Add EMIR_MIR_FOR_EACH_BIT_WIDTH to failing test

src/test/mir-opt/simplify-locals-removes-unused-discriminant-reads.rs

@@ -9,4 +9,5 @@ fn main() {
     map(None);
 }
 
+// EMIT_MIR_FOR_EACH_BIT_WIDTH
 // EMIT_MIR rustc.map.SimplifyLocals.diff

src/test/mir-opt/simplify-locals-removes-unused-discriminant-reads/32bit/rustc.map.SimplifyLocals.diff

@@ -0,0 +1,42 @@
+- // MIR for `map` before SimplifyLocals
++ // MIR for `map` after SimplifyLocals
+
+  fn map(_1: std::option::Option<std::boxed::Box<()>>) -> std::option::Option<std::boxed::Box<()>> {
+      debug x => _1;                       // in scope 0 at $DIR/simplify-locals-removes-unused-discriminant-reads.rs:1:8: 1:9
+      let mut _0: std::option::Option<std::boxed::Box<()>>; // return place in scope 0 at $DIR/simplify-locals-removes-unused-discriminant-reads.rs:1:31: 1:46
+      let mut _2: isize;                   // in scope 0 at $DIR/simplify-locals-removes-unused-discriminant-reads.rs:3:9: 3:13
+      let _3: std::boxed::Box<()>;         // in scope 0 at $DIR/simplify-locals-removes-unused-discriminant-reads.rs:4:14: 4:15
+-     let mut _4: std::boxed::Box<()>;     // in scope 0 at $DIR/simplify-locals-removes-unused-discriminant-reads.rs:4:25: 4:26
+-     let mut _5: isize;                   // in scope 0 at $DIR/simplify-locals-removes-unused-discriminant-reads.rs:6:1: 6:2
+-     let mut _6: isize;                   // in scope 0 at $DIR/simplify-locals-removes-unused-discriminant-reads.rs:6:1: 6:2
+      scope 1 {
+          debug x => _3;                   // in scope 1 at $DIR/simplify-locals-removes-unused-discriminant-reads.rs:4:14: 4:15
+      }
+
+      bb0: {
+          _2 = discriminant(_1);           // scope 0 at $DIR/simplify-locals-removes-unused-discriminant-reads.rs:3:9: 3:13
+          switchInt(move _2) -> [0isize: bb2, otherwise: bb1]; // scope 0 at $DIR/simplify-locals-removes-unused-discriminant-reads.rs:3:9: 3:13
+      }
+
+      bb1: {
+          _0 = move _1;                    // scope 1 at $DIR/simplify-locals-removes-unused-discriminant-reads.rs:4:20: 4:27
+          goto -> bb3;                     // scope 0 at $DIR/simplify-locals-removes-unused-discriminant-reads.rs:2:5: 5:6
+      }
+
+      bb2: {
+          _0 = const std::option::Option::<std::boxed::Box<()>>::None; // scope 0 at $DIR/simplify-locals-removes-unused-discriminant-reads.rs:3:17: 3:21
+                                           // ty::Const
+                                           // + ty: std::option::Option<std::boxed::Box<()>>
+                                           // + val: Value(Scalar(0x00000000))
+                                           // mir::Constant
+                                           // + span: $DIR/simplify-locals-removes-unused-discriminant-reads.rs:3:17: 3:21
+                                           // + literal: Const { ty: std::option::Option<std::boxed::Box<()>>, val: Value(Scalar(0x00000000)) }
+          goto -> bb3;                     // scope 0 at $DIR/simplify-locals-removes-unused-discriminant-reads.rs:2:5: 5:6
+      }
+
+      bb3: {
+-         _5 = discriminant(_1);           // scope 0 at $DIR/simplify-locals-removes-unused-discriminant-reads.rs:6:1: 6:2
+          return;                          // scope 0 at $DIR/simplify-locals-removes-unused-discriminant-reads.rs:6:2: 6:2
+      }
+  }
+