------- Comment #10 from richard dot guenther at gmail dot com 2007-06-23 19:24 ------- Subject: Re: [4.3 Regression] Segmentation fault in build_classic_dist_vector_1() at tree-data-ref.c:2700
On 6/23/07, Richard Guenther <[EMAIL PROTECTED]> wrote: > 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. Oh - and there is omit_two_operands which you should use to omit the two As. This takes care of side-effects. Richard. -- http://gcc.gnu.org/bugzilla/show_bug.cgi?id=32461
