Fix loop size estimate in tree-ssa-loop-ivcanon

Hi,
tree_estimate_loop_size contains one extra else that prevents it from determining
that the induction variable comparsion is going to be eliminated in both the peeled
copies as well as the last copy.  This patch fixes it
(it really removes one else, but need to reformat the conditional)

Bootstrapped/regtested x86_64-linux, comitted.

Honza

	* g++.dg/vect/pr36648.cc: Disable cunrolli
	* tree-ssa-loop-ivcanon.c (tree_estimate_loop_size): Fix estimation
	of comparsions in the last iteration.

On 16 June 2016 at 14:56, Jan Hubicka <hubicka@ucw.cz> wrote:
> Hi,
> tree_estimate_loop_size contains one extra else that prevents it from determining
> that the induction variable comparsion is going to be eliminated in both the peeled
> copies as well as the last copy.  This patch fixes it
> (it really removes one else, but need to reformat the conditional)
>
> Bootstrapped/regtested x86_64-linux, comitted.
>
> Honza
>
>         * g++.dg/vect/pr36648.cc: Disable cunrolli
>         * tree-ssa-loop-ivcanon.c (tree_estimate_loop_size): Fix estimation
>         of comparsions in the last iteration.

Hi,

This patch makes
FAIL: gcc.target/arm/unsigned-extend-2.c scan-assembler ands
on arm-none-linux-gnueabi --with-cpu=cortex-a9

Christophe




> Index: testsuite/g++.dg/vect/pr36648.cc
> ===================================================================
> --- testsuite/g++.dg/vect/pr36648.cc    (revision 237477)
> +++ testsuite/g++.dg/vect/pr36648.cc    (working copy)
> @@ -1,4 +1,5 @@
>  /* { dg-require-effective-target vect_float } */
> +// { dg-additional-options "-fdisable-tree-cunrolli" }
>
>  struct vector
>  {
> Index: tree-ssa-loop-ivcanon.c
> ===================================================================
> --- tree-ssa-loop-ivcanon.c     (revision 237477)
> +++ tree-ssa-loop-ivcanon.c     (working copy)
> @@ -255,69 +255,73 @@ tree_estimate_loop_size (struct loop *lo
>
>           /* Look for reasons why we might optimize this stmt away. */
>
> -         if (gimple_has_side_effects (stmt))
> -           ;
> -         /* Exit conditional.  */
> -         else if (exit && body[i] == exit->src
> -                  && stmt == last_stmt (exit->src))
> +         if (!gimple_has_side_effects (stmt))
>             {
> -             if (dump_file && (dump_flags & TDF_DETAILS))
> -               fprintf (dump_file, "   Exit condition will be eliminated "
> -                        "in peeled copies.\n");
> -             likely_eliminated_peeled = true;
> -           }
> -         else if (edge_to_cancel && body[i] == edge_to_cancel->src
> -                  && stmt == last_stmt (edge_to_cancel->src))
> -           {
> -             if (dump_file && (dump_flags & TDF_DETAILS))
> -               fprintf (dump_file, "   Exit condition will be eliminated "
> -                        "in last copy.\n");
> -             likely_eliminated_last = true;
> -           }
> -         /* Sets of IV variables  */
> -         else if (gimple_code (stmt) == GIMPLE_ASSIGN
> -             && constant_after_peeling (gimple_assign_lhs (stmt), stmt, loop))
> -           {
> -             if (dump_file && (dump_flags & TDF_DETAILS))
> -               fprintf (dump_file, "   Induction variable computation will"
> -                        " be folded away.\n");
> -             likely_eliminated = true;
> -           }
> -         /* Assignments of IV variables.  */
> -         else if (gimple_code (stmt) == GIMPLE_ASSIGN
> -                  && TREE_CODE (gimple_assign_lhs (stmt)) == SSA_NAME
> -                  && constant_after_peeling (gimple_assign_rhs1 (stmt), stmt,
> -                                             loop)
> -                  && (gimple_assign_rhs_class (stmt) != GIMPLE_BINARY_RHS
> -                      || constant_after_peeling (gimple_assign_rhs2 (stmt),
> -                                                 stmt, loop)))
> -           {
> -             size->constant_iv = true;
> -             if (dump_file && (dump_flags & TDF_DETAILS))
> -               fprintf (dump_file,
> -                        "   Constant expression will be folded away.\n");
> -             likely_eliminated = true;
> -           }
> -         /* Conditionals.  */
> -         else if ((gimple_code (stmt) == GIMPLE_COND
> -                   && constant_after_peeling (gimple_cond_lhs (stmt), stmt,
> -                                              loop)
> -                   && constant_after_peeling (gimple_cond_rhs (stmt), stmt,
> -                                              loop)
> -                   /* We don't simplify all constant compares so make sure
> -                      they are not both constant already.  See PR70288.  */
> -                   && (! is_gimple_min_invariant (gimple_cond_lhs (stmt))
> -                       || ! is_gimple_min_invariant (gimple_cond_rhs (stmt))))
> -                  || (gimple_code (stmt) == GIMPLE_SWITCH
> -                      && constant_after_peeling (gimple_switch_index (
> -                                                   as_a <gswitch *> (stmt)),
> +             /* Exit conditional.  */
> +             if (exit && body[i] == exit->src
> +                 && stmt == last_stmt (exit->src))
> +               {
> +                 if (dump_file && (dump_flags & TDF_DETAILS))
> +                   fprintf (dump_file, "   Exit condition will be eliminated "
> +                            "in peeled copies.\n");
> +                 likely_eliminated_peeled = true;
> +               }
> +             if (edge_to_cancel && body[i] == edge_to_cancel->src
> +                 && stmt == last_stmt (edge_to_cancel->src))
> +               {
> +                 if (dump_file && (dump_flags & TDF_DETAILS))
> +                   fprintf (dump_file, "   Exit condition will be eliminated "
> +                            "in last copy.\n");
> +                 likely_eliminated_last = true;
> +               }
> +             /* Sets of IV variables  */
> +             if (gimple_code (stmt) == GIMPLE_ASSIGN
> +                 && constant_after_peeling (gimple_assign_lhs (stmt), stmt, loop))
> +               {
> +                 if (dump_file && (dump_flags & TDF_DETAILS))
> +                   fprintf (dump_file, "   Induction variable computation will"
> +                            " be folded away.\n");
> +                 likely_eliminated = true;
> +               }
> +             /* Assignments of IV variables.  */
> +             else if (gimple_code (stmt) == GIMPLE_ASSIGN
> +                      && TREE_CODE (gimple_assign_lhs (stmt)) == SSA_NAME
> +                      && constant_after_peeling (gimple_assign_rhs1 (stmt),
>                                                   stmt, loop)
> -                      && ! is_gimple_min_invariant
> -                              (gimple_switch_index (as_a <gswitch *> (stmt)))))
> -           {
> -             if (dump_file && (dump_flags & TDF_DETAILS))
> -               fprintf (dump_file, "   Constant conditional.\n");
> -             likely_eliminated = true;
> +                      && (gimple_assign_rhs_class (stmt) != GIMPLE_BINARY_RHS
> +                          || constant_after_peeling (gimple_assign_rhs2 (stmt),
> +                                                     stmt, loop)))
> +               {
> +                 size->constant_iv = true;
> +                 if (dump_file && (dump_flags & TDF_DETAILS))
> +                   fprintf (dump_file,
> +                            "   Constant expression will be folded away.\n");
> +                 likely_eliminated = true;
> +               }
> +             /* Conditionals.  */
> +             else if ((gimple_code (stmt) == GIMPLE_COND
> +                       && constant_after_peeling (gimple_cond_lhs (stmt), stmt,
> +                                                  loop)
> +                       && constant_after_peeling (gimple_cond_rhs (stmt), stmt,
> +                                                  loop)
> +                       /* We don't simplify all constant compares so make sure
> +                          they are not both constant already.  See PR70288.  */
> +                       && (! is_gimple_min_invariant (gimple_cond_lhs (stmt))
> +                           || ! is_gimple_min_invariant
> +                                (gimple_cond_rhs (stmt))))
> +                      || (gimple_code (stmt) == GIMPLE_SWITCH
> +                          && constant_after_peeling (gimple_switch_index (
> +                                                       as_a <gswitch *>
> +                                                         (stmt)),
> +                                                     stmt, loop)
> +                          && ! is_gimple_min_invariant
> +                                  (gimple_switch_index
> +                                     (as_a <gswitch *> (stmt)))))
> +               {
> +                 if (dump_file && (dump_flags & TDF_DETAILS))
> +                   fprintf (dump_file, "   Constant conditional.\n");
> +                 likely_eliminated = true;
> +               }
>             }
>
>           size->overall += num;