On Thu, Dec 20, 2018 at 2:43 PM Joern Wolfgang Rennecke <g...@amylaar.uk> wrote: > > eSi-RISC has vector permute functionality, but no unaligned loads. We > see execution failures on gcc.dg/vect/slp-perm-12.c because loop > versioning is used to make the tptr aligned for the first loop > iteration, and then with a step of originally 11, 22 after > vectorization, and a vector alignment of 8 bytes, the second iteration > causes an AlignmentError exception. > The attached patch to tree-vect-data-refs.c suppresses attempts to align > data accesses where the > step alignment times the vectorization factor is insufficient to sustain > the alignment during the loop. > Bootstrapped and regression tested on x86_64-pc-linux-gnu . > > I have also attached a matching testsuite patch to not expect SLP > vectorization for slp-perm-12 when > no unaligned loads are available, although in terms of testing, I can > only say that it works for us.
vect_compute_data_ref_alignment uses DR_TARGET_ALIGNMENT and DR_STEP_ALIGNMENT () % dr_target-alignment == 0 as check. I think it's preferable to use the same or similar values for the desired alignment. Otherwise this looks OK to me. Richard.
