[Bug tree-optimization/40436] [4.5/4.6 regression] 0.5% code size regression caused by r147852

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

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40436

--- Comment #44 from Jan Hubicka <hubicka at gcc dot gnu.org> 2010-11-14 16:16:35 UTC ---
OK, ialloc is because 4.3 folds:
  oldbit_430 = 0;
  D.12699_431 = oldbit_430 & 1;
  D.12698_462 = D.12699_431;
  D.12095_241 = D.12698_462;
  if (D.12095_241 != 0)
    goto <bb 71>;
  else
    goto <bb 72>;

In mainline the same sequence misses oldbit_430 = 0.

static __inline__ int
test_and_set_bit_simple(unsigned long nr, volatile void * addr)
{
 unsigned long reg1, reg2;
        int oldbit;

        return oldbit & 1;
}





static __inline__ int
test_and_clear_bit_simple(unsigned long nr, volatile void * addr)
{
 unsigned long reg1, reg2;
        int oldbit;


        return oldbit & 1;
}





static __inline__ int
test_and_change_bit_simple(unsigned long nr, volatile void * addr)
{
 unsigned long reg1, reg2;
        int oldbit;


        return oldbit & 1;
}

So another source code bug.
Richard, do you remember if we dropped initialization by zero for uninitialized
vars?  

I am officially declaring kernel part of CSiBE irrelevant and will look at the
other tests.

Honza