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[PATCH] Fix PR ipa/58862 (profiled bootstrap failure)


This patch fixes a profiledbootstrap failure that occurred after I
added some profile fixup. The initial profile insanity occurred
upstream of my change, but my change caused the insanity to spread to
the edge probability, resulting in a verify failure. The patch below
ensures this doesn't occur.

Bootstrapped and tested on x86-64-unknown-linux-gnu. A
profiledbootstrap build also now succeeds. Ok for trunk?

Thanks,
Teresa

2013-10-29  Teresa Johnson  <tejohnson@google.com>

        PR ipa/58862
        * tree-ssa-tail-merge.c (replace_block_by): Tolerate profile
        insanities when updating probabilities.

Index: tree-ssa-tail-merge.c
===================================================================
--- tree-ssa-tail-merge.c       (revision 204166)
+++ tree-ssa-tail-merge.c       (working copy)
@@ -1467,7 +1467,7 @@ static void
 replace_block_by (basic_block bb1, basic_block bb2)
 {
   edge pred_edge;
-  edge e1;
+  edge e1, e2;
   edge_iterator ei;
   unsigned int i;
   gimple bb2_phi;
@@ -1502,16 +1502,22 @@ replace_block_by (basic_block bb1, basic_block bb2
   bb2->count += bb1->count;

   /* Merge the outgoing edge counts from bb1 onto bb2.  */
+  gcov_type out_sum = 0;
   FOR_EACH_EDGE (e1, ei, bb1->succs)
     {
-      edge e2;
       e2 = find_edge (bb2, e1->dest);
       gcc_assert (e2);
       e2->count += e1->count;
-      /* Recompute the probability from the new merged edge count (bb2->count
-         was updated above).  */
-      e2->probability = GCOV_COMPUTE_SCALE (e2->count, bb2->count);
+      out_sum += e2->count;
     }
+  /* Recompute the edge probabilities from the new merged edge count.
+     Use the sum of the new merged edge counts computed above instead
+     of bb2's merged count, in case there are profile count insanities
+     making the bb count inconsistent with the edge weights.  */
+  FOR_EACH_EDGE (e2, ei, bb2->succs)
+    {
+      e2->probability = GCOV_COMPUTE_SCALE (e2->count, out_sum);
+    }

   /* Do updates that use bb1, before deleting bb1.  */
   release_last_vdef (bb1);


-- 
Teresa Johnson | Software Engineer | tejohnson@google.com | 408-460-2413


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