diff mbox

Don't throw away loop structure unnecessarily

Message ID 52963E46.1080502@redhat.com
State New
Headers show

Commit Message

Jeff Law Nov. 27, 2013, 6:47 p.m. UTC 
Something Richi noticed.  If the call to thread_block is unsuccessful 
when threading a backedge to an interior loop node, then we do not have 
to clobber the loop structure.  We also need to cleanup in that case.

Bootstrapped and regression tested on x86_64-unknown-linux-gnu. 
Installed on the trunk.

Jeff
* tree-ssa-threadupdate.c (thread_through_all_blocks): Do not
	clobber the loop structure thread_block was unsuccessful.  If
	thread_block was unsuccessful, cleanup appropriately.
diff mbox

Patch

diff --git a/gcc/tree-ssa-threadupdate.c b/gcc/tree-ssa-threadupdate.c
index 1a52e47..24d0f42 100644
--- a/gcc/tree-ssa-threadupdate.c
+++ b/gcc/tree-ssa-threadupdate.c
@@ -1676,13 +1676,20 @@  thread_through_all_blocks (bool may_peel_loop_headers)
 		  {
 		    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;
+		    if (thread_block ((*path)[0]->e->dest, false))
+		      {
+			/* This jump thread likely totally scrambled this loop.
+			   So arrange for it to be fixed up.  */
+			loop->header = NULL;
+			loop->latch = NULL;
+			e->aux = NULL;
+		      }
+		    else
+		      {
+		        delete_jump_thread_path (path);
+			e->aux = NULL;
+			ei_next (&ei);
+		      }
 		  }
 	      }
 	   else