[Bug fortran/37536] [4.3/4.4 Regression] a mfcr is produced instead of branches for DO loops

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

------- Comment #7 from pault at gcc dot gnu dot org  2008-09-16 17:51 -------
(In reply to comment #2)
Hi Andrew,

Does this do it for you or is this all to rarified for this
Bear-of-little-brain to follow?

    D.1359 = *start - *offset;
    D.1360 = *end + *offset;
    D.1361 = *step;
    D.1364 = D.1361 > 0 ? D.1360 < D.1359 : D.1360 > D.1359; /* Fix the
result*/
    if (D.1364) goto L.2;                                    /* Then branch  */
    countm1.0 = (D.1361 > 0 ? (character(kind=4)) (D.1360 - D.1359) :
(character(kind=4)) (D.1359 - D.1360)) / (character(kind=4)) ABS_EXPR <D.1361>;
    i = D.1359;
    while (1)

Cheers

Paul

(In reply to comment #6)
> (In reply to comment #5)
> > (In reply to comment #2)
> > Hi Andrew,
> > 
> > Does this do it for you or is this all to rarified for this
> > Bear-of-little-brain to follow?
> > 
> >     D.1359 = *start - *offset;
> >     D.1360 = *end + *offset;
> >     D.1361 = *step;
> >     D.1364 = D.1361 > 0 ? D.1360 < D.1359 : D.1360 > D.1359; /* Fix the
> > result*/
> >     if (D.1364) goto L.2;                                    /* Then branch  */
> 
> The issue is that D.1364 is used to the store of the result of a comparison. 
> Since GCC does not currently optimize that case, the front-end could rewrite
> the if statement to begin with; this is what Jabuk's patch does (Thanks
> Jabuk!).
> 

Ahhhhh....!

Thanks

P.


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37536