PR rtl-optimization/82778

	PR rtl-optimization/82778
	PR rtl-optimization/82597
	* compare-elim.c (struct comparison): Add in_a_setter field.
	(find_comparison_dom_walker::before_dom_children): Remove killed
	bitmap and df_simulate_find_defs call, instead walk the defs.
	Compute last_setter and initialize in_a_setter.  Merge definitions
	with first initialization for a few variables.
	(try_validate_parallel): Use insn_invalid_p instead of
	recog_memoized.  Return insn rather than just the pattern.
	(try_merge_compare): Fix up comment.  Don't uselessly test if
	in_a is a REG_P.  Use cmp->in_a_setter instead of walking UD
	chains.
	(execute_compare_elim_after_reload): Remove df_chain_add_problem
	call.

	* g++.dg/opt/pr82778.C: New test.

2017-11-01  Michael Collison  <michael.collison@arm.com>

	PR rtl-optimization/82597
	* gcc.dg/pr82597.c: New test.

git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@254328 138bc75d-0d04-0410-961f-82ee72b054a4