Date: Wed, 27 Feb 2013 13:08:04 -0600 From: Brooks Davis <brooks@FreeBSD.org> To: Warner Losh <imp@bsdimp.com> Cc: freebsd-arch@FreeBSD.org Subject: Re: [RFC] external compiler support Message-ID: <20130227190804.GB17489@lor.one-eyed-alien.net> In-Reply-To: <51BB3E17-128A-4989-B272-D8B40D4B854B@bsdimp.com> References: <20130227003517.GB7348@lor.one-eyed-alien.net> <28404C12-67F3-44F0-AB28-02B749472873@bsdimp.com> <51BB3E17-128A-4989-B272-D8B40D4B854B@bsdimp.com>
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[-- Attachment #1 --] On Wed, Feb 27, 2013 at 09:08:05AM -0700, Warner Losh wrote: > Ooops, forgot to add one item.. > > > On Feb 27, 2013, at 8:57 AM, Warner Losh wrote: > > > > > On Feb 26, 2013, at 5:35 PM, Brooks Davis wrote: > > > >> Below (and at http://people.freebsd.org/~brooks/patches/xcc.diff) you > >> can find an initial patch with proposed commit for external compiler > >> support. It relies on the existing cross binutils as I'm finding that > >> the two are fairly separable. With this patch I've been able to build > >> from amd64 to arm, amd64, and i386 using clang from the lang/clang-devel > >> port. I've also compiled the tree with a customized clang being > >> developed at the University of Cambridge. > > > > Cool! > > > >> The patch is untested with gcc. > > > > I'd like to see it tested with gcc :) > > > >> Does this seem like a reasonable approach? I do plan to look at external > >> binutils support, but it's not on the critical path for our current work > >> so I've opted to avoid it for now. > > > > The patches I posted a few months ago had that as well... > > > >> As a bonus for those who don't need an external compiler, but do run > >> make buildworld frequently, the XCC, XCXX, and XCPP variables can be set > >> to the location of the installed base system compiler to avoid building > >> the compiler twice during buildworld. > > > > I think this will work, but it is kludgy. I had created a __X=<prefix-path> which was prepended to ${CC}, et al, in sys.mk. It was only defined when you set CROSS_COMPILER_PATH (or EXTERNAL_COMPILER_PATH, I forget) during the cross building stage. It also had the advantage of making external cross binutils available. Your patch could fairly easily use this interface instead of having to set 3 different variables, which will morph to 10 when you add binutil support. > I think something like this will have to be done for binutils given the way -B works, but I don't think it's workable in the general compiler case because I want to be able to use gcc46 or a future clang33 or similar as CC without changing the system compiler. Ideally I'd also like to support clang's method of finding appropriate binutils by looking first for /binutils/path/${TARGET_TRIPLE}-tool and then /binutils/path/tool. As a strawman, let's say we add a CROSS_COMPILER_PATH and a CROSS_BINUTILS_PATH. The former will set XCC, XCXX, and XCPP if they are unset. The latter will control -B and set the various binutils variables (XNM, XLD, etc). The sys.mk solution seems clean at first glance, but I don't think it's sufficently general. It's also insufficient because you need --sysroot unless you want to build a sysroot somewhere and hardcode paths to it into your toolchain. Worse, if you want rescue to work, --sysroot must be part of CC etc because crunchgen doesn't make it easy to manipulate CFLAGS. > I've also started looking into using clang --mumble to doing cross builds too, so I don't have to have 4 compilers configured and laying around for the different platforms I play with. That isn't reflected in the port. > I'm not sure what you mean by "That isn't reflected in the port". -- Brooks [-- Attachment #2 --] -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.11 (FreeBSD) iD8DBQFRLlmTXY6L6fI4GtQRAofbAKCopj7smMltMQoPyGfIgzdm2pOi5ACeNTl0 Pc/QCuHxdfM+ASNWYl1hTFA= =f5rX -----END PGP SIGNATURE-----help
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