[omp, hsa] Do not gridify simd constructs

[Martin Jambor]

Hi,

unfortunately, I have missed two execution failures when using HSA
(teams-6.f90 and target1.f90), both of which are caused by not
handling the simd part of combined target teams distribute parallel
for simd construct.  I have not really thought through how exactly
should GPUs teat the simd construct in a combined construct but of
course we must not miscompile.

So I'd like to commit the following patch which just disallows
gridification of such cases to trunk now and am working on a fix that
removes the simd loop for the hsa branch.  Eventually we might also
want to hsa-vectorize the body even though the explicit loop is
missing, but that will also mean that the HSA grid size has to shrink
appropriately.

Bootstrapped and tested on x86_64-linux, with and without HSA
enabled.  OK for trunk?

Thanks,

Martin

2016-02-17  Martin Jambor  <mjambor@suse.cz>

    * omp-low.c (grid_find_ungridifiable_statement): Store problematic
    statements to wi->info.  Also disallow omp simd constructs.
    (grid_target_follows_gridifiable_pattern): Use wi.info to dump reason
    for not gridifying.  Dump special string for omp_for.
---
 gcc/omp-low.c | 26 ++++++++++++++++++++++----
 1 file changed, 22 insertions(+), 4 deletions(-)

diff --git a/gcc/omp-low.c b/gcc/omp-low.c
index fcbb3e0..989d03e 100644
--- a/gcc/omp-low.c
+++ b/gcc/omp-low.c
@@ -17241,7 +17241,7 @@ grid_find_single_omp_among_assignments (gimple_seq seq, location_t target_loc,
 static tree
 grid_find_ungridifiable_statement (gimple_stmt_iterator *gsi,
 				   bool *handled_ops_p,
-				   struct walk_stmt_info *)
+				   struct walk_stmt_info *wi)
 {
   *handled_ops_p = false;
   gimple *stmt = gsi_stmt (*gsi);
@@ -17251,6 +17251,7 @@ grid_find_ungridifiable_statement (gimple_stmt_iterator *gsi,
       if (gimple_call_noreturn_p (as_a <gcall *> (stmt)))
 	{
 	  *handled_ops_p = true;
+	  wi->info = stmt;
 	  return error_mark_node;
 	}
       break;
@@ -17266,8 +17267,19 @@ grid_find_ungridifiable_statement (gimple_stmt_iterator *gsi,
     case GIMPLE_OMP_TARGET:
     case GIMPLE_OMP_ORDERED:
       *handled_ops_p = true;
+      wi->info = stmt;
       return error_mark_node;
 
+    case GIMPLE_OMP_FOR:
+      if ((gimple_omp_for_kind (stmt) & GF_OMP_FOR_SIMD)
+	  && gimple_omp_for_combined_into_p (stmt))
+	{
+	  *handled_ops_p = true;
+	  wi->info = stmt;
+	  return error_mark_node;
+	}
+      break;
+
     default:
       break;
     }
@@ -17509,10 +17521,11 @@ grid_target_follows_gridifiable_pattern (gomp_target *target, tree *group_size_p
 
   struct walk_stmt_info wi;
   memset (&wi, 0, sizeof (wi));
-  if (gimple *bad = walk_gimple_seq (gimple_omp_body (gfor),
-				     grid_find_ungridifiable_statement,
-				     NULL, &wi))
+  if (walk_gimple_seq (gimple_omp_body (gfor),
+		       grid_find_ungridifiable_statement,
+		       NULL, &wi))
     {
+      gimple *bad = (gimple *) wi.info;
       if (dump_enabled_p ())
 	{
 	  if (is_gimple_call (bad))
@@ -17520,6 +17533,11 @@ grid_target_follows_gridifiable_pattern (gomp_target *target, tree *group_size_p
 			     "Will not turn target construct into a gridified "
 			     " GPGPU kernel because the inner loop contains "
 			     "call to a noreturn function\n");
+	  if (gimple_code (bad) == GIMPLE_OMP_FOR)
+	    dump_printf_loc (MSG_NOTE, tloc,
+			     "Will not turn target construct into a gridified "
+			     " GPGPU kernel because the inner loop contains "
+			     "a simd construct\n");
 	  else
 	    dump_printf_loc (MSG_NOTE, tloc,
 			     "Will not turn target construct into a gridified "
-- 
2.7.1