2
       }
   }

src/test/mir-opt/remove_unneeded_drops.cannot_opt_generic.RemoveUnneededDrops.diff

@@ -14,6 +14,7 @@
           StorageLive(_2);                 // scope 0 at $DIR/remove_unneeded_drops.rs:21:5: 21:12
           StorageLive(_3);                 // scope 0 at $DIR/remove_unneeded_drops.rs:21:10: 21:11
           _3 = move _1;                    // scope 0 at $DIR/remove_unneeded_drops.rs:21:10: 21:11
+          nop;                             // scope 1 at $DIR/remove_unneeded_drops.rs:21:5: 21:12
           drop(_3) -> [return: bb2, unwind: bb1]; // scope 1 at $DIR/remove_unneeded_drops.rs:21:5: 21:12
       }
   
@@ -24,7 +25,7 @@
       bb2: {
           StorageDead(_3);                 // scope 0 at $DIR/remove_unneeded_drops.rs:21:11: 21:12
           StorageDead(_2);                 // scope 0 at $DIR/remove_unneeded_drops.rs:21:12: 21:13
-          _0 = const ();                   // scope 0 at $DIR/remove_unneeded_drops.rs:20:32: 22:2
+          nop;                             // scope 0 at $DIR/remove_unneeded_drops.rs:20:32: 22:2
           return;                          // scope 0 at $DIR/remove_unneeded_drops.rs:22:2: 22:2
       }
   }

src/test/mir-opt/remove_unneeded_drops.dont_opt.RemoveUnneededDrops.diff

@@ -14,6 +14,7 @@
           StorageLive(_2);                 // scope 0 at $DIR/remove_unneeded_drops.rs:9:5: 9:12
           StorageLive(_3);                 // scope 0 at $DIR/remove_unneeded_drops.rs:9:10: 9:11
           _3 = move _1;                    // scope 0 at $DIR/remove_unneeded_drops.rs:9:10: 9:11
+          nop;                             // scope 1 at $DIR/remove_unneeded_drops.rs:9:5: 9:12
           drop(_3) -> [return: bb2, unwind: bb1]; // scope 1 at $DIR/remove_unneeded_drops.rs:9:5: 9:12
       }
   
@@ -24,7 +25,7 @@
       bb2: {
           StorageDead(_3);                 // scope 0 at $DIR/remove_unneeded_drops.rs:9:11: 9:12
           StorageDead(_2);                 // scope 0 at $DIR/remove_unneeded_drops.rs:9:12: 9:13
-          _0 = const ();                   // scope 0 at $DIR/remove_unneeded_drops.rs:8:27: 10:2
+          nop;                             // scope 0 at $DIR/remove_unneeded_drops.rs:8:27: 10:2
           return;                          // scope 0 at $DIR/remove_unneeded_drops.rs:10:2: 10:2
       }
   }

src/test/mir-opt/remove_unneeded_drops.opt.RemoveUnneededDrops.diff

@@ -14,13 +14,14 @@
           StorageLive(_2);                 // scope 0 at $DIR/remove_unneeded_drops.rs:4:5: 4:12
           StorageLive(_3);                 // scope 0 at $DIR/remove_unneeded_drops.rs:4:10: 4:11
           _3 = _1;                         // scope 0 at $DIR/remove_unneeded_drops.rs:4:10: 4:11
+-         nop;                             // scope 1 at $DIR/remove_unneeded_drops.rs:4:5: 4:12
 -         drop(_3) -> bb1;                 // scope 1 at $DIR/remove_unneeded_drops.rs:4:5: 4:12
 -     }
 - 
 -     bb1: {
           StorageDead(_3);                 // scope 0 at $DIR/remove_unneeded_drops.rs:4:11: 4:12
           StorageDead(_2);                 // scope 0 at $DIR/remove_unneeded_drops.rs:4:12: 4:13
-          _0 = const ();                   // scope 0 at $DIR/remove_unneeded_drops.rs:3:17: 5:2
+-         nop;                             // scope 0 at $DIR/remove_unneeded_drops.rs:3:17: 5:2
           return;                          // scope 0 at $DIR/remove_unneeded_drops.rs:5:2: 5:2
       }
   }

src/test/mir-opt/remove_unneeded_drops.opt_generic_copy.RemoveUnneededDrops.diff

@@ -14,13 +14,14 @@
           StorageLive(_2);                 // scope 0 at $DIR/remove_unneeded_drops.rs:14:5: 14:12
           StorageLive(_3);                 // scope 0 at $DIR/remove_unneeded_drops.rs:14:10: 14:11
           _3 = _1;                         // scope 0 at $DIR/remove_unneeded_drops.rs:14:10: 14:11
+-         nop;                             // scope 1 at $DIR/remove_unneeded_drops.rs:14:5: 14:12
 -         drop(_3) -> bb1;                 // scope 1 at $DIR/remove_unneeded_drops.rs:14:5: 14:12
 -     }
 - 
 -     bb1: {
           StorageDead(_3);                 // scope 0 at $DIR/remove_unneeded_drops.rs:14:11: 14:12
           StorageDead(_2);                 // scope 0 at $DIR/remove_unneeded_drops.rs:14:12: 14:13
-          _0 = const ();                   // scope 0 at $DIR/remove_unneeded_drops.rs:13:36: 15:2
+-         nop;                             // scope 0 at $DIR/remove_unneeded_drops.rs:13:36: 15:2
           return;                          // scope 0 at $DIR/remove_unneeded_drops.rs:15:2: 15:2
       }
   }

src/test/mir-opt/simplify_arm_identity.main.SimplifyArmIdentity.32bit.diff

@@ -50,7 +50,7 @@
   
       bb4: {
           StorageDead(_2);                 // scope 1 at $DIR/simplify-arm-identity.rs:22:6: 22:7
-          _0 = const ();                   // scope 0 at $DIR/simplify-arm-identity.rs:17:11: 23:2
+          nop;                             // scope 0 at $DIR/simplify-arm-identity.rs:17:11: 23:2
           StorageDead(_1);                 // scope 0 at $DIR/simplify-arm-identity.rs:23:1: 23:2
           return;                          // scope 0 at $DIR/simplify-arm-identity.rs:23:2: 23:2
       }

src/test/mir-opt/simplify_arm_identity.main.SimplifyArmIdentity.64bit.diff

@@ -50,7 +50,7 @@
   
       bb4: {
           StorageDead(_2);                 // scope 1 at $DIR/simplify-arm-identity.rs:22:6: 22:7
-          _0 = const ();                   // scope 0 at $DIR/simplify-arm-identity.rs:17:11: 23:2
+          nop;                             // scope 0 at $DIR/simplify-arm-identity.rs:17:11: 23:2
           StorageDead(_1);                 // scope 0 at $DIR/simplify-arm-identity.rs:23:1: 23:2
           return;                          // scope 0 at $DIR/simplify-arm-identity.rs:23:2: 23:2
       }

src/test/mir-opt/simplify_if.main.SimplifyBranches-after-const-prop.diff

@@ -22,13 +22,13 @@
       }
   
       bb2: {
-          _0 = const ();                   // scope 0 at $DIR/simplify_if.rs:8:6: 8:6
+          nop;                             // scope 0 at $DIR/simplify_if.rs:8:6: 8:6
           goto -> bb4;                     // scope 0 at $DIR/simplify_if.rs:6:5: 8:6
       }
   
       bb3: {
           StorageDead(_2);                 // scope 0 at $DIR/simplify_if.rs:7:15: 7:16
-          _0 = const ();                   // scope 0 at $DIR/simplify_if.rs:6:14: 8:6
+          nop;                             // scope 0 at $DIR/simplify_if.rs:6:14: 8:6
           goto -> bb4;                     // scope 0 at $DIR/simplify_if.rs:6:5: 8:6
       }
   

src/test/mir-opt/simplify_locals.c.SimplifyLocals.diff

@@ -25,7 +25,6 @@
 -         StorageDead(_3);                 // scope 1 at $DIR/simplify-locals.rs:16:25: 16:26
 -         StorageDead(_4);                 // scope 1 at $DIR/simplify-locals.rs:16:26: 16:27
 -         StorageDead(_2);                 // scope 1 at $DIR/simplify-locals.rs:16:26: 16:27
--         _0 = const ();                   // scope 0 at $DIR/simplify-locals.rs:13:8: 17:2
           StorageDead(_1);                 // scope 0 at $DIR/simplify-locals.rs:17:1: 17:2
           return;                          // scope 0 at $DIR/simplify-locals.rs:17:2: 17:2
       }

src/test/mir-opt/simplify_locals.d1.SimplifyLocals.diff

@@ -11,7 +11,6 @@
 -         StorageLive(_1);                 // scope 0 at $DIR/simplify-locals.rs:22:13: 22:17
 -         discriminant(_1) = 0;            // scope 0 at $DIR/simplify-locals.rs:22:13: 22:17
 -         StorageDead(_1);                 // scope 0 at $DIR/simplify-locals.rs:22:17: 22:18
--         _0 = const ();                   // scope 0 at $DIR/simplify-locals.rs:20:9: 23:2
           return;                          // scope 0 at $DIR/simplify-locals.rs:23:2: 23:2
       }
   }

src/test/mir-opt/simplify_locals.d2.SimplifyLocals.diff

@@ -31,7 +31,6 @@
 -                                          // + literal: Const { ty: E, val: Value(Scalar(0x01)) }
 -         StorageDead(_1);                 // scope 0 at $DIR/simplify-locals.rs:28:25: 28:26
 -         StorageDead(_2);                 // scope 0 at $DIR/simplify-locals.rs:28:26: 28:27
--         _0 = const ();                   // scope 0 at $DIR/simplify-locals.rs:26:9: 29:2
           return;                          // scope 0 at $DIR/simplify-locals.rs:29:2: 29:2
       }
   }

src/test/mir-opt/simplify_locals.r.SimplifyLocals.diff

@@ -23,7 +23,6 @@
 -         StorageLive(_3);                 // scope 2 at $DIR/simplify-locals.rs:36:13: 36:19
 -         _3 = &mut _1;                    // scope 2 at $DIR/simplify-locals.rs:36:13: 36:19
 -         StorageDead(_3);                 // scope 2 at $DIR/simplify-locals.rs:36:19: 36:20
--         _0 = const ();                   // scope 0 at $DIR/simplify-locals.rs:32:8: 37:2
           StorageDead(_1);                 // scope 0 at $DIR/simplify-locals.rs:37:1: 37:2
           return;                          // scope 0 at $DIR/simplify-locals.rs:37:2: 37:2
       }

src/test/mir-opt/simplify_locals.t1.SimplifyLocals.diff

@@ -15,7 +15,6 @@
 -         _1 = (*_2);                      // scope 1 at $DIR/simplify-locals.rs:44:14: 44:15
 -         StorageDead(_2);                 // scope 0 at $DIR/simplify-locals.rs:44:17: 44:18
 -         StorageDead(_1);                 // scope 0 at $DIR/simplify-locals.rs:44:17: 44:18
--         _0 = const ();                   // scope 0 at $DIR/simplify-locals.rs:42:9: 45:2
           return;                          // scope 0 at $DIR/simplify-locals.rs:45:2: 45:2
       }
   }

src/test/mir-opt/simplify_locals.t2.SimplifyLocals.diff

@@ -15,7 +15,6 @@
 -         _1 = &mut (*_2);                 // scope 1 at $DIR/simplify-locals.rs:50:14: 50:20
 -         StorageDead(_2);                 // scope 0 at $DIR/simplify-locals.rs:50:22: 50:23
 -         StorageDead(_1);                 // scope 0 at $DIR/simplify-locals.rs:50:22: 50:23
--         _0 = const ();                   // scope 0 at $DIR/simplify-locals.rs:48:9: 51:2
           return;                          // scope 0 at $DIR/simplify-locals.rs:51:2: 51:2
       }
   }

src/test/mir-opt/simplify_locals.t3.SimplifyLocals.diff

@@ -19,7 +19,6 @@
 -         StorageDead(_3);                 // scope 0 at $DIR/simplify-locals.rs:56:23: 56:24
 -         StorageDead(_2);                 // scope 0 at $DIR/simplify-locals.rs:56:23: 56:24
 -         StorageDead(_1);                 // scope 0 at $DIR/simplify-locals.rs:56:23: 56:24
--         _0 = const ();                   // scope 0 at $DIR/simplify-locals.rs:54:9: 57:2
           return;                          // scope 0 at $DIR/simplify-locals.rs:57:2: 57:2
       }
   }

src/test/mir-opt/simplify_locals_fixedpoint.foo.SimplifyLocals.diff

@@ -30,7 +30,7 @@
       }
   
       bb1: {
--         _0 = const ();                   // scope 0 at $DIR/simplify-locals-fixedpoint.rs:8:6: 8:6
+          _0 = const ();                   // scope 0 at $DIR/simplify-locals-fixedpoint.rs:8:6: 8:6
           goto -> bb7;                     // scope 0 at $DIR/simplify-locals-fixedpoint.rs:4:5: 8:6
       }
   
@@ -51,12 +51,12 @@
       }
   
       bb4: {
--         _0 = const ();                   // scope 1 at $DIR/simplify-locals-fixedpoint.rs:5:21: 7:10
+          _0 = const ();                   // scope 1 at $DIR/simplify-locals-fixedpoint.rs:5:21: 7:10
           goto -> bb6;                     // scope 1 at $DIR/simplify-locals-fixedpoint.rs:5:9: 7:10
       }
   
       bb5: {
--         _0 = const ();                   // scope 1 at $DIR/simplify-locals-fixedpoint.rs:7:10: 7:10
+          _0 = const ();                   // scope 1 at $DIR/simplify-locals-fixedpoint.rs:7:10: 7:10
           goto -> bb6;                     // scope 1 at $DIR/simplify-locals-fixedpoint.rs:5:9: 7:10
       }
   

src/test/mir-opt/simplify_locals_removes_unused_consts.main.SimplifyLocals.diff

@@ -23,8 +23,6 @@
 -         StorageLive(_1);                 // scope 0 at $DIR/simplify-locals-removes-unused-consts.rs:13:20: 13:28
 -         StorageLive(_2);                 // scope 0 at $DIR/simplify-locals-removes-unused-consts.rs:13:21: 13:23
 -         StorageLive(_3);                 // scope 0 at $DIR/simplify-locals-removes-unused-consts.rs:13:25: 13:27
--         (_1.0: ()) = const ();           // scope 0 at $DIR/simplify-locals-removes-unused-consts.rs:13:20: 13:28
--         (_1.1: ()) = const ();           // scope 0 at $DIR/simplify-locals-removes-unused-consts.rs:13:20: 13:28
 -         StorageDead(_3);                 // scope 0 at $DIR/simplify-locals-removes-unused-consts.rs:13:27: 13:28
 -         StorageDead(_2);                 // scope 0 at $DIR/simplify-locals-removes-unused-consts.rs:13:27: 13:28
 -         StorageDead(_1);                 // scope 0 at $DIR/simplify-locals-removes-unused-consts.rs:13:28: 13:29
@@ -32,8 +30,6 @@
 -         StorageLive(_5);                 // scope 1 at $DIR/simplify-locals-removes-unused-consts.rs:14:13: 14:21
 -         StorageLive(_6);                 // scope 1 at $DIR/simplify-locals-removes-unused-consts.rs:14:14: 14:16
 -         StorageLive(_7);                 // scope 1 at $DIR/simplify-locals-removes-unused-consts.rs:14:18: 14:20
--         (_5.0: ()) = const ();           // scope 1 at $DIR/simplify-locals-removes-unused-consts.rs:14:13: 14:21
--         (_5.1: ()) = const ();           // scope 1 at $DIR/simplify-locals-removes-unused-consts.rs:14:13: 14:21
 -         StorageDead(_7);                 // scope 1 at $DIR/simplify-locals-removes-unused-consts.rs:14:20: 14:21
 -         StorageDead(_6);                 // scope 1 at $DIR/simplify-locals-removes-unused-consts.rs:14:20: 14:21
 -         _4 = use_zst(const ((), ())) -> bb1; // scope 1 at $DIR/simplify-locals-removes-unused-consts.rs:14:5: 14:22
@@ -71,7 +67,6 @@
 -         StorageDead(_9);                 // scope 1 at $DIR/simplify-locals-removes-unused-consts.rs:16:34: 16:35
 -         StorageDead(_11);                // scope 1 at $DIR/simplify-locals-removes-unused-consts.rs:16:35: 16:36
 -         StorageDead(_8);                 // scope 1 at $DIR/simplify-locals-removes-unused-consts.rs:16:35: 16:36
--         _0 = const ();                   // scope 0 at $DIR/simplify-locals-removes-unused-consts.rs:12:11: 17:2
 +         StorageDead(_2);                 // scope 1 at $DIR/simplify-locals-removes-unused-consts.rs:16:35: 16:36
           return;                          // scope 0 at $DIR/simplify-locals-removes-unused-consts.rs:17:2: 17:2
       }

src/test/mir-opt/simplify_match.main.ConstProp.diff

@@ -21,7 +21,7 @@
       }
   
       bb1: {
-          _0 = const ();                   // scope 0 at $DIR/simplify_match.rs:8:18: 8:20
+          nop;                             // scope 0 at $DIR/simplify_match.rs:8:18: 8:20
           goto -> bb3;                     // scope 0 at $DIR/simplify_match.rs:6:5: 9:6
       }
   

src/test/mir-opt/tls_access.main.SimplifyCfg-final.after.mir

@@ -20,7 +20,6 @@ fn main() -> () {
         _3 = &/*tls*/ mut FOO;           // scope 2 at $DIR/tls-access.rs:9:9: 9:12
         (*_3) = const 42_u8;             // scope 2 at $DIR/tls-access.rs:9:9: 9:17
         StorageDead(_3);                 // scope 2 at $DIR/tls-access.rs:9:17: 9:18
-        _0 = const ();                   // scope 1 at $DIR/tls-access.rs:7:5: 10:6
         StorageDead(_2);                 // scope 1 at $DIR/tls-access.rs:10:5: 10:6
         StorageDead(_1);                 // scope 1 at $DIR/tls-access.rs:10:5: 10:6
         return;                          // scope 0 at $DIR/tls-access.rs:11:2: 11:2

src/test/mir-opt/while_let_loops.change_loop_body.ConstProp.32bit.diff

@@ -25,7 +25,7 @@
       }
   
       bb1: {
-          _0 = const ();                   // scope 1 at $DIR/while_let_loops.rs:7:5: 10:6
+          nop;                             // scope 1 at $DIR/while_let_loops.rs:7:5: 10:6
           goto -> bb4;                     // scope 1 at $DIR/while_let_loops.rs:7:5: 10:6
       }
   
@@ -35,7 +35,7 @@
   
       bb3: {
           _1 = const 1_i32;                // scope 1 at $DIR/while_let_loops.rs:8:9: 8:15
-          _0 = const ();                   // scope 1 at $DIR/while_let_loops.rs:9:9: 9:14
+          nop;                             // scope 1 at $DIR/while_let_loops.rs:9:9: 9:14
           goto -> bb4;                     // scope 1 at $DIR/while_let_loops.rs:9:9: 9:14
       }
   

src/test/mir-opt/while_let_loops.change_loop_body.ConstProp.64bit.diff

@@ -25,7 +25,7 @@
       }
   
       bb1: {
-          _0 = const ();                   // scope 1 at $DIR/while_let_loops.rs:7:5: 10:6
+          nop;                             // scope 1 at $DIR/while_let_loops.rs:7:5: 10:6
           goto -> bb4;                     // scope 1 at $DIR/while_let_loops.rs:7:5: 10:6
       }
   
@@ -35,7 +35,7 @@
   
       bb3: {
           _1 = const 1_i32;                // scope 1 at $DIR/while_let_loops.rs:8:9: 8:15
-          _0 = const ();                   // scope 1 at $DIR/while_let_loops.rs:9:9: 9:14
+          nop;                             // scope 1 at $DIR/while_let_loops.rs:9:9: 9:14
           goto -> bb4;                     // scope 1 at $DIR/while_let_loops.rs:9:9: 9:14
       }
   

src/test/mir-opt/while_storage.while_loop.PreCodegen.after.mir

@@ -20,40 +20,36 @@ fn while_loop(_1: bool) -> () {
 
     bb1: {
         StorageDead(_3);                 // scope 0 at $DIR/while-storage.rs:10:21: 10:22
-        switchInt(_2) -> [false: bb2, otherwise: bb3]; // scope 0 at $DIR/while-storage.rs:10:5: 14:6
+        switchInt(_2) -> [false: bb6, otherwise: bb2]; // scope 0 at $DIR/while-storage.rs:10:5: 14:6
     }
 
     bb2: {
-        goto -> bb7;                     // scope 0 at $DIR/while-storage.rs:10:5: 14:6
-    }
-
-    bb3: {
         StorageLive(_4);                 // scope 0 at $DIR/while-storage.rs:11:12: 11:23
         StorageLive(_5);                 // scope 0 at $DIR/while-storage.rs:11:21: 11:22
         _5 = _1;                         // scope 0 at $DIR/while-storage.rs:11:21: 11:22
-        _4 = get_bool(move _5) -> bb4;   // scope 0 at $DIR/while-storage.rs:11:12: 11:23
+        _4 = get_bool(move _5) -> bb3;   // scope 0 at $DIR/while-storage.rs:11:12: 11:23
                                          // mir::Constant
                                          // + span: $DIR/while-storage.rs:11:12: 11:20
                                          // + literal: Const { ty: fn(bool) -> bool {get_bool}, val: Value(Scalar(<ZST>)) }
     }
 
-    bb4: {
+    bb3: {
         StorageDead(_5);                 // scope 0 at $DIR/while-storage.rs:11:22: 11:23
-        switchInt(move _4) -> [false: bb6, otherwise: bb5]; // scope 0 at $DIR/while-storage.rs:11:9: 13:10
+        switchInt(move _4) -> [false: bb5, otherwise: bb4]; // scope 0 at $DIR/while-storage.rs:11:9: 13:10
     }
 
-    bb5: {
+    bb4: {
         StorageDead(_4);                 // scope 0 at $DIR/while-storage.rs:13:9: 13:10
-        goto -> bb7;                     // scope 0 at $DIR/while-storage.rs:1:1: 1:1
+        goto -> bb6;                     // scope 0 at $DIR/while-storage.rs:1:1: 1:1
     }
 
-    bb6: {
+    bb5: {
         StorageDead(_4);                 // scope 0 at $DIR/while-storage.rs:13:9: 13:10
         StorageDead(_2);                 // scope 0 at $DIR/while-storage.rs:14:5: 14:6
         goto -> bb0;                     // scope 0 at $DIR/while-storage.rs:10:5: 14:6
     }
 
-    bb7: {
+    bb6: {
         StorageDead(_2);                 // scope 0 at $DIR/while-storage.rs:14:5: 14:6
         return;                          // scope 0 at $DIR/while-storage.rs:15:2: 15:2
     }

src/test/run-make/const_fn_mir/dump.mir

@@ -12,6 +12,7 @@ fn main() -> () {
     }
 
     bb1: {
+        _0 = const ();                   // scope 0 at main.rs:8:11: 10:2
         return;                          // scope 0 at main.rs:10:2: 10:2
     }
 }