From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from galois.linutronix.de (Galois.linutronix.de [193.142.43.55]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 893623CB57F for ; Thu, 20 Aug 2026 08:31:52 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=193.142.43.55 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787214713; cv=none; b=h1A9zF7wDFUqPph/zeIC9F7nGK85IJjE0HiRCewn0taonTc6S2DA9Ws84bNRM6zfJBVXYLpr2Wshi0Zx1a7DdOl+8t3DYK5SCLffTnGGUKzHtQrLL0b8IM+OPbXtBHL06Nzp36Miqb375KD+VHozPhCBV+yQTPMlvF0nwl/8pIY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787214713; c=relaxed/simple; bh=WMptsG1LH+UWCycqZ0+T1PCyR9MNYSyGteP4uPZu7cw=; h=From:To:Cc:Subject:In-Reply-To:References:Date:Message-ID: MIME-Version:Content-Type; b=t4ATFESNIlrY/3SvKdyq4jZucfbV3eNafLLW8WaQ2FDmIIeczvoYUF/cQcDMCPDG4DwjJdWUl2mEDuiSfDA+OEazCAToBPQZDUDqWKvVx396LeK2Z894cpTm12a3ao5vz1GVyw0eOAjjHQPBusWtmCIdy8yq7DICdrFfV6gaBPM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linutronix.de; spf=pass smtp.mailfrom=linutronix.de; dkim=pass (2048-bit key) header.d=linutronix.de header.i=@linutronix.de header.b=3d5x83jM; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b=Z32JNXkX; arc=none smtp.client-ip=193.142.43.55 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linutronix.de Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linutronix.de Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="3d5x83jM"; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="Z32JNXkX" From: Nam Cao DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1787214710; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=u5/EGqV2v+l03AcIOTEACre/7Mg9HbWMfa+eqHZllbw=; b=3d5x83jMOxZNFEAVx4xf2SuFPy4UsvGRi+V7ufvvXwgzOMRlxVYr3FSZwhAnlemNLy4LJh EhZsOVCcu/GfX+cZsDD4XvoPH04NJaEnnXE8vari1umm/z5E79grj2JTnAsiJNCtqn0am+ JDXpGG/Vt55whAFlH7oCxPyvXS+PLxaAYzpndpYFVimOJ//G5Dnd1dxnwZD5vl4WRnH9Gs bWrDICH7u3iV9/YgUUGD0CM/J4gwvCS0Y3IZjjD1x4Olgxmv7kD/J2jpOk3VHRpmLbkgJe T7ZspxwwkYpb1tUJsR/OzAeiNuJFdEdOcVJm/SapHvN1ddj6qyn6EWIobQpnQg== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1787214710; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=u5/EGqV2v+l03AcIOTEACre/7Mg9HbWMfa+eqHZllbw=; b=Z32JNXkXhXOB28Qk15h4uTBtfaYtpQvsA5V6LoesM+oEtap9Cjn9g+9baC/olG4L9DWDQ2 SX1wDWgm8o+NSGAA== To: Jisheng Zhang , Paul Walmsley , Palmer Dabbelt , Albert Ou , Alexandre Ghiti Cc: linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 1/3] riscv: word-at-a-time: improve find_zero() for !RISCV_ISA_ZBB In-Reply-To: <20260113122457.27507-2-jszhang@kernel.org> References: <20260113122457.27507-1-jszhang@kernel.org> <20260113122457.27507-2-jszhang@kernel.org> Date: Thu, 20 Aug 2026 10:31:49 +0200 Message-ID: <87mruh5h1m.fsf@yellow.woof> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain Jisheng Zhang writes: > +#if !(defined(CONFIG_RISCV_ISA_ZBB) && defined(CONFIG_TOOLCHAIN_HAS_ZBB)) > +#include > +#else Instead of this #if, would it be better to do static inline unsigned long find_zero(unsigned long mask) { if (IS_ENABLED(CONFIG_RISCV_ISA_ZBB) && IS_ENABLED(CONFIG_TOOLCHAIN_HAS_ZBB) && riscv_has_extension_likely(RISCV_ISA_EXT_ZBB)) return !mask ? 0 : ((__fls(mask) + 1) >> 3); return count_masked_bytes(mask); } and let compiler's dead code elimination does its job? Nam