[Bug pch/32636] [4.3 regression] 25_algorithms/search_n/iterator.cc: pch-related verify_ssa failure

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

------- Comment #12 from rguenth at gcc dot gnu dot org  2007-07-07 17:04 -------
So the problem is that we detect

PHI node __i$D47460$SharedInfo_92 copy-of chain: __i$D47460$SharedInfo_92 ->
__i$D47460$SharedInfo_40 -> SR.1030_31 -> SR.1030_31 [COPY]

but later replace with __i$D47460$SharedInfo_40 instead of SR.1030_31.

So the problem seems to be we sort of have

struct Foo {
  int x;
};

void use(int);

void foo(struct Foo *p, int q)
{
  int a = p->x;
  int b, c, d;

  if (a)
    c_1 = p->x;
  else
    {
      c_3 = a;
    }

# c_4 = PHI <c_1, c_3>
  use (c);
}

where copyprop figures that c_1 and a are the same load and so does
figure that c_4 is a copy of a and c_1 and c_3.  But there is no
code that figures the proper ssa_name loaded into as of a dominance
relationship.  (Of course the above testcase doesn't fail... but you
get the idea what happens.)


-- 

rguenth at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |dnovillo at gcc dot gnu dot
                   |                            |org
   Target Milestone|4.3.0                       |---


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=32636