Stop allowing `Indirect(..)` values to be propagated

Closes #72679
Closes #72372
Closes #72285

3 files changed, 73 insertions, 82 deletions

diff --git a/src/test/mir-opt/const_prop/discriminant.rs b/src/test/mir-opt/const_prop/discriminant.rs
index 04541b94ad7..13e8eb3e44e 100644
--- a/src/test/mir-opt/const_prop/discriminant.rs
+++ b/src/test/mir-opt/const_prop/discriminant.rs
@@ -1,5 +1,10 @@
 // compile-flags: -O
 
+// FIXME(wesleywiser): Ideally, we could const-prop away all of this and just be left with
+// `let x = 42` but that doesn't work because const-prop doesn't support `Operand::Indirect`
+// and `InterpCx::eval_place()` always forces an allocation which creates the `Indirect`.
+// Fixing either of those will allow us to const-prop this away.
+
 // EMIT_MIR_FOR_EACH_BIT_WIDTH
 // EMIT_MIR rustc.main.ConstProp.diff
 fn main() {
diff --git a/src/test/mir-opt/const_prop/discriminant/32bit/rustc.main.ConstProp.diff b/src/test/mir-opt/const_prop/discriminant/32bit/rustc.main.ConstProp.diff
index 9979ea95498..1c873f53f37 100644
--- a/src/test/mir-opt/const_prop/discriminant/32bit/rustc.main.ConstProp.diff
+++ b/src/test/mir-opt/const_prop/discriminant/32bit/rustc.main.ConstProp.diff
@@ -2,100 +2,93 @@
 + // MIR for `main` after ConstProp
   
   fn main() -> () {
-      let mut _0: ();                      // return place in scope 0 at $DIR/discriminant.rs:5:11: 5:11
-      let _1: i32;                         // in scope 0 at $DIR/discriminant.rs:6:9: 6:10
-      let mut _2: i32;                     // in scope 0 at $DIR/discriminant.rs:6:13: 6:64
-      let mut _3: std::option::Option<bool>; // in scope 0 at $DIR/discriminant.rs:6:34: 6:44
-      let mut _4: isize;                   // in scope 0 at $DIR/discriminant.rs:6:21: 6:31
+      let mut _0: ();                      // return place in scope 0 at $DIR/discriminant.rs:10:11: 10:11
+      let _1: i32;                         // in scope 0 at $DIR/discriminant.rs:11:9: 11:10
+      let mut _2: i32;                     // in scope 0 at $DIR/discriminant.rs:11:13: 11:64
+      let mut _3: std::option::Option<bool>; // in scope 0 at $DIR/discriminant.rs:11:34: 11:44
+      let mut _4: isize;                   // in scope 0 at $DIR/discriminant.rs:11:21: 11:31
       scope 1 {
-          debug x => _1;                   // in scope 1 at $DIR/discriminant.rs:6:9: 6:10
+          debug x => _1;                   // in scope 1 at $DIR/discriminant.rs:11:9: 11:10
       }
   
       bb0: {
-          StorageLive(_1);                 // scope 0 at $DIR/discriminant.rs:6:9: 6:10
-          StorageLive(_2);                 // scope 0 at $DIR/discriminant.rs:6:13: 6:64
-          StorageLive(_3);                 // scope 0 at $DIR/discriminant.rs:6:34: 6:44
--         _3 = std::option::Option::<bool>::Some(const true); // scope 0 at $DIR/discriminant.rs:6:34: 6:44
-+         _3 = const std::option::Option::<bool>::Some(true); // scope 0 at $DIR/discriminant.rs:6:34: 6:44
+          StorageLive(_1);                 // scope 0 at $DIR/discriminant.rs:11:9: 11:10
+          StorageLive(_2);                 // scope 0 at $DIR/discriminant.rs:11:13: 11:64
+          StorageLive(_3);                 // scope 0 at $DIR/discriminant.rs:11:34: 11:44
+-         _3 = std::option::Option::<bool>::Some(const true); // scope 0 at $DIR/discriminant.rs:11:34: 11:44
++         _3 = const std::option::Option::<bool>::Some(true); // scope 0 at $DIR/discriminant.rs:11:34: 11:44
                                            // ty::Const
 -                                          // + ty: bool
 +                                          // + ty: std::option::Option<bool>
                                            // + val: Value(Scalar(0x01))
                                            // mir::Constant
--                                          // + span: $DIR/discriminant.rs:6:39: 6:43
+-                                          // + span: $DIR/discriminant.rs:11:39: 11:43
 -                                          // + literal: Const { ty: bool, val: Value(Scalar(0x01)) }
--         _4 = discriminant(_3);           // scope 0 at $DIR/discriminant.rs:6:21: 6:31
--         switchInt(move _4) -> [1isize: bb2, otherwise: bb1]; // scope 0 at $DIR/discriminant.rs:6:21: 6:31
-+                                          // + span: $DIR/discriminant.rs:6:34: 6:44
+-         _4 = discriminant(_3);           // scope 0 at $DIR/discriminant.rs:11:21: 11:31
+-         switchInt(move _4) -> [1isize: bb2, otherwise: bb1]; // scope 0 at $DIR/discriminant.rs:11:21: 11:31
++                                          // + span: $DIR/discriminant.rs:11:34: 11:44
 +                                          // + literal: Const { ty: std::option::Option<bool>, val: Value(Scalar(0x01)) }
-+         _4 = const 1isize;               // scope 0 at $DIR/discriminant.rs:6:21: 6:31
++         _4 = const 1isize;               // scope 0 at $DIR/discriminant.rs:11:21: 11:31
 +                                          // ty::Const
 +                                          // + ty: isize
 +                                          // + val: Value(Scalar(0x00000001))
 +                                          // mir::Constant
-+                                          // + span: $DIR/discriminant.rs:6:21: 6:31
++                                          // + span: $DIR/discriminant.rs:11:21: 11:31
 +                                          // + literal: Const { ty: isize, val: Value(Scalar(0x00000001)) }
-+         switchInt(const 1isize) -> [1isize: bb2, otherwise: bb1]; // scope 0 at $DIR/discriminant.rs:6:21: 6:31
++         switchInt(const 1isize) -> [1isize: bb2, otherwise: bb1]; // scope 0 at $DIR/discriminant.rs:11:21: 11:31
 +                                          // ty::Const
 +                                          // + ty: isize
 +                                          // + val: Value(Scalar(0x00000001))
 +                                          // mir::Constant
-+                                          // + span: $DIR/discriminant.rs:6:21: 6:31
++                                          // + span: $DIR/discriminant.rs:11:21: 11:31
 +                                          // + literal: Const { ty: isize, val: Value(Scalar(0x00000001)) }
       }
   
       bb1: {
-          _2 = const 10i32;                // scope 0 at $DIR/discriminant.rs:6:59: 6:61
+          _2 = const 10i32;                // scope 0 at $DIR/discriminant.rs:11:59: 11:61
                                            // ty::Const
                                            // + ty: i32
                                            // + val: Value(Scalar(0x0000000a))
                                            // mir::Constant
-                                           // + span: $DIR/discriminant.rs:6:59: 6:61
+                                           // + span: $DIR/discriminant.rs:11:59: 11:61
                                            // + literal: Const { ty: i32, val: Value(Scalar(0x0000000a)) }
-          goto -> bb4;                     // scope 0 at $DIR/discriminant.rs:6:13: 6:64
+          goto -> bb4;                     // scope 0 at $DIR/discriminant.rs:11:13: 11:64
       }
   
       bb2: {
--         switchInt(((_3 as Some).0: bool)) -> [false: bb1, otherwise: bb3]; // scope 0 at $DIR/discriminant.rs:6:26: 6:30
-+         switchInt(const true) -> [false: bb1, otherwise: bb3]; // scope 0 at $DIR/discriminant.rs:6:26: 6:30
-+                                          // ty::Const
-+                                          // + ty: bool
-+                                          // + val: Value(Scalar(0x01))
-+                                          // mir::Constant
-+                                          // + span: $DIR/discriminant.rs:6:26: 6:30
-+                                          // + literal: Const { ty: bool, val: Value(Scalar(0x01)) }
+          switchInt(((_3 as Some).0: bool)) -> [false: bb1, otherwise: bb3]; // scope 0 at $DIR/discriminant.rs:11:26: 11:30
       }
   
       bb3: {
-          _2 = const 42i32;                // scope 0 at $DIR/discriminant.rs:6:47: 6:49
+          _2 = const 42i32;                // scope 0 at $DIR/discriminant.rs:11:47: 11:49
                                            // ty::Const
                                            // + ty: i32
                                            // + val: Value(Scalar(0x0000002a))
                                            // mir::Constant
-                                           // + span: $DIR/discriminant.rs:6:47: 6:49
+                                           // + span: $DIR/discriminant.rs:11:47: 11:49
                                            // + literal: Const { ty: i32, val: Value(Scalar(0x0000002a)) }
-          goto -> bb4;                     // scope 0 at $DIR/discriminant.rs:6:13: 6:64
+          goto -> bb4;                     // scope 0 at $DIR/discriminant.rs:11:13: 11:64
       }
   
       bb4: {
-          _1 = Add(move _2, const 0i32);   // scope 0 at $DIR/discriminant.rs:6:13: 6:68
+          _1 = Add(move _2, const 0i32);   // scope 0 at $DIR/discriminant.rs:11:13: 11:68
                                            // ty::Const
                                            // + ty: i32
                                            // + val: Value(Scalar(0x00000000))
                                            // mir::Constant
-                                           // + span: $DIR/discriminant.rs:6:67: 6:68
+                                           // + span: $DIR/discriminant.rs:11:67: 11:68
                                            // + literal: Const { ty: i32, val: Value(Scalar(0x00000000)) }
-          StorageDead(_2);                 // scope 0 at $DIR/discriminant.rs:6:67: 6:68
-          StorageDead(_3);                 // scope 0 at $DIR/discriminant.rs:6:68: 6:69
-          _0 = const ();                   // scope 0 at $DIR/discriminant.rs:5:11: 7:2
+          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
                                            // ty::Const
                                            // + ty: ()
                                            // + val: Value(Scalar(<ZST>))
                                            // mir::Constant
-                                           // + span: $DIR/discriminant.rs:5:11: 7:2
+                                           // + span: $DIR/discriminant.rs:10:11: 12:2
                                            // + literal: Const { ty: (), val: Value(Scalar(<ZST>)) }
-          StorageDead(_1);                 // scope 0 at $DIR/discriminant.rs:7:1: 7:2
-          return;                          // scope 0 at $DIR/discriminant.rs:7:2: 7:2
+          StorageDead(_1);                 // scope 0 at $DIR/discriminant.rs:12:1: 12:2
+          return;                          // scope 0 at $DIR/discriminant.rs:12:2: 12:2
       }
   }
   
diff --git a/src/test/mir-opt/const_prop/discriminant/64bit/rustc.main.ConstProp.diff b/src/test/mir-opt/const_prop/discriminant/64bit/rustc.main.ConstProp.diff
index ec0341e3de2..75b4b7e5a62 100644
--- a/src/test/mir-opt/const_prop/discriminant/64bit/rustc.main.ConstProp.diff
+++ b/src/test/mir-opt/const_prop/discriminant/64bit/rustc.main.ConstProp.diff
@@ -2,100 +2,93 @@
 + // MIR for `main` after ConstProp
   
   fn main() -> () {
-      let mut _0: ();                      // return place in scope 0 at $DIR/discriminant.rs:5:11: 5:11
-      let _1: i32;                         // in scope 0 at $DIR/discriminant.rs:6:9: 6:10
-      let mut _2: i32;                     // in scope 0 at $DIR/discriminant.rs:6:13: 6:64
-      let mut _3: std::option::Option<bool>; // in scope 0 at $DIR/discriminant.rs:6:34: 6:44
-      let mut _4: isize;                   // in scope 0 at $DIR/discriminant.rs:6:21: 6:31
+      let mut _0: ();                      // return place in scope 0 at $DIR/discriminant.rs:10:11: 10:11
+      let _1: i32;                         // in scope 0 at $DIR/discriminant.rs:11:9: 11:10
+      let mut _2: i32;                     // in scope 0 at $DIR/discriminant.rs:11:13: 11:64
+      let mut _3: std::option::Option<bool>; // in scope 0 at $DIR/discriminant.rs:11:34: 11:44
+      let mut _4: isize;                   // in scope 0 at $DIR/discriminant.rs:11:21: 11:31
       scope 1 {
-          debug x => _1;                   // in scope 1 at $DIR/discriminant.rs:6:9: 6:10
+          debug x => _1;                   // in scope 1 at $DIR/discriminant.rs:11:9: 11:10
       }
   
       bb0: {
-          StorageLive(_1);                 // scope 0 at $DIR/discriminant.rs:6:9: 6:10
-          StorageLive(_2);                 // scope 0 at $DIR/discriminant.rs:6:13: 6:64
-          StorageLive(_3);                 // scope 0 at $DIR/discriminant.rs:6:34: 6:44
--         _3 = std::option::Option::<bool>::Some(const true); // scope 0 at $DIR/discriminant.rs:6:34: 6:44
-+         _3 = const std::option::Option::<bool>::Some(true); // scope 0 at $DIR/discriminant.rs:6:34: 6:44
+          StorageLive(_1);                 // scope 0 at $DIR/discriminant.rs:11:9: 11:10
+          StorageLive(_2);                 // scope 0 at $DIR/discriminant.rs:11:13: 11:64
+          StorageLive(_3);                 // scope 0 at $DIR/discriminant.rs:11:34: 11:44
+-         _3 = std::option::Option::<bool>::Some(const true); // scope 0 at $DIR/discriminant.rs:11:34: 11:44
++         _3 = const std::option::Option::<bool>::Some(true); // scope 0 at $DIR/discriminant.rs:11:34: 11:44
                                            // ty::Const
 -                                          // + ty: bool
 +                                          // + ty: std::option::Option<bool>
                                            // + val: Value(Scalar(0x01))
                                            // mir::Constant
--                                          // + span: $DIR/discriminant.rs:6:39: 6:43
+-                                          // + span: $DIR/discriminant.rs:11:39: 11:43
 -                                          // + literal: Const { ty: bool, val: Value(Scalar(0x01)) }
--         _4 = discriminant(_3);           // scope 0 at $DIR/discriminant.rs:6:21: 6:31
--         switchInt(move _4) -> [1isize: bb2, otherwise: bb1]; // scope 0 at $DIR/discriminant.rs:6:21: 6:31
-+                                          // + span: $DIR/discriminant.rs:6:34: 6:44
+-         _4 = discriminant(_3);           // scope 0 at $DIR/discriminant.rs:11:21: 11:31
+-         switchInt(move _4) -> [1isize: bb2, otherwise: bb1]; // scope 0 at $DIR/discriminant.rs:11:21: 11:31
++                                          // + span: $DIR/discriminant.rs:11:34: 11:44
 +                                          // + literal: Const { ty: std::option::Option<bool>, val: Value(Scalar(0x01)) }
-+         _4 = const 1isize;               // scope 0 at $DIR/discriminant.rs:6:21: 6:31
++         _4 = const 1isize;               // scope 0 at $DIR/discriminant.rs:11:21: 11:31
 +                                          // ty::Const
 +                                          // + ty: isize
 +                                          // + val: Value(Scalar(0x0000000000000001))
 +                                          // mir::Constant
-+                                          // + span: $DIR/discriminant.rs:6:21: 6:31
++                                          // + span: $DIR/discriminant.rs:11:21: 11:31
 +                                          // + literal: Const { ty: isize, val: Value(Scalar(0x0000000000000001)) }
-+         switchInt(const 1isize) -> [1isize: bb2, otherwise: bb1]; // scope 0 at $DIR/discriminant.rs:6:21: 6:31
++         switchInt(const 1isize) -> [1isize: bb2, otherwise: bb1]; // scope 0 at $DIR/discriminant.rs:11:21: 11:31
 +                                          // ty::Const
 +                                          // + ty: isize
 +                                          // + val: Value(Scalar(0x0000000000000001))
 +                                          // mir::Constant
-+                                          // + span: $DIR/discriminant.rs:6:21: 6:31
++                                          // + span: $DIR/discriminant.rs:11:21: 11:31
 +                                          // + literal: Const { ty: isize, val: Value(Scalar(0x0000000000000001)) }
       }
   
       bb1: {
-          _2 = const 10i32;                // scope 0 at $DIR/discriminant.rs:6:59: 6:61
+          _2 = const 10i32;                // scope 0 at $DIR/discriminant.rs:11:59: 11:61
                                            // ty::Const
                                            // + ty: i32
                                            // + val: Value(Scalar(0x0000000a))
                                            // mir::Constant
-                                           // + span: $DIR/discriminant.rs:6:59: 6:61
+                                           // + span: $DIR/discriminant.rs:11:59: 11:61
                                            // + literal: Const { ty: i32, val: Value(Scalar(0x0000000a)) }
-          goto -> bb4;                     // scope 0 at $DIR/discriminant.rs:6:13: 6:64
+          goto -> bb4;                     // scope 0 at $DIR/discriminant.rs:11:13: 11:64
       }
   
       bb2: {
--         switchInt(((_3 as Some).0: bool)) -> [false: bb1, otherwise: bb3]; // scope 0 at $DIR/discriminant.rs:6:26: 6:30
-+         switchInt(const true) -> [false: bb1, otherwise: bb3]; // scope 0 at $DIR/discriminant.rs:6:26: 6:30
-+                                          // ty::Const
-+                                          // + ty: bool
-+                                          // + val: Value(Scalar(0x01))
-+                                          // mir::Constant
-+                                          // + span: $DIR/discriminant.rs:6:26: 6:30
-+                                          // + literal: Const { ty: bool, val: Value(Scalar(0x01)) }
+          switchInt(((_3 as Some).0: bool)) -> [false: bb1, otherwise: bb3]; // scope 0 at $DIR/discriminant.rs:11:26: 11:30
       }
   
       bb3: {
-          _2 = const 42i32;                // scope 0 at $DIR/discriminant.rs:6:47: 6:49
+          _2 = const 42i32;                // scope 0 at $DIR/discriminant.rs:11:47: 11:49
                                            // ty::Const
                                            // + ty: i32
                                            // + val: Value(Scalar(0x0000002a))
                                            // mir::Constant
-                                           // + span: $DIR/discriminant.rs:6:47: 6:49
+                                           // + span: $DIR/discriminant.rs:11:47: 11:49
                                            // + literal: Const { ty: i32, val: Value(Scalar(0x0000002a)) }
-          goto -> bb4;                     // scope 0 at $DIR/discriminant.rs:6:13: 6:64
+          goto -> bb4;                     // scope 0 at $DIR/discriminant.rs:11:13: 11:64
       }
   
       bb4: {
-          _1 = Add(move _2, const 0i32);   // scope 0 at $DIR/discriminant.rs:6:13: 6:68
+          _1 = Add(move _2, const 0i32);   // scope 0 at $DIR/discriminant.rs:11:13: 11:68
                                            // ty::Const
                                            // + ty: i32
                                            // + val: Value(Scalar(0x00000000))
                                            // mir::Constant
-                                           // + span: $DIR/discriminant.rs:6:67: 6:68
+                                           // + span: $DIR/discriminant.rs:11:67: 11:68
                                            // + literal: Const { ty: i32, val: Value(Scalar(0x00000000)) }
-          StorageDead(_2);                 // scope 0 at $DIR/discriminant.rs:6:67: 6:68
-          StorageDead(_3);                 // scope 0 at $DIR/discriminant.rs:6:68: 6:69
-          _0 = const ();                   // scope 0 at $DIR/discriminant.rs:5:11: 7:2
+          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
                                            // ty::Const
                                            // + ty: ()
                                            // + val: Value(Scalar(<ZST>))
                                            // mir::Constant
-                                           // + span: $DIR/discriminant.rs:5:11: 7:2
+                                           // + span: $DIR/discriminant.rs:10:11: 12:2
                                            // + literal: Const { ty: (), val: Value(Scalar(<ZST>)) }
-          StorageDead(_1);                 // scope 0 at $DIR/discriminant.rs:7:1: 7:2
-          return;                          // scope 0 at $DIR/discriminant.rs:7:2: 7:2
+          StorageDead(_1);                 // scope 0 at $DIR/discriminant.rs:12:1: 12:2
+          return;                          // scope 0 at $DIR/discriminant.rs:12:2: 12:2
       }
   }