gcc-patches-ow...@gcc.gnu.org wrote on 12/04/2011 04:38:54 PM:
> vectorizable_store contains the code:
>
> for (j = 0; j < ncopies; j++)
> {
> for (i = 0; i < vec_num; i++)
> {
> ...
> if (j == 0)
> STMT_VINFO_VEC_STMT (stmt_info) = *vec_stmt = new_stmt;
> else
> STMT_VINFO_RELATED_STMT (prev_stmt_info) = new_stmt;
> prev_stmt_info = vinfo_for_stmt (new_stmt);
> }
> }
>
> That is, STMT_VINFO_VEC_STMT (stmt_info) and *vec_stmt contain the last
> statement emitted for the _last_ vector of the first copy. However,
> for later copies, the last statement for _every_ vector is chained using
> STMT_VINFO_RELATED_STMT. This seems a bit inconsistent, and isn't
> what I expected from the comments. It also seems different from
> other vectorisation functions, where each copy has exactly one
> STMT_VINFO_RELATED_STMT. I wasn't sure whether the difference here
> was deliberate or not.
I think it doesn't really matter because STMT_VINFO_RELATED_STMT is used
for retrieving copies of vector operands, and stores don't define any.
>
> The reason I'm changing it is that it makes the control flow for
> the new code more obvious.
>
> Tested on x86_64-linux-gnu and arm-linux-gnueabi. OK to install?
OK.
Thanks,
Ira
>
> Richard
>
>
> gcc/
> * tree-vect-stmts.c (vectorizable_store): Only chain one related
> statement per copy.
>
> Index: gcc/tree-vect-stmts.c
> ===================================================================
> --- gcc/tree-vect-stmts.c 2011-04-12 11:55:08.000000000 +0100
> +++ gcc/tree-vect-stmts.c 2011-04-12 11:55:09.000000000 +0100
> @@ -3612,6 +3612,7 @@ vectorizable_store (gimple stmt, gimple_
>
> if (1)
> {
> + new_stmt = NULL;
> if (strided_store)
> {
> result_chain = VEC_alloc (tree, heap, group_size);
> @@ -3669,17 +3670,19 @@ vectorizable_store (gimple stmt, gimple_
> if (slp)
> continue;
>
> - if (j == 0)
> - STMT_VINFO_VEC_STMT (stmt_info) = *vec_stmt = new_stmt;
> - else
> - STMT_VINFO_RELATED_STMT (prev_stmt_info) = new_stmt;
> -
> - prev_stmt_info = vinfo_for_stmt (new_stmt);
> next_stmt = DR_GROUP_NEXT_DR (vinfo_for_stmt (next_stmt));
> if (!next_stmt)
> break;
> }
> }
> + if (!slp)
> + {
> + if (j == 0)
> + STMT_VINFO_VEC_STMT (stmt_info) = *vec_stmt = new_stmt;
> + else
> + STMT_VINFO_RELATED_STMT (prev_stmt_info) = new_stmt;
> + prev_stmt_info = vinfo_for_stmt (new_stmt);
> + }
> }
>
> VEC_free (tree, heap, dr_chain);
