Date: Tue, 6 Aug 2013 13:47:16 -0400 From: John Baldwin <jhb@freebsd.org> To: Dimitry Andric <dim@freebsd.org> Cc: "svn-src-head@freebsd.org" <svn-src-head@freebsd.org>, Matthew Fleming <mdf@freebsd.org>, "svn-src-all@freebsd.org" <svn-src-all@freebsd.org>, "src-committers@freebsd.org" <src-committers@freebsd.org> Subject: Re: svn commit: r253802 - head/contrib/llvm/tools/clang/lib/Headers Message-ID: <201308061347.16796.jhb@freebsd.org> In-Reply-To: <A7A9F3E9-AFB6-44C3-8B3F-E28F813229F5@freebsd.org> References: <201307301233.r6UCXLT8012177@svn.freebsd.org> <201307301216.15235.jhb@freebsd.org> <A7A9F3E9-AFB6-44C3-8B3F-E28F813229F5@freebsd.org>
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On Wednesday, July 31, 2013 8:21:42 am Dimitry Andric wrote: > On Jul 30, 2013, at 18:16, John Baldwin <jhb@freebsd.org> wrote: > > On Tuesday, July 30, 2013 10:09:35 am Matthew Fleming wrote: > >> On Tue, Jul 30, 2013 at 5:33 AM, Dimitry Andric <dim@freebsd.org> wrote: > >> > >>> Author: dim > >>> Date: Tue Jul 30 12:33:21 2013 > >>> New Revision: 253802 > >>> URL: http://svnweb.freebsd.org/changeset/base/253802 > ... > >> PIC mode on amd64 also uses %ebx. The difference is that FreeBSD makefiles > >> set -fPIC for i386 kernel compile but not amd64. Locally we use -fPIC for > >> amd64 (it was added 6 years ago to our environment because it gave better > >> kernel debugging). > > > > Note that this is used in userland and the kernel. > > > >> Anyways, is there some way to detect PIC mode and use that to decide > >> whether to use %ebx for the cpuid instruction, rather than using i386? > > > > Does clang supply a reliable #define to indicate that PIC is in use? If not, > > then this should use the PIC path always to be safe. > > Just like gcc, clang defines both __pic__ and __PIC__ as 1 for -fpic, > and as 2 for -fPIC (though on x86, there is no difference between the > two). Similarly, __pie__ and __PIE__ are defined as 1 for -fpie, and as > 2 for -fPIE. Ok, can you fix the header to check for __PIC__ then and push the change upstream? Also, feel free to make any changes to bit_* that you need and push those upstream as well. -- John Baldwin
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