PR rtl-optimization/39871

	PR rtl-optimization/39871
	PR rtl-optimization/40615
	PR rtl-optimization/42500
	PR rtl-optimization/42502
	* ira.c (init_reg_equiv_memory_loc: New function.
	(ira): Call it twice.
	* reload.h (calculate_elim_costs_all_insns): Declare.
	* ira-costs.c: Include "reload.h".
	(regno_equiv_gains): New static variable.
	(init_costs): Allocate it.
	(finish_costs): Free it.
	(ira_costs): Call calculate_elim_costs_all_insns.
	(find_costs_and_classes): Take estimated elimination costs
	into account.
	(ira_adjust_equiv_reg_cost): New function.
	* ira.h (ira_adjust_equiv_reg_cost): Declare it.
	* reload1.c (init_eliminable_invariants, free_reg_equiv,
	elimination_costs_in_insn, note_reg_elim_costly): New static
	functions.
	(elim_bb): New static variable.
	(reload): Move code out of here into init_eliminable_invariants and
	free_reg_equiv.  Call them.
	(calculate_elim_costs_all_insns): New function.
	(eliminate_regs_1): Declare.  Add extra arg FOR_COSTS;
	all callers changed.  If FOR_COSTS is true, don't call alter_reg,
	but call note_reg_elim_costly if we turned a valid memory address
	into an invalid one.
	* Makefile.in (ira-costs.o): Depend on reload.h.

testsuite/
	PR rtl-optimization/39871
	PR rtl-optimization/40615
	PR rtl-optimization/42500
	PR rtl-optimization/42502
	* gcc.target/arm/eliminate.c: New test.

git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@160260 138bc75d-0d04-0410-961f-82ee72b054a4