[PATCH] Update SSA_NAME manager to use two lists

	* gimple-ssa.h (gimple_df): Add free_ssanames_queue field.
	* passes.c: Include tree-ssanames.h.
	(execute_function_todo): Flush the pending free SSA_NAMEs after
	eliminating unreachable basic blocks.
	* tree-ssanames.c (FREE_SSANAMES_QUEUE): new.
	(init_ssanames): Initialize FREE_SSANAMES_QUEUE.
	(fini_ssanames): Finalize FREE_SSANAMES_QUEUE.
	(flush_ssanames_freelist): New function.
	(release_ssaname_fn): Put released names on the queue.
	(pass_release_ssa_names::execute): Call flush_ssanames_freelist.
	* tree-ssanames.h (flush_ssanames_freelist): Declare.

From-SVN: r228302

1 files changed, 9 insertions, 0 deletions

diff --git a/gcc/passes.c b/gcc/passes.c
index d06a293..5b41102 100644
--- a/gcc/passes.c
+++ b/gcc/passes.c
@@ -84,6 +84,7 @@ along with GCC; see the file COPYING3.  If not see
 #include "cfgrtl.h"
 #include "tree-ssa-live.h"  /* For remove_unused_locals.  */
 #include "tree-cfgcleanup.h"
+#include "tree-ssanames.h"
 
 using namespace gcc;
 
@@ -1913,6 +1914,14 @@ execute_function_todo (function *fn, void *data)
     {
       cleanup_tree_cfg ();
 
+      /* Once unreachable nodes have been removed from the CFG,
+	 there can't be any lingering references to released
+	 SSA_NAMES (because there is no more unreachable code).
+
+	 Thus, now is the time to flush the SSA_NAMEs freelist.  */
+      if (fn->gimple_df)
+	flush_ssaname_freelist ();
+
       /* When cleanup_tree_cfg merges consecutive blocks, it may
 	 perform some simplistic propagation when removing single
 	 valued PHI nodes.  This propagation may, in turn, cause the