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 84132495CA for ; Fri, 30 May 2025 00:46:18 +0000 (UTC) Received: from [127.0.1.1] (localhost [127.0.0.1]) by ffbox0-bg.ffmpeg.org (Postfix) with ESMTP id 0710068D3AA; Fri, 30 May 2025 03:46:14 +0300 (EEST) Received: from relay7-d.mail.gandi.net (relay7-d.mail.gandi.net [217.70.183.200]) by ffbox0-bg.ffmpeg.org (Postfix) with ESMTPS id 96CEB68CF45 for ; Fri, 30 May 2025 03:46:07 +0300 (EEST) Received: by mail.gandi.net (Postfix) with ESMTPSA id EB7394396B for ; Fri, 30 May 2025 00:46:06 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=niedermayer.cc; s=gm1; t=1748565967; 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=2azujf2GPOe7srsf0/psfJFcoxNF9wTZkPKR6HFFGIk=; b=nbTKms2QebD51/W62NdQUeCVXC5vLR+zq9LSEgvVHnoEe6+bET8QvfKvVQenLpX3B1fieY qii6suhaKkhmYHbPXPVDhGcTatIlKflh89PsaflLP3wCqC6ON92OV6Tp9MkUnhwAq/M9Bh Ug1+59lyJvEHqC7do+cV8fdU323WdnKRZhlyBQ3A3+/M5xzi5V4PPfucOJVuYoAqVrqnzf DhFKV+Qv9B+xKmfFkgk+VEyIiIW/euqHY4Ht1P+c4z4mPQ39jovNcfDyeAf9N9RhDOLNWG 1GqNjQdEIvR9QQkXz1pK2+CNKw1wlDUfUyxDoDjygSoRiBo8usFEnUTUNVNWVA== Date: Fri, 30 May 2025 02:46:05 +0200 From: Michael Niedermayer To: FFmpeg development discussions and patches Message-ID: <20250530004605.GF29660@pb2> References: <20250521061750.54882-1-jiawei@iscas.ac.cn> <49f0532f-444c-4881-982a-26ed53e5e4b0@frankplowman.com> <09d91570-6c20-49a7-aada-ceb18d77c6c3@iscas.ac.cn> <3356719.44csPzL39Z@basile.remlab.net> <20250525213708.GO29660@pb2> MIME-Version: 1.0 In-Reply-To: X-GND-State: clean X-GND-Score: -70 X-GND-Cause: gggruggvucftvghtrhhoucdtuddrgeeffedrtddtgddvjeeiudculddtuddrgeefvddrtddtmdcutefuodetggdotefrodftvfcurfhrohhfihhlvgemucfitefpfffkpdcuggftfghnshhusghstghrihgsvgenuceurghilhhouhhtmecufedtudenucesvcftvggtihhpihgvnhhtshculddquddttddmnegfrhhlucfvnfffucdlfedtmdenucfjughrpeffhffvuffkfhggtggujgesghdtreertddtjeenucfhrhhomhepofhitghhrggvlhcupfhivgguvghrmhgrhigvrhcuoehmihgthhgrvghlsehnihgvuggvrhhmrgihvghrrdgttgeqnecuggftrfgrthhtvghrnhepleekgefgffeiudefjeeuffejudehtddtudeltdehveevvedtieeulefhtdeutdeknecukfhppeeguddrieeirdeijedruddufeenucevlhhushhtvghrufhiiigvpedtnecurfgrrhgrmhepihhnvghtpeeguddrieeirdeijedruddufedphhgvlhhopehlohgtrghlhhhoshhtpdhmrghilhhfrhhomhepmhhitghhrggvlhesnhhivgguvghrmhgrhigvrhdrtggtpdhnsggprhgtphhtthhopedupdhrtghpthhtohepfhhfmhhpvghgqdguvghvvghlsehffhhmphgvghdrohhrgh 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="===============2125853807759987774==" Errors-To: ffmpeg-devel-bounces@ffmpeg.org Sender: "ffmpeg-devel" Archived-At: List-Archive: List-Post: --===============2125853807759987774== Content-Type: multipart/signed; micalg=pgp-sha512; protocol="application/pgp-signature"; boundary="TLTCiq8VFLhFIWrm" Content-Disposition: inline --TLTCiq8VFLhFIWrm Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Mon, May 26, 2025 at 11:43:15AM +0300, R=C3=A9mi Denis-Courmont wrote: >=20 >=20 > Le 26 mai 2025 00:37:08 GMT+03:00, Michael Niedermayer a =C3=A9crit=C2=A0: > >Hi R=C3=A9mi > > > >On Sat, May 24, 2025 at 07:10:57PM +0300, R=C3=A9mi Denis-Courmont wrote: > >> Le torstaina 22. toukokuuta 2025, 9.32.18 It=C3=A4-Euroopan kes=C3=A4a= ika Jiawei a =C3=A9crit=20 > >> : > >> > > The RISC-V autovectorised output looks like it has a warning "Odd > >> > > rotation angle" which is not present in the non-autovectorised out= put. > >> >=20 > >> > I found this occured when using '-ffast-math' in RISC-V, also occur = in > >> > -O3 -ffast-math -fno-tree-vectorize case(much slower due to the > >> > -ffast-math)=EF=BC=8Csupplementary more comparison results here: > >>=20 > > > >> Unfortunately, the FFmpeg code is written with x87 semantics in mind. > > > >I dont remember ever writing code intentionally with x87 semantics. And i > >have doubts other people did. >=20 > It doesn't have to be intentional. FFmpeg was started and mostly develope= d with x86-32 then x86-64 in mind. It's entirely possible that this happene= d innocently. >=20 > Specifically, FFmpeg uses open-code for minimum, maximum, absolute value = and so on (see FFMIN, FFMAX, FFABS). They work nicely for integer maths. Th= ey also work nicely on x87 with the current set of FPU optimisations, but t= hey differ from IEEE semantics because of NaNs, negative zeros and such. >=20 > Because of that the compiler will *not* use the native FPU instructions o= n platforms with native IEEE floats. replace all FFMIN with fminf() / fmin() where the arguments are float or double, assuming that has no ill performance effects thx [...] --=20 Michael GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB If the United States is serious about tackling the national security threat= s=20 related to an insecure 5G network, it needs to rethink the extent to which = it values corporate profits and government espionage over security.-Bruce Schn= eier --TLTCiq8VFLhFIWrm Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iF0EABEKAB0WIQSf8hKLFH72cwut8TNhHseHBAsPqwUCaDj/ygAKCRBhHseHBAsP q+eFAJ4/PNnVLTj0mTjMp7I6ilqPHNM/IgCeJKyJJgUAKWu42goUY7Toje9BWbw= =ahdd -----END PGP SIGNATURE----- --TLTCiq8VFLhFIWrm-- --===============2125853807759987774== 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". --===============2125853807759987774==--