In that case, if my insert_stmt immediately follows dep_stmt and both
have the same UID, not_dominated_by would return true and I will end
up updating insert_stmt to dep_stmt which is wrong.
- Easwaran
On Fri, May 24, 2013 at 1:07 AM, Richard Biener
<richard.guent...@gmail.com> wrote:
> 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;
>> }
