gcc/testsuite/gcc.dg/uninit-25-gimple.c

   1 /* { dg-do compile } */
   2 /* { dg-options "-fgimple -O -Wmaybe-uninitialized" } */
   3
   4 unsigned int __GIMPLE (ssa,startwith("uninit1"))
   5 foo (unsigned int v)
   6 {
   7   unsigned int undef;        /* { dg-warning "may be used uninitialized" } */
   8   unsigned int _2;
   9   unsigned int _9;
  10   unsigned int _10;
  11
  12   __BB(2):
  13   if (v_4(D) != 1u)
  14     goto __BB3;
  15   else
  16     goto __BB4;
  17
  18   __BB(3):
  19   undef_8 = 8u; // 'undef' is defined conditionally (under 'v != 1' predicate)
  20   goto __BB4;
  21
  22   __BB(4):
  23   // An undef value flows into a phi.
  24   undef_1 = __PHI (__BB2: undef_5(D), __BB3: undef_8);
  25   if (v_4(D) != 2u) // This condition is neither a superset nor a subset of 'v != 1'.
  26     goto __BB5;
  27   else
  28     goto __BB6;
  29
  30   __BB(5):
  31   _9 = undef_1; // The phi value is used here (under 'v != 2' predicate).
  32   goto __BB7;
  33
  34   __BB(6):
  35   _10 = v_4(D);
  36   goto __BB7;
  37
  38   __BB(7):
  39   _2 = __PHI (__BB5: _9, __BB6: _10);
  40   return _2;
  41 }