------- Comment #11 from spop at gcc dot gnu dot org 2007-06-24 06:48 -------
Subject: Re: [4.3 Regression] Segmentation fault in
build_classic_dist_vector_1() at tree-data-ref.c:2700
Hi,
On 6/23/07, Richard Guenther <[EMAIL PROTECTED]> wrote:
> > First - can you check why the asociate: case in fold_binary does not do
> > the transformation and maybe fix that instead if possible?
> >
The associate case is the last case for MINUS_EXPR, but the case
/* A - B -> A + (-B) if B is easily negatable. */
applies, and returns ~(unsigned int) i_434 + (unsigned int) i_434
before going to execute the associate code.
Unfortunately I haven't seen the suggestion of Håkan Hjort to also
implement the fold of ~a + a ==> ~0. I could add a new patch for this
one too in the next bootstrap if the current patch still has issues.
> > + && integer_zerop (fold_build2 (MINUS_EXPR, type, arg0,
> > + TREE_OPERAND (arg1, 0))))
> >
> > to avoid creating trees and just throwing them away you should use
> > operand_equal_p (arg0, TREE_OPERAND (arg1, 0)) instead.
Hmm, this was my first implementation, as I just mimicked the code
just before, that is using operand_equal_p. However in my case I have
'A' and 'nop(unsigned int, A)' so they are not exactly the same trees,
but the difference is zero.
> > You similarly may want to check operand 1 for A - (B + A)?
> >
yes, okay.
> > + && TYPE_UNSIGNED (type)
> >
> > you should check TYPE_OVERFLOW_WRAPS (type) instead.
>
> Oh - and there is omit_two_operands which you should use to
> omit the two As. This takes care of side-effects.
>
done.
The attached patch bootstrapped and passed test on i686-linux.
Sebastian
------- Comment #12 from spop at gcc dot gnu dot org 2007-06-24 06:48 -------
Created an attachment (id=13770)
--> (http://gcc.gnu.org/bugzilla/attachment.cgi?id=13770&action=view)
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=32461
