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Sat, 26 Apr 2025 02:14:41 -0700 (PDT) Received: from visitorckw-System-Product-Name ([140.113.216.168]) by smtp.gmail.com with ESMTPSA id d2e1a72fcca58-73e259412b2sm4594535b3a.66.2025.04.26.02.14.31 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 26 Apr 2025 02:14:40 -0700 (PDT) Date: Sat, 26 Apr 2025 17:14:29 +0800 From: Kuan-Wei Chiu To: "H. Peter Anvin" , Yury Norov Cc: Yury Norov , tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, dave.hansen@linux.intel.com, x86@kernel.org, jk@ozlabs.org, joel@jms.id.au, eajames@linux.ibm.com, andrzej.hajda@intel.com, neil.armstrong@linaro.org, rfoss@kernel.org, maarten.lankhorst@linux.intel.com, mripard@kernel.org, tzimmermann@suse.de, airlied@gmail.com, simona@ffwll.ch, dmitry.torokhov@gmail.com, mchehab@kernel.org, awalls@md.metrocast.net, hverkuil@xs4all.nl, miquel.raynal@bootlin.com, richard@nod.at, vigneshr@ti.com, louis.peens@corigine.com, andrew+netdev@lunn.ch, davem@davemloft.net, edumazet@google.com, pabeni@redhat.com, parthiban.veerasooran@microchip.com, arend.vanspriel@broadcom.com, johannes@sipsolutions.net, gregkh@linuxfoundation.org, jirislaby@kernel.org, akpm@linux-foundation.org, jdelvare@suse.com, linux@roeck-us.net, alexandre.belloni@bootlin.com, pgaj@cadence.com, alistair@popple.id.au, linux@rasmusvillemoes.dk, Laurent.pinchart@ideasonboard.com, jonas@kwiboo.se, jernej.skrabec@gmail.com, kuba@kernel.org, linux-kernel@vger.kernel.org, linux-fsi@lists.ozlabs.org, dri-devel@lists.freedesktop.org, linux-input@vger.kernel.org, linux-media@vger.kernel.org, linux-mtd@lists.infradead.org, oss-drivers@corigine.com, netdev@vger.kernel.org, linux-wireless@vger.kernel.org, brcm80211@lists.linux.dev, brcm80211-dev-list.pdl@broadcom.com, linux-serial@vger.kernel.org, bpf@vger.kernel.org, jserv@ccns.ncku.edu.tw, Frank.Li@nxp.com, linux-hwmon@vger.kernel.org, linux-i3c@lists.infradead.org, david.laight.linux@gmail.com, andrew.cooper3@citrix.com, Yu-Chun Lin Subject: Re: [PATCH v4 00/13] Introduce parity_odd() and refactor redundant parity code Message-ID: References: <20250409154356.423512-1-visitorckw@gmail.com> <8571fd6f-4e71-4a6d-b2e8-16d9d72fa56e@zytor.com> Precedence: bulk X-Mailing-List: linux-input@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <8571fd6f-4e71-4a6d-b2e8-16d9d72fa56e@zytor.com> On Fri, Apr 25, 2025 at 12:33:21PM -0700, H. Peter Anvin wrote: > On 4/11/25 09:34, Kuan-Wei Chiu wrote: > > > > > > In either case, instead of packing the cascade into one function, make good > > > use of it. > > > > > > In the latter case, __builtin_constant_p() isn't necessary as it puts the > > > onus on the architecture to separate out const and non-const cases, if it > > > matters -- which it doesn't if the architecture simply wants to use > > > __builtin_parity: > > > > > > #define parity8(x) ((bool) __builtin_parity((u8)(x))) > > > #define parity16(x) ((bool) __builtin_parity((u16)(x))) > > > #define parity32(x) ((bool) __builtin_parity((u32)(x))) > > > #define parity64(x) ((bool) __builtin_parityll((u64)(x))) > > > > > > As stated before, I don't really see that the parity function itself would > > > be very suitable for a generic helper, but if it were to, then using the > > > "standard" macro construct for it would seem to be the better option. > > > > > > (And I would be very much in favor of not open-coding the helper everywhere > > > but to macroize it; effectively creating a C++ template equivalent. It is > > > out of scope for this project, though.) > > > > > IIUC, you prefer using the parity8/16/32/64() interface with > > __builtin_parity(), regardless of whether there are users on the hot > > path? > > As a per-architecture opt-in, yes. > I'd prefer to see Yury agree first, otherwise there's a high risk of a maintainer NAK after the next submission. Regards, Kuan-Wei