* flow.c: Update comment.

        (notice_stack_pointer_modification): New static function.
        (record_volatile_insns): Use it.
        (mark_regs_live_at_end): Mark the stack pointer as alive
        at the end of the function if current_function_sp_is_unchanging
        is set.
        (life_analysis_1): Set current_function_sp_is_unchanging.
        * function.c: Define it.
        (init_function_start): Initialize it.
        * output.h: Declare it.
        * reorg.c (fill_simple_delay_slots, dbr_schedule): Mark
        the stack pointer as alive at the end of the function if
        current_function_sp_is_unchanging is set.
        * i386.c (ix86_epilogue): Optimize the restoring
        of the stack pointer.


git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@23009 138bc75d-0d04-0410-961f-82ee72b054a4