Date: Tue, 30 Jul 2013 07:09:35 -0700 From: Matthew Fleming <mdf@FreeBSD.org> To: Dimitry Andric <dim@freebsd.org> Cc: "svn-src-head@freebsd.org" <svn-src-head@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: <CAMBSHm8xDvWsKJiLAzPF8azMKLHq3WWWQ3X1d6-6nJSAppux9Q@mail.gmail.com> In-Reply-To: <201307301233.r6UCXLT8012177@svn.freebsd.org> References: <201307301233.r6UCXLT8012177@svn.freebsd.org>
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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 > > Log: > Pull in r186696 from upstream clang trunk: > > This patch implements __get_cpuid_max() as an inline and __cpuid() > and __cpuid_count() as macros to be compatible with GCC's cpuid.h. > It also adds bit_<foo> constants for the various feature bits as > described in version 039 (May 2011) of Intel's SDM Volume 2 in the > description of the CPUID instruction. The list of bit_<foo> > constants is a bit exhaustive (GCC doesn't do near this many). More > bits could be added from a newer version of SDM if desired. > > Patch by John Baldwin! > > This should fix several ports which depend on this functionality being > available. > > MFC after: 1 week > > Modified: > head/contrib/llvm/tools/clang/lib/Headers/cpuid.h > > Modified: head/contrib/llvm/tools/clang/lib/Headers/cpuid.h > > ============================================================================== > --- head/contrib/llvm/tools/clang/lib/Headers/cpuid.h Tue Jul 30 > 12:17:45 2013 (r253801) > +++ head/contrib/llvm/tools/clang/lib/Headers/cpuid.h Tue Jul 30 > 12:33:21 2013 (r253802) > +/* PIC on i386 uses %ebx, so preserve it. */ > +#if __i386__ > +#define __cpuid(__level, __eax, __ebx, __ecx, __edx) \ > + __asm(" pushl %%ebx\n" \ > + " cpuid\n" \ > + " mov %%ebx,%1\n" \ > + " popl %%ebx" \ > + : "=a"(__eax), "=r" (__ebx), "=c"(__ecx), "=d"(__edx) \ > + : "0"(__level)) > + > +#define __cpuid_count(__level, __count, __eax, __ebx, __ecx, __edx) \ > + __asm(" pushl %%ebx\n" \ > + " cpuid\n" \ > + " mov %%ebx,%1\n" \ > + " popl %%ebx" \ > + : "=a"(__eax), "=r" (__ebx), "=c"(__ecx), "=d"(__edx) \ > + : "0"(__level), "2"(__count)) > +#else > +#define __cpuid(__level, __eax, __ebx, __ecx, __edx) \ > + __asm("cpuid" : "=a"(__eax), "=b" (__ebx), "=c"(__ecx), "=d"(__edx) \ > + : "0"(__level)) > + > +#define __cpuid_count(__level, __count, __eax, __ebx, __ecx, __edx) \ > + __asm("cpuid" : "=a"(__eax), "=b" (__ebx), "=c"(__ecx), "=d"(__edx) \ > + : "0"(__level), "2"(__count)) > +#endif > 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). 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? Thanks, matthew
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