flow.c (last_loop_beg_note): New function.

	* flow.c (last_loop_beg_note): New function.
	(redirect_edge_and_branch): Use it.
	(split_edge): Likewise.

	* alias.c (loop_p): Avoid uninitialized memory access.

	* flow.c (try_forward_edges): Avoid accessing freed memory.

	* flow.c (backward_edge_of_syntactic_loop_p): Avoid uninitialized
	variable access.

From-SVN: r44429

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index f63d7add6eec00cbd1f1ec2b93e6e1dfbfb387d8..8a0143f6c3ccdfba9f59ef363ae59c0eee7085b2 100644 (file)
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,16 @@
+Fri Jul 27 17:53:00 CEST 2001  Jan Hubicka  <jh@suse.cz>
+
+       * flow.c (last_loop_beg_note): New function.
+       (redirect_edge_and_branch): Use it.
+       (split_edge): Likewise.
+
+       * alias.c (loop_p): Avoid uninitialized memory access.
+
+       * flow.c (try_forward_edges): Avoid accessing freed memory.
+
+       * flow.c (backward_edge_of_syntactic_loop_p): Avoid uninitialized
+       variable access.
+
 2001-07-27  Gerald Pfeifer  <pfeifer@dbai.tuwien.ac.at>
 
        * doc/install.texi (Configuration): Properly link the host

diff --git a/gcc/alias.c b/gcc/alias.c
index 599676d416693e0dfdca9fd180765c35fdbe30dd..84a7663ce7b55bd1b781fcd18bccf3655155807c 100644 (file)
--- a/gcc/alias.c
+++ b/gcc/alias.c
@@ -2118,7 +2118,7 @@ loop_p ()
        }
       else
        {
-         if (dest != EXIT_BLOCK_PTR
+         if (dest != EXIT_BLOCK_PTR && src != ENTRY_BLOCK_PTR
              && pre[src->index] >= pre[dest->index]
              && post[dest->index] == 0)
            break;

diff --git a/gcc/flow.c b/gcc/flow.c
index a4b2ae1a864c51032a1343be0ad90c2aac305990..4f339cd7076ef774d0c07e3eee4f5a4d1d189276 100644 (file)
--- a/gcc/flow.c
+++ b/gcc/flow.c
@@ -1748,6 +1748,30 @@ try_redirect_by_replacing_jump (e, target)
   return true;
 }
 
+/* Return last loop_beg note appearing after INSN, before start of next
+   basic block.  Return INSN if there are no such notes.
+
+   When emmiting jump to redirect an fallthru edge, it should always
+   appear after the LOOP_BEG notes, as loop optimizer expect loop to
+   eighter start by fallthru edge or jump following the LOOP_BEG note
+   jumping to the loop exit test.
+ */
+rtx
+last_loop_beg_note (insn)
+     rtx insn;
+{
+  rtx last = insn;
+  insn = NEXT_INSN (insn);
+  while (GET_CODE (insn) == NOTE
+        && NOTE_LINE_NUMBER (insn) != NOTE_INSN_BASIC_BLOCK)
+    {
+      if (NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_BEG)
+       last = insn;
+      insn = NEXT_INSN (insn);
+    }
+  return last;
+}
+
 /* Attempt to change code to redirect edge E to TARGET.
    Don't do that on expense of adding new instructions or reordering
    basic blocks.
@@ -1877,7 +1901,8 @@ redirect_edge_and_branch_force (e, target)
   /* Case of the fallthru block.  */
   if (!e->src->succ->succ_next)
     {
-      e->src->end = emit_jump_insn_after (gen_jump (label), e->src->end);
+      e->src->end = emit_jump_insn_after (gen_jump (label),
+                                         last_loop_beg_note (e->src->end));
       JUMP_LABEL (e->src->end) = label;
       LABEL_NUSES (label)++;
       if (basic_block_for_insn)
@@ -1906,7 +1931,7 @@ redirect_edge_and_branch_force (e, target)
 
   memset (new_bb, 0, sizeof (*new_bb));
 
-  new_bb->end = new_bb->head = e->src->end;
+  new_bb->end = new_bb->head = last_loop_beg_note (e->src->end);
   new_bb->succ = NULL;
   new_bb->pred = new_edge;
   new_bb->count = e->count;
@@ -1976,7 +2001,7 @@ back_edge_of_syntactic_loop_p (bb1, bb2)
        basic_block bb1, bb2;
 {
   rtx insn;
-  int count;
+  int count = 0;
   if (bb1->index > bb2->index)
     return false;
   if (bb1->index == bb2->index)
@@ -2088,7 +2113,7 @@ split_edge (edge_in)
 
          /* Now add the jump insn ...  */
          pos = emit_jump_insn_after (gen_jump (old_succ->head),
-                                     jump_block->end);
+                                     last_loop_beg_note (jump_block->end));
          jump_block->end = pos;
          if (basic_block_for_insn)
            set_block_for_new_insns (pos, jump_block);
@@ -3159,29 +3184,38 @@ try_forward_edges (b)
        }
       else if (target == first)
        ; /* We didn't do anything.  */
-      else if (redirect_edge_and_branch (e, target))
+      else
        {
-         /* We successfully forwarded the edge.  Now update profile
-            data: for each edge we traversed in the chain, remove
-            the original edge's execution count.  */
-         do
+         /* Save the values now, as the edge may get removed.  */
+         gcov_type edge_count = e->count;
+         int edge_probability = e->probability;
+
+         if (redirect_edge_and_branch (e, target))
            {
-             first->count -= e->count;
-             first->succ->count -= e->count;
-             first->frequency -= ((e->probability * b->frequency
-                                   + REG_BR_PROB_BASE / 2)
-                                  / REG_BR_PROB_BASE);
-             first = first->succ->dest;
-           }
-         while (first != target);
+             /* We successfully forwarded the edge.  Now update profile
+                data: for each edge we traversed in the chain, remove
+                the original edge's execution count.  */
+             int edge_frequency = ((edge_probability * b->frequency
+                                    + REG_BR_PROB_BASE / 2)
+                                   / REG_BR_PROB_BASE);
+
+             do
+               {
+                 first->count -= edge_count;
+                 first->succ->count -= edge_count;
+                 first->frequency -= edge_frequency;
+                 first = first->succ->dest;
+               }
+             while (first != target);
 
-         changed = true;
-       }
-      else
-       {
-         if (rtl_dump_file)
-           fprintf (rtl_dump_file, "Forwarding edge %i->%i to %i failed.\n",
-                    b->index, e->dest->index, target->index);
+             changed = true;
+           }
+         else
+           {
+             if (rtl_dump_file)
+               fprintf (rtl_dump_file, "Forwarding edge %i->%i to %i failed.\n",
+                        b->index, e->dest->index, target->index);
+           }
        }
     }