2 files changed, 54 insertions, 0 deletions
diff --git a/tests/mir-opt/gvn_overlapping.overlapping.GVN.diff b/tests/mir-opt/gvn_overlapping.overlapping.GVN.diff
new file mode 100644
index 00000000000..fcabcdbcfef
--- /dev/null
+++ b/tests/mir-opt/gvn_overlapping.overlapping.GVN.diff
@@ -0,0 +1,18 @@
+- // MIR for `overlapping` before GVN
++ // MIR for `overlapping` after GVN
+  
+  fn overlapping(_1: Adt) -> () {
+      let mut _0: ();
+      let mut _2: *mut Adt;
+      let mut _3: u32;
+      let mut _4: &Adt;
+  
+      bb0: {
+          _2 = &raw mut _1;
+          _4 = &(*_2);
+          _3 = copy (((*_4) as variant#1).0: u32);
+          (*_2) = Adt::Some(copy _3);
+          return;
+      }
+  }
+  
diff --git a/tests/mir-opt/gvn_overlapping.rs b/tests/mir-opt/gvn_overlapping.rs
new file mode 100644
index 00000000000..99113445e68
--- /dev/null
+++ b/tests/mir-opt/gvn_overlapping.rs
@@ -0,0 +1,36 @@
+//@ test-mir-pass: GVN
+
+#![feature(custom_mir, core_intrinsics)]
+
+// Check that we do not create overlapping assignments.
+
+use std::intrinsics::mir::*;
+
+// EMIT_MIR gvn_overlapping.overlapping.GVN.diff
+#[custom_mir(dialect = "runtime")]
+fn overlapping(_17: Adt) {
+    // CHECK-LABEL: fn overlapping(
+    // CHECK: let mut [[PTR:.*]]: *mut Adt;
+    // CHECK: (*[[PTR]]) = Adt::Some(copy {{.*}});
+    mir! {
+        let _33: *mut Adt;
+        let _48: u32;
+        let _73: &Adt;
+        {
+            _33 = core::ptr::addr_of_mut!(_17);
+            _73 = &(*_33);
+            _48 = Field(Variant((*_73), 1), 0);
+            (*_33) = Adt::Some(_48);
+            Return()
+        }
+    }
+}
+
+fn main() {
+    overlapping(Adt::Some(0));
+}
+
+enum Adt {
+    None,
+    Some(u32),
+}