re PR middle-end/89790 (ICE segfault in operand_equal_p() at fold-const.c:3000 with -Wduplicated-cond since r269838)

2019-03-25  Richard Biener  <rguenther@suse.de>

	PR middle-end/89790
	* fold-const.c (operand_equal_p): Revert last change with
	updated comment.

	* g++.dg/pr89790.C: New testcase.

From-SVN: r269907