gcc/testsuite/g++.dg/tree-ssa/pr19786.C

   1 // { dg-do run }
   2 /* { dg-options "-O2" } */
   3
   4 // We used to get alias grouping wrong on this one, hoisting accesses
   5 // to the vector's end out of the loop.
   6
   7 #include <vector>
   8 #include <cassert>
   9
  10 struct A
  11 {
  12   double unused;      // If I remove it => it works.
  13   std::vector<int> v;
  14
  15   A() : v(1) {}
  16 };
  17
  18 inline // If not inline => it works.
  19 A g()
  20 {
  21   A r;
  22   r.v.resize(2);
  23   r.v[0] = 1;
  24
  25   while (!r.v.empty() && r.v.back() == 0)
  26     r.v.pop_back();
  27
  28   return r;
  29 }
  30
  31 A f(const A &a)
  32 {
  33   if (a.v.empty())  return a;
  34   if (a.v.empty())  return a;
  35
  36   // A z = g(); return z;  // If I return like this => it works.
  37   return g();
  38 }
  39
  40 int main()
  41 {
  42   A a;
  43   A b;
  44   A r = f(a);
  45   assert(r.v.size() != 0);
  46
  47   return 0;
  48 }