Remove other Rvalues

diff --git a/src/librustc_mir/transform/simplify.rs b/src/librustc_mir/transform/simplify.rs
index c0da2c446d65fa30c81654a392f7aa2c82b85d35..da79a065eb797da938866a24caee7b8d8eb63320 100644 (file)
--- a/src/librustc_mir/transform/simplify.rs
+++ b/src/librustc_mir/transform/simplify.rs
@@ -368,21 +368,39 @@ fn visit_local(&mut self, local: &Local, ctx: PlaceContext, location: Location)
             if location.statement_index != block.statements.len() {
                 let stmt = &block.statements[location.statement_index];
 
+                fn can_skip_constant(c: &ty::Const<'tcx>) -> bool {
+                    // Keep assignments from unevaluated constants around, since the
+                    // evaluation may report errors, even if the use of the constant
+                    // is dead code.
+                    !matches!(c.val, ty::ConstKind::Unevaluated(..))
+                }
+
+                fn can_skip_operand(o: &Operand<'_>) -> bool {
+                    match o {
+                        Operand::Copy(p) | Operand::Move(p) => !p.is_indirect(),
+                        Operand::Constant(c) => can_skip_constant(c.literal),
+                    }
+                }
+
                 if let StatementKind::Assign(box (dest, rvalue)) = &stmt.kind {
                     if !dest.is_indirect() && dest.local == *local {
-                        if let Rvalue::Use(Operand::Constant(c)) = rvalue {
-                            match c.literal.val {
-                                // Keep assignments from unevaluated constants around, since the
-                                // evaluation may report errors, even if the use of the constant
-                                // is dead code.
-                                ty::ConstKind::Unevaluated(..) => {}
-                                _ => {
-                                    trace!("skipping store of const value {:?} to {:?}", c, dest);
-                                    return;
-                                }
+                        let can_skip = match rvalue {
+                            Rvalue::Use(op) => can_skip_operand(op),
+                            Rvalue::Discriminant(_) => true,
+                            Rvalue::BinaryOp(_, l, r) | Rvalue::CheckedBinaryOp(_, l, r) => {
+                                can_skip_operand(l) && can_skip_operand(r)
                             }
-                        } else if let Rvalue::Discriminant(d) = rvalue {
-                            trace!("skipping store of discriminant value {:?} to {:?}", d, dest);
+                            Rvalue::Repeat(op, c) => can_skip_operand(op) && can_skip_constant(c),
+                            Rvalue::AddressOf(_, _) => true,
+                            Rvalue::Len(_) => true,
+                            Rvalue::UnaryOp(_, op) => can_skip_operand(op),
+                            Rvalue::Aggregate(_, operands) => operands.iter().all(can_skip_operand),
+
+                            _ => false,
+                        };
+
+                        if can_skip {
+                            trace!("skipping store of {:?} to {:?}", rvalue, dest);
                             return;
                         }
                     }

diff --git a/src/test/mir-opt/const_allocation3/32bit/rustc.main.ConstProp.after.mir b/src/test/mir-opt/const_allocation3/32bit/rustc.main.ConstProp.after.mir
index 323134553c195a25f03e3ef5db2182f2da878fd2..63e6b8358a534d3ae3e9dd566df55f0c75e0c7de 100644 (file)
--- a/src/test/mir-opt/const_allocation3/32bit/rustc.main.ConstProp.after.mir
+++ b/src/test/mir-opt/const_allocation3/32bit/rustc.main.ConstProp.after.mir
@@ -30,30 +30,30 @@ fn main() -> () {
 }
 
 alloc0 (static: FOO, size: 4, align: 4) {
-    ╾alloc10+0╼                                     │ ╾──╼
+    ╾alloc9+0─╼                                     │ ╾──╼
 }
 
-alloc10 (size: 168, align: 1) {
+alloc9 (size: 168, align: 1) {
     0x00 │ ab ab ab ab ab ab ab ab ab ab ab ab ab ab ab ab │ ................
-    0x10 │ ab ab ab ab ab ab ab ab ab ab ab ab ╾alloc5+0─╼ │ ............╾──╼
+    0x10 │ ab ab ab ab ab ab ab ab ab ab ab ab ╾alloc4+0─╼ │ ............╾──╼
     0x20 │ 01 ef cd ab 00 00 00 00 00 00 00 00 00 00 00 00 │ ................
     0x30 │ 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 │ ................
     0x40 │ 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 │ ................
     0x50 │ 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 │ ................
     0x60 │ 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 │ ................
     0x70 │ 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 │ ................
-    0x80 │ 00 00 00 00 00 00 00 00 00 00 ╾alloc7+0─╼ 00 00 │ ..........╾──╼..
-    0x90 │ ╾alloc8+99╼ 00 00 00 00 00 00 00 00 00 00 00 00 │ ╾──╼............
+    0x80 │ 00 00 00 00 00 00 00 00 00 00 ╾alloc6+0─╼ 00 00 │ ..........╾──╼..
+    0x90 │ ╾alloc7+99╼ 00 00 00 00 00 00 00 00 00 00 00 00 │ ╾──╼............
     0xa0 │ 00 00 00 00 00 00 00 00                         │ ........
 }
 
-alloc5 (size: 4, align: 4) {
+alloc4 (size: 4, align: 4) {
     2a 00 00 00                                     │ *...
 }
 
-alloc7 (fn: main)
+alloc6 (fn: main)
 
-alloc8 (size: 100, align: 1) {
+alloc7 (size: 100, align: 1) {
     0x00 │ 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 │ ................
     0x10 │ 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 │ ................
     0x20 │ 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 │ ................

diff --git a/src/test/mir-opt/const_allocation3/64bit/rustc.main.ConstProp.after.mir b/src/test/mir-opt/const_allocation3/64bit/rustc.main.ConstProp.after.mir
index 952fe8336cd0ea6a43484b3cb3c50228a7f1f816..7dea5c664d858db302169c17c7997e6dd5b0f2d1 100644 (file)
--- a/src/test/mir-opt/const_allocation3/64bit/rustc.main.ConstProp.after.mir
+++ b/src/test/mir-opt/const_allocation3/64bit/rustc.main.ConstProp.after.mir
@@ -30,12 +30,12 @@ fn main() -> () {
 }
 
 alloc0 (static: FOO, size: 8, align: 8) {
-    ╾──────alloc10+0──────╼                         │ ╾──────╼
+    ╾──────alloc9+0───────╼                         │ ╾──────╼
 }
 
-alloc10 (size: 180, align: 1) {
+alloc9 (size: 180, align: 1) {
     0x00 │ ab ab ab ab ab ab ab ab ab ab ab ab ab ab ab ab │ ................
-    0x10 │ ab ab ab ab ab ab ab ab ab ab ab ab ╾─alloc5+0─ │ ............╾───
+    0x10 │ ab ab ab ab ab ab ab ab ab ab ab ab ╾─alloc4+0─ │ ............╾───
     0x20 │ ──────────╼ 01 ef cd ab 00 00 00 00 00 00 00 00 │ ───╼............
     0x30 │ 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 │ ................
     0x40 │ 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 │ ................
@@ -43,18 +43,18 @@ alloc10 (size: 180, align: 1) {
     0x60 │ 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 │ ................
     0x70 │ 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 │ ................
     0x80 │ 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ╾──── │ ..............╾─
-    0x90 │ ────alloc7+0────╼ 00 00 ╾──────alloc8+99──────╼ │ ─────╼..╾──────╼
+    0x90 │ ────alloc6+0────╼ 00 00 ╾──────alloc7+99──────╼ │ ─────╼..╾──────╼
     0xa0 │ 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 │ ................
     0xb0 │ 00 00 00 00                                     │ ....
 }
 
-alloc5 (size: 4, align: 4) {
+alloc4 (size: 4, align: 4) {
     2a 00 00 00                                     │ *...
 }
 
-alloc7 (fn: main)
+alloc6 (fn: main)
 
-alloc8 (size: 100, align: 1) {
+alloc7 (size: 100, align: 1) {
     0x00 │ 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 │ ................
     0x10 │ 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 │ ................
     0x20 │ 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 │ ................

diff --git a/src/test/mir-opt/const_prop/optimizes_into_variable/32bit/rustc.main.SimplifyLocals.after.mir b/src/test/mir-opt/const_prop/optimizes_into_variable/32bit/rustc.main.SimplifyLocals.after.mir
index 5e2a8af060be81e79387414b9fd58a1f34cc21b2..f8aea27df6660c846f9281e1332a50cee391c35a 100644 (file)
--- a/src/test/mir-opt/const_prop/optimizes_into_variable/32bit/rustc.main.SimplifyLocals.after.mir
+++ b/src/test/mir-opt/const_prop/optimizes_into_variable/32bit/rustc.main.SimplifyLocals.after.mir
@@ -3,15 +3,14 @@
 fn main() -> () {
     let mut _0: ();                      // return place in scope 0 at $DIR/optimizes_into_variable.rs:11:11: 11:11
     let _1: i32;                         // in scope 0 at $DIR/optimizes_into_variable.rs:12:9: 12:10
-    let mut _3: [i32; 6];                // in scope 0 at $DIR/optimizes_into_variable.rs:13:13: 13:31
     scope 1 {
         debug x => _1;                   // in scope 1 at $DIR/optimizes_into_variable.rs:12:9: 12:10
         let _2: i32;                     // in scope 1 at $DIR/optimizes_into_variable.rs:13:9: 13:10
         scope 2 {
             debug y => _2;               // in scope 2 at $DIR/optimizes_into_variable.rs:13:9: 13:10
-            let _4: u32;                 // in scope 2 at $DIR/optimizes_into_variable.rs:14:9: 14:10
+            let _3: u32;                 // in scope 2 at $DIR/optimizes_into_variable.rs:14:9: 14:10
             scope 3 {
-                debug z => _4;           // in scope 3 at $DIR/optimizes_into_variable.rs:14:9: 14:10
+                debug z => _3;           // in scope 3 at $DIR/optimizes_into_variable.rs:14:9: 14:10
             }
         }
     }
@@ -26,70 +25,31 @@ fn main() -> () {
                                          // + span: $DIR/optimizes_into_variable.rs:12:13: 12:18
                                          // + literal: Const { ty: i32, val: Value(Scalar(0x00000004)) }
         StorageLive(_2);                 // bb0[2]: scope 1 at $DIR/optimizes_into_variable.rs:13:9: 13:10
-        StorageLive(_3);                 // bb0[3]: scope 1 at $DIR/optimizes_into_variable.rs:13:13: 13:31
-        _3 = [const 0i32, const 1i32, const 2i32, const 3i32, const 4i32, const 5i32]; // bb0[4]: scope 1 at $DIR/optimizes_into_variable.rs:13:13: 13:31
-                                         // ty::Const
-                                         // + ty: i32
-                                         // + val: Value(Scalar(0x00000000))
-                                         // mir::Constant
-                                         // + span: $DIR/optimizes_into_variable.rs:13:14: 13:15
-                                         // + literal: Const { ty: i32, val: Value(Scalar(0x00000000)) }
-                                         // ty::Const
-                                         // + ty: i32
-                                         // + val: Value(Scalar(0x00000001))
-                                         // mir::Constant
-                                         // + span: $DIR/optimizes_into_variable.rs:13:17: 13:18
-                                         // + literal: Const { ty: i32, val: Value(Scalar(0x00000001)) }
-                                         // ty::Const
-                                         // + ty: i32
-                                         // + val: Value(Scalar(0x00000002))
-                                         // mir::Constant
-                                         // + span: $DIR/optimizes_into_variable.rs:13:20: 13:21
-                                         // + literal: Const { ty: i32, val: Value(Scalar(0x00000002)) }
-                                         // ty::Const
-                                         // + ty: i32
-                                         // + val: Value(Scalar(0x00000003))
-                                         // mir::Constant
-                                         // + span: $DIR/optimizes_into_variable.rs:13:23: 13:24
-                                         // + literal: Const { ty: i32, val: Value(Scalar(0x00000003)) }
-                                         // ty::Const
-                                         // + ty: i32
-                                         // + val: Value(Scalar(0x00000004))
-                                         // mir::Constant
-                                         // + span: $DIR/optimizes_into_variable.rs:13:26: 13:27
-                                         // + literal: Const { ty: i32, val: Value(Scalar(0x00000004)) }
-                                         // ty::Const
-                                         // + ty: i32
-                                         // + val: Value(Scalar(0x00000005))
-                                         // mir::Constant
-                                         // + span: $DIR/optimizes_into_variable.rs:13:29: 13:30
-                                         // + literal: Const { ty: i32, val: Value(Scalar(0x00000005)) }
-        _2 = const 3i32;                 // bb0[5]: scope 1 at $DIR/optimizes_into_variable.rs:13:13: 13:34
+        _2 = const 3i32;                 // bb0[3]: scope 1 at $DIR/optimizes_into_variable.rs:13:13: 13:34
                                          // ty::Const
                                          // + ty: i32
                                          // + val: Value(Scalar(0x00000003))
                                          // mir::Constant
                                          // + span: $DIR/optimizes_into_variable.rs:13:13: 13:34
                                          // + literal: Const { ty: i32, val: Value(Scalar(0x00000003)) }
-        StorageDead(_3);                 // bb0[6]: scope 1 at $DIR/optimizes_into_variable.rs:13:34: 13:35
-        StorageLive(_4);                 // bb0[7]: scope 2 at $DIR/optimizes_into_variable.rs:14:9: 14:10
-        _4 = const 42u32;                // bb0[8]: scope 2 at $DIR/optimizes_into_variable.rs:14:13: 14:38
+        StorageLive(_3);                 // bb0[4]: scope 2 at $DIR/optimizes_into_variable.rs:14:9: 14:10
+        _3 = const 42u32;                // bb0[5]: scope 2 at $DIR/optimizes_into_variable.rs:14:13: 14:38
                                          // ty::Const
                                          // + ty: u32
                                          // + val: Value(Scalar(0x0000002a))
                                          // mir::Constant
                                          // + span: $DIR/optimizes_into_variable.rs:14:13: 14:38
                                          // + literal: Const { ty: u32, val: Value(Scalar(0x0000002a)) }
-        _0 = const ();                   // bb0[9]: scope 0 at $DIR/optimizes_into_variable.rs:11:11: 15:2
+        _0 = const ();                   // bb0[6]: scope 0 at $DIR/optimizes_into_variable.rs:11:11: 15:2
                                          // ty::Const
                                          // + ty: ()
                                          // + val: Value(Scalar(<ZST>))
                                          // mir::Constant
                                          // + span: $DIR/optimizes_into_variable.rs:11:11: 15:2
                                          // + literal: Const { ty: (), val: Value(Scalar(<ZST>)) }
-        StorageDead(_4);                 // bb0[10]: scope 2 at $DIR/optimizes_into_variable.rs:15:1: 15:2
-        StorageDead(_2);                 // bb0[11]: scope 1 at $DIR/optimizes_into_variable.rs:15:1: 15:2
-        StorageDead(_1);                 // bb0[12]: scope 0 at $DIR/optimizes_into_variable.rs:15:1: 15:2
-        return;                          // bb0[13]: scope 0 at $DIR/optimizes_into_variable.rs:15:2: 15:2
+        StorageDead(_3);                 // bb0[7]: scope 2 at $DIR/optimizes_into_variable.rs:15:1: 15:2
+        StorageDead(_2);                 // bb0[8]: scope 1 at $DIR/optimizes_into_variable.rs:15:1: 15:2
+        StorageDead(_1);                 // bb0[9]: scope 0 at $DIR/optimizes_into_variable.rs:15:1: 15:2
+        return;                          // bb0[10]: scope 0 at $DIR/optimizes_into_variable.rs:15:2: 15:2
     }
 }

diff --git a/src/test/mir-opt/const_prop/optimizes_into_variable/64bit/rustc.main.SimplifyLocals.after.mir b/src/test/mir-opt/const_prop/optimizes_into_variable/64bit/rustc.main.SimplifyLocals.after.mir
index 5e2a8af060be81e79387414b9fd58a1f34cc21b2..f8aea27df6660c846f9281e1332a50cee391c35a 100644 (file)
--- a/src/test/mir-opt/const_prop/optimizes_into_variable/64bit/rustc.main.SimplifyLocals.after.mir
+++ b/src/test/mir-opt/const_prop/optimizes_into_variable/64bit/rustc.main.SimplifyLocals.after.mir
@@ -3,15 +3,14 @@
 fn main() -> () {
     let mut _0: ();                      // return place in scope 0 at $DIR/optimizes_into_variable.rs:11:11: 11:11
     let _1: i32;                         // in scope 0 at $DIR/optimizes_into_variable.rs:12:9: 12:10
-    let mut _3: [i32; 6];                // in scope 0 at $DIR/optimizes_into_variable.rs:13:13: 13:31
     scope 1 {
         debug x => _1;                   // in scope 1 at $DIR/optimizes_into_variable.rs:12:9: 12:10
         let _2: i32;                     // in scope 1 at $DIR/optimizes_into_variable.rs:13:9: 13:10
         scope 2 {
             debug y => _2;               // in scope 2 at $DIR/optimizes_into_variable.rs:13:9: 13:10
-            let _4: u32;                 // in scope 2 at $DIR/optimizes_into_variable.rs:14:9: 14:10
+            let _3: u32;                 // in scope 2 at $DIR/optimizes_into_variable.rs:14:9: 14:10
             scope 3 {
-                debug z => _4;           // in scope 3 at $DIR/optimizes_into_variable.rs:14:9: 14:10
+                debug z => _3;           // in scope 3 at $DIR/optimizes_into_variable.rs:14:9: 14:10
             }
         }
     }
@@ -26,70 +25,31 @@ fn main() -> () {
                                          // + span: $DIR/optimizes_into_variable.rs:12:13: 12:18
                                          // + literal: Const { ty: i32, val: Value(Scalar(0x00000004)) }
         StorageLive(_2);                 // bb0[2]: scope 1 at $DIR/optimizes_into_variable.rs:13:9: 13:10
-        StorageLive(_3);                 // bb0[3]: scope 1 at $DIR/optimizes_into_variable.rs:13:13: 13:31
-        _3 = [const 0i32, const 1i32, const 2i32, const 3i32, const 4i32, const 5i32]; // bb0[4]: scope 1 at $DIR/optimizes_into_variable.rs:13:13: 13:31
-                                         // ty::Const
-                                         // + ty: i32
-                                         // + val: Value(Scalar(0x00000000))
-                                         // mir::Constant
-                                         // + span: $DIR/optimizes_into_variable.rs:13:14: 13:15
-                                         // + literal: Const { ty: i32, val: Value(Scalar(0x00000000)) }
-                                         // ty::Const
-                                         // + ty: i32
-                                         // + val: Value(Scalar(0x00000001))
-                                         // mir::Constant
-                                         // + span: $DIR/optimizes_into_variable.rs:13:17: 13:18
-                                         // + literal: Const { ty: i32, val: Value(Scalar(0x00000001)) }
-                                         // ty::Const
-                                         // + ty: i32
-                                         // + val: Value(Scalar(0x00000002))
-                                         // mir::Constant
-                                         // + span: $DIR/optimizes_into_variable.rs:13:20: 13:21
-                                         // + literal: Const { ty: i32, val: Value(Scalar(0x00000002)) }
-                                         // ty::Const
-                                         // + ty: i32
-                                         // + val: Value(Scalar(0x00000003))
-                                         // mir::Constant
-                                         // + span: $DIR/optimizes_into_variable.rs:13:23: 13:24
-                                         // + literal: Const { ty: i32, val: Value(Scalar(0x00000003)) }
-                                         // ty::Const
-                                         // + ty: i32
-                                         // + val: Value(Scalar(0x00000004))
-                                         // mir::Constant
-                                         // + span: $DIR/optimizes_into_variable.rs:13:26: 13:27
-                                         // + literal: Const { ty: i32, val: Value(Scalar(0x00000004)) }
-                                         // ty::Const
-                                         // + ty: i32
-                                         // + val: Value(Scalar(0x00000005))
-                                         // mir::Constant
-                                         // + span: $DIR/optimizes_into_variable.rs:13:29: 13:30
-                                         // + literal: Const { ty: i32, val: Value(Scalar(0x00000005)) }
-        _2 = const 3i32;                 // bb0[5]: scope 1 at $DIR/optimizes_into_variable.rs:13:13: 13:34
+        _2 = const 3i32;                 // bb0[3]: scope 1 at $DIR/optimizes_into_variable.rs:13:13: 13:34
                                          // ty::Const
                                          // + ty: i32
                                          // + val: Value(Scalar(0x00000003))
                                          // mir::Constant
                                          // + span: $DIR/optimizes_into_variable.rs:13:13: 13:34
                                          // + literal: Const { ty: i32, val: Value(Scalar(0x00000003)) }
-        StorageDead(_3);                 // bb0[6]: scope 1 at $DIR/optimizes_into_variable.rs:13:34: 13:35
-        StorageLive(_4);                 // bb0[7]: scope 2 at $DIR/optimizes_into_variable.rs:14:9: 14:10
-        _4 = const 42u32;                // bb0[8]: scope 2 at $DIR/optimizes_into_variable.rs:14:13: 14:38
+        StorageLive(_3);                 // bb0[4]: scope 2 at $DIR/optimizes_into_variable.rs:14:9: 14:10
+        _3 = const 42u32;                // bb0[5]: scope 2 at $DIR/optimizes_into_variable.rs:14:13: 14:38
                                          // ty::Const
                                          // + ty: u32
                                          // + val: Value(Scalar(0x0000002a))
                                          // mir::Constant
                                          // + span: $DIR/optimizes_into_variable.rs:14:13: 14:38
                                          // + literal: Const { ty: u32, val: Value(Scalar(0x0000002a)) }
-        _0 = const ();                   // bb0[9]: scope 0 at $DIR/optimizes_into_variable.rs:11:11: 15:2
+        _0 = const ();                   // bb0[6]: scope 0 at $DIR/optimizes_into_variable.rs:11:11: 15:2
                                          // ty::Const
                                          // + ty: ()
                                          // + val: Value(Scalar(<ZST>))
                                          // mir::Constant
                                          // + span: $DIR/optimizes_into_variable.rs:11:11: 15:2
                                          // + literal: Const { ty: (), val: Value(Scalar(<ZST>)) }
-        StorageDead(_4);                 // bb0[10]: scope 2 at $DIR/optimizes_into_variable.rs:15:1: 15:2
-        StorageDead(_2);                 // bb0[11]: scope 1 at $DIR/optimizes_into_variable.rs:15:1: 15:2
-        StorageDead(_1);                 // bb0[12]: scope 0 at $DIR/optimizes_into_variable.rs:15:1: 15:2
-        return;                          // bb0[13]: scope 0 at $DIR/optimizes_into_variable.rs:15:2: 15:2
+        StorageDead(_3);                 // bb0[7]: scope 2 at $DIR/optimizes_into_variable.rs:15:1: 15:2
+        StorageDead(_2);                 // bb0[8]: scope 1 at $DIR/optimizes_into_variable.rs:15:1: 15:2
+        StorageDead(_1);                 // bb0[9]: scope 0 at $DIR/optimizes_into_variable.rs:15:1: 15:2
+        return;                          // bb0[10]: scope 0 at $DIR/optimizes_into_variable.rs:15:2: 15:2
     }
 }

diff --git a/src/test/mir-opt/simplify-locals-fixedpoint/rustc.foo.SimplifyLocals.diff b/src/test/mir-opt/simplify-locals-fixedpoint/rustc.foo.SimplifyLocals.diff
index 89326e8e3f6753207ab50118e525fa838a4b5a01..bc59be48eee0fb565108da5d360f250b285cd854 100644 (file)
--- a/src/test/mir-opt/simplify-locals-fixedpoint/rustc.foo.SimplifyLocals.diff
+++ b/src/test/mir-opt/simplify-locals-fixedpoint/rustc.foo.SimplifyLocals.diff
@@ -26,40 +26,77 @@
           StorageDead(_3);                 // bb0[7]: scope 0 at $DIR/simplify-locals-fixedpoint.rs:4:68: 4:69
           StorageDead(_2);                 // bb0[8]: scope 0 at $DIR/simplify-locals-fixedpoint.rs:4:68: 4:69
           _5 = discriminant((_1.0: std::option::Option<u8>)); // bb0[9]: scope 0 at $DIR/simplify-locals-fixedpoint.rs:4:13: 4:20
-          switchInt(move _5) -> [1isize: bb1, otherwise: bb3]; // bb0[10]: scope 0 at $DIR/simplify-locals-fixedpoint.rs:4:13: 4:20
+          switchInt(move _5) -> [1isize: bb2, otherwise: bb1]; // bb0[10]: scope 0 at $DIR/simplify-locals-fixedpoint.rs:4:13: 4:20
       }
   
       bb1: {
-          _4 = discriminant((_1.1: std::option::Option<T>)); // bb1[0]: scope 0 at $DIR/simplify-locals-fixedpoint.rs:4:22: 4:26
-          switchInt(move _4) -> [0isize: bb2, otherwise: bb3]; // bb1[1]: scope 0 at $DIR/simplify-locals-fixedpoint.rs:4:22: 4:26
+          _0 = const ();                   // bb1[0]: scope 0 at $DIR/simplify-locals-fixedpoint.rs:4:5: 8:6
+                                           // ty::Const
+                                           // + ty: ()
+                                           // + val: Value(Scalar(<ZST>))
+                                           // mir::Constant
+                                           // + span: $DIR/simplify-locals-fixedpoint.rs:4:5: 8:6
+                                           // + literal: Const { ty: (), val: Value(Scalar(<ZST>)) }
+          goto -> bb7;                     // bb1[1]: scope 0 at $DIR/simplify-locals-fixedpoint.rs:4:5: 8:6
       }
   
       bb2: {
-          StorageLive(_6);                 // bb2[0]: scope 0 at $DIR/simplify-locals-fixedpoint.rs:4:18: 4:19
-          _6 = (((_1.0: std::option::Option<u8>) as Some).0: u8); // bb2[1]: scope 0 at $DIR/simplify-locals-fixedpoint.rs:4:18: 4:19
-          StorageLive(_7);                 // bb2[2]: scope 1 at $DIR/simplify-locals-fixedpoint.rs:5:12: 5:20
-          StorageLive(_8);                 // bb2[3]: scope 1 at $DIR/simplify-locals-fixedpoint.rs:5:12: 5:13
-          _8 = _6;                         // bb2[4]: scope 1 at $DIR/simplify-locals-fixedpoint.rs:5:12: 5:13
-          _7 = Gt(move _8, const 42u8);    // bb2[5]: scope 1 at $DIR/simplify-locals-fixedpoint.rs:5:12: 5:20
+          _4 = discriminant((_1.1: std::option::Option<T>)); // bb2[0]: scope 0 at $DIR/simplify-locals-fixedpoint.rs:4:22: 4:26
+          switchInt(move _4) -> [0isize: bb3, otherwise: bb1]; // bb2[1]: scope 0 at $DIR/simplify-locals-fixedpoint.rs:4:22: 4:26
+      }
+  
+      bb3: {
+          StorageLive(_6);                 // bb3[0]: scope 0 at $DIR/simplify-locals-fixedpoint.rs:4:18: 4:19
+          _6 = (((_1.0: std::option::Option<u8>) as Some).0: u8); // bb3[1]: scope 0 at $DIR/simplify-locals-fixedpoint.rs:4:18: 4:19
+          StorageLive(_7);                 // bb3[2]: scope 1 at $DIR/simplify-locals-fixedpoint.rs:5:12: 5:20
+          StorageLive(_8);                 // bb3[3]: scope 1 at $DIR/simplify-locals-fixedpoint.rs:5:12: 5:13
+          _8 = _6;                         // bb3[4]: scope 1 at $DIR/simplify-locals-fixedpoint.rs:5:12: 5:13
+          _7 = Gt(move _8, const 42u8);    // bb3[5]: scope 1 at $DIR/simplify-locals-fixedpoint.rs:5:12: 5:20
                                            // ty::Const
                                            // + ty: u8
                                            // + val: Value(Scalar(0x2a))
                                            // mir::Constant
                                            // + span: $DIR/simplify-locals-fixedpoint.rs:5:16: 5:20
                                            // + literal: Const { ty: u8, val: Value(Scalar(0x2a)) }
-          StorageDead(_8);                 // bb2[6]: scope 1 at $DIR/simplify-locals-fixedpoint.rs:5:19: 5:20
-          StorageDead(_7);                 // bb2[7]: scope 1 at $DIR/simplify-locals-fixedpoint.rs:8:5: 8:6
-          StorageDead(_6);                 // bb2[8]: scope 0 at $DIR/simplify-locals-fixedpoint.rs:8:5: 8:6
-          goto -> bb3;                     // bb2[9]: scope 0 at $DIR/simplify-locals-fixedpoint.rs:4:5: 8:6
+          StorageDead(_8);                 // bb3[6]: scope 1 at $DIR/simplify-locals-fixedpoint.rs:5:19: 5:20
+          switchInt(_7) -> [false: bb4, otherwise: bb5]; // bb3[7]: scope 1 at $DIR/simplify-locals-fixedpoint.rs:5:9: 7:10
       }
   
-      bb3: {
-          drop(_1) -> bb4;                 // bb3[0]: scope 0 at $DIR/simplify-locals-fixedpoint.rs:9:1: 9:2
+      bb4: {
+          _0 = const ();                   // bb4[0]: scope 1 at $DIR/simplify-locals-fixedpoint.rs:5:9: 7:10
+                                           // ty::Const
+                                           // + ty: ()
+                                           // + val: Value(Scalar(<ZST>))
+                                           // mir::Constant
+                                           // + span: $DIR/simplify-locals-fixedpoint.rs:5:9: 7:10
+                                           // + literal: Const { ty: (), val: Value(Scalar(<ZST>)) }
+          goto -> bb6;                     // bb4[1]: scope 1 at $DIR/simplify-locals-fixedpoint.rs:5:9: 7:10
       }
   
-      bb4: {
-          StorageDead(_1);                 // bb4[0]: scope 0 at $DIR/simplify-locals-fixedpoint.rs:9:1: 9:2
-          return;                          // bb4[1]: scope 0 at $DIR/simplify-locals-fixedpoint.rs:9:2: 9:2
+      bb5: {
+          _0 = const ();                   // bb5[0]: scope 1 at $DIR/simplify-locals-fixedpoint.rs:5:21: 7:10
+                                           // ty::Const
+                                           // + ty: ()
+                                           // + val: Value(Scalar(<ZST>))
+                                           // mir::Constant
+                                           // + span: $DIR/simplify-locals-fixedpoint.rs:5:21: 7:10
+                                           // + literal: Const { ty: (), val: Value(Scalar(<ZST>)) }
+          goto -> bb6;                     // bb5[1]: scope 1 at $DIR/simplify-locals-fixedpoint.rs:5:9: 7:10
+      }
+  
+      bb6: {
+          StorageDead(_7);                 // bb6[0]: scope 1 at $DIR/simplify-locals-fixedpoint.rs:8:5: 8:6
+          StorageDead(_6);                 // bb6[1]: scope 0 at $DIR/simplify-locals-fixedpoint.rs:8:5: 8:6
+          goto -> bb7;                     // bb6[2]: scope 0 at $DIR/simplify-locals-fixedpoint.rs:4:5: 8:6
+      }
+  
+      bb7: {
+          drop(_1) -> bb8;                 // bb7[0]: scope 0 at $DIR/simplify-locals-fixedpoint.rs:9:1: 9:2
+      }
+  
+      bb8: {
+          StorageDead(_1);                 // bb8[0]: scope 0 at $DIR/simplify-locals-fixedpoint.rs:9:1: 9:2
+          return;                          // bb8[1]: scope 0 at $DIR/simplify-locals-fixedpoint.rs:9:2: 9:2
       }
   }