Do final value replacement in try_create_reduction_list

2015-11-18  Tom de Vries  <tom@codesourcery.com>

	* tree-scalar-evolution.c (final_value_replacement_loop): Factor out of ...
	(scev_const_prop): ... here.
	* tree-scalar-evolution.h (final_value_replacement_loop): Declare.
	* tree-parloops.c (try_create_reduction_list): Call
	final_value_replacement_loop.

	* gcc.dg/autopar/pr68373.c: New test.

---
 gcc/testsuite/gcc.dg/autopar/pr68373.c |  14 ++
 gcc/tree-parloops.c                    |   3 +
 gcc/tree-scalar-evolution.c            | 248 +++++++++++++++++----------------
 gcc/tree-scalar-evolution.h            |   1 +
 4 files changed, 145 insertions(+), 121 deletions(-)

diff --git a/gcc/testsuite/gcc.dg/autopar/pr68373.c b/gcc/testsuite/gcc.dg/autopar/pr68373.c
new file mode 100644
index 0000000..8e0f8a5
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/autopar/pr68373.c
@@ -0,0 +1,14 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -ftree-parallelize-loops=2 -fdump-tree-parloops-details" } */
+
+unsigned int
+foo (int *a, unsigned int n)
+{
+  unsigned int i;
+  for (i = 0; i < n; ++i)
+    a[i] = 1;
+
+  return i;
+}
+
+/* { dg-final { scan-tree-dump-times "SUCCESS: may be parallelized" 1 "parloops" } } */
diff --git a/gcc/tree-parloops.c b/gcc/tree-parloops.c
index 17415a8..8d7912d 100644
--- a/gcc/tree-parloops.c
+++ b/gcc/tree-parloops.c
@@ -2539,6 +2539,9 @@ try_create_reduction_list (loop_p loop,
 
   gcc_assert (exit);
 
+  /* Try to get rid of exit phis.  */
+  final_value_replacement_loop (loop);
+
   gather_scalar_reductions (loop, reduction_list);
 
 
diff --git a/gcc/tree-scalar-evolution.c b/gcc/tree-scalar-evolution.c
index 27630f0..9b33693 100644
--- a/gcc/tree-scalar-evolution.c
+++ b/gcc/tree-scalar-evolution.c
@@ -3417,6 +3417,131 @@ expression_expensive_p (tree expr)
     }
 }
 
+/* Do final value replacement for LOOP.  */
+
+void
+final_value_replacement_loop (struct loop *loop)
+{
+  /* If we do not know exact number of iterations of the loop, we cannot
+     replace the final value.  */
+  edge exit = single_exit (loop);
+  if (!exit)
+    return;
+
+  tree niter = number_of_latch_executions (loop);
+  if (niter == chrec_dont_know)
+    return;
+
+  /* Ensure that it is possible to insert new statements somewhere.  */
+  if (!single_pred_p (exit->dest))
+    split_loop_exit_edge (exit);
+
+  /* Set stmt insertion pointer.  All stmts are inserted before this point.  */
+  gimple_stmt_iterator gsi = gsi_after_labels (exit->dest);
+
+  struct loop *ex_loop
+    = superloop_at_depth (loop,
+			  loop_depth (exit->dest->loop_father) + 1);
+
+  gphi_iterator psi;
+  for (psi = gsi_start_phis (exit->dest); !gsi_end_p (psi); )
+    {
+      gphi *phi = psi.phi ();
+      tree rslt = PHI_RESULT (phi);
+      tree def = PHI_ARG_DEF_FROM_EDGE (phi, exit);
+      if (virtual_operand_p (def))
+	{
+	  gsi_next (&psi);
+	  continue;
+	}
+
+      if (!POINTER_TYPE_P (TREE_TYPE (def))
+	  && !INTEGRAL_TYPE_P (TREE_TYPE (def)))
+	{
+	  gsi_next (&psi);
+	  continue;
+	}
+
+      bool folded_casts;
+      def = analyze_scalar_evolution_in_loop (ex_loop, loop, def,
+					      &folded_casts);
+      def = compute_overall_effect_of_inner_loop (ex_loop, def);
+      if (!tree_does_not_contain_chrecs (def)
+	  || chrec_contains_symbols_defined_in_loop (def, ex_loop->num)
+	  /* Moving the computation from the loop may prolong life range
+	     of some ssa names, which may cause problems if they appear
+	     on abnormal edges.  */
+	  || contains_abnormal_ssa_name_p (def)
+	  /* Do not emit expensive expressions.  The rationale is that
+	     when someone writes a code like
+
+	     while (n > 45) n -= 45;
+
+	     he probably knows that n is not large, and does not want it
+	     to be turned into n %= 45.  */
+	  || expression_expensive_p (def))
+	{
+	  if (dump_file && (dump_flags & TDF_DETAILS))
+	    {
+	      fprintf (dump_file, "not replacing:\n  ");
+	      print_gimple_stmt (dump_file, phi, 0, 0);
+	      fprintf (dump_file, "\n");
+	    }
+	  gsi_next (&psi);
+	  continue;
+	}
+
+      /* Eliminate the PHI node and replace it by a computation outside
+	 the loop.  */
+      if (dump_file)
+	{
+	  fprintf (dump_file, "\nfinal value replacement:\n  ");
+	  print_gimple_stmt (dump_file, phi, 0, 0);
+	  fprintf (dump_file, "  with\n  ");
+	}
+      def = unshare_expr (def);
+      remove_phi_node (&psi, false);
+
+      /* If def's type has undefined overflow and there were folded
+	 casts, rewrite all stmts added for def into arithmetics
+	 with defined overflow behavior.  */
+      if (folded_casts && ANY_INTEGRAL_TYPE_P (TREE_TYPE (def))
+	  && TYPE_OVERFLOW_UNDEFINED (TREE_TYPE (def)))
+	{
+	  gimple_seq stmts;
+	  gimple_stmt_iterator gsi2;
+	  def = force_gimple_operand (def, &stmts, true, NULL_TREE);
+	  gsi2 = gsi_start (stmts);
+	  while (!gsi_end_p (gsi2))
+	    {
+	      gimple *stmt = gsi_stmt (gsi2);
+	      gimple_stmt_iterator gsi3 = gsi2;
+	      gsi_next (&gsi2);
+	      gsi_remove (&gsi3, false);
+	      if (is_gimple_assign (stmt)
+		  && arith_code_with_undefined_signed_overflow
+		  (gimple_assign_rhs_code (stmt)))
+		gsi_insert_seq_before (&gsi,
+				       rewrite_to_defined_overflow (stmt),
+				       GSI_SAME_STMT);
+	      else
+		gsi_insert_before (&gsi, stmt, GSI_SAME_STMT);
+	    }
+	}
+      else
+	def = force_gimple_operand_gsi (&gsi, def, false, NULL_TREE,
+					true, GSI_SAME_STMT);
+
+      gassign *ass = gimple_build_assign (rslt, def);
+      gsi_insert_before (&gsi, ass, GSI_SAME_STMT);
+      if (dump_file)
+	{
+	  print_gimple_stmt (dump_file, ass, 0, 0);
+	  fprintf (dump_file, "\n");
+	}
+    }
+}
+
 /* Replace ssa names for that scev can prove they are constant by the
    appropriate constants.  Also perform final value replacement in loops,
    in case the replacement expressions are cheap.
@@ -3430,8 +3555,7 @@ scev_const_prop (void)
   basic_block bb;
   tree name, type, ev;
   gphi *phi;
-  gassign *ass;
-  struct loop *loop, *ex_loop;
+  struct loop *loop;
   bitmap ssa_names_to_remove = NULL;
   unsigned i;
   gphi_iterator psi;
@@ -3507,126 +3631,8 @@ scev_const_prop (void)
 
   /* Now the regular final value replacement.  */
   FOR_EACH_LOOP (loop, LI_FROM_INNERMOST)
-    {
-      edge exit;
-      tree def, rslt, niter;
-      gimple_stmt_iterator gsi;
-
-      /* If we do not know exact number of iterations of the loop, we cannot
-	 replace the final value.  */
-      exit = single_exit (loop);
-      if (!exit)
-	continue;
-
-      niter = number_of_latch_executions (loop);
-      if (niter == chrec_dont_know)
-	continue;
-
-      /* Ensure that it is possible to insert new statements somewhere.  */
-      if (!single_pred_p (exit->dest))
-	split_loop_exit_edge (exit);
-      gsi = gsi_after_labels (exit->dest);
+    final_value_replacement_loop (loop);
 
-      ex_loop = superloop_at_depth (loop,
-				    loop_depth (exit->dest->loop_father) + 1);
-
-      for (psi = gsi_start_phis (exit->dest); !gsi_end_p (psi); )
-	{
-	  phi = psi.phi ();
-	  rslt = PHI_RESULT (phi);
-	  def = PHI_ARG_DEF_FROM_EDGE (phi, exit);
-	  if (virtual_operand_p (def))
-	    {
-	      gsi_next (&psi);
-	      continue;
-	    }
-
-	  if (!POINTER_TYPE_P (TREE_TYPE (def))
-	      && !INTEGRAL_TYPE_P (TREE_TYPE (def)))
-	    {
-	      gsi_next (&psi);
-	      continue;
-	    }
-
-	  bool folded_casts;
-	  def = analyze_scalar_evolution_in_loop (ex_loop, loop, def,
-						  &folded_casts);
-	  def = compute_overall_effect_of_inner_loop (ex_loop, def);
-	  if (!tree_does_not_contain_chrecs (def)
-	      || chrec_contains_symbols_defined_in_loop (def, ex_loop->num)
-	      /* Moving the computation from the loop may prolong life range
-		 of some ssa names, which may cause problems if they appear
-		 on abnormal edges.  */
-	      || contains_abnormal_ssa_name_p (def)
-	      /* Do not emit expensive expressions.  The rationale is that
-		 when someone writes a code like
-
-		 while (n > 45) n -= 45;
-
-		 he probably knows that n is not large, and does not want it
-		 to be turned into n %= 45.  */
-	      || expression_expensive_p (def))
-	    {
-	      if (dump_file && (dump_flags & TDF_DETAILS))
-		{
-	          fprintf (dump_file, "not replacing:\n  ");
-	          print_gimple_stmt (dump_file, phi, 0, 0);
-	          fprintf (dump_file, "\n");
-		}
-	      gsi_next (&psi);
-	      continue;
-	    }
-
-	  /* Eliminate the PHI node and replace it by a computation outside
-	     the loop.  */
-	  if (dump_file)
-	    {
-	      fprintf (dump_file, "\nfinal value replacement:\n  ");
-	      print_gimple_stmt (dump_file, phi, 0, 0);
-	      fprintf (dump_file, "  with\n  ");
-	    }
-	  def = unshare_expr (def);
-	  remove_phi_node (&psi, false);
-
-	  /* If def's type has undefined overflow and there were folded
-	     casts, rewrite all stmts added for def into arithmetics
-	     with defined overflow behavior.  */
-	  if (folded_casts && ANY_INTEGRAL_TYPE_P (TREE_TYPE (def))
-	      && TYPE_OVERFLOW_UNDEFINED (TREE_TYPE (def)))
-	    {
-	      gimple_seq stmts;
-	      gimple_stmt_iterator gsi2;
-	      def = force_gimple_operand (def, &stmts, true, NULL_TREE);
-	      gsi2 = gsi_start (stmts);
-	      while (!gsi_end_p (gsi2))
-		{
-		  gimple *stmt = gsi_stmt (gsi2);
-		  gimple_stmt_iterator gsi3 = gsi2;
-		  gsi_next (&gsi2);
-		  gsi_remove (&gsi3, false);
-		  if (is_gimple_assign (stmt)
-		      && arith_code_with_undefined_signed_overflow
-					(gimple_assign_rhs_code (stmt)))
-		    gsi_insert_seq_before (&gsi,
-					   rewrite_to_defined_overflow (stmt),
-					   GSI_SAME_STMT);
-		  else
-		    gsi_insert_before (&gsi, stmt, GSI_SAME_STMT);
-		}
-	    }
-	  else
-	    def = force_gimple_operand_gsi (&gsi, def, false, NULL_TREE,
-					    true, GSI_SAME_STMT);
-
-	  ass = gimple_build_assign (rslt, def);
-	  gsi_insert_before (&gsi, ass, GSI_SAME_STMT);
-	  if (dump_file)
-	    {
-	      print_gimple_stmt (dump_file, ass, 0, 0);
-	      fprintf (dump_file, "\n");
-	    }
-	}
-    }
   return 0;
 }
 
diff --git a/gcc/tree-scalar-evolution.h b/gcc/tree-scalar-evolution.h
index 6d31280..29c7cd4 100644
--- a/gcc/tree-scalar-evolution.h
+++ b/gcc/tree-scalar-evolution.h
@@ -33,6 +33,7 @@ extern tree analyze_scalar_evolution (struct loop *, tree);
 extern tree instantiate_scev (basic_block, struct loop *, tree);
 extern tree resolve_mixers (struct loop *, tree, bool *);
 extern void gather_stats_on_scev_database (void);
+extern void final_value_replacement_loop (struct loop *);
 extern unsigned int scev_const_prop (void);
 extern bool expression_expensive_p (tree);
 extern bool simple_iv (struct loop *, struct loop *, tree, struct affine_iv *,
