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From: Philipp Tomsich <philipp.tomsich@vrull.eu>
To: Jeff Law <jeffreyalaw@gmail.com>
Cc: gcc-patches@gcc.gnu.org, Kito Cheng <kito.cheng@gmail.com>,
	 Christoph Muellner <christoph.muellner@vrull.eu>,
	Vineet Gupta <vineetg@rivosinc.com>,
	 Jeff Law <jlaw@ventanamicro.com>,
	Palmer Dabbelt <palmer@rivosinc.com>
Subject: Re: [PATCH] RISC-V: Use binvi to cover more immediates than with xori alone
Date: Wed, 16 Nov 2022 10:17:42 +0100	[thread overview]
Message-ID: <CAAeLtUBNmeUEZkF5ODXxG-dMtRz9UQ8T6uHPonQf0XZF1aQjmg@mail.gmail.com> (raw)
In-Reply-To: <1c091d0d-e355-8fd8-8c6b-1bfe77f20291@gmail.com>

On Wed, 16 Nov 2022 at 04:45, Jeff Law <jeffreyalaw@gmail.com> wrote:
>
>
> On 11/10/22 14:35, Philipp Tomsich wrote:
> > Sequences of the form "a ^ C" with C being the positive half of a
> > signed immediate's range with one extra bit set in addtion are mapped
> > to xori and one binvi to avoid using a temporary (and a multi-insn
> > sequence to load C into that temporary).
> >
> > gcc/ChangeLog:
> >
> >       * config/riscv/bitmanip.md (*binvi<mode>_extrabit): New pattern.
> >
> > gcc/testsuite/ChangeLog:
> >
> >       * gcc.target/riscv/zbs-binvi.c: New test.
>
> Could this have been potentially done by extending the ior pattern with
> a code iterator that covered IOR/XOR?
>
>
> Not a big deal, but if it'd work, consider to avoid the pattern duplication.

We'll rework to using an iterator and a mapping in v2 for the
following cases, folding into a single patch:
 - X | C => bseti
 - X & ~C => bclri
 - X ^ C => binvi

Thanks.
Philipp.

      reply	other threads:[~2022-11-16  9:17 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-11-10 21:35 Philipp Tomsich
2022-11-16  3:45 ` Jeff Law
2022-11-16  9:17   ` Philipp Tomsich [this message]

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