fix up hot/cold partitioning on ports that don't have long conditional branches

[Mike Stump]

This patch fixes up hot/cold partitioning on ports that don't have long 
conditional branches.  I'll note that the entire file has lots of other jump 
optimizations that are suspect.

Ok?


2011-04-21  Mike Stump  <mikest...@comcast.net>

        * reorg.c (relax_delay_slots): Don't delete a jump that crosses a
        section boundary.
        (follow_jumps): Don't replace a short conditional jump with a
        long conditional jump when the port doesn't have long
        conditional jumps.
        (fill_slots_from_thread): Pass insn to follow_jumps.
        (relax_delay_slots): Likewise.

Index: reorg.c
===================================================================
--- reorg.c     (revision 1301)
+++ reorg.c     (working copy)
@@ -2509,7 +2509,7 @@
    since that tells caller to avoid changing the insn.  */
 
 static rtx
-follow_jumps (rtx label)
+follow_jumps (rtx label, rtx jump)
 {
   rtx insn;
   rtx next;
@@ -2529,6 +2529,16 @@
     {
       rtx tem;
 
+      /* If a label crosses a section boundary and we're thinking
+        about changing a conditional jump to be a conditional jump
+        across that boundary, don't do it if the port doesn't have
+        long conditional branches.  We can however jump to the label
+        just before we cross such a boundary.  */
+      if (!HAS_LONG_COND_BRANCH
+         && find_reg_note (insn, REG_CROSSING_JUMP, NULL_RTX)
+         && (condjump_p (jump) || condjump_in_parallel_p (jump)))
+       return value;
+
       /* If we have found a cycle, make the insn jump to itself.  */
       if (JUMP_LABEL (insn) == label)
        return label;
@@ -2991,7 +3001,7 @@
          && redirect_with_delay_list_safe_p (insn,
                                              JUMP_LABEL (new_thread),
                                              delay_list))
-       new_thread = follow_jumps (JUMP_LABEL (new_thread));
+       new_thread = follow_jumps (JUMP_LABEL (new_thread), new_thread);
 
       if (new_thread == 0)
        label = find_end_label ();
@@ -3342,12 +3352,13 @@
          && (condjump_p (insn) || condjump_in_parallel_p (insn))
          && (target_label = JUMP_LABEL (insn)) != 0)
        {
-         target_label = skip_consecutive_labels (follow_jumps (target_label));
+         target_label = skip_consecutive_labels (follow_jumps (target_label, 
insn));
          if (target_label == 0)
            target_label = find_end_label ();
 
          if (target_label && next_active_insn (target_label) == next
-             && ! condjump_in_parallel_p (insn))
+             && ! condjump_in_parallel_p (insn)
+             && find_reg_note (insn, REG_CROSSING_JUMP, NULL_RTX) == NULL_RTX)
            {
              delete_jump (insn);
              continue;
@@ -3492,7 +3503,7 @@
        {
          /* If this jump goes to another unconditional jump, thread it, but
             don't convert a jump into a RETURN here.  */
-         trial = skip_consecutive_labels (follow_jumps (target_label));
+         trial = skip_consecutive_labels (follow_jumps (target_label, 
delay_insn));
          if (trial == 0)
            trial = find_end_label ();