------- Comment #9 from richard dot guenther at gmail dot com 2007-06-23 18:36 ------- Subject: Re: [4.3 Regression] Segmentation fault in build_classic_dist_vector_1() at tree-data-ref.c:2700
On 6/23/07, Sebastian Pop <[EMAIL PROTECTED]> wrote: > Hi, > > In data dependence analysis, when the dependence distance is > lexicographically negative, we recompute the dependence by inverting > the source and the sink memory accesses, and thus we compute the > dependence again but in the opposite direction. In one way we > compute: > > MINUS_EXPR > (unsigned int) i_434 + 1 > (unsigned int) i_434 > = > 1 > > but when going the other way, backwards, we have to compute: > > MINUS_EXPR > (unsigned int) i_434 > (unsigned int) i_434 + 1 > = > ~(unsigned int) i_434 + (unsigned int) i_434 > > and instead of getting an integer_cst, we get that ugly expression > from fold, the dependence test fails, and everything goes wrong from > that point. > > With this patch we get the expected 0xffffffffffffffff for the above > case. The patch teaches fold how to compute the minus expression for > unsigned int and pointer expressions. > > Bootstrapped and tested on i686-linux. Okay for trunk? First - can you check why the asociate: case in fold_binary does not do the transformation and maybe fix that instead if possible? Then there is a ChangeLog missing. Further... + && 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. You similarly may want to check operand 1 for A - (B + A)? + && TYPE_UNSIGNED (type) you should check TYPE_OVERFLOW_WRAPS (type) instead. Thanks, Richard. -- http://gcc.gnu.org/bugzilla/show_bug.cgi?id=32461
