Re: [PATCH] [graphite] translate reads and writes in a single traversal of memory ops

[Richard Biener <richard dot guenther at gmail dot com>]

On Mon, Oct 2, 2017 at 6:53 AM, Sebastian Pop <sebpop.llvm@gmail.com> wrote:
> The patch moves the code that translates reads and writes to isl representation
> in a same loop.  This is to avoid traversing the scop blocks and arrays with
> memory operations 3 times.

LGTM.

Richard.

>         * graphite-dependences.c (scop_get_reads): Move code to...
>         (scop_get_must_writes): Move code to...
>         (scop_get_may_writes): Move code to...
>         (scop_get_reads_and_writes): ... here.
>         (scop_get_dependences): Call scop_get_reads_and_writes.
> ---
>  gcc/graphite-dependences.c | 78 +++++++++++++---------------------------------
>  1 file changed, 21 insertions(+), 57 deletions(-)
>
> diff --git a/gcc/graphite-dependences.c b/gcc/graphite-dependences.c
> index 4ed9d00..2066b2e 100644
> --- a/gcc/graphite-dependences.c
> +++ b/gcc/graphite-dependences.c
> @@ -63,20 +63,21 @@ add_pdr_constraints (poly_dr_p pdr, poly_bb_p pbb)
>    return constrain_domain (x, isl_set_copy (pbb->domain));
>  }
>
> -/* Returns all the memory reads in SCOP.  */
> +/* Returns an isl description of all memory operations in SCOP.  The memory
> +   reads are returned in READS and writes in MUST_WRITES and MAY_WRITES.  */
>
> -static isl_union_map *
> -scop_get_reads (scop_p scop)
> +static void
> +scop_get_reads_and_writes (scop_p scop, isl_union_map *reads,
> +                          isl_union_map *must_writes,
> +                          isl_union_map *may_writes)
>  {
>    int i, j;
>    poly_bb_p pbb;
>    poly_dr_p pdr;
> -  isl_space *space = isl_set_get_space (scop->param_context);
> -  isl_union_map *res = isl_union_map_empty (space);
>
>    FOR_EACH_VEC_ELT (scop->pbbs, i, pbb)
>      {
> -      FOR_EACH_VEC_ELT (PBB_DRS (pbb), j, pdr)
> +      FOR_EACH_VEC_ELT (PBB_DRS (pbb), j, pdr) {
>         if (pdr_read_p (pdr))
>           {
>             if (dump_file)
> @@ -86,33 +87,14 @@ scop_get_reads (scop_p scop)
>               }
>             isl_union_map *um
>               = isl_union_map_from_map (add_pdr_constraints (pdr, pbb));
> -           res = isl_union_map_union (res, um);
> +           reads = isl_union_map_union (reads, um);
>             if (dump_file)
>               {
>                 fprintf (dump_file, "Reads depedence graph: ");
> -               print_isl_union_map (dump_file, res);
> +               print_isl_union_map (dump_file, reads);
>               }
>           }
> -    }
> -
> -  return isl_union_map_coalesce (res);
> -}
> -
> -/* Returns all the memory must writes in SCOP.  */
> -
> -static isl_union_map *
> -scop_get_must_writes (scop_p scop)
> -{
> -  int i, j;
> -  poly_bb_p pbb;
> -  poly_dr_p pdr;
> -  isl_space *space = isl_set_get_space (scop->param_context);
> -  isl_union_map *res = isl_union_map_empty (space);
> -
> -  FOR_EACH_VEC_ELT (scop->pbbs, i, pbb)
> -    {
> -      FOR_EACH_VEC_ELT (PBB_DRS (pbb), j, pdr)
> -       if (pdr_write_p (pdr))
> +       else if (pdr_write_p (pdr))
>           {
>             if (dump_file)
>               {
> @@ -121,33 +103,14 @@ scop_get_must_writes (scop_p scop)
>               }
>             isl_union_map *um
>               = isl_union_map_from_map (add_pdr_constraints (pdr, pbb));
> -           res = isl_union_map_union (res, um);
> +           must_writes = isl_union_map_union (must_writes, um);
>             if (dump_file)
>               {
>                 fprintf (dump_file, "Must writes depedence graph: ");
> -               print_isl_union_map (dump_file, res);
> +               print_isl_union_map (dump_file, must_writes);
>               }
>           }
> -    }
> -
> -  return isl_union_map_coalesce (res);
> -}
> -
> -/* Returns all the memory may writes in SCOP.  */
> -
> -static isl_union_map *
> -scop_get_may_writes (scop_p scop)
> -{
> -  int i, j;
> -  poly_bb_p pbb;
> -  poly_dr_p pdr;
> -  isl_space *space = isl_set_get_space (scop->param_context);
> -  isl_union_map *res = isl_union_map_empty (space);
> -
> -  FOR_EACH_VEC_ELT (scop->pbbs, i, pbb)
> -    {
> -      FOR_EACH_VEC_ELT (PBB_DRS (pbb), j, pdr)
> -       if (pdr_may_write_p (pdr))
> +       else if (pdr_may_write_p (pdr))
>           {
>             if (dump_file)
>               {
> @@ -156,16 +119,15 @@ scop_get_may_writes (scop_p scop)
>               }
>             isl_union_map *um
>               = isl_union_map_from_map (add_pdr_constraints (pdr, pbb));
> -           res = isl_union_map_union (res, um);
> +           may_writes = isl_union_map_union (may_writes, um);
>             if (dump_file)
>               {
>                 fprintf (dump_file, "May writes depedence graph: ");
> -               print_isl_union_map (dump_file, res);
> +               print_isl_union_map (dump_file, may_writes);
>               }
>           }
> +      }
>      }
> -
> -  return isl_union_map_coalesce (res);
>  }
>
>  /* Helper function used on each MAP of a isl_union_map.  Computes the
> @@ -300,9 +262,11 @@ scop_get_dependences (scop_p scop)
>    if (scop->dependence)
>      return;
>
> -  isl_union_map *reads = scop_get_reads (scop);
> -  isl_union_map *must_writes = scop_get_must_writes (scop);
> -  isl_union_map *may_writes = scop_get_may_writes (scop);
> +  isl_space *space = isl_set_get_space (scop->param_context);
> +  isl_union_map *reads = isl_union_map_empty (isl_space_copy (space));
> +  isl_union_map *must_writes = isl_union_map_empty (isl_space_copy (space));
> +  isl_union_map *may_writes = isl_union_map_empty (space);
> +  scop_get_reads_and_writes (scop, reads, must_writes, may_writes);
>
>    if (dump_file)
>      {
> --
> 2.7.4
>