openmp: Improve composite triangular loop lowering and expansion

This propagates needed values from the point where number of iterations
is calculated on composite loops to the places where that information
is needed to use the more efficient square root discovery to compute
the starting iterator values from the logical iteration number.

2020-10-13  Jakub Jelinek  <jakub@redhat.com>

	* omp-low.c (add_taskreg_looptemp_clauses): For triangular loops
	with non-constant number of iterations add another 4 _looptemp_
	clauses before the (optional) one for lastprivate.
	(lower_omp_for_lastprivate): Skip those clauses when looking for
	the lastprivate clause.
	(lower_omp_for): For triangular loops with non-constant number of
	iterations add another 4 _looptemp_ clauses.
	* omp-expand.c (expand_omp_for_init_counts): For triangular loops
	with non-constant number of iterations set counts[0],
	fd->first_inner_iterations, fd->factor and fd->adjn1 from the newly
	added _looptemp_ clauses.
	(expand_omp_for_init_vars): Initialize the newly added _looptemp_
	clauses.
	(find_lastprivate_looptemp): New function.
	(expand_omp_for_static_nochunk, expand_omp_for_static_chunk,
	expand_omp_taskloop_for_outer): Use it instead of manually skipping
	_looptemp_ clauses.

1 files changed, 69 insertions, 33 deletions

diff --git a/gcc/omp-expand.c b/gcc/omp-expand.c
index 0d30089..6583c88 100644
--- a/gcc/omp-expand.c
+++ b/gcc/omp-expand.c
@@ -1790,6 +1790,23 @@ expand_omp_for_init_counts (struct omp_for_data *fd, gimple_stmt_iterator *gsi,
 	  else
 	    counts[0] = NULL_TREE;
 	}
+      if (fd->non_rect
+	  && fd->last_nonrect == fd->first_nonrect + 1
+	  && !TYPE_UNSIGNED (TREE_TYPE (fd->loops[fd->last_nonrect].v)))
+	{
+	  tree c[4];
+	  for (i = 0; i < 4; i++)
+	    {
+	      innerc = omp_find_clause (OMP_CLAUSE_CHAIN (innerc),
+					OMP_CLAUSE__LOOPTEMP_);
+	      gcc_assert (innerc);
+	      c[i] = OMP_CLAUSE_DECL (innerc);
+	    }
+	  counts[0] = c[0];
+	  fd->first_inner_iterations = c[1];
+	  fd->factor = c[2];
+	  fd->adjn1 = c[3];
+	}
       return;
     }
 
@@ -2434,7 +2451,12 @@ expand_omp_for_init_vars (struct omp_for_data *fd, gimple_stmt_iterator *gsi,
 	 use it.  */
       tree innerc = omp_find_clause (clauses, OMP_CLAUSE__LOOPTEMP_);
       gcc_assert (innerc);
-      for (i = 0; i < fd->collapse; i++)
+      int count = 0;
+      if (fd->non_rect
+	  && fd->last_nonrect == fd->first_nonrect + 1
+	  && !TYPE_UNSIGNED (TREE_TYPE (fd->loops[fd->last_nonrect].v)))
+	count = 4;
+      for (i = 0; i < fd->collapse + count; i++)
 	{
 	  innerc = omp_find_clause (OMP_CLAUSE_CHAIN (innerc),
 				    OMP_CLAUSE__LOOPTEMP_);
@@ -2442,7 +2464,19 @@ expand_omp_for_init_vars (struct omp_for_data *fd, gimple_stmt_iterator *gsi,
 	  if (i)
 	    {
 	      tree tem = OMP_CLAUSE_DECL (innerc);
-	      tree t = fold_convert (TREE_TYPE (tem), counts[i]);
+	      tree t;
+	      if (i < fd->collapse)
+		t = counts[i];
+	      else
+		switch (i - fd->collapse)
+		  {
+		  case 0: t = counts[0]; break;
+		  case 1: t = fd->first_inner_iterations; break;
+		  case 2: t = fd->factor; break;
+		  case 3: t = fd->adjn1; break;
+		  default: gcc_unreachable ();
+		  }
+	      t = fold_convert (TREE_TYPE (tem), t);
 	      t = force_gimple_operand_gsi (gsi, t, false, NULL_TREE,
 					    false, GSI_CONTINUE_LINKING);
 	      gassign *stmt = gimple_build_assign (tem, t);
@@ -2478,10 +2512,7 @@ expand_omp_for_init_vars (struct omp_for_data *fd, gimple_stmt_iterator *gsi,
 	  basic_block bb_triang = NULL, bb_triang_dom = NULL;
 	  if (fd->first_nonrect + 1 == fd->last_nonrect
 	      && (TREE_CODE (fd->loop.n2) == INTEGER_CST
-		  || (fd->first_inner_iterations
-		      /* For now.  Later add clauses to propagate the
-			 values.  */
-		      && !gimple_omp_for_combined_into_p (fd->for_stmt)))
+		  || fd->first_inner_iterations)
 	      && (optab_handler (sqrt_optab, TYPE_MODE (double_type_node))
 		  != CODE_FOR_nothing))
 	    {
@@ -4641,6 +4672,35 @@ expand_omp_scantemp_alloc (tree clauses, tree ptr, unsigned HOST_WIDE_INT sz,
     return ptr;
 }
 
+/* Return the last _looptemp_ clause if one has been created for
+   lastprivate on distribute parallel for{, simd} or taskloop.
+   FD is the loop data and INNERC should be the second _looptemp_
+   clause (the one holding the end of the range).
+   This is followed by collapse - 1 _looptemp_ clauses for the
+   counts[1] and up, and for triangular loops followed by 4
+   further _looptemp_ clauses (one for counts[0], one first_inner_iterations,
+   one factor and one adjn1).  After this there is optionally one
+   _looptemp_ clause that this function returns.  */
+
+static tree
+find_lastprivate_looptemp (struct omp_for_data *fd, tree innerc)
+{
+  gcc_assert (innerc);
+  int count = fd->collapse - 1;
+  if (fd->non_rect
+      && fd->last_nonrect == fd->first_nonrect + 1
+      && !TYPE_UNSIGNED (TREE_TYPE (fd->loops[fd->last_nonrect].v)))
+    count += 4;
+  for (int i = 0; i < count; i++)
+    {
+      innerc = omp_find_clause (OMP_CLAUSE_CHAIN (innerc),
+				OMP_CLAUSE__LOOPTEMP_);
+      gcc_assert (innerc);
+    }
+  return omp_find_clause (OMP_CLAUSE_CHAIN (innerc),
+			  OMP_CLAUSE__LOOPTEMP_);
+}
+
 /* A subroutine of expand_omp_for.  Generate code for a parallel
    loop with static schedule and no specified chunk size.  Given
    parameters:
@@ -5065,15 +5125,7 @@ expand_omp_for_static_nochunk (struct omp_region *region,
       if (fd->collapse > 1 && TREE_CODE (fd->loop.n2) != INTEGER_CST
 	  && gimple_omp_for_kind (fd->for_stmt) == GF_OMP_FOR_KIND_DISTRIBUTE)
 	{
-	  int i;
-	  for (i = 1; i < fd->collapse; i++)
-	    {
-	      innerc = omp_find_clause (OMP_CLAUSE_CHAIN (innerc),
-					OMP_CLAUSE__LOOPTEMP_);
-	      gcc_assert (innerc);
-	    }
-	  innerc = omp_find_clause (OMP_CLAUSE_CHAIN (innerc),
-				    OMP_CLAUSE__LOOPTEMP_);
+	  innerc = find_lastprivate_looptemp (fd, innerc);
 	  if (innerc)
 	    {
 	      /* If needed (distribute parallel for with lastprivate),
@@ -5790,15 +5842,7 @@ expand_omp_for_static_chunk (struct omp_region *region,
       if (fd->collapse > 1 && TREE_CODE (fd->loop.n2) != INTEGER_CST
 	  && gimple_omp_for_kind (fd->for_stmt) == GF_OMP_FOR_KIND_DISTRIBUTE)
 	{
-	  int i;
-	  for (i = 1; i < fd->collapse; i++)
-	    {
-	      innerc = omp_find_clause (OMP_CLAUSE_CHAIN (innerc),
-					OMP_CLAUSE__LOOPTEMP_);
-	      gcc_assert (innerc);
-	    }
-	  innerc = omp_find_clause (OMP_CLAUSE_CHAIN (innerc),
-				    OMP_CLAUSE__LOOPTEMP_);
+	  innerc = find_lastprivate_looptemp (fd, innerc);
 	  if (innerc)
 	    {
 	      /* If needed (distribute parallel for with lastprivate),
@@ -7041,15 +7085,7 @@ expand_omp_taskloop_for_outer (struct omp_region *region,
   tree endvar = OMP_CLAUSE_DECL (innerc);
   if (fd->collapse > 1 && TREE_CODE (fd->loop.n2) != INTEGER_CST)
     {
-      gcc_assert (innerc);
-      for (i = 1; i < fd->collapse; i++)
-	{
-	  innerc = omp_find_clause (OMP_CLAUSE_CHAIN (innerc),
-				    OMP_CLAUSE__LOOPTEMP_);
-	  gcc_assert (innerc);
-	}
-      innerc = omp_find_clause (OMP_CLAUSE_CHAIN (innerc),
-				OMP_CLAUSE__LOOPTEMP_);
+      innerc = find_lastprivate_looptemp (fd, innerc);
       if (innerc)
 	{
 	  /* If needed (inner taskloop has lastprivate clause), propagate