------- Comment #5 from irar at il dot ibm dot com 2008-09-14 12:05 ------- (In reply to comment #4) > For the 32bit case the problem is really the choice of the vector > type for the store (where is this decided on?). As the type of > b is int it should have chosen vector int instead of vector long.
Now I am completely confused. The decision to base the type of the store on the rhs was made to fix pr 37385 (http://gcc.gnu.org/ml/gcc-patches/2008-09/msg00674.html). Without it, there is ICE in set_mem_alias_set... Vector pointers are created in vect_create_data_ref_ptr. When called from vectorizable_store, it gets the type of vectorized rhs and creates a vector pointer of that type (this was the patch for pr 37385). > Note that it is perfectly valid (on 32bit) to assign a vector long > to a vector int. So with a change like > > > The vectorized version (if the alias check is removed) is: > > ... > > vector long int * ivtmp.120; > > vector int * ivtmp.120; > > > vector long int vect_var_.113; > > ... > > > > vect_var_.111_20 = *ivtmp.110_18; > > ivtmp.110_21 = ivtmp.110_18 + 16; > > vect_var_.112_22 = *ivtmp.110_21; > > vect_var_.113_23 = __builtin_ia32_vec_pack_sfix (vect_var_.111_20, > > vect_var_.112_22); > > *ivtmp.120_26 = vect_var_.113_23; > > > > The alias check is for the store, checking *ivtmp.120_26 and b. > > the alias check would be fine. This part I do understand ;) > > So, > > /* The type of the vector store is determined by the rhs. */ > vectype = get_vectype_for_scalar_type (TREE_TYPE (op)); > > the type should be determined by the lhs not if we base the vectype on the scalar type of the rhs... > (after all we try to check > if the new vector lhs aliases the old scalar lhs). But of course > this means the vector lhs type should be chosen to actually match > the scalar type of the lhs. > > if (!useless_type_conversion_p (TREE_TYPE (op), TREE_TYPE > (scalar_dest))) > { > if (vect_print_dump_info (REPORT_DETAILS)) > fprintf (vect_dump, "operands of different types"); > return false; > } > > This test should then be adjusted to check > > if (!useless_type_conversion_p (TREE_TYPE (TREE_TYPE > (vectype)), TREE_TYPE (op))) > > first, it was the wrong way around, second we should check if the > conversion from the rhs (op) to the element type of the lhs > vector type (vectype) is useless. Do you mean if (!useless_type_conversion_p (TREE_TYPE (scalar_dest), TREE_TYPE (op)))? If vectype is built based on TREE_TYPE (scalar_dest) it should be the same, no? > > Now the interesting part is of course where we select the type > for the induction variable for the store (I can't find this > atm). Isn't it ivtmp.120_26 itself? (The updating of vector pointers is done in vect_create_data_ref_ptr as well). Thanks, Ira > > Hope this helps, > Richard. > -- http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37491
