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From: Andrea Parri <andrea@rivosinc.com>
To: Patrick O'Neill <patrick@rivosinc.com>
Cc: gcc-patches@gcc.gnu.org, jeffreyalaw@gmail.com,
	palmer@rivosinc.com, vineetg@rivosinc.com, andrew@sifive.com,
	kito.cheng@sifive.com, dlustig@nvidia.com, cmuellner@gcc.gnu.org,
	hboehm@google.com, gnu-toolchain@rivosinc.com
Subject: Re: [RFC] RISC-V: Add proposed Ztso atomic mappings
Date: Fri, 5 May 2023 20:55:31 +0200	[thread overview]
Message-ID: <ZFVRI4/CXK8o4BPY@andrea> (raw)
In-Reply-To: <20230505171256.1380528-1-patrick@rivosinc.com>

On Fri, May 05, 2023 at 10:12:56AM -0700, Patrick O'Neill wrote:
> The RISC-V Ztso extension currently has no effect on generated code.
> With the additional ordering constraints guarenteed by Ztso, we can emit
> more optimized atomic mappings than the RVWMO mappings.
> 
> This patch implements Andrea Parri's proposed Ztso mappings ("Proposed
> Mapping").
>   https://github.com/preames/public-notes/blob/master/riscv-tso-mappings.rst
> 
> LLVM has implemented this same mapping (Ztso is still behind a
> experimental flag in LLVM, so there is *not* a defined ABI for this yet).
>   https://reviews.llvm.org/D143076

Given the recent patches/discussions, it seems worth pointing out the
the Ztso mappings referred to above was designed to be compatible with
the mappings in Table A.6 and that they are _not_ compatible with the
mappings in Table A.7 or with a "subset" of A.7 (even assuming RVTSO).

  Andrea

  reply	other threads:[~2023-05-05 18:55 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-05-05 17:12 Patrick O'Neill
2023-05-05 18:55 ` Andrea Parri [this message]
2023-05-05 19:18   ` Palmer Dabbelt
2023-05-05 20:10     ` Andrea Parri
2023-05-05 21:42       ` Hans Boehm
2023-05-05 21:52         ` Andrew Waterman
2023-05-05 22:01         ` Andrea Parri
2023-07-17 21:28 ` [RFC v2] RISC-V: Add " Patrick O'Neill
2023-08-01  5:04   ` Jeff Law
2023-08-08 21:56     ` Patrick O'Neill
2023-08-08 21:52   ` [PATCH v3] " Patrick O'Neill
2023-08-08 21:54     ` Palmer Dabbelt
2023-08-10 21:14       ` [Committed] " Patrick O'Neill

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