* tree-ssa-threadupdate.c (thread_through_all_blocks): Selectively

	invalidate loop information.

git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@205361 138bc75d-0d04-0410-961f-82ee72b054a4

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 8f235de..28b415b 100644 (file)
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,8 @@
+2013-11-25  Jeff Law  <law@redhat.com>
+
+       * tree-ssa-threadupdate.c (thread_through_all_blocks): Selectively
+       invalidate loop information.
+
 2013-11-25  Oleg Endo  <olegendo@gcc.gnu.org>
 
        * config/sh/sh.md (doloop_end_split): Add missing SI mode.

diff --git a/gcc/tree-ssa-threadupdate.c b/gcc/tree-ssa-threadupdate.c
index ee0c838..1a52e47 100644 (file)
--- a/gcc/tree-ssa-threadupdate.c
+++ b/gcc/tree-ssa-threadupdate.c
@@ -1579,7 +1579,6 @@ thread_through_all_blocks (bool may_peel_loop_headers)
   bitmap_iterator bi;
   bitmap threaded_blocks;
   struct loop *loop;
-  bool totally_clobbered_loops = false;
 
   /* We must know about loops in order to preserve them.  */
   gcc_assert (current_loops != NULL);
@@ -1675,9 +1674,15 @@ thread_through_all_blocks (bool may_peel_loop_headers)
                /* Our path is still valid, thread it.  */
                if (e->aux)
                  {
-                   totally_clobbered_loops
-                     |= thread_block ((*path)[0]->e->dest, false);
+                   struct loop *loop = (*path)[0]->e->dest->loop_father;
+
+                   retval |= thread_block ((*path)[0]->e->dest, false);
                    e->aux = NULL;
+
+                   /* This jump thread likely totally scrambled this loop.
+                      So arrange for it to be fixed up.  */
+                   loop->header = NULL;
+                   loop->latch = NULL;
                  }
              }
           else
@@ -1700,32 +1705,7 @@ thread_through_all_blocks (bool may_peel_loop_headers)
   threaded_blocks = NULL;
   paths.release ();
 
-  /* If we made changes to the CFG that might have totally messed
-     up the loop structure, then drop the old loop structure and
-     rebuild.  */
-  if (totally_clobbered_loops)
-    {
-      /* Release the current loop structures, they are totally
-        clobbered at this point.  */
-      loop_optimizer_finalize ();
-      current_loops = NULL;
-
-      /* Similarly for dominance information.  */
-      free_dominance_info (CDI_DOMINATORS);
-      free_dominance_info (CDI_POST_DOMINATORS);
-
-      /* Before we can rebuild the loop structures, we need dominators,
-        which requires no unreachable code.  So remove unreachable code.  */
-      delete_unreachable_blocks ();
-
-      /* Now rebuild the loop structures.  */
-      cfun->curr_properties &= ~PROP_loops;
-      loop_optimizer_init (AVOID_CFG_MODIFICATIONS);
-      cfun->curr_properties |= PROP_loops;
-      retval = 1;
-    }
-
-  if (retval && current_loops)
+  if (retval)
     loops_state_set (LOOPS_NEED_FIXUP);
 
   return retval;