[PATCH] Fix PR60518, split_block not updating loops properly

[Richard Biener]

The following fixes PR60518 where split_block does not fixup
all loops that the block was a latch of (without simple latches
a latch need not belong to its loop but can be an exit block
of a nested loop).

Bootstrap and regtest running on x86_64-unknown-linux-gnu.

Richard.

2014-03-14  Richard Biener  <rguent...@suse.de>

        PR middle-end/60518
        * cfghooks.c (split_block): Properly adjust all loops the
        block was a latch of.

        * g++.dg/pr60518.C: New testcase.

Index: gcc/cfghooks.c
===================================================================
*** gcc/cfghooks.c      (revision 208536)
--- gcc/cfghooks.c      (working copy)
*************** split_block (basic_block bb, void *i)
*** 510,518 ****
  
    if (current_loops != NULL)
      {
        add_bb_to_loop (new_bb, bb->loop_father);
!       if (bb->loop_father->latch == bb)
!       bb->loop_father->latch = new_bb;
      }
  
    res = make_single_succ_edge (bb, new_bb, EDGE_FALLTHRU);
--- 510,522 ----
  
    if (current_loops != NULL)
      {
+       edge_iterator ei;
+       edge e;
        add_bb_to_loop (new_bb, bb->loop_father);
!       /* Identify all loops bb may have been the latch of and adjust them.  */
!       FOR_EACH_EDGE (e, ei, new_bb->succs)
!       if (e->dest->loop_father->latch == bb)
!         e->dest->loop_father->latch = new_bb;
      }
  
    res = make_single_succ_edge (bb, new_bb, EDGE_FALLTHRU);
Index: gcc/testsuite/g++.dg/pr60518.C
===================================================================
*** gcc/testsuite/g++.dg/pr60518.C      (revision 0)
--- gcc/testsuite/g++.dg/pr60518.C      (working copy)
***************
*** 0 ****
--- 1,13 ----
+ // { dg-do compile }
+ // { dg-options "-Os -fprofile-use" }
+ 
+ int a;
+ int fn1 () { return a == ',' || a == ';'; }
+ 
+ void fn2 ()
+ {
+     do
+           while (fn1 ())
+                 ;
+       while (1);
+ }