[PATCH, 1/2] Merge rewrite_virtuals_into_loop_closed_ssa from gomp4 branch

[Tom de Vries <Tom_deVries@mentor.com>]

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Hi,

this patch merges rewrite_virtuals_into_loop_closed_ssa (originally 
submitted here: https://gcc.gnu.org/ml/gcc-patches/2015-06/msg01236.html 
) to trunk.

Bootstrapped and reg-tested on x86_64.

OK for trunk?

Thanks,
- Tom

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Merge rewrite_virtuals_into_loop_closed_ssa from gomp4 branch

2015-06-24  Tom de Vries  <tom@codesourcery.com>

	merge from gomp4 branch:
	2015-06-24  Tom de Vries  <tom@codesourcery.com>

	* tree-ssa-loop-manip.c (get_virtual_phi): Factor out of ...
	(rewrite_virtuals_into_loop_closed_ssa): ... here.

	* tree-ssa-loop-manip.c (replace_uses_in_dominated_bbs): Factor out
	of ...
	(rewrite_virtuals_into_loop_closed_ssa): ... here.

	* dominance.c (bitmap_get_dominated_by): New function.
	* dominance.h (bitmap_get_dominated_by): Declare.
	* tree-ssa-loop-manip.c (rewrite_virtuals_into_loop_closed_ssa): Use
	bitmap_get_dominated_by.

	* tree-parloops.c (replace_uses_in_bbs_by)
	(rewrite_virtuals_into_loop_closed_ssa): Move to ...
	* tree-ssa-loop-manip.c: here.
	* tree-ssa-loop-manip.h (rewrite_virtuals_into_loop_closed_ssa):
	Declare.

	2015-06-18  Tom de Vries  <tom@codesourcery.com>

	* tree-parloops.c (rewrite_virtuals_into_loop_closed_ssa): New function.
	(transform_to_exit_first_loop_alt): Use
	rewrite_virtuals_into_loop_closed_ssa.
---
 gcc/dominance.c           | 21 ++++++++++++
 gcc/dominance.h           |  1 +
 gcc/tree-parloops.c       | 43 +++++--------------------
 gcc/tree-ssa-loop-manip.c | 81 +++++++++++++++++++++++++++++++++++++++++++++++
 gcc/tree-ssa-loop-manip.h |  1 +
 5 files changed, 112 insertions(+), 35 deletions(-)

diff --git a/gcc/dominance.c b/gcc/dominance.c
index 9c66ca2..9b52d79 100644
--- a/gcc/dominance.c
+++ b/gcc/dominance.c
@@ -753,6 +753,27 @@ set_immediate_dominator (enum cdi_direction dir, basic_block bb,
     dom_computed[dir_index] = DOM_NO_FAST_QUERY;
 }
 
+/* Returns in BBS the list of basic blocks immediately dominated by BB, in the
+   direction DIR.  As get_dominated_by, but returns result as a bitmap.  */
+
+void
+bitmap_get_dominated_by (enum cdi_direction dir, basic_block bb, bitmap bbs)
+{
+  unsigned int dir_index = dom_convert_dir_to_idx (dir);
+  struct et_node *node = bb->dom[dir_index], *son = node->son, *ason;
+
+  bitmap_clear (bbs);
+
+  gcc_checking_assert (dom_computed[dir_index]);
+
+  if (!son)
+    return;
+
+  bitmap_set_bit (bbs, ((basic_block) son->data)->index);
+  for (ason = son->right; ason != son; ason = ason->right)
+    bitmap_set_bit (bbs, ((basic_block) son->data)->index);
+}
+
 /* Returns the list of basic blocks immediately dominated by BB, in the
    direction DIR.  */
 vec<basic_block> 
diff --git a/gcc/dominance.h b/gcc/dominance.h
index 37e138b..0a1a13e 100644
--- a/gcc/dominance.h
+++ b/gcc/dominance.h
@@ -41,6 +41,7 @@ extern void free_dominance_info (enum cdi_direction);
 extern basic_block get_immediate_dominator (enum cdi_direction, basic_block);
 extern void set_immediate_dominator (enum cdi_direction, basic_block,
 				     basic_block);
+extern void bitmap_get_dominated_by (enum cdi_direction, basic_block, bitmap);
 extern vec<basic_block> get_dominated_by (enum cdi_direction, basic_block);
 extern vec<basic_block> get_dominated_by_region (enum cdi_direction,
 							 basic_block *,
diff --git a/gcc/tree-parloops.c b/gcc/tree-parloops.c
index e582fe7..df7c351 100644
--- a/gcc/tree-parloops.c
+++ b/gcc/tree-parloops.c
@@ -1498,25 +1498,6 @@ replace_uses_in_bb_by (tree name, tree val, basic_block bb)
     }
 }
 
-/* Replace uses of NAME by VAL in blocks BBS.  */
-
-static void
-replace_uses_in_bbs_by (tree name, tree val, bitmap bbs)
-{
-  gimple use_stmt;
-  imm_use_iterator imm_iter;
-
-  FOR_EACH_IMM_USE_STMT (use_stmt, imm_iter, name)
-    {
-      if (!bitmap_bit_p (bbs, gimple_bb (use_stmt)->index))
-	continue;
-
-      use_operand_p use_p;
-      FOR_EACH_IMM_USE_ON_STMT (use_p, imm_iter)
-	SET_USE (use_p, val);
-    }
-}
-
 /* Do transformation from:
 
      <bb preheader>:
@@ -1637,18 +1618,11 @@ transform_to_exit_first_loop_alt (struct loop *loop,
   tree control = gimple_cond_lhs (cond_stmt);
   edge e;
 
-  /* Gather the bbs dominated by the exit block.  */
-  bitmap exit_dominated = BITMAP_ALLOC (NULL);
-  bitmap_set_bit (exit_dominated, exit_block->index);
-  vec<basic_block> exit_dominated_vec
-    = get_dominated_by (CDI_DOMINATORS, exit_block);
-
-  int i;
-  basic_block dom_bb;
-  FOR_EACH_VEC_ELT (exit_dominated_vec, i, dom_bb)
-    bitmap_set_bit (exit_dominated, dom_bb->index);
-
-  exit_dominated_vec.release ();
+  /* Rewriting virtuals into loop-closed ssa normal form makes this
+     transformation simpler.  It also ensures that the virtuals are in
+     loop-closed ssa normal from after the transformation, which is required by
+     create_parallel_loop.  */
+  rewrite_virtuals_into_loop_closed_ssa (loop);
 
   /* Create the new_header block.  */
   basic_block new_header = split_block_before_cond_jump (exit->src);
@@ -1681,6 +1655,7 @@ transform_to_exit_first_loop_alt (struct loop *loop,
   vec<edge_var_map> *v = redirect_edge_var_map_vector (post_inc_edge);
   edge_var_map *vm;
   gphi_iterator gsi;
+  int i;
   for (gsi = gsi_start_phis (header), i = 0;
        !gsi_end_p (gsi) && v->iterate (i, &vm);
        gsi_next (&gsi), i++)
@@ -1698,10 +1673,9 @@ transform_to_exit_first_loop_alt (struct loop *loop,
       /* Replace ivtmp/sum_b with ivtmp/sum_c in header phi.  */
       add_phi_arg (phi, res_c, post_cond_edge, UNKNOWN_LOCATION);
 
-      /* Replace sum_b with sum_c in exit phi.  Loop-closed ssa does not hold
-	 for virtuals, so we cannot get away with exit_block only.  */
+      /* Replace sum_b with sum_c in exit phi.  */
       tree res_b = redirect_edge_var_map_def (vm);
-      replace_uses_in_bbs_by (res_b, res_c, exit_dominated);
+      replace_uses_in_bb_by (res_b, res_c, exit_block);
 
       struct reduction_info *red = reduction_phi (reduction_list, phi);
       gcc_assert (virtual_operand_p (res_a)
@@ -1716,7 +1690,6 @@ transform_to_exit_first_loop_alt (struct loop *loop,
 	}
     }
   gcc_assert (gsi_end_p (gsi) && !v->iterate (i, &vm));
-  BITMAP_FREE (exit_dominated);
 
   /* Set the preheader argument of the new phis to ivtmp/sum_init.  */
   flush_pending_stmts (entry);
diff --git a/gcc/tree-ssa-loop-manip.c b/gcc/tree-ssa-loop-manip.c
index 29f701c..d8ab013 100644
--- a/gcc/tree-ssa-loop-manip.c
+++ b/gcc/tree-ssa-loop-manip.c
@@ -560,6 +560,87 @@ rewrite_into_loop_closed_ssa (bitmap changed_bbs, unsigned update_flag)
   free (use_blocks);
 }
 
+/* Replace uses of NAME by VAL in blocks BBS.  */
+
+static void
+replace_uses_in_bbs_by (tree name, tree val, bitmap bbs)
+{
+  gimple use_stmt;
+  imm_use_iterator imm_iter;
+
+  FOR_EACH_IMM_USE_STMT (use_stmt, imm_iter, name)
+    {
+      if (!bitmap_bit_p (bbs, gimple_bb (use_stmt)->index))
+	continue;
+
+      use_operand_p use_p;
+      FOR_EACH_IMM_USE_ON_STMT (use_p, imm_iter)
+	SET_USE (use_p, val);
+    }
+}
+
+/* Replace uses of OLD_VAL with NEW_VAL in bbs dominated by BB.  */
+
+static void
+replace_uses_in_dominated_bbs (tree old_val, tree new_val, basic_block bb)
+{
+  bitmap dominated = BITMAP_ALLOC (NULL);
+
+  bitmap_get_dominated_by (CDI_DOMINATORS, bb, dominated);
+  bitmap_set_bit (dominated, bb->index);
+
+  replace_uses_in_bbs_by (old_val, new_val, dominated);
+
+  BITMAP_FREE (dominated);
+}
+
+/* Return the virtual phi in BB.  */
+
+static gphi *
+get_virtual_phi (basic_block bb)
+{
+  for (gphi_iterator gsi = gsi_start_phis (bb);
+       !gsi_end_p (gsi);
+       gsi_next (&gsi))
+    {
+      gphi *phi = gsi.phi ();
+
+      if (virtual_operand_p (PHI_RESULT (phi)))
+	return phi;
+    }
+
+  return NULL;
+}
+
+/* Ensure a virtual phi is present in the exit block, if LOOP contains a vdef.
+   In other words, ensure loop-closed ssa normal form for virtuals.  */
+
+void
+rewrite_virtuals_into_loop_closed_ssa (struct loop *loop)
+{
+  gphi *phi;
+  edge exit = single_dom_exit (loop);
+
+  phi = get_virtual_phi (loop->header);
+  if (phi == NULL)
+    return;
+
+  tree final_loop = PHI_ARG_DEF_FROM_EDGE (phi, single_succ_edge (loop->latch));
+
+  phi = get_virtual_phi (exit->dest);
+  if (phi != NULL)
+    {
+      tree final_exit = PHI_ARG_DEF_FROM_EDGE (phi, exit);
+      gcc_assert (operand_equal_p (final_loop, final_exit, 0));
+      return;
+    }
+
+  tree res_new = copy_ssa_name (final_loop, NULL);
+  gphi *nphi = create_phi_node (res_new, exit->dest);
+  replace_uses_in_dominated_bbs (final_loop, res_new, exit->dest);
+  add_phi_arg (nphi, final_loop, exit, UNKNOWN_LOCATION);
+}
+
 /* Check invariants of the loop closed ssa form for the USE in BB.  */
 
 static void
diff --git a/gcc/tree-ssa-loop-manip.h b/gcc/tree-ssa-loop-manip.h
index ad0c381..9285718 100644
--- a/gcc/tree-ssa-loop-manip.h
+++ b/gcc/tree-ssa-loop-manip.h
@@ -25,6 +25,7 @@ typedef void (*transform_callback)(struct loop *, void *);
 extern void create_iv (tree, tree, tree, struct loop *, gimple_stmt_iterator *,
 		       bool, tree *, tree *);
 extern void rewrite_into_loop_closed_ssa (bitmap, unsigned);
+extern void rewrite_virtuals_into_loop_closed_ssa (struct loop *);
 extern void verify_loop_closed_ssa (bool);
 extern basic_block split_loop_exit_edge (edge);
 extern basic_block ip_end_pos (struct loop *);
-- 
1.9.1