* sel-sched-ir.h (register_unavailable_p): Declare.
* sel-sched-ir.c (register_unavailable_p): New. Use it...
(set_unavailable_target_for_expr): ... here to properly test
availability of a register.
(speculate_expr): Ditto.
* sel-sched.c (substitute_reg_in_expr): Ditto.
(av_set_could_be_blocked_by_bookkeeping_p): Ditto.