https://gcc.gnu.org/bugzilla/show_bug.cgi?id=90796
--- Comment #10 from rguenther at suse dot de <rguenther at suse dot de> --- On August 6, 2019 5:36:49 PM GMT+02:00, "matz at gcc dot gnu.org" <gcc-bugzi...@gcc.gnu.org> wrote: >https://gcc.gnu.org/bugzilla/show_bug.cgi?id=90796 > >--- Comment #9 from Michael Matz <matz at gcc dot gnu.org> --- >(In reply to rguent...@suse.de from comment #8) >> >The fun thing is, there's a difference between these two loop nests: >> > >> > for (i) for (j) a[i][0] = f(a[i+1][0]); >> > for (i) for (j) b[i][j] = f(a[i+1][j]); >> >> What about >> >> B[i][j/2]... >> >> ? > >That would be a problem as well, but luckily that's not an affine >function of >j, >and hence has no analyzable access function, and so isn't fused for >different >reasons. > >> It's really surprising that only invariants are special here. > >It's the only affine functions that don't progress with each iteration. > I >think, at least :) Hm. At least we analyze wrapping ones, but I guess 0, 1, 0, 1 would be caught in another way..
