rust-lang · saethlin · Dec 2, 2022
diff --git a/compiler/rustc_mir_transform/src/lib.rs b/compiler/rustc_mir_transform/src/lib.rs
@@ -74,6 +74,7 @@ mod instcombine;
 mod lower_intrinsics;
 mod lower_slice_len;
 mod match_branches;
+mod move_to_copy;
 mod multiple_return_terminators;
 mod normalize_array_len;
 mod nrvo;
@@ -557,6 +558,7 @@ fn run_optimization_passes<'tcx>(tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>) {
             &normalize_array_len::NormalizeArrayLen, // has to run after `slice::len` lowering
             &unreachable_prop::UnreachablePropagation,
             &uninhabited_enum_branching::UninhabitedEnumBranching,
+            &move_to_copy::MoveToCopy,
             &o1(simplify::SimplifyCfg::new("after-uninhabited-enum-branching")),
             &inline::Inline,
             &remove_storage_markers::RemoveStorageMarkers,

diff --git a/compiler/rustc_mir_transform/src/move_to_copy.rs b/compiler/rustc_mir_transform/src/move_to_copy.rs
@@ -0,0 +1,97 @@
+use crate::MirPass;
+use rustc_middle::mir::visit::MutVisitor;
+use rustc_middle::mir::*;
+use rustc_middle::ty::{FnDef, TyCtxt};
+
+/// Within-block replacement empowers ConstProp, DataflowConstProp, and DestProp. (based on looking
+/// at the tests)
+///
+/// SwitchInt replacement causes some basic blocks which only contain a goto to be deleted. (based
+/// on looking at core and alloc)
+/// It also makes EarlyOtherwiseBranch much more effective, but that pass is currently marked as
+/// unsound so this effect is not useful yet.
+///
+/// At time of writing, Assert replacement has no effect. Most likely we don't often need the
+/// asserted predicate for anything else, and aren't smart enough to optimize into a form that
+/// could use it anyway.
+///
+/// Enabling this pass for Call arguments breaks the moved-from local reuse optimization that
+/// Inline does, so without DestinationPropagation, modifying call arguments is just a regression.
+/// Except for calls to intrinsics, because those cannot be inlined.
+pub struct MoveToCopy;
+
+impl<'tcx> MirPass<'tcx> for MoveToCopy {
+    fn run_pass(&self, tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>) {
+        let mut visitor = MoveToCopyVisitor { tcx };
+        let mut call_visitor = MoveToCopyCallVisitor { tcx, local_decls: &body.local_decls };
+        for (block, block_data) in body.basic_blocks.as_mut().iter_enumerated_mut() {
+            for (statement_index, statement) in block_data.statements.iter_mut().enumerate() {
+                visitor.visit_statement(statement, Location { block, statement_index });
+            }
+            let Some(terminator) = &mut block_data.terminator else {
+                continue;
+            };
+            match &terminator.kind {
+                TerminatorKind::SwitchInt { .. } | TerminatorKind::Assert { .. } => {
+                    visitor.visit_terminator(
+                        terminator,
+                        Location { block, statement_index: block_data.statements.len() },
+                    );
+                }
+                TerminatorKind::Call { func, .. } => {
+                    let func_ty = func.ty(call_visitor.local_decls, tcx);
+                    let is_intrinsic = if let FnDef(def_id, _) = *func_ty.kind() {
+                        tcx.is_intrinsic(def_id)
+                    } else {
+                        false
+                    };
+                    if is_intrinsic || tcx.sess.mir_opt_level() >= 3 {
+                        call_visitor.visit_terminator(
+                            terminator,
+                            Location { block, statement_index: block_data.statements.len() },
+                        );
+                    }
+                }
+                _ => {}
+            }
+        }
+    }
+}
+
+struct MoveToCopyCallVisitor<'a, 'tcx> {
+    tcx: TyCtxt<'tcx>,
+    local_decls: &'a LocalDecls<'tcx>,
+}
+
+impl<'a, 'tcx> MutVisitor<'tcx> for MoveToCopyCallVisitor<'a, 'tcx> {
+    fn tcx(&self) -> TyCtxt<'tcx> {
+        self.tcx
+    }
+
+    fn visit_operand(&mut self, operand: &mut Operand<'tcx>, location: Location) {
+        if let Operand::Move(place) = operand {
+            let ty = place.ty(self.local_decls, self.tcx).ty;
+            if ty.is_numeric() || ty.is_bool() || ty.is_char() {
+                *operand = Operand::Copy(*place);
+            }
+        }
+        self.super_operand(operand, location);
+    }
+}
+
+struct MoveToCopyVisitor<'tcx> {
+    tcx: TyCtxt<'tcx>,
+}
+
+impl<'tcx> MutVisitor<'tcx> for MoveToCopyVisitor<'tcx> {
+    fn tcx(&self) -> TyCtxt<'tcx> {
+        self.tcx
+    }
+
+    fn visit_operand(&mut self, operand: &mut Operand<'tcx>, location: Location) {
+        if let Operand::Move(place) = operand {
+            *operand = Operand::Copy(*place);
+        }
+        self.super_operand(operand, location);
+    }
+}
diff --git a/src/test/mir-opt/76803_regression.encode.SimplifyBranchSame.diff b/src/test/mir-opt/76803_regression.encode.SimplifyBranchSame.diff
@@ -8,11 +8,11 @@
 
       bb0: {
           _2 = discriminant(_1);           // scope 0 at $DIR/76803_regression.rs:+1:11: +1:12
-          switchInt(move _2) -> [0: bb2, otherwise: bb1]; // scope 0 at $DIR/76803_regression.rs:+1:5: +1:12
+          switchInt(_2) -> [0: bb2, otherwise: bb1]; // scope 0 at $DIR/76803_regression.rs:+1:5: +1:12
       }
 
       bb1: {
-          _0 = move _1;                    // scope 0 at $DIR/76803_regression.rs:+3:14: +3:15
+          _0 = _1;                         // scope 0 at $DIR/76803_regression.rs:+3:14: +3:15
           goto -> bb3;                     // scope 0 at $DIR/76803_regression.rs:+3:14: +3:15
       }
 

diff --git a/src/test/mir-opt/bool_compare.opt1.InstCombine.diff b/src/test/mir-opt/bool_compare.opt1.InstCombine.diff
@@ -11,10 +11,10 @@
           StorageLive(_2);                 // scope 0 at $DIR/bool_compare.rs:+1:8: +1:17
           StorageLive(_3);                 // scope 0 at $DIR/bool_compare.rs:+1:8: +1:9
           _3 = _1;                         // scope 0 at $DIR/bool_compare.rs:+1:8: +1:9
--         _2 = Ne(move _3, const true);    // scope 0 at $DIR/bool_compare.rs:+1:8: +1:17
-+         _2 = Not(move _3);               // scope 0 at $DIR/bool_compare.rs:+1:8: +1:17
+-         _2 = Ne(_3, const true);         // scope 0 at $DIR/bool_compare.rs:+1:8: +1:17
++         _2 = Not(_3);                    // scope 0 at $DIR/bool_compare.rs:+1:8: +1:17
           StorageDead(_3);                 // scope 0 at $DIR/bool_compare.rs:+1:16: +1:17
-          switchInt(move _2) -> [0: bb2, otherwise: bb1]; // scope 0 at $DIR/bool_compare.rs:+1:8: +1:17
+          switchInt(_2) -> [0: bb2, otherwise: bb1]; // scope 0 at $DIR/bool_compare.rs:+1:8: +1:17
       }
 
       bb1: {

diff --git a/src/test/mir-opt/bool_compare.opt2.InstCombine.diff b/src/test/mir-opt/bool_compare.opt2.InstCombine.diff
@@ -11,10 +11,10 @@
           StorageLive(_2);                 // scope 0 at $DIR/bool_compare.rs:+1:8: +1:17
           StorageLive(_3);                 // scope 0 at $DIR/bool_compare.rs:+1:16: +1:17
           _3 = _1;                         // scope 0 at $DIR/bool_compare.rs:+1:16: +1:17
--         _2 = Ne(const true, move _3);    // scope 0 at $DIR/bool_compare.rs:+1:8: +1:17
-+         _2 = Not(move _3);               // scope 0 at $DIR/bool_compare.rs:+1:8: +1:17
+-         _2 = Ne(const true, _3);         // scope 0 at $DIR/bool_compare.rs:+1:8: +1:17
++         _2 = Not(_3);                    // scope 0 at $DIR/bool_compare.rs:+1:8: +1:17
           StorageDead(_3);                 // scope 0 at $DIR/bool_compare.rs:+1:16: +1:17
-          switchInt(move _2) -> [0: bb2, otherwise: bb1]; // scope 0 at $DIR/bool_compare.rs:+1:8: +1:17
+          switchInt(_2) -> [0: bb2, otherwise: bb1]; // scope 0 at $DIR/bool_compare.rs:+1:8: +1:17
       }
 
       bb1: {

diff --git a/src/test/mir-opt/bool_compare.opt3.InstCombine.diff b/src/test/mir-opt/bool_compare.opt3.InstCombine.diff
@@ -11,10 +11,10 @@
           StorageLive(_2);                 // scope 0 at $DIR/bool_compare.rs:+1:8: +1:18
           StorageLive(_3);                 // scope 0 at $DIR/bool_compare.rs:+1:8: +1:9
           _3 = _1;                         // scope 0 at $DIR/bool_compare.rs:+1:8: +1:9
--         _2 = Eq(move _3, const false);   // scope 0 at $DIR/bool_compare.rs:+1:8: +1:18
-+         _2 = Not(move _3);               // scope 0 at $DIR/bool_compare.rs:+1:8: +1:18
+-         _2 = Eq(_3, const false);        // scope 0 at $DIR/bool_compare.rs:+1:8: +1:18
++         _2 = Not(_3);                    // scope 0 at $DIR/bool_compare.rs:+1:8: +1:18
           StorageDead(_3);                 // scope 0 at $DIR/bool_compare.rs:+1:17: +1:18
-          switchInt(move _2) -> [0: bb2, otherwise: bb1]; // scope 0 at $DIR/bool_compare.rs:+1:8: +1:18
+          switchInt(_2) -> [0: bb2, otherwise: bb1]; // scope 0 at $DIR/bool_compare.rs:+1:8: +1:18
       }
 
       bb1: {

diff --git a/src/test/mir-opt/bool_compare.opt4.InstCombine.diff b/src/test/mir-opt/bool_compare.opt4.InstCombine.diff
@@ -11,10 +11,10 @@
           StorageLive(_2);                 // scope 0 at $DIR/bool_compare.rs:+1:8: +1:18
           StorageLive(_3);                 // scope 0 at $DIR/bool_compare.rs:+1:17: +1:18
           _3 = _1;                         // scope 0 at $DIR/bool_compare.rs:+1:17: +1:18
--         _2 = Eq(const false, move _3);   // scope 0 at $DIR/bool_compare.rs:+1:8: +1:18
-+         _2 = Not(move _3);               // scope 0 at $DIR/bool_compare.rs:+1:8: +1:18
+-         _2 = Eq(const false, _3);        // scope 0 at $DIR/bool_compare.rs:+1:8: +1:18
++         _2 = Not(_3);                    // scope 0 at $DIR/bool_compare.rs:+1:8: +1:18
           StorageDead(_3);                 // scope 0 at $DIR/bool_compare.rs:+1:17: +1:18
-          switchInt(move _2) -> [0: bb2, otherwise: bb1]; // scope 0 at $DIR/bool_compare.rs:+1:8: +1:18
+          switchInt(_2) -> [0: bb2, otherwise: bb1]; // scope 0 at $DIR/bool_compare.rs:+1:8: +1:18
       }
 
       bb1: {

diff --git a/src/test/mir-opt/combine_array_len.norm2.InstCombine.diff b/src/test/mir-opt/combine_array_len.norm2.InstCombine.diff
@@ -32,7 +32,7 @@
 -         _4 = Len(_1);                    // scope 0 at $DIR/combine_array_len.rs:+1:13: +1:17
 +         _4 = const 2_usize;              // scope 0 at $DIR/combine_array_len.rs:+1:13: +1:17
           _5 = Lt(_3, _4);                 // scope 0 at $DIR/combine_array_len.rs:+1:13: +1:17
-          assert(move _5, "index out of bounds: the length is {} but the index is {}", move _4, _3) -> bb1; // scope 0 at $DIR/combine_array_len.rs:+1:13: +1:17
+          assert(_5, "index out of bounds: the length is {} but the index is {}", _4, _3) -> bb1; // scope 0 at $DIR/combine_array_len.rs:+1:13: +1:17
       }
 
       bb1: {
@@ -44,7 +44,7 @@
 -         _8 = Len(_1);                    // scope 1 at $DIR/combine_array_len.rs:+2:13: +2:17
 +         _8 = const 2_usize;              // scope 1 at $DIR/combine_array_len.rs:+2:13: +2:17
           _9 = Lt(_7, _8);                 // scope 1 at $DIR/combine_array_len.rs:+2:13: +2:17
-          assert(move _9, "index out of bounds: the length is {} but the index is {}", move _8, _7) -> bb2; // scope 1 at $DIR/combine_array_len.rs:+2:13: +2:17
+          assert(_9, "index out of bounds: the length is {} but the index is {}", _8, _7) -> bb2; // scope 1 at $DIR/combine_array_len.rs:+2:13: +2:17
       }
 
       bb2: {
@@ -55,18 +55,18 @@
           _11 = _2;                        // scope 2 at $DIR/combine_array_len.rs:+3:5: +3:6
           StorageLive(_12);                // scope 2 at $DIR/combine_array_len.rs:+3:7: +3:8
           _12 = _2;                        // scope 2 at $DIR/combine_array_len.rs:+3:7: +3:8
-          _10 = Mul(move _11, move _12);   // scope 2 at $DIR/combine_array_len.rs:+3:5: +3:8
+          _10 = Mul(_11, _12);             // scope 2 at $DIR/combine_array_len.rs:+3:5: +3:8
           StorageDead(_12);                // scope 2 at $DIR/combine_array_len.rs:+3:7: +3:8
           StorageDead(_11);                // scope 2 at $DIR/combine_array_len.rs:+3:7: +3:8
           StorageLive(_13);                // scope 2 at $DIR/combine_array_len.rs:+3:11: +3:14
           StorageLive(_14);                // scope 2 at $DIR/combine_array_len.rs:+3:11: +3:12
           _14 = _6;                        // scope 2 at $DIR/combine_array_len.rs:+3:11: +3:12
           StorageLive(_15);                // scope 2 at $DIR/combine_array_len.rs:+3:13: +3:14
           _15 = _6;                        // scope 2 at $DIR/combine_array_len.rs:+3:13: +3:14
-          _13 = Mul(move _14, move _15);   // scope 2 at $DIR/combine_array_len.rs:+3:11: +3:14
+          _13 = Mul(_14, _15);             // scope 2 at $DIR/combine_array_len.rs:+3:11: +3:14
           StorageDead(_15);                // scope 2 at $DIR/combine_array_len.rs:+3:13: +3:14
           StorageDead(_14);                // scope 2 at $DIR/combine_array_len.rs:+3:13: +3:14
-          _0 = Add(move _10, move _13);    // scope 2 at $DIR/combine_array_len.rs:+3:5: +3:14
+          _0 = Add(_10, _13);              // scope 2 at $DIR/combine_array_len.rs:+3:5: +3:14
           StorageDead(_13);                // scope 2 at $DIR/combine_array_len.rs:+3:13: +3:14
           StorageDead(_10);                // scope 2 at $DIR/combine_array_len.rs:+3:13: +3:14
           StorageDead(_6);                 // scope 1 at $DIR/combine_array_len.rs:+4:1: +4:2

diff --git a/src/test/mir-opt/combine_clone_of_primitives.{impl#0}-clone.InstCombine.diff b/src/test/mir-opt/combine_clone_of_primitives.{impl#0}-clone.InstCombine.diff
@@ -62,9 +62,9 @@
       bb3: {
           StorageDead(_9);                 // scope 0 at $DIR/combine_clone_of_primitives.rs:10:15: 10:16
           Deinit(_0);                      // scope 0 at $DIR/combine_clone_of_primitives.rs:+0:10: +0:15
-          (_0.0: T) = move _2;             // scope 0 at $DIR/combine_clone_of_primitives.rs:+0:10: +0:15
-          (_0.1: u64) = move _5;           // scope 0 at $DIR/combine_clone_of_primitives.rs:+0:10: +0:15
-          (_0.2: [f32; 3]) = move _8;      // scope 0 at $DIR/combine_clone_of_primitives.rs:+0:10: +0:15
+          (_0.0: T) = _2;                  // scope 0 at $DIR/combine_clone_of_primitives.rs:+0:10: +0:15
+          (_0.1: u64) = _5;                // scope 0 at $DIR/combine_clone_of_primitives.rs:+0:10: +0:15
+          (_0.2: [f32; 3]) = _8;           // scope 0 at $DIR/combine_clone_of_primitives.rs:+0:10: +0:15
           StorageDead(_8);                 // scope 0 at $DIR/combine_clone_of_primitives.rs:+0:14: +0:15
           StorageDead(_5);                 // scope 0 at $DIR/combine_clone_of_primitives.rs:+0:14: +0:15
           StorageDead(_2);                 // scope 0 at $DIR/combine_clone_of_primitives.rs:+0:14: +0:15

diff --git a/src/test/mir-opt/const_goto.issue_77355_opt.ConstGoto.diff b/src/test/mir-opt/const_goto.issue_77355_opt.ConstGoto.diff
@@ -11,9 +11,9 @@
       bb0: {
 -         StorageLive(_2);                 // scope 0 at $SRC_DIR/core/src/macros/mod.rs:LL:COL
 -         _3 = discriminant(_1);           // scope 0 at $DIR/const_goto.rs:+1:17: +1:20
--         switchInt(move _3) -> [1: bb2, 2: bb2, otherwise: bb1]; // scope 0 at $SRC_DIR/core/src/macros/mod.rs:LL:COL
+-         switchInt(_3) -> [1: bb2, 2: bb2, otherwise: bb1]; // scope 0 at $SRC_DIR/core/src/macros/mod.rs:LL:COL
 +         _2 = discriminant(_1);           // scope 0 at $DIR/const_goto.rs:+1:17: +1:20
-+         switchInt(move _2) -> [1: bb2, 2: bb2, otherwise: bb1]; // scope 0 at $SRC_DIR/core/src/macros/mod.rs:LL:COL
++         switchInt(_2) -> [1: bb2, 2: bb2, otherwise: bb1]; // scope 0 at $SRC_DIR/core/src/macros/mod.rs:LL:COL
       }
 
       bb1: {
@@ -29,7 +29,7 @@
 -     }
 - 
 -     bb3: {
--         switchInt(move _2) -> [0: bb5, otherwise: bb4]; // scope 0 at $SRC_DIR/core/src/macros/mod.rs:LL:COL
+-         switchInt(_2) -> [0: bb5, otherwise: bb4]; // scope 0 at $SRC_DIR/core/src/macros/mod.rs:LL:COL
 -     }
 - 
 -     bb4: {

diff --git a/src/test/mir-opt/const_goto_storage.match_nested_if.ConstGoto.diff b/src/test/mir-opt/const_goto_storage.match_nested_if.ConstGoto.diff
@@ -23,10 +23,10 @@
 -         StorageLive(_5);                 // scope 0 at $DIR/const_goto_storage.rs:+2:21: +2:52
 -         StorageLive(_6);                 // scope 0 at $DIR/const_goto_storage.rs:+2:24: +2:28
 -         _6 = const true;                 // scope 0 at $DIR/const_goto_storage.rs:+2:24: +2:28
--         switchInt(move _6) -> [0: bb2, otherwise: bb1]; // scope 0 at $DIR/const_goto_storage.rs:+2:24: +2:28
+-         switchInt(_6) -> [0: bb2, otherwise: bb1]; // scope 0 at $DIR/const_goto_storage.rs:+2:24: +2:28
 +         StorageLive(_2);                 // scope 0 at $DIR/const_goto_storage.rs:+2:24: +2:28
 +         _2 = const true;                 // scope 0 at $DIR/const_goto_storage.rs:+2:24: +2:28
-+         switchInt(move _2) -> [0: bb2, otherwise: bb1]; // scope 0 at $DIR/const_goto_storage.rs:+2:24: +2:28
++         switchInt(_2) -> [0: bb2, otherwise: bb1]; // scope 0 at $DIR/const_goto_storage.rs:+2:24: +2:28
       }
 
       bb1: {
@@ -41,7 +41,7 @@
 - 
 -     bb3: {
 -         StorageDead(_6);                 // scope 0 at $DIR/const_goto_storage.rs:+2:51: +2:52
--         switchInt(move _5) -> [0: bb5, otherwise: bb4]; // scope 0 at $DIR/const_goto_storage.rs:+2:21: +2:52
+-         switchInt(_5) -> [0: bb5, otherwise: bb4]; // scope 0 at $DIR/const_goto_storage.rs:+2:21: +2:52
 -     }
 - 
 -     bb4: {
@@ -56,7 +56,7 @@
 - 
 -     bb6: {
 -         StorageDead(_5);                 // scope 0 at $DIR/const_goto_storage.rs:+2:75: +2:76
--         switchInt(move _4) -> [0: bb8, otherwise: bb7]; // scope 0 at $DIR/const_goto_storage.rs:+2:18: +2:76
+-         switchInt(_4) -> [0: bb8, otherwise: bb7]; // scope 0 at $DIR/const_goto_storage.rs:+2:18: +2:76
 -     }
 - 
 -     bb7: {
@@ -70,7 +70,7 @@
 -     }
 - 
 -     bb9: {
--         switchInt(move _3) -> [0: bb11, otherwise: bb10]; // scope 0 at $DIR/const_goto_storage.rs:+2:15: +6:10
+-         switchInt(_3) -> [0: bb11, otherwise: bb10]; // scope 0 at $DIR/const_goto_storage.rs:+2:15: +6:10
 -     }
 - 
 -     bb10: {

diff --git a/src/test/mir-opt/const_prop/aggregate.main.ConstProp.diff b/src/test/mir-opt/const_prop/aggregate.main.ConstProp.diff
@@ -19,7 +19,7 @@
           (_3.1: i32) = const 1_i32;       // scope 0 at $DIR/aggregate.rs:+1:13: +1:22
           (_3.2: i32) = const 2_i32;       // scope 0 at $DIR/aggregate.rs:+1:13: +1:22
 -         _2 = (_3.1: i32);                // scope 0 at $DIR/aggregate.rs:+1:13: +1:24
--         _1 = Add(move _2, const 0_i32);  // scope 0 at $DIR/aggregate.rs:+1:13: +1:28
+-         _1 = Add(_2, const 0_i32);       // scope 0 at $DIR/aggregate.rs:+1:13: +1:28
 +         _2 = const 1_i32;                // scope 0 at $DIR/aggregate.rs:+1:13: +1:24
 +         _1 = const 1_i32;                // scope 0 at $DIR/aggregate.rs:+1:13: +1:28
           StorageDead(_2);                 // scope 0 at $DIR/aggregate.rs:+1:27: +1:28

diff --git a/src/test/mir-opt/const_prop/array_index.main.ConstProp.32bit.diff b/src/test/mir-opt/const_prop/array_index.main.ConstProp.32bit.diff
@@ -20,10 +20,10 @@
           _3 = const 2_usize;              // scope 0 at $DIR/array_index.rs:+1:31: +1:32
 -         _4 = Len(_2);                    // scope 0 at $DIR/array_index.rs:+1:18: +1:33
 -         _5 = Lt(_3, _4);                 // scope 0 at $DIR/array_index.rs:+1:18: +1:33
--         assert(move _5, "index out of bounds: the length is {} but the index is {}", move _4, _3) -> bb1; // scope 0 at $DIR/array_index.rs:+1:18: +1:33
+-         assert(_5, "index out of bounds: the length is {} but the index is {}", _4, _3) -> bb1; // scope 0 at $DIR/array_index.rs:+1:18: +1:33
 +         _4 = const 4_usize;              // scope 0 at $DIR/array_index.rs:+1:18: +1:33
 +         _5 = const true;                 // scope 0 at $DIR/array_index.rs:+1:18: +1:33
-+         assert(const true, "index out of bounds: the length is {} but the index is {}", move _4, _3) -> bb1; // scope 0 at $DIR/array_index.rs:+1:18: +1:33
++         assert(const true, "index out of bounds: the length is {} but the index is {}", _4, _3) -> bb1; // scope 0 at $DIR/array_index.rs:+1:18: +1:33
       }
 
       bb1: {

diff --git a/src/test/mir-opt/const_prop/array_index.main.ConstProp.64bit.diff b/src/test/mir-opt/const_prop/array_index.main.ConstProp.64bit.diff
@@ -20,10 +20,10 @@
           _3 = const 2_usize;              // scope 0 at $DIR/array_index.rs:+1:31: +1:32
 -         _4 = Len(_2);                    // scope 0 at $DIR/array_index.rs:+1:18: +1:33
 -         _5 = Lt(_3, _4);                 // scope 0 at $DIR/array_index.rs:+1:18: +1:33
--         assert(move _5, "index out of bounds: the length is {} but the index is {}", move _4, _3) -> bb1; // scope 0 at $DIR/array_index.rs:+1:18: +1:33
+-         assert(_5, "index out of bounds: the length is {} but the index is {}", _4, _3) -> bb1; // scope 0 at $DIR/array_index.rs:+1:18: +1:33
 +         _4 = const 4_usize;              // scope 0 at $DIR/array_index.rs:+1:18: +1:33
 +         _5 = const true;                 // scope 0 at $DIR/array_index.rs:+1:18: +1:33
-+         assert(const true, "index out of bounds: the length is {} but the index is {}", move _4, _3) -> bb1; // scope 0 at $DIR/array_index.rs:+1:18: +1:33
++         assert(const true, "index out of bounds: the length is {} but the index is {}", _4, _3) -> bb1; // scope 0 at $DIR/array_index.rs:+1:18: +1:33
       }
 
       bb1: {