On Wed, May 9, 2012 at 2:38 PM, Michael Matz <[email protected]> wrote:
> Hi,
>
> the current code for strided loads can't deal with the situation when a
> prologue loop (peeling for alignment) is created after analyzing the data
> refs. There are multiple issues (non-constant steps in DRs mainly), so
> this is a simple stop gap.
>
> Regtesting on x86_64-linux (all langs) in progress. Okay for trunk?
Ok.
Thanks,
Richard.
>
> Ciao,
> Michael.
> --------------------
> PR tree-optimization/53185
> * tree-vect-data-refs.c (vect_enhance_data_refs_alignment): Disable
> peeling when we see strided loads.
>
> testsuite/
> * gcc.dg/vect/pr53185.c: New test.
>
> Index: tree-vect-data-refs.c
> ===================================================================
> --- tree-vect-data-refs.c (revision 187287)
> +++ tree-vect-data-refs.c (working copy)
> @@ -1507,6 +1507,17 @@ vect_enhance_data_refs_alignment (loop_v
> && GROUP_FIRST_ELEMENT (stmt_info) != stmt)
> continue;
>
> + /* FORNOW: Any strided load prevents peeling. The induction
> + variable analysis will fail when the prologue loop is generated,
> + and so we can't generate the new base for the pointer. */
> + if (STMT_VINFO_STRIDE_LOAD_P (stmt_info))
> + {
> + if (vect_print_dump_info (REPORT_DETAILS))
> + fprintf (vect_dump, "strided load prevents peeling");
> + do_peeling = false;
> + break;
> + }
> +
> /* For invariant accesses there is nothing to enhance. */
> if (integer_zerop (DR_STEP (dr)))
> continue;
> Index: testsuite/gcc.dg/vect/pr53185.c
> ===================================================================
> --- testsuite/gcc.dg/vect/pr53185.c (revision 0)
> +++ testsuite/gcc.dg/vect/pr53185.c (revision 0)
> @@ -0,0 +1,16 @@
> +/* { dg-do compile } */
> +/* { dg-options "-O3 -ftree-vectorize" } */
> +unsigned short a, e;
> +int *b, *d;
> +int c;
> +extern int fn2();
> +void fn1 () {
> + void *f;
> + for (;;) {
> + fn2 ();
> + b = f;
> + e = 0;
> + for (; e < a; ++e)
> + b[e] = d[e * c];
> + }
> +}
