[PATCH, 5/16] Add in_oacc_kernels_region in struct loop

[Tom de Vries <Tom_deVries at mentor dot com>]

On 09/11/15 16:35, Tom de Vries wrote:
> Hi,
>
> this patch series for stage1 trunk adds support to:
> - parallelize oacc kernels regions using parloops, and
> - map the loops onto the oacc gang dimension.
>
> The patch series contains these patches:
>
>       1    Insert new exit block only when needed in
>          transform_to_exit_first_loop_alt
>       2    Make create_parallel_loop return void
>       3    Ignore reduction clause on kernels directive
>       4    Implement -foffload-alias
>       5    Add in_oacc_kernels_region in struct loop
>       6    Add pass_oacc_kernels
>       7    Add pass_dominator_oacc_kernels
>       8    Add pass_ch_oacc_kernels
>       9    Add pass_parallelize_loops_oacc_kernels
>      10    Add pass_oacc_kernels pass group in passes.def
>      11    Update testcases after adding kernels pass group
>      12    Handle acc loop directive
>      13    Add c-c++-common/goacc/kernels-*.c
>      14    Add gfortran.dg/goacc/kernels-*.f95
>      15    Add libgomp.oacc-c-c++-common/kernels-*.c
>      16    Add libgomp.oacc-fortran/kernels-*.f95
>
> The first 9 patches are more or less independent, but patches 10-16 are
> intended to be committed at the same time.
>
> Bootstrapped and reg-tested on x86_64.
>
> Build and reg-tested with nvidia accelerator, in combination with a
> patch that enables accelerator testing (which is submitted at
> https://gcc.gnu.org/ml/gcc-patches/2015-10/msg01771.html ).
>
> I'll post the individual patches in reply to this message.

this patch adds and initializes the field in_oacc_kernels_region field 
in struct loop.

The field is used to signal to subsequent passes that we're dealing with 
a loop in a kernels region that we're trying parallelize.

Note that we do not parallelize kernels regions with more than one loop 
nest. [ In general, kernels regions with more than one loop nest should 
be split up into seperate kernels regions, but that's not supported atm. ]

Thanks,
- Tom

Add in_oacc_kernels_region in struct loop

2015-11-09  Tom de Vries  <tom@codesourcery.com>

	* cfgloop.h (struct loop): Add in_oacc_kernels_region field.
	* omp-low.c (mark_loops_in_oacc_kernels_region): New function.
	(expand_omp_target): Call mark_loops_in_oacc_kernels_region.
---
 gcc/cfgloop.h |  3 +++
 gcc/omp-low.c | 58 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 61 insertions(+)

diff --git a/gcc/cfgloop.h b/gcc/cfgloop.h
index 6af6893..ee73bf9 100644
--- a/gcc/cfgloop.h
+++ b/gcc/cfgloop.h
@@ -191,6 +191,9 @@ struct GTY ((chain_next ("%h.next"))) loop {
   /* True if we should try harder to vectorize this loop.  */
   bool force_vectorize;
 
+  /* True if the loop is part of an oacc kernels region.  */
+  bool in_oacc_kernels_region;
+
   /* For SIMD loops, this is a unique identifier of the loop, referenced
      by IFN_GOMP_SIMD_VF, IFN_GOMP_SIMD_LANE and IFN_GOMP_SIMD_LAST_LANE
      builtins.  */
diff --git a/gcc/omp-low.c b/gcc/omp-low.c
index d052c13..7121d73 100644
--- a/gcc/omp-low.c
+++ b/gcc/omp-low.c
@@ -12429,6 +12429,61 @@ get_oacc_ifn_dim_arg (const gimple *stmt)
   return (int) axis;
 }
 
+/* Mark the loops inside the kernels region starting at REGION_ENTRY and ending
+   at REGION_EXIT.  */
+
+static void
+mark_loops_in_oacc_kernels_region (basic_block region_entry,
+				   basic_block region_exit)
+{
+  bitmap dominated_bitmap = BITMAP_GGC_ALLOC ();
+  bitmap excludes_bitmap = BITMAP_GGC_ALLOC ();
+  unsigned di;
+  basic_block bb;
+
+  bitmap_clear (dominated_bitmap);
+  bitmap_clear (excludes_bitmap);
+
+  /* Get all the blocks dominated by the region entry.  That will include the
+     entire region.  */
+  vec<basic_block> dominated
+    = get_all_dominated_blocks (CDI_DOMINATORS, region_entry);
+  FOR_EACH_VEC_ELT (dominated, di, bb)
+      bitmap_set_bit (dominated_bitmap, bb->index);
+
+  /* Exclude all the blocks which are not in the region: the blocks dominated by
+     the region exit.  */
+  if (region_exit != NULL)
+    {
+      vec<basic_block> excludes
+	= get_all_dominated_blocks (CDI_DOMINATORS, region_exit);
+      FOR_EACH_VEC_ELT (excludes, di, bb)
+	bitmap_set_bit (excludes_bitmap, bb->index);
+    }
+
+  /* Don't parallelize the kernels region if it contains more than one outer
+     loop.  */
+  unsigned int nr_outer_loops = 0;
+  struct loop *loop;
+  FOR_EACH_LOOP (loop, 0)
+    {
+      if (loop_outer (loop) != current_loops->tree_root)
+	continue;
+
+      if (bitmap_bit_p (dominated_bitmap, loop->header->index)
+	  && !bitmap_bit_p (excludes_bitmap, loop->header->index))
+	nr_outer_loops++;
+    }
+  if (nr_outer_loops != 1)
+    return;
+
+  /* Mark the loops in the region.  */
+  FOR_EACH_LOOP (loop, 0)
+    if (bitmap_bit_p (dominated_bitmap, loop->header->index)
+	&& !bitmap_bit_p (excludes_bitmap, loop->header->index))
+      loop->in_oacc_kernels_region = true;
+}
+
 /* Expand the GIMPLE_OMP_TARGET starting at REGION.  */
 
 static void
@@ -12483,6 +12538,9 @@ expand_omp_target (struct omp_region *region)
   entry_bb = region->entry;
   exit_bb = region->exit;
 
+  if (gimple_omp_target_kind (entry_stmt) == GF_OMP_TARGET_KIND_OACC_KERNELS)
+    mark_loops_in_oacc_kernels_region (region->entry, region->exit);
+
   if (offloaded)
     {
       unsigned srcidx, dstidx, num;
-- 
1.9.1