[PATCH] Optimize COND_EXPR where then/else operands are INTEGER_CSTs of different size than the comparison operands

[Ira Rosen]

On 6 October 2011 18:17, Jakub Jelinek <jakub@redhat.com> wrote:
> Hi!
>
> Since Richard's changes recently to allow different modes in vcond
> patterns (so far on i?86/x86_64 only I think) we can vectorize more
> COND_EXPRs than before, and this patch improves it a tiny bit more
> - even i?86/x86_64 support vconds only if the sizes of vector element
> modes are the same.  With this patch we can optimize even if it is wider
> or narrower, by vectorizing it as the COND_EXPR in integer mode matching
> the size of the comparsion operands and then a cast.
>
> Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?
>

OK, but...

> --- gcc/tree-vect-stmts.c.jj    2011-09-29 14:25:46.000000000 +0200
> +++ gcc/tree-vect-stmts.c       2011-10-06 12:16:43.000000000 +0200
> @@ -652,9 +652,26 @@ vect_mark_stmts_to_be_vectorized (loop_v
>              have to scan the RHS or function arguments instead.  */
>           if (is_gimple_assign (stmt))
>             {
> -              for (i = 1; i < gimple_num_ops (stmt); i++)
> +             enum tree_code rhs_code = gimple_assign_rhs_code (stmt);
> +             tree op = gimple_assign_rhs1 (stmt);
> +
> +             i = 1;
> +             if ((rhs_code == COND_EXPR || rhs_code == VEC_COND_EXPR)

I don't understand why we need VEC_COND_EXPR here.

> +                 && COMPARISON_CLASS_P (op))
> +               {
> +                 if (!process_use (stmt, TREE_OPERAND (op, 0), loop_vinfo,
> +                                   live_p, relevant, &worklist)
> +                     || !process_use (stmt, TREE_OPERAND (op, 1), loop_vinfo,
> +                                      live_p, relevant, &worklist))
> +                   {
> +                     VEC_free (gimple, heap, worklist);
> +                     return false;
> +                   }
> +                 i = 2;
> +               }
> +             for (; i < gimple_num_ops (stmt); i++)
>                 {
> -                  tree op = gimple_op (stmt, i);
> +                 op = gimple_op (stmt, i);
>                   if (!process_use (stmt, op, loop_vinfo, live_p, relevant,
>                                     &worklist))
>                     {
>

Thanks,
Ira