[Bug rtl-optimization/45354] [4.6 regression] ICE with -fselective-scheduling and -freorder-blocks-and-partition

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

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=45354

Alexander Monakov <amonakov at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |ASSIGNED
         AssignedTo|unassigned at gcc dot       |amonakov at gcc dot gnu.org
                   |gnu.org                     |

--- Comment #9 from Alexander Monakov <amonakov at gcc dot gnu.org> 2010-11-29 13:58:45 UTC ---
Thanks.  We go over-eager when cleaning up degenerate jumps and don't pay
attention to EDGE_CROSSING.

diff --git a/gcc/sel-sched-ir.c b/gcc/sel-sched-ir.c
index 7956cd8..0adc836 100644
--- a/gcc/sel-sched-ir.c
+++ b/gcc/sel-sched-ir.c
@@ -156,6 +156,7 @@ static void move_bb_info (basic_block, basic_block);
 static void remove_empty_bb (basic_block, bool);
 static void sel_merge_blocks (basic_block, basic_block);
 static void sel_remove_loop_preheader (void);
+static bool have_removable_jump_p (basic_block, basic_block);

 static bool insn_is_the_only_one_in_bb_p (insn_t);
 static void create_initial_data_sets (basic_block);
@@ -3675,7 +3676,7 @@ tidy_control_flow (basic_block xbb, bool full_tidying)
     return changed;

   /* Check if there is a unnecessary jump after insn left.  */
-  if (jump_leads_only_to_bb_p (BB_END (xbb), xbb->next_bb)
+  if (have_removable_jump_p (xbb, xbb->next_bb)
       && INSN_SCHED_TIMES (BB_END (xbb)) == 0
       && !IN_CURRENT_FENCE_P (BB_END (xbb)))
     {
@@ -3716,7 +3717,7 @@ tidy_control_flow (basic_block xbb, bool full_tidying)
       /* And unconditional jump in previous basic block leads to
          next basic block of XBB and this jump can be safely removed.  */
       && in_current_region_p (xbb->prev_bb)
-      && jump_leads_only_to_bb_p (BB_END (xbb->prev_bb), xbb->next_bb)
+      && have_removable_jump_p (xbb->prev_bb, xbb->next_bb)
       && INSN_SCHED_TIMES (BB_END (xbb->prev_bb)) == 0
       /* Also this jump is not at the scheduling boundary.  */
       && !IN_CURRENT_FENCE_P (BB_END (xbb->prev_bb)))
@@ -6104,11 +6105,13 @@ sel_is_loop_preheader_p (basic_block bb)
   return false;
 }

-/* Checks whether JUMP leads to basic block DEST_BB and no other blocks.  */
-bool
-jump_leads_only_to_bb_p (insn_t jump, basic_block dest_bb)
+/* Check whether JUMP_BB ends with a jump insn that leads only to DEST_BB and
+   can be removed, making the corresponding edge fallthrough (assuming that
+   all basic blocks between JUMP_BB and DEST_BB are empty).  */
+static bool
+have_removable_jump_p (basic_block jump_bb, basic_block dest_bb)
 {
-  basic_block jump_bb = BLOCK_FOR_INSN (jump);
+  insn_t jump = BB_END (jump_bb);

   /* It is not jump, jump with side-effects or jump can lead to several
      basic blocks.  */
@@ -6119,7 +6122,7 @@ jump_leads_only_to_bb_p (insn_t jump, basic_block
dest_bb)
   /* Several outgoing edges, abnormal edge or destination of jump is
      not DEST_BB.  */
   if (EDGE_COUNT (jump_bb->succs) != 1
-      || EDGE_SUCC (jump_bb, 0)->flags & EDGE_ABNORMAL
+      || EDGE_SUCC (jump_bb, 0)->flags & (EDGE_ABNORMAL | EDGE_CROSSING)
       || EDGE_SUCC (jump_bb, 0)->dest != dest_bb)
     return false;

@@ -6199,7 +6202,7 @@ sel_remove_loop_preheader (void)
                  basic block if it becomes empty.  */
           if (next_bb->prev_bb == prev_bb
                   && prev_bb != ENTRY_BLOCK_PTR
-                  && jump_leads_only_to_bb_p (BB_END (prev_bb), next_bb))
+                  && have_removable_jump_p (prev_bb, next_bb))
                 {
                   redirect_edge_and_branch (EDGE_SUCC (prev_bb, 0), next_bb);
                   if (BB_END (prev_bb) == bb_note (prev_bb))
diff --git a/gcc/sel-sched-ir.h b/gcc/sel-sched-ir.h
index 9ab0466..1f3dec4 100644
--- a/gcc/sel-sched-ir.h
+++ b/gcc/sel-sched-ir.h
@@ -1590,7 +1590,6 @@ extern bool sel_remove_insn (insn_t, bool, bool);
 extern bool bb_header_p (insn_t);
 extern void sel_init_invalid_data_sets (insn_t);
 extern bool insn_at_boundary_p (insn_t);
-extern bool jump_leads_only_to_bb_p (insn_t, basic_block);

 /* Basic block and CFG functions.  */