re PR tree-optimization/18048 (mgrid loop performance regression with ivopts (registe...

re PR tree-optimization/18048 (mgrid loop performance regression with ivopts (register pressure))

	PR tree-optimization/18048
	* fold-const.c (try_move_mult_to_index): New function.
	(fold): Use try_move_mult_to_index.
	* tree-ssa-loop-ivopts.c (try_add_cand_for): Prefer common candidates.
	* tree-ssa-loop-niter.c (number_of_iterations_cond): Produce
	an all-ones unsigned constant without extra bits.
	* tree.c (build_low_bits_mask): New function.
	* tree.h (build_low_bits_mask): Declare.

From-SVN: r89708