1 files changed, 48 insertions, 0 deletions
diff --git a/gcc/testsuite/g++.dg/tree-ssa/pr19786.C b/gcc/testsuite/g++.dg/tree-ssa/pr19786.C
new file mode 100644
index 00000000000..faaecdfd971
--- /dev/null
+++ b/gcc/testsuite/g++.dg/tree-ssa/pr19786.C
@@ -0,0 +1,48 @@
+// { dg-do run }
+/* { dg-options "-O2" } */
+
+// We used to get alias grouping wrong on this one, hoisting accesses
+// to the vector's end out of the loop.
+
+#include <vector>
+#include <cassert>
+
+struct A
+{
+  double unused;      // If I remove it => it works.
+  std::vector<int> v;
+
+  A() : v(1) {}
+};
+
+inline // If not inline => it works.
+A g()
+{
+  A r;
+  r.v.resize(2);
+  r.v[0] = 1;
+
+  while (!r.v.empty() && r.v.back() == 0)
+    r.v.pop_back();
+
+  return r;
+}
+
+A f(const A &a)
+{
+  if (a.v.empty())  return a;
+  if (a.v.empty())  return a;
+
+  // A z = g(); return z;  // If I return like this => it works.
+  return g();
+}
+
+int main()
+{
+  A a;
+  A b;
+  A r = f(a);
+  assert(r.v.size() != 0);
+
+  return 0;
+}