[Bug rtl-optimization/34171] [4.3 Regression] Segfault in df_chain_remove_problem with -O3 on alpha

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

------- Comment #16 from spark at gcc dot gnu dot org  2007-11-22 00:30 -------
I'm bootstrapping the following patch. This includes some slight refactoring of
set_block_for_insn/df_insn_change_bb loops within cfgrtl.c.
It's mostly cosmetic change on top of the patch on comment #15.

diff -r fad6feb87420 gcc/cfgrtl.c
--- a/gcc/cfgrtl.c      Wed Nov 21 00:17:50 2007 +0000
+++ b/gcc/cfgrtl.c      Wed Nov 21 23:48:55 2007 +0000
@@ -465,23 +465,48 @@ emit_insn_at_entry (rtx insn)
   commit_edge_insertions ();
 }

-/* Update insns block within BB.  */
+/* Update BLOCK_FOR_INSN of insns between BEGIN and END
+   including BEGIN but not END, and notify df of the change.
+   Note that NEXT_INSN (END) has to have a valid value
+   (either NULL or a pointer to a valid insn). */
+
+static void
+update_bb_for_insns (rtx begin, rtx end, basic_block bb)
+{
+  rtx insn;
+
+  for (insn = begin; insn != end; insn = NEXT_INSN (insn))
+    {
+      if (!BARRIER_P (insn))
+       {
+         set_block_for_insn (insn, bb);
+         df_insn_change_bb (insn);
+       }
+    }
+}
+
+/* Call df_insn_change_bb for insns between BEGIN and END
+   including BEGIN but not END.
+   Note that NEXT_INSN (END) has to have a valid value
+   (either NULL or a pointer to a valid insn). */
+
+static void
+notify_bb_change_for_insns (rtx begin, rtx end)
+{
+  rtx insn;
+
+  for (insn = begin; insn != end; insn = NEXT_INSN (insn))
+    if (!BARRIER_P (insn))
+      df_insn_change_bb (insn);
+}
+
+/* Update BLOCK_FOR_INSN of insns in BB to BB,
+   and notify df of the change.  */

 void
 update_bb_for_insn (basic_block bb)
 {
-  rtx insn;
-
-  for (insn = BB_HEAD (bb); ; insn = NEXT_INSN (insn))
-    {
-      if (!BARRIER_P (insn))
-       {
-         set_block_for_insn (insn, bb);
-         df_insn_change_bb (insn);
-       }
-      if (insn == BB_END (bb))
-       break;
-    }
+  update_bb_for_insns (BB_HEAD (bb), NEXT_INSN (BB_END (bb)), bb);
 }


 /* Return the INSN immediately following the NOTE_INSN_BASIC_BLOCK
@@ -629,16 +654,7 @@ rtl_merge_blocks (basic_block a, basic_b
   /* Reassociate the insns of B with A.  */
   if (!b_empty)
     {
-      rtx x;
-
-      for (x = a_end; x != b_end; x = NEXT_INSN (x))
-       {
-         set_block_for_insn (x, a);
-         df_insn_change_bb (x);
-       }
-
-      set_block_for_insn (b_end, a);
-      df_insn_change_bb (b_end);
+      update_bb_for_insns (a_end, NEXT_INSN (b_end), a);

       a_end = b_end;
     }
@@ -843,14 +859,9 @@ try_redirect_by_replacing_jump (edge e,
                 which originally were or were created before jump table are
                 inside the basic block.  */
              rtx new_insn = BB_END (src);
-             rtx tmp;
-
-             for (tmp = NEXT_INSN (BB_END (src)); tmp != barrier;
-                  tmp = NEXT_INSN (tmp))
-               {
-                 set_block_for_insn (tmp, src);
-                 df_insn_change_bb (tmp);
-               }
+
+             update_bb_for_insns (NEXT_INSN (BB_END (src)),
+                                  barrier, src);

              NEXT_INSN (PREV_INSN (new_insn)) = NEXT_INSN (new_insn);
              PREV_INSN (NEXT_INSN (new_insn)) = PREV_INSN (new_insn);
@@ -2637,6 +2648,12 @@ cfg_layout_merge_blocks (basic_block a,
        first = NEXT_INSN (first);
       gcc_assert (NOTE_INSN_BASIC_BLOCK_P (first));
       BB_HEAD (b) = NULL;
+
+      /* emit_insn_after_noloc doesn't call df_insn_change_bb.
+         We need to explicitly notify. */
+      notify_bb_change_for_insns (NEXT_INSN (first),
+                                 NEXT_INSN (BB_END (b)));
+
       delete_insn (first);
     }
   /* Otherwise just re-associate the instructions.  */
@@ -2644,13 +2661,8 @@ cfg_layout_merge_blocks (basic_block a,
     {
       rtx insn;

-      for (insn = BB_HEAD (b);
-          insn != NEXT_INSN (BB_END (b));
-          insn = NEXT_INSN (insn))
-       {
-         set_block_for_insn (insn, a);
-         df_insn_change_bb (insn);
-       }
+      update_bb_for_insns (BB_HEAD (b),
+                           NEXT_INSN (BB_END (b)), a);

       insn = BB_HEAD (b);
       /* Skip possible DELETED_LABEL insn.  */


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=34171