Re: [PATCH 3/4] xtensa: Improve instruction cost estimation and suggestion

[Max Filippov <jcmvbkbc@gmail.com>]

On Thu, Jun 9, 2022 at 9:26 PM Takayuki 'January June' Suwa
<jjsuwa_sys3175@yahoo.co.jp> wrote:
>
> This patch implements a new target-specific relative RTL insn cost function
> because of suboptimal cost estimation by default, and fixes several "length"
> insn attributes (related to the cost estimation).
>
> And also introduces a new machine-dependent option "-mextra-l32r-costs="
> that tells implementation-specific InstRAM/ROM access penalty for L32R
> instruction to the compiler (in clock-cycle units, 0 by default).
>
> gcc/ChangeLog:
>
>         * config/xtensa/xtensa.cc (xtensa_rtx_costs): Correct wrong case
>         for ABS and NEG, add missing case for BSWAP and CLRSB, and
>         double the costs for integer divisions using libfuncs if
>         optimizing for speed, in order to take advantage of fast constant
>         division by multiplication.
>         (TARGET_INSN_COST): New macro definition.
>         (xtensa_is_insn_L32R_p, xtensa_insn_cost): New functions for
>         calculating relative costs of a RTL insns, for both of speed and
>         size.
>         * config/xtensa/xtensa.md (return, nop, trap): Correct values of
>         the attribute "length" that depends on TARGET_DENSITY.
>         (define_asm_attributes, blockage, frame_blockage): Add missing
>         attributes.
>         * config/xtensa/xtensa.opt (-mextra-l32r-costs=): New machine-
>         dependent option, however, preparatory work for now.
> ---
>   gcc/config/xtensa/xtensa.cc  | 116 ++++++++++++++++++++++++++++++++---
>   gcc/config/xtensa/xtensa.md  |  29 ++++++---
>   gcc/config/xtensa/xtensa.opt |   4 ++
>   3 files changed, 134 insertions(+), 15 deletions(-)

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

-- 
Thanks.
-- Max