https://gcc.gnu.org/bugzilla/show_bug.cgi?id=70729
--- Comment #24 from rguenther at suse dot de <rguenther at suse dot de> --- On Wed, 8 Jun 2016, ysrumyan at gmail dot com wrote: > https://gcc.gnu.org/bugzilla/show_bug.cgi?id=70729 > > --- Comment #23 from Yuri Rumyantsev <ysrumyan at gmail dot com> --- > OK. I will try to prepare the second part of patch. > Few comments about vect-simd-clone-5.c test failure. > 1. This loop is marked with safelen=MAX_INT. > 2. It contains the following stmt's: > D.3301 = foo.simdclone.1 (vect_vec_iv_.25_12, 123, _17); > # VUSE <.MEM_39> > _22 = MEM[(vector(2) long long int[2] *)&D.3301]; > # VUSE <.MEM_39> > _23 = MEM[(vector(2) long long int[2] *)&D.3301 + 16B]; > # .MEM_40 = VDEF <.MEM_39> > D.3301 ={v} {CLOBBER}; > vect__3.28_24 = VEC_PACK_TRUNC_EXPR <_22, _23>; > and fuction ref_indep_Loop_p_1 checks that references > MEM[(vector(2) long long int[2] *)&D.3301] > and > MEM[(vector(2) long long int[2] *)&D.3301 + 16B] > are independent. > We can avoid such bad behavior of safelen-check (1) put restriction that loop > does not contain non-analyzed references; (2) add additional check that > reference does not have operands defined inside loop (D.3301 in our case). > > What approach is more profitable for you? I think that we cannot use safelen() to disregard dependences against "non-analyzed" references. This is because of exactly such case. In future we might want to make less references "non-analyzed" and use the general alias oracle on them (the LIM dependence analysis predates that). So - simply put the safelen() check after the check for non-analyzed reference in the disambiguator.
