re PR ipa/44563 (GCC uses a lot of RAM when compiling a large numbers of functions)

2015-03-10  Richard Biener  <rguenther@suse.de>

	PR middle-end/44563
	* tree-cfgcleanup.c (split_bb_on_noreturn_calls): Remove.
	(cleanup_tree_cfg_1): Do not call it.
	(execute_cleanup_cfg_post_optimizing): Fixup the CFG here.
	(fixup_noreturn_call): Mark the stmt as control altering.
	* tree-cfg.c (execute_fixup_cfg): Do not dump the function
	here.
	(pass_data_fixup_cfg): Produce a dump file.
	* tree-ssa-dom.c: Include tree-cfgcleanup.h.
	(need_noreturn_fixup): New global.
	(pass_dominator::execute): Fixup queued noreturn calls.
	(optimize_stmt): Queue calls that became noreturn for fixup.
	* tree-ssa-forwprop.c (pass_forwprop::execute): Likewise.
	* tree-ssa-pre.c: Include tree-cfgcleanup.h.
	(el_to_fixup): New global.
	(eliminate_dom_walker::before_dom_childre): Queue calls that
	became noreturn for fixup.
	(eliminate): Fixup queued noreturn calls.
	* tree-ssa-propagate.c: Include tree-cfgcleanup.h.
	(substitute_and_fold_dom_walker): New member stmts_to_fixup.
	(substitute_and_fold_dom_walker::before_dom_children): Queue
	alls that became noreturn for fixup.
	(substitute_and_fold): Fixup queued noreturn calls.

From-SVN: r221409

1 files changed, 22 insertions, 0 deletions

diff --git a/gcc/tree-ssa-forwprop.c b/gcc/tree-ssa-forwprop.c
index d8db20a..93f92f3 100644
--- a/gcc/tree-ssa-forwprop.c
+++ b/gcc/tree-ssa-forwprop.c
@@ -2141,6 +2141,7 @@ pass_forwprop::execute (function *fun)
   lattice.quick_grow_cleared (num_ssa_names);
   int *postorder = XNEWVEC (int, n_basic_blocks_for_fn (fun));
   int postorder_num = inverted_post_order_compute (postorder);
+  auto_vec<gimple, 4> to_fixup;
   to_purge = BITMAP_ALLOC (NULL);
   for (int i = 0; i < postorder_num; ++i)
     {
@@ -2340,6 +2341,8 @@ pass_forwprop::execute (function *fun)
 	  gimple stmt = gsi_stmt (gsi);
 	  gimple orig_stmt = stmt;
 	  bool changed = false;
+	  bool was_noreturn = (is_gimple_call (stmt)
+			       && gimple_call_noreturn_p (stmt));
 
 	  /* Mark stmt as potentially needing revisiting.  */
 	  gimple_set_plf (stmt, GF_PLF_1, false);
@@ -2350,6 +2353,9 @@ pass_forwprop::execute (function *fun)
 	      stmt = gsi_stmt (gsi);
 	      if (maybe_clean_or_replace_eh_stmt (orig_stmt, stmt))
 		bitmap_set_bit (to_purge, bb->index);
+	      if (!was_noreturn
+		  && is_gimple_call (stmt) && gimple_call_noreturn_p (stmt))
+		to_fixup.safe_push (stmt);
 	      /* Cleanup the CFG if we simplified a condition to
 	         true or false.  */
 	      if (gcond *cond = dyn_cast <gcond *> (stmt))
@@ -2470,6 +2476,22 @@ pass_forwprop::execute (function *fun)
   free (postorder);
   lattice.release ();
 
+  /* Fixup stmts that became noreturn calls.  This may require splitting
+     blocks and thus isn't possible during the walk.  Do this
+     in reverse order so we don't inadvertedly remove a stmt we want to
+     fixup by visiting a dominating now noreturn call first.  */
+  while (!to_fixup.is_empty ())
+    {
+      gimple stmt = to_fixup.pop ();
+      if (dump_file && dump_flags & TDF_DETAILS)
+	{
+	  fprintf (dump_file, "Fixing up noreturn call ");
+	  print_gimple_stmt (dump_file, stmt, 0, 0);
+	  fprintf (dump_file, "\n");
+	}
+      cfg_changed |= fixup_noreturn_call (stmt);
+    }
+
   cfg_changed |= gimple_purge_all_dead_eh_edges (to_purge);
   BITMAP_FREE (to_purge);