tree-ssa-loop-niter.c (number_of_iterations_popcount): If popcount argument is checked for zero before entering loop, avoid checking again.

gcc/ChangeLog:

2018-07-06  Kugan Vivekanandarajah  <kuganv@linaro.org>

	* tree-ssa-loop-niter.c (number_of_iterations_popcount): If popcount
	argument is checked for zero before entering loop, avoid checking again.

From-SVN: r262487