[Bug tree-optimization/33615] New: Hoisting of potentially-throwing values for -fnon-call-exceptions

["rsandifo at gcc dot gnu dot org" <gcc-bugzilla at gcc dot gnu dot org>]

If the following C++ code is compiled with -fnon-call-exceptions,
the tree optimisers still hoist 1.0 / 0.0:

---------------------------------------------------------
extern volatile int y;

double
foo (double a, int x)
{
  while (x--)
    {
      y++;
      a += 1.0 / 0.0;
    }
  return a;
}
---------------------------------------------------------

Header copying ensures that 1.0 / 0.0 is only executed when the
incoming x is nonzero, but the division happens before the
assignment to "y".

At -O, the hoisting is done by LIM; at -O2, it's done be PRE.


-- 
           Summary: Hoisting of potentially-throwing values for -fnon-call-
                    exceptions
           Product: gcc
           Version: 4.3.0
            Status: UNCONFIRMED
          Keywords: wrong-code
          Severity: normal
          Priority: P3
         Component: tree-optimization
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: rsandifo at gcc dot gnu dot org
 GCC build triplet: x86_64-linux-gnu
  GCC host triplet: x86_64-linux-gnu
GCC target triplet: x86_64-linux-gnu


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=33615