------- Comment #11 from rguenther at suse dot de 2008-05-07 08:21 ------- Subject: Re: [4.1/4.3/4.4 Regression] Wrong code involving restricted pointers to non-restricted pointers
On Tue, 6 May 2008, jakub at gcc dot gnu dot org wrote: > ------- Comment #6 from jakub at gcc dot gnu dot org 2008-05-06 22:56 ------- > Created an attachment (id=15588) --> (http://gcc.gnu.org/bugzilla/attachment.cgi?id=15588&action=view) > --> (http://gcc.gnu.org/bugzilla/attachment.cgi?id=15588&action=view) > gcc44-pr36013.patch > > Patch I've bootstrapped/regtested on x86_64-linux. Will you check this in, or > should I mail it to gcc-patches? > > I've played with testcases like: > > int > foo (int *__restrict p, int *__restrict q) > { > int *r, *s, t; > *p = 1; > *q = 2; > p[6] = 3; > q[6] = 4; > for (r = p, s = q, t = 0; r < p + 64; r++, s++) > { > *r = 7; > *s = 88; > t += *r; > } > return t; > } > > and here neither tree nor RTL aliasing is ATM able to optimize the subsequent > read from *r out - while the accesses before the loop use different alias sets > (3 resp. 4), in the loop everything uses alias set 2, but that isn't a > regression introduced with this patch, so probably DECL_BASED_ON_RESTRICT_P > stuff needs more work, but that is unrelated to this bug. The patch/rfc I posted two days ago optimizes the above case on the tree level. I will make sure something like that goes into 4.4. Richard. -- http://gcc.gnu.org/bugzilla/show_bug.cgi?id=36013
