PR rtl-optimization/15422
* reg-stack.c (starting_stack_p): New static global.
(straighten_stack): Delete prototype. Change to update the stack
before the current insn.
(subst_stack_regs): Update call to straighten stack.
(emit_swap_insn): Delete prototype. For the first insn in a
basic block, update stack_in instead of emitting a real swap.
(change_stack): When changing the stack before the first insn
in a basic block, update stack_in instead of emitting real code.
(compensate_edges): Clear starting_stack_p during compensation.
(convert_regs_1): Keep track of starting_stack_p whilst processing
a basic block.
From-SVN: r100370
