[Bug tree-optimization/25918] gcc.dg/vect/vect-reduc-dot-s16.c scan-tree-dump-times vectorized 1 loops 1 and gcc.dg/vect/vect-reduc-pattern-2.c scan-tree-dump-times vectorized 2 loops 1 fail

[wilson at gcc dot gnu dot org]

------- Comment #4 from wilson at gcc dot gnu dot org  2006-02-08 02:07 -------
The vect-reduc-dot-s16.c testcase fails because two loops were vectorized, and
we only expected one to be vectorized.

The problem here is that the loop in foo1 is not supposed to be recognized and
vectorized as a dot-product loop.  And it isn't, as expected.  However, on
IA-64, it is recognized and vectorized as a widen-sum loop.  This happens
because the IA-64 port defines the widen_ssumv4hi3 pattern.  The IA-64 port is
the only one that defines this pattern, and hence is probably the only port
"broken" here.  All others will presumably fail to vectorize this loop.

So the IA-64 port emits to the -fdump-tree-vect-details file
tmp.c:23: note: pattern recognized: prod_14 w+ result_3
tmp.c:23: note: vectorized 1 loops in function.
tmp.c:38: note: pattern recognized:  DOT_PROD_EXPR < D.2127_14 , D.2125_10 ...
tmp.c:38: note: vectorized 1 loops in function.
and the testcase fails because we only expected 1 loop to be vectorized.

I think the only thing wrong here is that the dg-final tests in the testcase
are not precise enough to handle this case.


-- 

wilson at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
     Ever Confirmed|0                           |1
   Last reconfirmed|0000-00-00 00:00:00         |2006-02-08 02:07:47
               date|                            |


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=25918