2019-07-17  Richard Biener  <rguenther@suse.de>

	PR tree-optimization/91178
	* tree-ssa.c (release_defs_bitset): Iterate from higher to
	lower SSA names to avoid quadratic behavior in the common case.
	* tree-data-ref.c (split_constant_offset): Add limit argument
	and pass it down.  Initialize it from PARAM_SSA_NAME_DEF_CHAIN_LIMIT.
	(split_constant_offset_1): Add limit argument and use it to
	limit SSA def walking.  Optimize the common plus/minus case.

From-SVN: r273550