Date: Thu, 23 Jun 2016 01:21:49 -0700 From: Mark Millard <markmi@dsl-only.net> To: Bryan Drewery <bdrewery@FreeBSD.org>, FreeBSD Current <freebsd-current@freebsd.org>, FreeBSD Toolchain <freebsd-toolchain@freebsd.org> Cc: freebsd-arm <freebsd-arm@freebsd.org>, FreeBSD PowerPC ML <freebsd-ppc@freebsd.org> Subject: Re: WITH_SYSTEM_COMPILER default on Message-ID: <6C3A4F2A-9583-49FB-B1E7-69A0044B3887@dsl-only.net> In-Reply-To: <39C98FFD-B0BB-4F25-A1D1-2447A2FDDFBD@dsl-only.net> References: <39C98FFD-B0BB-4F25-A1D1-2447A2FDDFBD@dsl-only.net>
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On 2016-Jun-21, at 3:11 PM, Mark Millard <markmi at dsl-only.net> wrote:
> Bryan Drewery bdrewery at FreeBSD.org wrote on Tue Jun 21 19:03:46 UTC =
2016 :
>=20
>> This feature is where the bootstrap compiler in buildworld is not =
built
>> if the one in /usr/bin/cc matches what would be built. It is very
>> conservative and requires a complete match of major/minor version and
>> the compiler revision (__FreeBSD_cc_version).
>>=20
>> The only complaint so far about this feature was that when we bumped =
the
>> compiler revision, too much of clang would rebuild. That was =
addressed
>> in r301277.
>>=20
>> I would like to enable this feature by default in head for 11.0.
>>=20
>> Unless there are any objections I will do so in a few days.
>>=20
>> --=20
>> Regards,
>> Bryan Drewery
>=20
> I've only been using WITH_SYSTEM_COMPILER=3D for system-clang based =
builds with the host matching TARGET_ARCH ("self hosted").
>=20
> For xtoolchain use (self-hosted or not) I've been using in my src.conf =
files for such contexts:=20
>=20
> WITHOUT_CROSS_COMPILER=3D
> WITHOUT_SYSTEM_COMPILER=3D
> WITHOUT_BINUTILS_BOOTSTRAP=3D
> WITHOUT_CLANG_BOOTSTRAP=3D
>=20
> For cross builds (all being amd64 -> something else, such as armv6, =
powerpc64, or powerpc) based on using some build of the system clang =
3.8.0 I've been using:
>=20
> WITH_CROSS_COMPILER=3D
> WITHOUT_SYSTEM_COMPILER=3D
> WITH_BINUTILS_BOOTSTRAP=3D
> WITH_CLANG_BOOTSTRAP=3D
>=20
> As I understand the history the paths for finding tools, headers, etc. =
built into the clang cross compiler were not necessarily the same as for =
the live the system compiler that has paths appropriate specifically to =
self-hosting. This helped avoid getting the wrong versions of files =
involved.
A historical example was cross builds running the live-system's ld when =
the use of ld was implicit in a clang/clang++ command instead of being a =
direct use of ${XLD}.
In other words: such implicit use of ld by /usr/bin/clang and =
/usr/bin/clang++ would not go find the ld built by =
WITH_BINUTILS_BOOTSTRAP=3D but would instead use /usr/bin/ld (which was =
for the wrong TARGET_ARCH).
It looks like testing the current handling of such WITH_SYSTEM_COMPILER=3D=
issues in a form that allows WITHOUT_CROSS_COMPILER=3D operation =
requires building not using WITH_META_MODE=3D : man src.conf says that =
WITH_META_MODE=3D enforces WITHOUT_SYSTEM_COMPILER=3D .
My normal build procedures now use WITH_META_MODE=3D so such a test =
would be special. Let me know if you want my to make such a test.
> This was true despite the normal clang code generation being able to =
target other architectures.
>=20
> As for self-hosted system-clang based builds I've been using:
>=20
> #WITH_CROSS_COMPILER=3D
> WITH_SYSTEM_COMPILER=3D
> WITH_BINUTILS_BOOTSTRAP=3D
> #WITH_CLANG_BOOTSTRAP=3D
>=20
> (So in this case I've left some things implicit in operation.)
>=20
> As stands I'll not notice the SYSTEM_COMPILER default's consequences =
because I'm always explicit about WITH vs. WITHOUT for SYSTM_COMPILER. =
If you want some sort of experiment(s), let me know.
>=20
> But I only currently have an amd64 context and a rpi2 armv6 context. =
The dual-proessor, each dual-core powerpc64 was much faster at =
self-hosted xtoolchain builds compared to any self-hosted rpi2 build but =
I do not have access to the powerpc family for now. Self-hosted amd64 =
xtoolchain builds do not work yet for normal settings: duplicate =
declarations tend to stop the builds if one leaves on the =
warnings-as-errors status for buildkernel. (At least last that I tried =
such.)
>=20
> =3D=3D=3D
> Mark Millard
> markmi at dsl-only.net
=3D=3D=3D
Mark Millard
markmi at dsl-only.net
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