Date: Thu, 18 Dec 2014 07:51:47 -0700 From: Warner Losh <imp@bsdimp.com> To: Dimitry Andric <dim@FreeBSD.org> Cc: FreeBSD ARM <freebsd-arm@freebsd.org>, Robert Huff <roberthuff@rcn.com>, NGie Cooper <yaneurabeya@gmail.com>, FreeBSD ports <freebsd-ports@freebsd.org>, FreeBSD-Current <freebsd-current@freebsd.org> Subject: Re: RFT: Please help testing the llvm/clang 3.5.0 import Message-ID: <9D9850F8-62D6-4A85-BED3-1B4AB4DE5C14@bsdimp.com> In-Reply-To: <E2670EBE-CD53-43D5-89EA-DC5460849BE5@FreeBSD.org> References: <8598B1D4-5485-426F-B6D6-22BF26AC5FE1@FreeBSD.org> <CAGHfRMBPkQiTgW0Eahkoe1QwArBst-BZ-Lawor_CDda1x8K9xg@mail.gmail.com> <D9C5A8D1-2158-4B37-9C9C-067A4DDE6E44@FreeBSD.org> <21650.55288.425711.209975@jerusalem.litteratus.org> <E2670EBE-CD53-43D5-89EA-DC5460849BE5@FreeBSD.org>
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--Apple-Mail=_8585A9CA-84EF-42F8-B871-2B3E958B1A69 Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset=us-ascii > On Dec 18, 2014, at 7:44 AM, Dimitry Andric <dim@FreeBSD.org> wrote: > > On 18 Dec 2014, at 14:34, Robert Huff wrote: >> Dimitry Andric writes: >> >>>> - Could a "MK_CLANG_ALL_TARGETS" or something similar option be >>>> added to src.opts.mk to fine tune this process for those of us who >>>> don't want to build a cross-compile toolchain every iteration for our >>>> target MACHINE/MACHINE_ARCH? >>> >>> I would be fine with something like this, as long as it is turned off by >>> default, or if it is only used for the bootstrap stages. It is actually >>> an extremely useful feature of clang that you can target multiple >>> architectures with one compiler binary. >> >> Point of information: this seems useful for developers, and >> (almost entirely) useless for everyone else. Are there other >> cohorts that want this badly? >> If that's correct, and there's a simple switch for >> configuration ... why should this default to what's useful for the >> (much?) smaller number of people? About what am I ignorant? > > It's not a simple switch, at least not now. If you use the upstream > build system for llvm, e.g. autoconf or CMake, it has an option to > select all the architectures that are supported. Several config files > are then generated differently, and parts of the target support > subdirectories are selectively enabled or disabled. > > In fact, we already build just a subset of the available architectures, > since FreeBSD only supports about 5 of them. We can probably arrange > for a more minimal configuration in our build system, but since the > build time saved is quite small, I don't think it makes much sense in > complicating our build system even further. > > If people are really so interested in shaving off a little, for more > complication, that is fine with me. But unfortunately, I have too many > tasks on my plate right now, and I cannot work on it. Besides, doing > such a new feature now would interfere with the current branch work. With the recent parallelism work, the is true. It might save a couple percent off the build time. Before those changes, though, disabling all non target arches saved about 10% of the buildworld time. Creating a hack to do this is easy (which is how I measured it). But Dimitry is right that creating a robust solution is hard. Even harder if you want it to be completely clean. > Also, after the 3.5.0 import, there are much more interesting fish to > fry, in my opinion. For example, importing newer versions of libc++ and > compiler-rt, which can bring address sanitizer support, etc. I tend to agree. IMHO, supporting the work going on to bring the meta-mode stuff will pay far higher dividends than optimizing this corner of the build. Warner --Apple-Mail=_8585A9CA-84EF-42F8-B871-2B3E958B1A69 Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=signature.asc Content-Type: application/pgp-signature; name=signature.asc Content-Description: Message signed with OpenPGP using GPGMail -----BEGIN PGP SIGNATURE----- Comment: GPGTools - https://gpgtools.org iQIcBAEBCgAGBQJUkuoDAAoJEGwc0Sh9sBEAC2cP/RZEnJNk6MLxkknDLYxAZNsm pu69tosuAMV1rbYPjRjRwJxAhASrEsAq7vSGGMRjKIxtmXh5FILqm6EMPIPpnGdw zWGD6ILWp1OWCp9niZY3C6Ps4dyOERhGZwW+S5yDCRFARGBvU7G4fQ7hp9QzztPf ZJOLWeVcIYIKq0wQdeFxb5EzYRTWzg40LBBh3ko8b7ZTK4xTzuEqynGp78nrkDe3 vxeKNGZtcQCIOCHMSvZECwG8q/ZG6aim9QE9OaB8rrbMl1rdQS3Yjb4zaLNRJhaT q2YWrVo32Po7QVAlan0SymZe+wdu9pVfeqmyjvOEB2s/esjacOgAZxDc7gV2hKfE ZVE8DIyaaDItRrqTsaCPCW37/VVXrkDMTvj+5finiKf+/0BqKazLaBmLKUDRahZf ylIH+YtQB2K/wVc2POuJyfcLzyF4yCQHZdnBSaan2aonb9ob1Rovdz3FP96M+gJ5 8g3CKF87ZtnwUSAGZOZJ8mvaQvl6l8w50s8eE12KOuHJTXSJIrJZCOb9A0DBSTMS vD4VOnX0mTcXGa+4yME5j1cXHgjzqr7xxT//ofdkpbw1FXz4v/wzuVNNeKwHOdWV RJthyZVWplsoFkqetPwXUwJgWsCqkupx/1bUiYd7YWEu0BJpY9oBX44z2yc8hvm5 n1ug/eyRZtpdJOP4bqXp =k1B6 -----END PGP SIGNATURE----- --Apple-Mail=_8585A9CA-84EF-42F8-B871-2B3E958B1A69--
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