* tree-ssa-pre.c (do_regular_insertion): Add FIXME markers at points

	of potentially huge memset overhead.
	(do_partial_partial_insertion): Likewise.
	* cfgexpand.c (gimple_expand_cfg): Use XCNEWVEC instead of xcalloc.
	* tree-vrp.c (find_assert_locations): Use XNEWVEC instead of XCNEWVEC
	for arrays to be filled by pre_and_rev_post_order_compute.  Allocate
	the right number of slots, not that number plus NUM_FIXED_BLOCKS.
	* tree-ssa-reassoc.c (init_reassoc): Likewise.
	* cfganal.c (dfs_enumerate_from): Use XNEWVEC instead of XCNEWVEC for
	array used as stack.
	* tree-ssa-sccvn.c (init_scc_vn): Use XNEWVEC instead of XCNEWVEC for
	arrays to be filled by pre_and_rev_post_order_compute.
	* cfgloopmanip.c (find_path): Use XNEWVEC instead of XCNEWVEC for
	array to be filled by dfs_enumerate_from.
	(remove_path): Likewise.
	(duplicate_loop_to_header_edge): Use XNEWVEC instead of XCNEWVEC for
	array of loops that is filled on the next lines.
	* cfgloop.c (get_loop_body): Use XNEWVEC instead of XCNEWVEC for
	array of basic blocks to be returned.
	(get_loop_body_in_dom_order): Likewise.
	(get_loop_body_in_bfs_order): Likewise.
	* tree-ssa-loop-manip.c (loop_renamer_obstack): New static obstack
	for all bitmaps used for rewriting into loop-closed SSA form.
	(add_exit_phis_var): Allocate the def bitmap on it.  Clear the livein
	bitmap at the end to release a lot of memory.
	(add_exit_phis): Allocate the exits bitmap on the new obstack.
	(get_loops_exits): Allocate the exits bitmap on the new obstack.
	(find_uses_to_rename_use): Allocate a use_blocks bitmap if ver is
	seen for the first time.
	(find_uses_to_rename): Add "???" for why the whole function must
	be re-scanned if changed_bbs is empty.
	(rewrite_into_loop_closed_ssa): Allocate bitmaps on the new obstack.
	Use XNEWVEC to allocate the use_blocks array.  Initialize the new
	obstack, and free it at the end.  Remove loop over all SSA names.
	(check_loop_closed_ssa_stmt): Look only at SSA_OP_USE operands.
	* tree-cfg.c (move_sese_region_to_fn): Use XNEWVEC instead of
	xcalloc to allocate edge_pred and edge_flag arrays.



git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@190359 138bc75d-0d04-0410-961f-82ee72b054a4

1 files changed, 24 insertions, 15 deletions

diff --git a/gcc/tree-ssa-loop-manip.c b/gcc/tree-ssa-loop-manip.c
index 5aa8c7d3c3f..98846138e7c 100644
--- a/gcc/tree-ssa-loop-manip.c
+++ b/gcc/tree-ssa-loop-manip.c
@@ -34,6 +34,10 @@ along with GCC; see the file COPYING3.  If not see
 #include "tree-inline.h"
 #include "langhooks.h"
 
+/* All bitmaps for rewriting into loop-closed SSA go on this obstack,
+   so that we can free them all at once.  */
+static bitmap_obstack loop_renamer_obstack;
+
 /* Creates an induction variable with value BASE + STEP * iteration in LOOP.
    It is expected that neither BASE nor STEP are shared with other expressions
    (unless the sharing rules allow this).  Use VAR as a base var_decl for it
@@ -168,7 +172,7 @@ add_exit_phis_var (tree var, bitmap livein, bitmap exits)
   gcc_checking_assert (is_gimple_reg (var));
   bitmap_clear_bit (livein, def_bb->index);
 
-  def = BITMAP_ALLOC (NULL);
+  def = BITMAP_ALLOC (&loop_renamer_obstack);
   bitmap_set_bit (def, def_bb->index);
   compute_global_livein (livein, def);
   BITMAP_FREE (def);
@@ -177,6 +181,10 @@ add_exit_phis_var (tree var, bitmap livein, bitmap exits)
     {
       add_exit_phis_edge (BASIC_BLOCK (index), var);
     }
+
+  /* Free the livein bitmap.  We'll not be needing it anymore, and
+     it may have grown quite large.  No reason to hold on to it.  */
+  bitmap_clear (livein);
 }
 
 /* Add exit phis for the names marked in NAMES_TO_RENAME.
@@ -200,7 +208,7 @@ add_exit_phis (bitmap names_to_rename, bitmap *use_blocks, bitmap loop_exits)
 static bitmap
 get_loops_exits (void)
 {
-  bitmap exits = BITMAP_ALLOC (NULL);
+  bitmap exits = BITMAP_ALLOC (&loop_renamer_obstack);
   basic_block bb;
   edge e;
   edge_iterator ei;
@@ -253,11 +261,11 @@ find_uses_to_rename_use (basic_block bb, tree use, bitmap *use_blocks,
   if (flow_bb_inside_loop_p (def_loop, bb))
     return;
 
-  if (!use_blocks[ver])
-    use_blocks[ver] = BITMAP_ALLOC (NULL);
+  /* If we're seeing VER for the first time, we still have to allocate
+     a bitmap for its uses.  */
+  if (bitmap_set_bit (need_phis, ver))
+    use_blocks[ver] = BITMAP_ALLOC (&loop_renamer_obstack);
   bitmap_set_bit (use_blocks[ver], bb->index);
-
-  bitmap_set_bit (need_phis, ver);
 }
 
 /* For uses in STMT, mark names that are used outside of the loop they are
@@ -312,6 +320,7 @@ find_uses_to_rename (bitmap changed_bbs, bitmap *use_blocks, bitmap need_phis)
   unsigned index;
   bitmap_iterator bi;
 
+  /* ??? If CHANGED_BBS is empty we rewrite the whole function -- why?  */
   if (changed_bbs && !bitmap_empty_p (changed_bbs))
     {
       EXECUTE_IF_SET_IN_BITMAP (changed_bbs, 0, index, bi)
@@ -365,22 +374,25 @@ rewrite_into_loop_closed_ssa (bitmap changed_bbs, unsigned update_flag)
 {
   bitmap loop_exits;
   bitmap *use_blocks;
-  unsigned i, old_num_ssa_names;
   bitmap names_to_rename;
 
   loops_state_set (LOOP_CLOSED_SSA);
   if (number_of_loops () <= 1)
     return;
 
+  bitmap_obstack_initialize (&loop_renamer_obstack);
+
   loop_exits = get_loops_exits ();
-  names_to_rename = BITMAP_ALLOC (NULL);
+  names_to_rename = BITMAP_ALLOC (&loop_renamer_obstack);
 
   /* If the pass has caused the SSA form to be out-of-date, update it
      now.  */
   update_ssa (update_flag);
 
-  old_num_ssa_names = num_ssa_names;
-  use_blocks = XCNEWVEC (bitmap, old_num_ssa_names);
+  /* Uses of names to rename.  We don't have to initialize this array,
+     because we know that we will only have entries for the SSA names
+     in NAMES_TO_RENAME.  */
+  use_blocks = XCNEWVEC (bitmap, num_ssa_names);
 
   /* Find the uses outside loops.  */
   find_uses_to_rename (changed_bbs, use_blocks, names_to_rename);
@@ -389,11 +401,8 @@ rewrite_into_loop_closed_ssa (bitmap changed_bbs, unsigned update_flag)
      rewrite.  */
   add_exit_phis (names_to_rename, use_blocks, loop_exits);
 
-  for (i = 0; i < old_num_ssa_names; i++)
-    BITMAP_FREE (use_blocks[i]);
+  bitmap_obstack_release (&loop_renamer_obstack);
   free (use_blocks);
-  BITMAP_FREE (loop_exits);
-  BITMAP_FREE (names_to_rename);
 
   /* Fix up all the names found to be used outside their original
      loops.  */
@@ -428,7 +437,7 @@ check_loop_closed_ssa_stmt (basic_block bb, gimple stmt)
   if (is_gimple_debug (stmt))
     return;
 
-  FOR_EACH_SSA_TREE_OPERAND (var, stmt, iter, SSA_OP_ALL_USES)
+  FOR_EACH_SSA_TREE_OPERAND (var, stmt, iter, SSA_OP_USE)
     check_loop_closed_ssa_use (bb, var);
 }