Re: [PATCH] xtensa: Remove old broken tweak for leaf function

[Max Filippov <jcmvbkbc@gmail.com>]

On Fri, Jan 13, 2023 at 9:03 PM Takayuki 'January June' Suwa
<jjsuwa_sys3175@yahoo.co.jp> wrote:
>
> In the before-IRA era, ORDER_REGS_FOR_LOCAL_ALLOC was called for each
> function in Xtensa, and there was register allocation table reordering
> for leaf functions to compensate for the poor performance of local-alloc.
>
> Today the adjustment hook is still called via its alternative
> ADJUST_REG_ALLOC_ORDER, but it is only called once at the start of the IRA,
> and leaf_function_p() erroneously returns true and also gives no argument
> count.
>
> That straightforwardly misleads register allocation that all functions are
> always leaves with no arguments, which leads to inefficiencies in allocation
> results.
>
> Fortunately, IRA is smart enough than local-alloc to not need such assistance.
>
> This patch does away with the antiquated by removing the wreckage that no
> longer works.
>
> gcc/ChangeLog:
>
>         * config/xtensa/xtensa-protos.h (order_regs_for_local_alloc):
>           Rename to xtensa_adjust_reg_alloc_order.
>         * config/xtensa/xtensa.cc (xtensa_adjust_reg_alloc_order):
>           Ditto.  And also remove code to reorder register numbers for
>           leaf functions, rename the tables, and adjust the allocation
>           order for the call0 ABI to use register A0 more.
>           (xtensa_leaf_regs): Remove.
>         * config/xtensa/xtensa.h (REG_ALLOC_ORDER): Cosmetics.
>           (order_regs_for_local_alloc): Rename as the above.
>           (LEAF_REGISTERS, LEAF_REG_REMAP, leaf_function): Remove.
> ---
>  gcc/config/xtensa/xtensa-protos.h |  2 +-
>  gcc/config/xtensa/xtensa.cc       | 77 +++++++------------------------
>  gcc/config/xtensa/xtensa.h        | 51 ++++++--------------
>  3 files changed, 31 insertions(+), 99 deletions(-)

Regtested for target=xtensa-linux-uclibc, no new regressions.
Committed to master.

-- 
Thanks.
-- Max