1 files changed, 56 insertions, 0 deletions
diff --git a/gcc/testsuite/g++.dg/opt/alias4.C b/gcc/testsuite/g++.dg/opt/alias4.C
new file mode 100644
index 000000000..6965b8c73
--- /dev/null
+++ b/gcc/testsuite/g++.dg/opt/alias4.C
@@ -0,0 +1,56 @@
+// PR c++/27768
+// Alias grouping was losing some may_aliases, causing us to think
+// the store to w.p was dead.
+
+// { dg-do run }
+// { dg-options "-O2" }
+
+int N = 1;
+
+struct VA
+{
+  int *p, *q, *r;
+
+  VA() : p(), q() {}
+  VA(const VA&) : p(), q() {}
+  ~VA() { if (p) --N; }
+};
+
+inline void foo(VA, VA, VA) {}
+
+struct VB
+{
+  VA va;
+
+  VB() {}
+
+  VB(const VB&)
+  {
+    va.p = new int(va.q - va.p);
+    va.r = va.p + (va.q - va.p);
+    foo(va, va, va);
+  }
+};
+
+struct VC : VB { char c; };
+struct V : VC {};
+
+struct WA
+{
+  struct X {};
+  X **p, **q, **r;
+
+  WA() : p() {}
+  ~WA() { if (p) --N; }
+};
+
+struct W : WA {};
+
+int main()
+{
+  {
+    V v, u(v);
+    W w;
+  }
+  return N;
+}