2016-07-13  Richard Biener  <rguenther@suse.de>

	PR tree-optimization/24574
	* tree-ssa-phiopt.c (absorbing_element_p): Pass in argument
	position and add shift, rotate, divison and modulo support
	for left zero.
	(value_replacement): Pass in argument position to absorbing_element_p.

	* gcc.dg/pr24574.c: New testcase.

From-SVN: r238299