[Bug tree-optimization/48641] [4.7 Regression] ICE: verify_flow_info failed: Wrong frequency of block 77 -419530 with -O -fno-tree-ccp -fno-tree-copy-prop

[hubicka at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=48641

--- Comment #4 from Jan Hubicka <hubicka at gcc dot gnu.org> 2011-12-23 
21:47:08 UTC ---
OK, the problem is that profile is wrong and jump threading gets into
conflicting results and the results are propagated through the testcase because
of specific CFG.  I think all we can do is to add capping. I am testing
Index: tree-ssa-threadupdate.c
===================================================================
--- tree-ssa-threadupdate.c     (revision 182657)
+++ tree-ssa-threadupdate.c     (working copy)
@@ -513,7 +513,11 @@ redirect_edges (void **slot, void *data)
                     e->src->index, e->dest->index, rd->dup_block->index);

          rd->dup_block->count += e->count;
-         rd->dup_block->frequency += EDGE_FREQUENCY (e);
+
+         /* Excessive jump threading may make frequencies large enough so
+            the computation overflows.  */
+         if (rd->dup_block->frequency < BB_FREQ_MAX * 2)
+           rd->dup_block->frequency += EDGE_FREQUENCY (e);
          EDGE_SUCC (rd->dup_block, 0)->count += e->count;
          /* Redirect the incoming edge to the appropriate duplicate
             block.  */