Added a failing test

Author: ohadravid

tests/mir-opt/copy-prop/copy_prop_storage_dead_twice.dead_twice.CopyProp.panic-abort.diff

@@ -0,0 +1,28 @@
+- // MIR for `dead_twice` before CopyProp
++ // MIR for `dead_twice` after CopyProp
+  
+  fn dead_twice(_1: T) -> T {
+      let mut _0: T;
+      let mut _2: T;
+      let mut _3: T;
+      let mut _4: T;
+  
+      bb0: {
+-         StorageLive(_2);
+          _2 = opaque::<T>(move _1) -> [return: bb1, unwind unreachable];
+      }
+  
+      bb1: {
+-         _4 = move _2;
+-         StorageDead(_2);
+-         StorageLive(_2);
+-         _0 = opaque::<T>(move _4) -> [return: bb2, unwind unreachable];
++         _0 = opaque::<T>(move _2) -> [return: bb2, unwind unreachable];
+      }
+  
+      bb2: {
+-         StorageDead(_2);
+          return;
+      }
+  }
+  

tests/mir-opt/copy-prop/copy_prop_storage_dead_twice.dead_twice.CopyProp.panic-unwind.diff

@@ -0,0 +1,28 @@
+- // MIR for `dead_twice` before CopyProp
++ // MIR for `dead_twice` after CopyProp
+  
+  fn dead_twice(_1: T) -> T {
+      let mut _0: T;
+      let mut _2: T;
+      let mut _3: T;
+      let mut _4: T;
+  
+      bb0: {
+-         StorageLive(_2);
+          _2 = opaque::<T>(move _1) -> [return: bb1, unwind unreachable];
+      }
+  
+      bb1: {
+-         _4 = move _2;
+-         StorageDead(_2);
+-         StorageLive(_2);
+-         _0 = opaque::<T>(move _4) -> [return: bb2, unwind unreachable];
++         _0 = opaque::<T>(move _2) -> [return: bb2, unwind unreachable];
+      }
+  
+      bb2: {
+-         StorageDead(_2);
+          return;
+      }
+  }
+  

tests/mir-opt/copy-prop/copy_prop_storage_dead_twice.rs

@@ -0,0 +1,37 @@
+// skip-filecheck
+// EMIT_MIR_FOR_EACH_PANIC_STRATEGY
+//@ test-mir-pass: CopyProp
+
+#![feature(custom_mir, core_intrinsics)]
+
+// Check that we do not introduce out-of-bounds access.
+
+use std::intrinsics::mir::*;
+
+// EMIT_MIR copy_prop_storage_dead_twice.dead_twice.CopyProp.diff
+#[custom_mir(dialect = "runtime")]
+pub fn dead_twice<T: Copy>(_1: T) -> T {
+    mir! {
+        let _2: T;
+        let _3: T;
+        {
+            StorageLive(_2);
+            Call(_2 = opaque(Move(_1)), ReturnTo(bb1), UnwindUnreachable())
+        }
+        bb1 = {
+            let _3 = Move(_2);
+            StorageDead(_2);
+            StorageLive(_2);
+            Call(RET = opaque(Move(_3)), ReturnTo(bb2), UnwindUnreachable())
+        }
+        bb2 = {
+            StorageDead(_2);
+            Return()
+        }
+    }
+}
+
+#[inline(never)]
+fn opaque<T>(a: T) -> T {
+    a
+}