Repurpose defunct test.

Author: cjgillot

tests/mir-opt/const_prop/union.main.GVN.diff

@@ -0,0 +1,42 @@
+- // MIR for `main` before GVN
++ // MIR for `main` after GVN
+  
+  fn main() -> () {
+      let mut _0: ();
+      let _1: main::Un;
+      let mut _2: u32;
+      let _3: ();
+      let mut _4: u32;
+      scope 1 {
+          debug un => _1;
+          scope 3 (inlined std::mem::drop::<u32>) {
+          }
+      }
+      scope 2 (inlined val) {
+      }
+  
+      bb0: {
+          StorageLive(_1);
+-         StorageLive(_2);
++         nop;
+          _2 = const 1_u32;
+-         _1 = Un { us: move _2 };
+-         StorageDead(_2);
++         _1 = const Un {{ us: 1_u32 }};
++         nop;
+          StorageLive(_3);
+          StorageLive(_4);
+-         _4 = copy (_1.0: u32);
++         _4 = const 1_u32;
+          StorageDead(_4);
+          StorageDead(_3);
+          _0 = const ();
+          StorageDead(_1);
+          return;
+      }
++ }
++ 
++ ALLOC0 (size: 4, align: 4) {
++     01 00 00 00                                     │ ....
+  }
+  

tests/mir-opt/dest-prop/union.rs renamed to tests/mir-opt/const_prop/union.rs

@@ -1,17 +1,17 @@
-// EMIT_MIR_FOR_EACH_PANIC_STRATEGY
 //! Tests that we can propagate into places that are projections into unions
-//@ compile-flags: -Zunsound-mir-opts -C debuginfo=full
+//@ test-mir-pass: GVN
+//@ compile-flags: -Zinline-mir
+
 fn val() -> u32 {
     1
 }
 
-// EMIT_MIR union.main.DestinationPropagation.diff
+// EMIT_MIR union.main.GVN.diff
 fn main() {
     // CHECK-LABEL: fn main(
-    // CHECK: debug un => const Un
-    // CHECK: debug _x => const 1_u32;
+    // CHECK: debug un => [[un:_.*]];
     // CHECK: bb0: {
-    // CHECK-NEXT: return;
+    // CHECK: [[un]] = const Un {{{{ us: 1_u32 }}}};
     union Un {
         us: u32,
     }