On Thu, May 23, 2013 at 7:26 PM, Easwaran Raman <era...@google.com> wrote:
> This addresses the case where UID alone is not sufficient to figure
> out which statement appears earlier in a BB. Bootstraps and no test
> regressions in x86_64 on linux. Ok for trunk?
Why not simply conservatively use gimple_uid (a) <= gimple_uid (b)
in not_dominated_by?
Richard.
> Thanks,
> Easwaran
>
>
> 2013-05-23 Easwaran Raman <era...@google.com>
>
> PR tree-optimization/57337
> * tree-ssa-reassoc.c (appears_later_in_bb): New function.
> (find_insert_point): Correctly identify the insertion point
> when two statements with the same UID is compared.
>
> Index: gcc/tree-ssa-reassoc.c
> ===================================================================
> --- gcc/tree-ssa-reassoc.c (revision 199211)
> +++ gcc/tree-ssa-reassoc.c (working copy)
> @@ -2866,6 +2866,31 @@ not_dominated_by (gimple a, gimple b)
>
> }
>
> +/* Among STMT1 and STMT2, return the statement that appears later. Both
> + statements are in same BB and have the same UID. */
> +
> +static gimple
> +appears_later_in_bb (gimple stmt1, gimple stmt2)
> +{
> + unsigned uid = gimple_uid (stmt1);
> + gimple_stmt_iterator gsi = gsi_for_stmt (stmt1);
> + gsi_next (&gsi);
> + if (gsi_end_p (gsi))
> + return stmt1;
> + for (; !gsi_end_p (gsi); gsi_next (&gsi))
> + {
> + gimple stmt = gsi_stmt (gsi);
> +
> + /* If STMT has a different UID than STMT1 and we haven't seen
> + STMT2 during traversal, we know STMT1 appears later. */
> + if (gimple_uid (stmt) != uid)
> + return stmt1;
> + else if (stmt == stmt2)
> + return stmt2;
> + }
> + gcc_unreachable ();
> +}
> +
> /* Find the statement after which STMT must be moved so that the
> dependency from DEP_STMT to STMT is maintained. */
>
> @@ -2875,7 +2900,11 @@ find_insert_point (gimple stmt, gimple dep_stmt)
> gimple insert_stmt = stmt;
> if (dep_stmt == NULL)
> return stmt;
> - if (not_dominated_by (insert_stmt, dep_stmt))
> + if (gimple_uid (insert_stmt) == gimple_uid (dep_stmt)
> + && gimple_bb (insert_stmt) == gimple_bb (dep_stmt)
> + && insert_stmt != dep_stmt)
> + insert_stmt = appears_later_in_bb (insert_stmt, dep_stmt);
> + else if (not_dominated_by (insert_stmt, dep_stmt))
> insert_stmt = dep_stmt;
> return insert_stmt;
> }
