[Bug target/51106] [4.5/4.6 Regression] ICE in move_insn, at haifa-sched.c:2314

["abel at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51106

--- Comment #16 from Andrey Belevantsev <abel at gcc dot gnu.org> 2012-03-27 13:28:03 UTC ---
So, something like the below patch, or even better -- as we want to fold all
RTL-build related pseudo passes into expand, make pass_instantiate_virtual_regs
also the expand part (thus, until the into_cfglayout pass), and then the new
cleanup_cfg will nicely work at the end of expand. 

diff --git a/gcc/cfgrtl.c b/gcc/cfgrtl.c
index b86cc74..0c27d11 100644
--- a/gcc/cfgrtl.c
+++ b/gcc/cfgrtl.c
@@ -2261,7 +2261,7 @@ purge_dead_edges (basic_block bb)
   edge e;
   rtx insn = BB_END (bb), note;
   bool purged = false;
-  bool found;
+  bool found, fallthru;
   edge_iterator ei;

   if (DEBUG_INSN_P (insn) && insn != BB_HEAD (bb))
@@ -2433,16 +2433,22 @@ purge_dead_edges (basic_block bb)
      as these are only created by conditional branches.  If we find such an
      edge we know that there used to be a jump here and can then safely
      remove all non-fallthru edges.  */
-  found = false;
+  found = fallthru = false;
   FOR_EACH_EDGE (e, ei, bb->succs)
-    if (! (e->flags & (EDGE_COMPLEX | EDGE_FALLTHRU)))
-      {
+    {
+      if (! (e->flags & (EDGE_COMPLEX | EDGE_FALLTHRU)))
        found = true;
-       break;
-      }
-
+      if (e->flags & (EDGE_FALLTHRU | EDGE_FAKE))
+       fallthru = true;
+    }
   if (!found)
     return purged;
+  if (!fallthru)
+    {
+      gcc_assert (single_succ_p (bb));
+      single_succ_edge (bb)->flags |= EDGE_FALLTHRU;
+      return purged;
+    }

   /* Remove all but the fake and fallthru edges.  The fake edge may be
      the only successor for this block in the case of noreturn