On Tue, 14 Jan 2014, Jakub Jelinek wrote:
> On Tue, Jan 14, 2014 at 10:01:06AM +0100, Richard Biener wrote:
> > Jakub, adding the new flag is ok with me.
>
> So like this?
Ok if it passes testing.
Thanks,
Richard.
> 2014-01-14 Jakub Jelinek <ja...@redhat.com>
>
> * tree-vectorizer.h (struct _loop_vec_info): Add no_data_dependencies
> field.
> (LOOP_VINFO_NO_DATA_DEPENDENCIES): Define.
> * tree-vect-data-refs.c (vect_analyze_data_ref_dependence): Clear it
> when not giving up or versioning for alias only because of
> loop->safelen.
> (vect_analyze_data_ref_dependences): Set to true.
> * tree-vect-stmts.c (vectorizable_load): Use
> LOOP_VINFO_NO_DATA_DEPENDENCIES instead of
> LOOP_REQUIRES_VERSIONING_FOR_ALIAS.
>
> --- gcc/tree-vectorizer.h.jj 2014-01-03 11:40:57.000000000 +0100
> +++ gcc/tree-vectorizer.h 2014-01-14 13:10:00.477989924 +0100
> @@ -347,6 +347,25 @@ typedef struct _loop_vec_info {
> fix it up. */
> bool operands_swapped;
>
> + /* True if there are no loop carried data dependencies in the loop.
> + If loop->safelen <= 1, then this is always true, either the loop
> + didn't have any loop carried data dependencies, or the loop is being
> + vectorized guarded with some runtime alias checks, or couldn't
> + be vectorized at all, but then this field shouldn't be used.
> + For loop->safelen >= 2, the user has asserted that there are no
> + backward dependencies, but there still could be loop carried forward
> + dependencies in such loops. This flag will be false if normal
> + vectorizer data dependency analysis would fail or require versioning
> + for alias, but because of loop->safelen >= 2 it has been vectorized
> + even without versioning for alias. E.g. in:
> + #pragma omp simd
> + for (int i = 0; i < m; i++)
> + a[i] = a[i + k] * c;
> + (or #pragma simd or #pragma ivdep) we can vectorize this and it will
> + DTRT even for k > 0 && k < m, but without safelen we would not
> + vectorize this, so this field would be false. */
> + bool no_data_dependencies;
> +
> /* If if-conversion versioned this loop before conversion, this is the
> loop version without if-conversion. */
> struct loop *scalar_loop;
> @@ -385,6 +404,7 @@ typedef struct _loop_vec_info {
> #define LOOP_VINFO_PEELING_FOR_GAPS(L) (L)->peeling_for_gaps
> #define LOOP_VINFO_OPERANDS_SWAPPED(L) (L)->operands_swapped
> #define LOOP_VINFO_PEELING_FOR_NITER(L) (L)->peeling_for_niter
> +#define LOOP_VINFO_NO_DATA_DEPENDENCIES(L) (L)->no_data_dependencies
> #define LOOP_VINFO_SCALAR_LOOP(L) (L)->scalar_loop
>
> #define LOOP_REQUIRES_VERSIONING_FOR_ALIGNMENT(L) \
> --- gcc/tree-vect-data-refs.c.jj 2014-01-10 00:38:26.000000000 +0100
> +++ gcc/tree-vect-data-refs.c 2014-01-14 13:12:06.056342116 +0100
> @@ -244,6 +244,7 @@ vect_analyze_data_ref_dependence (struct
> {
> if (loop->safelen < *max_vf)
> *max_vf = loop->safelen;
> + LOOP_VINFO_NO_DATA_DEPENDENCIES (loop_vinfo) = false;
> return false;
> }
>
> @@ -291,6 +292,7 @@ vect_analyze_data_ref_dependence (struct
> {
> if (loop->safelen < *max_vf)
> *max_vf = loop->safelen;
> + LOOP_VINFO_NO_DATA_DEPENDENCIES (loop_vinfo) = false;
> return false;
> }
>
> @@ -447,6 +449,7 @@ vect_analyze_data_ref_dependences (loop_
> dump_printf_loc (MSG_NOTE, vect_location,
> "=== vect_analyze_data_ref_dependences ===\n");
>
> + LOOP_VINFO_NO_DATA_DEPENDENCIES (loop_vinfo) = true;
> if (!compute_all_dependences (LOOP_VINFO_DATAREFS (loop_vinfo),
> &LOOP_VINFO_DDRS (loop_vinfo),
> LOOP_VINFO_LOOP_NEST (loop_vinfo), true))
> --- gcc/tree-vect-stmts.c.jj 2014-01-14 10:33:21.000000000 +0100
> +++ gcc/tree-vect-stmts.c 2014-01-14 13:14:15.157677243 +0100
> @@ -6381,10 +6381,11 @@ vectorizable_load (gimple stmt, gimple_s
> if (inv_p && !bb_vinfo)
> {
> gcc_assert (!grouped_load);
> - /* If we have versioned for aliasing then we are sure
> - this is a loop invariant load and thus we can insert
> - it on the preheader edge. */
> - if (LOOP_REQUIRES_VERSIONING_FOR_ALIAS (loop_vinfo))
> + /* If we have versioned for aliasing or the loop doesn't
> + have any data dependencies that would preclude this,
> + then we are sure this is a loop invariant load and
> + thus we can insert it on the preheader edge. */
> + if (LOOP_VINFO_NO_DATA_DEPENDENCIES (loop_vinfo))
> {
> if (dump_enabled_p ())
> {
>
>
> Jakub
>
>
--
Richard Biener <rguent...@suse.de>
SUSE / SUSE Labs
SUSE LINUX Products GmbH - Nuernberg - AG Nuernberg - HRB 16746
GF: Jeff Hawn, Jennifer Guild, Felix Imend"orffer
