Re: Fix ppc64le bootstrap comparison failure

[Andrew Pinski <pinskia at gmail dot com>]

On Fri, Jan 13, 2017 at 10:24 PM, Jeff Law <law@redhat.com> wrote:
>
>
> Given a block with more than one dead store, one of which is the last
> statement in the block, the existence debugging statements can change the
> generated code which is of course bad.
>
> The problem is when I moved the code to delete the dead statement into its
> own function, I passed in the statement rather than the iterator. As a
> result  dse_dom_walker::before_dom_children would not see the iterator in
> the proper state and it would fail to walk all the statements if
> dse_optimize_stmt deleted the last statement in the block.
>
> In a debug build that scenario was much less likely to trigger because of
> the existence of debug statements.
>
> I'm installing this on the trunk now to fix the bootstrap issues.  I'll try
> to construct a testcase Monday.
>
> Bootstrapped and regression tested on x86_64-linux-gnu and ppc64-linux-gnu.
> Installing on the trunk.
>
> Sorry for the breakage.

This fixed the bootstrap issue I was seeing on aarch64-linux-gnu.

Thanks,
Andrew


>
> Jeff
>
> diff --git a/gcc/ChangeLog b/gcc/ChangeLog
> index 3c74b19..d07b1f5 100644
> --- a/gcc/ChangeLog
> +++ b/gcc/ChangeLog
> @@ -1,3 +1,14 @@
> +2017-01-13  Jeff Law  <law@redhat.com>
> +
> +       PR tree-optimization/33562
> +       PR tree-optimization/61912
> +       PR tree-optimization/77485
> +       * tree-ssa-dse.c (delete_dead_call): Accept gsi rather than
> +       a statement.
> +       (delete_dead_assignment): Likewise.
> +       (dse_dom_walker::dse_optimize_stmt): Pass in the gsi rather than
> +       statement to delete_dead_call and delete_dead_assignment.
> +
>  2017-01-13  David Malcolm  <dmalcolm@redhat.com>
>
>         PR c/78304
> diff --git a/gcc/tree-ssa-dse.c b/gcc/tree-ssa-dse.c
> index 20cf3b4..2e6f8ff 100644
> --- a/gcc/tree-ssa-dse.c
> +++ b/gcc/tree-ssa-dse.c
> @@ -600,10 +600,11 @@ private:
>    void dse_optimize_stmt (gimple_stmt_iterator *);
>  };
>
> -/* Delete a dead call STMT, which is mem* call of some kind.  */
> +/* Delete a dead call at GSI, which is mem* call of some kind.  */
>  static void
> -delete_dead_call (gimple *stmt)
> +delete_dead_call (gimple_stmt_iterator *gsi)
>  {
> +  gimple *stmt = gsi_stmt (*gsi);
>    if (dump_file && (dump_flags & TDF_DETAILS))
>      {
>        fprintf (dump_file, "  Deleted dead call: ");
> @@ -612,13 +613,12 @@ delete_dead_call (gimple *stmt)
>      }
>
>    tree lhs = gimple_call_lhs (stmt);
> -  gimple_stmt_iterator gsi = gsi_for_stmt (stmt);
>    if (lhs)
>      {
>        tree ptr = gimple_call_arg (stmt, 0);
>        gimple *new_stmt = gimple_build_assign (lhs, ptr);
>        unlink_stmt_vdef (stmt);
> -      if (gsi_replace (&gsi, new_stmt, true))
> +      if (gsi_replace (gsi, new_stmt, true))
>          bitmap_set_bit (need_eh_cleanup, gimple_bb (stmt)->index);
>      }
>    else
> @@ -627,17 +627,18 @@ delete_dead_call (gimple *stmt)
>        unlink_stmt_vdef (stmt);
>
>        /* Remove the dead store.  */
> -      if (gsi_remove (&gsi, true))
> +      if (gsi_remove (gsi, true))
>         bitmap_set_bit (need_eh_cleanup, gimple_bb (stmt)->index);
>        release_defs (stmt);
>      }
>  }
>
> -/* Delete a dead store STMT, which is a gimple assignment. */
> +/* Delete a dead store at GSI, which is a gimple assignment. */
>
>  static void
> -delete_dead_assignment (gimple *stmt)
> +delete_dead_assignment (gimple_stmt_iterator *gsi)
>  {
> +  gimple *stmt = gsi_stmt (*gsi);
>    if (dump_file && (dump_flags & TDF_DETAILS))
>      {
>        fprintf (dump_file, "  Deleted dead store: ");
> @@ -649,9 +650,8 @@ delete_dead_assignment (gimple *stmt)
>    unlink_stmt_vdef (stmt);
>
>    /* Remove the dead store.  */
> -  gimple_stmt_iterator gsi = gsi_for_stmt (stmt);
>    basic_block bb = gimple_bb (stmt);
> -  if (gsi_remove (&gsi, true))
> +  if (gsi_remove (gsi, true))
>      bitmap_set_bit (need_eh_cleanup, bb->index);
>
>    /* And release any SSA_NAMEs set in this statement back to the
> @@ -717,7 +717,7 @@ dse_dom_walker::dse_optimize_stmt (gimple_stmt_iterator
> *gsi)
>                 }
>
>               if (store_status == DSE_STORE_DEAD)
> -               delete_dead_call (stmt);
> +               delete_dead_call (gsi);
>               return;
>             }
>
> @@ -760,7 +760,7 @@ dse_dom_walker::dse_optimize_stmt (gimple_stmt_iterator
> *gsi)
>           && !gimple_clobber_p (use_stmt))
>         return;
>
> -      delete_dead_assignment (stmt);
> +      delete_dead_assignment (gsi);
>      }
>  }
>
>