gcc/testsuite/gcc.dg/tree-ssa/forwprop-6.c

   1 /* { dg-do compile } */
   2 /* { dg-options "-O2 -fdump-tree-ccp1 -W -Wall" } */
   3 #if (__SIZEOF_INT__ == __SIZEOF_FLOAT__)
   4 typedef int intflt;
   5 #elif (__SIZEOF_LONG__ == __SIZEOF_FLOAT__)
   6 typedef long intflt;
   7 #else
   8 #error Add target support here for type that will union float size
   9 #endif
  10
  11 intflt b;
  12 void f(void)
  13 {
  14   float a;
  15   a = 1;
  16   b = *(intflt*)&a; /* { dg-warning "aliasing" } */
  17 }
  18
  19 /* We should be able to convert the cast to a VCE in forwprop1,
  20    even if there is an aliasing violation.
  21    ???  While this would be useful and nice to our users in this
  22    particular situation before doing this transformation we have to
  23    assure that a is killed by a dominating store via type float for
  24    it to be valid.  Then we might as well handle the situation by
  25    value-numbering, removing the load altogether.
  26    ???  We now do this after CPP re-writes a into SSA form.  */
  27 /* { dg-final { scan-tree-dump-times "VIEW_CONVERT_EXPR" 1 "ccp1" } } */