Review request (S): 6611837: block frequency is zero

[Chuck Rasbold]

http://webrev.invokedynamic.info/rasbold/6611837/index.html

6611837: block frequency is zero
Summary: insert_goto_at should set frequency for newly created blocks
Reviewed-by:

The insert_goto_at() function fails to set the frequency for blocks 
inserted during block cleanup in Remove_Empty().

We can compute a frequency estimate for the new block from the frequency 
of the pred block and a branch probability estimate.

In some cases, an implicit null check has been created during lcm and 
the original Op_If is gone along with the predicted probability. In such 
situations, we reverse engineer the probability from the successors blocks.