From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from ffbox0-bg.ffmpeg.org (ffbox0-bg.ffmpeg.org [79.124.17.100]) by master.gitmailbox.com (Postfix) with ESMTPS id D81784B28B for ; Wed, 21 May 2025 11:09:45 +0000 (UTC) Received: from [127.0.1.1] (localhost [127.0.0.1]) by ffbox0-bg.ffmpeg.org (Postfix) with ESMTP id 23E4F68D06E; Wed, 21 May 2025 14:09:41 +0300 (EEST) Received: from relay3-d.mail.gandi.net (relay3-d.mail.gandi.net [217.70.183.195]) by ffbox0-bg.ffmpeg.org (Postfix) with ESMTPS id EA49E68CD5F for ; Wed, 21 May 2025 14:09:33 +0300 (EEST) Received: by mail.gandi.net (Postfix) with ESMTPSA id 4D5481FCEA for ; Wed, 21 May 2025 11:09:33 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=niedermayer.cc; s=gm1; t=1747825773; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=KI/F0lc8wtrHazTLtSre2V42ITAWiC2UFTCE6XMHaig=; b=J+Vq7b41gsXU/mUOaCmHVZUEJ6I3J49G3bL7xzIElYPk45bX9FIr50DXA/M5ZL12lIUcjg zmZGl6gJLzl9nW3MqFFDgKWBzLF5hO/Qnx2TZF6lyAEzOttuKuU/71JhjhmjMk2H8BzHQw 3FzvgUQX8Y0Th9HMUa5eOLCaerZfzbgQs1TWgSneS7XHCo0KBxxCXC2gEkLd8zC2axmLmt CW14RK6BE5r+eGX4JLhD71gWc/LdXPoRdkwH+wOkEdqKX3/cdumkWa7KFaGqILljagSNud FW1dmXmWAYGkj5+3huLFK1P7bvUpRKEztQ6LsLGoz1Sba4g4icFIYxehiMj5Yw== Date: Wed, 21 May 2025 13:09:31 +0200 From: Michael Niedermayer To: FFmpeg development discussions and patches Message-ID: <20250521110931.GO29660@pb2> References: <20250521061750.54882-1-jiawei@iscas.ac.cn> <20250521074645.GM29660@pb2> <00e8baaf-c975-4cc8-a4a4-538a84fab9eb@iscas.ac.cn> MIME-Version: 1.0 In-Reply-To: <00e8baaf-c975-4cc8-a4a4-538a84fab9eb@iscas.ac.cn> X-GND-State: clean X-GND-Score: -85 X-GND-Cause: gggruggvucftvghtrhhoucdtuddrgeeffedrtddtgddvledvucdltddurdegfedvrddttddmucetufdoteggodetrfdotffvucfrrhhofhhilhgvmecuifetpfffkfdpucggtfgfnhhsuhgsshgtrhhisggvnecuuegrihhlohhuthemuceftddunecusecvtfgvtghiphhivghnthhsucdlqddutddtmdenfghrlhcuvffnffculdduhedmnecujfgurhepfffhvffukfhfgggtuggjsehgtderredttdejnecuhfhrohhmpefoihgthhgrvghlucfpihgvuggvrhhmrgihvghruceomhhitghhrggvlhesnhhivgguvghrmhgrhigvrhdrtggtqeenucggtffrrghtthgvrhhnpeffheevhfdvvdfhtdfgtefhtdeuleeftdevkeffleejtefhgedthfefgffgueeftdenucffohhmrghinhepfhhfmhhpvghgrdhorhhgnecukfhppeeguddrieeirdeijedruddufeenucevlhhushhtvghrufhiiigvpedtnecurfgrrhgrmhepihhnvghtpeeguddrieeirdeijedruddufedphhgvlhhopehlohgtrghlhhhoshhtpdhmrghilhhfrhhomhepmhhitghhrggvlhesnhhivgguvghrmhgrhigvrhdrtggtpdhnsggprhgtphhtthhopedupdhrtghpthhtohepfhhfmhhpvghgqdguvghvvghlsehffhhmphgvghdrohhrgh X-GND-Sasl: michael@niedermayer.cc Subject: Re: [FFmpeg-devel] gcc: Remove auto-vectorization limitation. X-BeenThere: ffmpeg-devel@ffmpeg.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: FFmpeg development discussions and patches List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Reply-To: FFmpeg development discussions and patches Content-Type: multipart/mixed; boundary="===============5058992290933643789==" Errors-To: ffmpeg-devel-bounces@ffmpeg.org Sender: "ffmpeg-devel" Archived-At: List-Archive: List-Post: --===============5058992290933643789== Content-Type: multipart/signed; micalg=pgp-sha512; protocol="application/pgp-signature"; boundary="C9Vi41mBIqDChCuc" Content-Disposition: inline --C9Vi41mBIqDChCuc Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Wed, May 21, 2025 at 06:32:49PM +0800, Jiawei wrote: >=20 > =E5=9C=A8 2025/5/21 15:46, Michael Niedermayer =E5=86=99=E9=81=93: > > On Wed, May 21, 2025 at 02:17:50PM +0800, Jiawei wrote: > > > This patch modifies the FFmpeg build system to remove the explicit di= sabling > > > of GCC's auto-vectorization feature. > > >=20 > > > Modern GCC versions (>=3D 10.0) have demonstrated stable auto-vectori= zation > > > capabilities through extensive optimizations in loop analysis and SIMD > > > code generation. The explicit -fno-tree-vectorize flag originally add= ed > > > in commit 973859f (2009) to workaround early GCC vectorization instab= ility > > > is no longer necessary. > > >=20 > > > Key improvements justifying this change: > > > 1. Enhanced heuristics for loop vectorization cost models > > > 2. Mature handling of alignment and memory access patterns > > > 3. Robust fallback mechanisms for unsupported architectures > > >=20 > > > This change allows FFmpeg to benefit from automated SIMD optimizations > > > when built with -O3 optimization level, particularly improving > > > performance on x86_64 (AVX), ARM64 (SVE) and RISC-V(RVV) architecture= s. > > >=20 > > > [1] https://git.ffmpeg.org/gitweb/ffmpeg.git/commit/973859f5230e77bee= a7bb59dc081870689d6d191 > > >=20 > > > --- > > > configure | 1 - > > > 1 file changed, 1 deletion(-) > > >=20 > > > diff --git a/configure b/configure > > > index 3730b0524c..b9e95ce4ec 100755 > > > --- a/configure > > > +++ b/configure > > > @@ -7656,7 +7656,6 @@ if enabled icc; then > > > disable aligned_stack > > > fi > > > elif enabled gcc; then > > > - check_optflags -fno-tree-vectorize > > > check_cflags -Werror=3Dformat-security > > > check_cflags -Werror=3Dimplicit-function-declaration > > > check_cflags -Werror=3Dmissing-prototypes > > Your text speaks about this change being ok in a gcc version dependant > > way > >=20 > > Your patch has no gcc version dependancy > >=20 > > If you claim that all issues where solved, please show the issues happe= ning > > in version v and no longer happening in w>v . Then it make sense to > > change the flags for version w > >=20 > > Thx > > [...] >=20 >=20 > Sorry I forgot about that, thanks for reminding me. Here still exist many > old version gcc user, >=20 > And I am not sure how will this impact them. >=20 > Maybe a later version gcc checking is good, like gcc 13-15, what you think > about it? i cannot speak about gcc versions, i know of them little more than i know numbers from a dice throw. But if we can turn on optimizations and make the code faster without breaki= ng anything, iam in favor of that. Its just that i cannot awnser the question what checks, what exact version or other spatial limitation may be needed. You would have to verify that the issues people encountered previously no longer affect version XY and then put a XY check in the patch. thx [...] --=20 Michael GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB The greatest way to live with honor in this world is to be what we pretend to be. -- Socrates --C9Vi41mBIqDChCuc Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iF0EABEKAB0WIQSf8hKLFH72cwut8TNhHseHBAsPqwUCaC20aAAKCRBhHseHBAsP q20lAJ4mHJDqXkKvoHHc57pZDIM4e1L24ACdHHRFUAjvp2DrmtNY/vXoSRPF0Zs= =Hv4x -----END PGP SIGNATURE----- --C9Vi41mBIqDChCuc-- --===============5058992290933643789== Content-Type: text/plain; charset="us-ascii" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Content-Disposition: inline _______________________________________________ ffmpeg-devel mailing list ffmpeg-devel@ffmpeg.org https://ffmpeg.org/mailman/listinfo/ffmpeg-devel To unsubscribe, visit link above, or email ffmpeg-devel-request@ffmpeg.org with subject "unsubscribe". --===============5058992290933643789==--