re PR sanitizer/81097 (UBSAN: false positive for not existing negation operator and a bogus message)

2017-06-20  Richard Biener  <rguenther@suse.de>

	PR middle-end/81097
	* fold-const.c (split_tree): Fold to type before negating.

	* c-c++-common/ubsan/pr81097.c: New testcase.

From-SVN: r249407