Re: [patch] Fix a problem in examination of may-alias sets with partitions

[Ira Rosen <IRAR at il dot ibm dot com>]

Daniel's "Change may_aliases to use bitmaps" patch fixed this problem.
There is no need in my patch anymore.

I committed the fix to vect-37.c as obvious.

Thanks,
Ira


Ira Rosen/Haifa/IBM wrote on 15/01/2007 15:14:43:

> In function is_aliased_with (tree-ssa-alias.c) every entry of tag's
> may-alias set is compared to a given symbol to find out whether this
> symbol belongs to the may-alias set. Since MEM-SSA has been merged,
> may-alias set can also contain MPTs. Therefore, we now also have to
> check whether the symbol belongs to one of the MPTs of the may-alias set.
>
> The testcases vect-37.c, vect-57.c and vect-61.c are supposed not to
> get vectorized because of aliasing. With MEM-SSA, NMTs' may-alias
> sets in these tests contain MPTs, causing is_aliased_with() return a
> wrong answer, and, therefore, causing vectorization of the loops in
> the tests. Currently, vect-57.c and vect-61.c xpass. vect-37.c was
> changed to expect pass in the MEM-SSA merge. This patch will restore
> the original behavior of vect-37.c and will make vect-57.c and
> vect-61.c to fail as they should.
>
> Bootstrapped and tested on ppc-linux.
>
> O.K. for mainline?
>
> Thanks,
> Ira
>
> ChangeLog entry:
>
>  * tree-ssa-alias.c (is_aliased_with): Check if the symbol belongs
> to MPTs of the may-alias set.
>
> The patch:
>
> Index: tree-ssa-alias.c
> ===================================================================
> *** tree-ssa-alias.c    (revision 120765)
> --- tree-ssa-alias.c    (working copy)
> *************** is_aliased_with (tree tag, tree sym)
> *** 2591,2598 ****
>         return false;
>
>         for (i = 0; VEC_iterate (tree, aliases, i, al); i++)
> !       if (al == sym)
> !         return true;
>       }
>     else
>       {
> --- 2591,2602 ----
>         return false;
>          for (i = 0; VEC_iterate (tree, aliases, i, al); i++)
> !       {
> !         if ((al == sym)
> !             || (TREE_CODE (al) == MEMORY_PARTITION_TAG
> !                 && memory_partition (sym) == al))
> !             return true;
> !       }
>       }
>     else
>       {
> *************** is_aliased_with (tree tag, tree sym)
> *** 2602,2614 ****
>         return false;
>
>         for (i = 0; VEC_iterate (tree, aliases, i, al); i++)
> !       if (al == tag)
>           return true;
>       }
>
>     return false;
>   }
>
>   /* The following is based on code in add_stmt_operand to ensure that
the
>      same defs/uses/vdefs/vuses will be found after replacing a reference
>      to var (or ARRAY_REF to var) with an INDIRECT_REF to ptr whose value
> --- 2606,2649 ----
>         return false;
>
>         for (i = 0; VEC_iterate (tree, aliases, i, al); i++)
> !       if (al == tag
> !           || (TREE_CODE (al) == MEMORY_PARTITION_TAG
> !               && memory_partition (tag) == al))
>           return true;
>       }
>
>     return false;
>   }
> Index: testsuite/gcc.dg/vect/vect-37.c
> ===================================================================
> *** testsuite/gcc.dg/vect/vect-37.c     (revision 120765)
> --- testsuite/gcc.dg/vect/vect-37.c     (working copy)
> *************** int main (void)
> *** 53,57 ****
>     return main1 (x);
>   }
>
> ! /* { dg-final { scan-tree-dump-times "vectorized 2 loops" 1 "vect" } }
*/
>   /* { dg-final { cleanup-tree-dump "vect" } } */
> --- 53,61 ----
>     return main1 (x);
>   }
>
> ! /* Currently the loops fail to vectorize due to aliasing problems.
> !    If/when the aliasing problems are resolved, unalignment may
> !    prevent vectorization on some targets.  */
> ! /* { dg-final { scan-tree-dump-times "vectorized 2 loops" 1 "vect"
> { xfail *-*-* } } } */
> ! /* { dg-final { scan-tree-dump-times "can't determine dependence
> between" 2 "vect" } } */
>   /* { dg-final { cleanup-tree-dump "vect" } } */
>
> :ADDPATCH SSA: