On Fri, Oct 17, 2014 at 7:58 PM, Carrot Wei <car...@google.com> wrote: > Hi > > In current vectorization pass, when a new vector pointer is created, > its alignment is not set correctly. We should use DR_MISALIGNMENT (dr) > since only this alignment is adjusted when loop peeling or multi > version is occurred. > > This patch passed following tests: > x86_64 bootstrap. > x86_64 regression test. > armv7 regression test. > > OK for trunk and 4.9 branch?
I miss a testcase. I also miss a comment before this code explaining why DR_MISALIGNMENT if not -1 is valid and why it is not valid if 'offset' is supplied (what about 'byte_offset' btw?). Also if peeling for alignment aligned this ref (misalign == 0) you don't set the alignment. Thus you may fix a bug (not sure without a testcase) but the new code certainly doesn't look 100% correct. That said, I would have expected that we can unconditionally do set_ptr_info_alignment (..., align, misalign) if misalign is != -1 and if we adjust misalign by offset * step + byte_offset (usually both are constants). Also we can still trust the alignment copied from addr_base modulo vector element size even if DR_MISALIGN is -1. This may matter for targets that require element-alignment for vector accesses. Thanks, Richard. > thanks > Guozhi Wei > > 2014-10-17 Guozhi Wei <car...@google.com> > > PR tree-optimization/63530 > tree-vect-data-refs.c (vect_create_addr_base_for_vector_ref): Set > pointer alignment according to DR_MISALIGNMENT.
