[Bug bootstrap/63432] [5 Regression] profiledbootstrap failure with bootstrap-lto

[hjl.tools at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63432

H.J. Lu <hjl.tools at gmail dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2014-10-03
     Ever confirmed|0                           |1

--- Comment #8 from H.J. Lu <hjl.tools at gmail dot com> ---
Bug is in

static void 
recompute_probabilities (basic_block bb)
{
  edge esucc;
  edge_iterator ei;
  FOR_EACH_EDGE (esucc, ei, bb->succs)
    {    
      if (bb->count)
        esucc->probability = GCOV_COMPUTE_SCALE (esucc->count,
                                                 bb->count);
      if (esucc->probability > REG_BR_PROB_BASE)
        {

We got

(gdb) whatis esucc->probability
type = int
(gdb) p esucc->count
$7 = 2822215
(gdb) p bb->count
$8 = 1
(gdb) p esucc->probability 
$9 = -1842621072
(gdb) 

When count is set from frequency scaled up by REG_BR_PROB_BASE,
probability may overflow.