[Bug tree-optimization/58860] tail-merge doesn't merge asm statements with vdef

[vries at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58860

vries at gcc dot gnu.org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2013-11-26
     Ever confirmed|0                           |1

--- Comment #1 from vries at gcc dot gnu.org ---
>  __asm__ ("" : "=&p" (t), "=p" (*r));

Before pre, the asm looks like this:
...
  # .MEM_9 = VDEF <.MEM_3(D)>
  __asm__("" : "=&p" t_7, "=p" *x_4(D));
...

I don't think we will be able to handle this particular example, since it has
an ssa result (t_7), which we do not value number. 

But we should be able to handle simpler examples, f.i. using:
...
  __asm__ ("" : "=p" (*r));
...