Fix linux kernel -foptimize-sibling-calls miscompilation
* config/ia64/ia64.c (ia64_expand_epilogue): Emit alloc if sibcall_p.
(first_instruction): New static variable.
(rtx_needs_barrier): Return 1 for alloc.
(init_insn_group_barriers): Set first_instruction.
(rws_sum): Delete duplicate definition.
(group_barrier_needed_p): Return 0 when first_instruction true.
(safe_group_barrier_needed_p): Save and restore first_instruction
around group_barrier_needed_p call.
From-SVN: r41347
