tree-ssa/20030807-4.c

[Richard Henderson <rth at redhat dot com>]

Um, how is it that you expect two if's here?  

    cppchar_t i = 0, overflow = 0;
    while (*pstr < limit)
      {
        overflow |= i ^ (i << 4 >> 4);
        i = arf ();
      }
    if (overflow | (i != (i & mask)))

I don't see anything that proves that overflow must 
contain a non-zero value.  The IFs that I see in the
current dom3 are:

  if (T.3<D1069>_15 < limit<D1056>_16) goto <L0>; else goto <L2>;

	The while loop.  Clearly needed.

  if (T.9<D1077>_17 != i<D1060>_1) goto <L12>; else goto <L7>;

	Implementing (i != (i & mask)).  We seem to be
	somewhat schitzophrenic about doing

		T = (x != 0)
	    vs
		if (x != 0)
		   T = 1
		else
		   T = 0

	We should probably pick one or the other, and
	canonicalize on it.  I'm not sure what's better
	for either rtl or tree-ssa optimizers.

	Anyway, we thread the true edge going out, 
	which means we're left with ...

  if (overflow<D1061>_2 != 0) goto <L12>; else goto <L13>;

	This check.  We do skip the OR.


You say at

   http://gcc.gnu.org/ml/gcc-patches/2003-08/msg00704.html

only that a patch is "in testing".  Did it ever get done?

I might assume the test should be xfailed, but given the
above I'm not sure that it shouldn't just be deleted.
What did you have in mind, exactly?


r~