Re: [PATCH 2/4] xtensa: Make one_cmplsi2 optimizer-friendly

[Max Filippov <jcmvbkbc@gmail.com>]

On Sun, May 29, 2022 at 4:00 AM Takayuki 'January June' Suwa
<jjsuwa_sys3175@yahoo.co.jp> wrote:
>
> In Xtensa ISA, there is no single machine instruction that calculates unary
> bitwise negation.  But a few optimizers assume that bitwise negation can be
> done by a single insn.
>
> As a result, '((x < 0) ? ~x : x)' cannot be optimized to '(x ^ (x >> 31))'
> ever before, for example.
>
> This patch relaxes such limitation, by putting the insn expansion off till
> the split pass.
>
> gcc/ChangeLog:
>
>         * config/xtensa/xtensa.md (one_cmplsi2):
>         Rearrange as an insn_and_split pattern.
>
> gcc/testsuite/ChangeLog:
>
>         * gcc.target/xtensa/one_cmpl_abs.c: New.
> ---
>   gcc/config/xtensa/xtensa.md                   | 26 +++++++++++++------
>   .../gcc.target/xtensa/one_cmpl_abs.c          |  9 +++++++
>   2 files changed, 27 insertions(+), 8 deletions(-)
>   create mode 100644 gcc/testsuite/gcc.target/xtensa/one_cmpl_abs.c

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

-- 
Thanks.
-- Max