Serious performance regression -- some tree optimizer questions

[Toon Moene]

Jakub Jelinek wrote:

> On Wed, Dec 29, 2004 at 03:45:31PM +0100, Ulrich Weigand wrote:

[ Serious performance regression in SPEC2000's mgrid*.f* ]

> It is not always constant.
> Consider say unsigned int i; on LP64 target and
> char A[(long) UINT_MAX + 1];
> &A[i+1] - &A[i] is (ptrdiff_t) 1 unless i == UINT_MAX, for which
> it is - (ptrdiff_t) UINT_MAX.

Oh, sure, but we are talking Fortran here - you can't apply the 
limitations of C to a discussion about optimizing Fortran code.  Fortran 
knows of no UINT_MAX, or the intrincacies of C's ptrdiff_t.

:-)

-- 
Toon Moene - e-mail: toon@moene.indiv.nluug.nl - phone: +31 346 214290
Saturnushof 14, 3738 XG  Maartensdijk, The Netherlands
Maintainer, GNU Fortran 77: http://gcc.gnu.org/onlinedocs/g77_news.html
A maintainer of GNU Fortran 95: http://gcc.gnu.org/fortran/