Date: Sat, 10 Nov 2012 01:33:40 +0100 From: Dimitry Andric <dim@FreeBSD.org> To: Steve Kargl <sgk@troutmask.apl.washington.edu> Cc: freebsd-current@freebsd.org Subject: Re: clang and static linking? Message-ID: <509DA0E4.9060906@FreeBSD.org> In-Reply-To: <509D90EC.5040302@FreeBSD.org> References: <20121108231349.GA79485@troutmask.apl.washington.edu> <509D4548.7030806@FreeBSD.org> <20121109182810.GA61338@troutmask.apl.washington.edu> <509D5BC3.9020704@FreeBSD.org> <509D90EC.5040302@FreeBSD.org>
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On 2012-11-10 00:25, Dimitry Andric wrote:
...
> The more difficult way out is to not define any duplicate functions in
> libc.a and libm.a. For the shared libraries, this should not be a
> problem, since the dynamic linker will figure out which of the two
> copies will get precedence. The functions must stay available for
> backwards compatibility reasons anyway.
>
> For static libraries, this compatibility seems to be unnecessary, as
> they will only be used to link new programs. Therefore, it would
> probably be best to remove the whole isnan.o member from libc.a, and
> move all the isnan functions to libm.a instead.
>
> Currently, isnan() is commented out in lib/msun/src/s_isnan.c, maybe we
> can enable it whenever PIC is not defined? Then we could simply skip
> building lib/libc/gen/isnan.c for libc.a.
More concretely, here is a patch that seems to achieve the above:
- Only define isnan, isnanf, __isnan and __isnanf in libc.so, not in
libc.a and libc_p.a.
- Define isnan in libm.a and libm_p.a, not in libm.so. I don't think
there is a need to define __isnan in the .a files, so I left that out.
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Index: lib/libc/gen/isnan.c
===================================================================
--- lib/libc/gen/isnan.c (revision 242841)
+++ lib/libc/gen/isnan.c (working copy)
@@ -35,6 +35,7 @@
* binary compat until we can bump libm's major version number.
*/
+#ifdef PIC
__weak_reference(__isnan, isnan);
__weak_reference(__isnanf, isnanf);
@@ -55,3 +56,4 @@ __isnanf(float f)
u.f = f;
return (u.bits.exp == 255 && u.bits.man != 0);
}
+#endif /* PIC */
Index: lib/msun/src/s_isnan.c
===================================================================
--- lib/msun/src/s_isnan.c (revision 242841)
+++ lib/msun/src/s_isnan.c (working copy)
@@ -30,8 +30,9 @@
#include "fpmath.h"
-/* Provided by libc */
-#if 0
+/* Provided by libc.so */
+#ifndef PIC
+#undef isnan
int
isnan(double d)
{
@@ -40,7 +41,7 @@ isnan(double d)
u.d = d;
return (u.bits.exp == 2047 && (u.bits.manl != 0 || u.bits.manh != 0));
}
-#endif
+#endif /* !PIC */
int
__isnanf(float f)
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