PR tree-optimization/52272

	PR tree-optimization/52272
	* tree-ssa-loop-ivopts.c (struct iv_common_cand): New struct.
	(struct iv_common_cand_hasher): New struct.
	(iv_common_cand_hasher::hash): New function.
	(iv_common_cand_hasher::equal): New function.
	(struct ivopts_data): New fields, iv_common_cand_tab and
	iv_common_cands.
	(tree_ssa_iv_optimize_init): Initialize above fields.
	(record_common_cand, common_cand_cmp): New functions.
	(add_iv_candidate_derived_from_uses): New function.
	(add_iv_candidate_for_use): Record iv_common_cands derived from
	iv use in hash table, instead of adding candidates directly.
	(add_iv_candidate_for_uses): Call add_iv_candidate_derived_from_uses.
	(record_important_candidates): Add important candidates to iv uses'
	related_cands.  Always keep related_cands for future use.
	(try_add_cand_for): Use iv uses' related_cands.
	(free_loop_data, tree_ssa_iv_optimize_finalize): Release new fields
	in struct ivopts_data, iv_common_cand_tab and iv_common_cands.

git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@230647 138bc75d-0d04-0410-961f-82ee72b054a4