* i386.h (PREFERRED_STACK_BOUNDARY): Define.
        * i386.c (ix86_compute_frame_size): New function.
        (ix86_prologue, ix86_epilogue): Use it.
        * i386.h (INITIAL_ELIMINATION_OFFSET): Likewise.
        * reload1.c: Provide default for PREFERRED_STACK_BOUNDARY.

From-SVN: r25909