8173196: [REDO] C2 does not optimize redundant memory operations with G1 Reviewed-by: thartmann, kvn

8223363: Bad node estimate assertion failure 8223502: Node estimate for loop unswitching is not correct: assert(delta <= 2 * required) failed: Bad node estimate 8224648: assert(!exceeding_node_budget()) failed: Too many NODES required! failure with ctw Summary: Tighten the node estimates. New est_loop_clone_sz() implementation that will compute a "fan-out" complexity estimate as part of the size estimate (to better estimate complex loop body size after cloning). New est_loop_unroll_sz() function, used to estimate the size of a loop body att full/maximal unrolling. Correction to node budget final tests and asserts. Reviewed-by: neliasso, kvn