Re: [PATCH i386][google]With -mtune=core2, avoid generating the slow unaligned vector load/store (issue5488054)

[Sriraman Tallam <tmsriram at google dot com>]

On Mon, Dec 12, 2011 at 9:54 PM, Ira Rosen <IRAR@il.ibm.com> wrote:
>
>
> gcc-patches-owner@gcc.gnu.org wrote on 13/12/2011 04:05:57 AM:
>
>> On core2, unaligned vector load/store using movdqu is a very slow
> operation.
>> Experiments show it is six times slower than movdqa (aligned) and this is
>> irrespective of whether the resulting data happens to be aligned or not.
>> For Corei7, there is no performance difference between the two and on
> AMDs,
>> movdqu is only about 10% slower.
>>
>> This patch does not vectorize loops that need to generate the slow
> unaligned
>> memory load/stores on core2.
>>
>>
>> ? ?Do not vectorize loops on Core2 that need to use unaligned
>> ? ?vector load/stores.
>> ? ?* tree-vect-stmts.c (is_slow_vect_unaligned_load_store): New function.
>> ? ?(vect_analyze_stmt): Check if the vectorizable load/store is slow.
>> ? ?* target.def (TARGET_SLOW_UNALIGNED_VECTOR_MEMOP): New target hook.
>> ? ?* doc/m.texi.in: Document new target hook:
>> ? ?TARGET_SLOW_UNALIGNED_VECTOR_MEMOP
>> ? ?* doc/m.texi: Regenerate.
>> ? ?* config/i386/i386.c (ix86_slow_unaligned_vector_memop): New function.
>> ? ?(TARGET_SLOW_UNALIGNED_VECTOR_MEMOP): New macro.
>>
>
>
>> @@ -5065,27 +5112,43 @@ vect_analyze_stmt (gimple stmt, bool
> *need_to_vect
>> ? ? if (!bb_vinfo
>> ? ? ? ? && (STMT_VINFO_RELEVANT_P (stmt_info)
>> ? ? ? ? ? ? || STMT_VINFO_DEF_TYPE (stmt_info) == vect_reduction_def))
>> + ? ?{
>> ? ? ? ?ok = (vectorizable_type_promotion (stmt, NULL, NULL, NULL)
>> ? ? ? ? ? ? ?|| vectorizable_type_demotion (stmt, NULL, NULL, NULL)
>> ? ? ? ? ? ? ?|| vectorizable_conversion (stmt, NULL, NULL, NULL)
>> ? ? ? ? ? ? ?|| vectorizable_shift (stmt, NULL, NULL, NULL)
>> ? ? ? ? ? ? ?|| vectorizable_operation (stmt, NULL, NULL, NULL)
>> ? ? ? ? ? ? ?|| vectorizable_assignment (stmt, NULL, NULL, NULL)
>> - ? ? ? ? ? ?|| vectorizable_load (stmt, NULL, NULL, NULL, NULL)
>> ? ? ? ? ? ? ?|| vectorizable_call (stmt, NULL, NULL)
>> - ? ? ? ? ? ?|| vectorizable_store (stmt, NULL, NULL, NULL)
>> - ? ? ? ? ? ?|| vectorizable_reduction (stmt, NULL, NULL, NULL)
>> + ? ? ? || vectorizable_reduction (stmt, NULL, NULL, NULL)
>> ? ? ? ? ? ? ?|| vectorizable_condition (stmt, NULL, NULL, NULL, 0));
>> +
>> + ? ? ?if (!ok)
>> + ? {
>> + ? ? ? ? ?ok = (vectorizable_load (stmt, NULL, NULL, NULL, NULL)
>> + ? ? ? ? ? || vectorizable_store (stmt, NULL, NULL, NULL));
>> +
>> + ? ? if (ok && is_slow_vect_unaligned_load_store (stmt))
>> + ? ? ? ok = false;
>
> Why not call is_slow_vect_unaligned_load_store from
> vectorizable_load/store?

Yes, I should have done that. Somehow, I missed that!

>
> Ira
>
>
>> + ? }
>> + ? ?}
>> ? ? ?else
>> ? ? ? ?{
>> ? ? ? ? ?if (bb_vinfo)
>> - ? ? ? ? ?ok = (vectorizable_type_promotion (stmt, NULL, NULL, node)
>> - ? ? ? ? ? ? ? ?|| vectorizable_type_demotion (stmt, NULL, NULL, node)
>> - ? ? ? ? ? ? ? || vectorizable_shift (stmt, NULL, NULL, node)
>> - ? ? ? ? ? ? ? ?|| vectorizable_operation (stmt, NULL, NULL, node)
>> - ? ? ? ? ? ? ? ?|| vectorizable_assignment (stmt, NULL, NULL, node)
>> - ? ? ? ? ? ? ? ?|| vectorizable_load (stmt, NULL, NULL, node, NULL)
>> - ? ? ? ? ? ? ? ?|| vectorizable_store (stmt, NULL, NULL, node));
>> + ? ? {
>> + ? ? ? ok = (vectorizable_type_promotion (stmt, NULL, NULL, node)
>> + ? ? ? ?|| vectorizable_type_demotion (stmt, NULL, NULL, node)
>> + ? ? ? ?|| vectorizable_shift (stmt, NULL, NULL, node)
>> + ? ? ? ? ? ? ? ? ?|| vectorizable_operation (stmt, NULL, NULL, node)
>> + ? ? ? ? ? ? ? ? ?|| vectorizable_assignment (stmt, NULL, NULL, node));
>> + ? ? ? ? ? ?if (!ok)
>> + ? ? ? ? {
>> + ? ? ? ? ? ? ? ?ok = (vectorizable_load (stmt, NULL, NULL, node, NULL)
>> + ? ? ? ? ? ?|| vectorizable_store (stmt, NULL, NULL, node));
>> + ? ? ? ? ? if (ok && is_slow_vect_unaligned_load_store (stmt))
>> + ? ? ? ?ok = false;
>> + ? ? ? ? }
>> + ? ? }
>> ? ? ? ?}
>