Re: [PATCH] Do not provide inlines for GCC build-in functions

[Andreas Jaeger <aj at suse dot de>]

On 05/17/2012 06:12 AM, Carlos O'Donell wrote:
> On Tue, May 15, 2012 at 3:36 PM, Andreas Jaeger<aj@suse.de>  wrote:
> > As mentioned previously
> > (http://sourceware.org/ml/libc-alpha/2012-05/msg00106.html), GCC 3.4
> > introduced builtin functions and thus the inlines are not needed at all.
> >
> > Patch was tested on Linux/x86-64 and I compared libc.so and libm.so and
> > found no difference in the assembly.
> >
> > Looking at math/test-idouble I found a couple of places where GCC used
> > now the builtins - instead of a function call like previously. So, GCC
> > does a better job than the inlines.
> >
> > Ok to commit?
> >
> > Andreas
> >
> > 2012-05-15  Andreas Jaeger<aj@suse.de>
> >
> >         * sysdeps/x86_64/fpu/bits/mathinline.h (lrintf): Make inline
> >         function only available for GCCs before 3.4 since GCC 3.4
> >         introduced a builtin.
> >         (lrint): Likewise.
> >         (llrintf): Likewise.
> >         (llrint): Likewise.
> >         (fmaxf): Likewise.
> >         (fmax): Likewise.
> >         (fminf): Likewise.
> >         (fmin): Likewise.
> >         (rint): Likewise.
> >         (rintf): Likewise.
> >         (nearbyint): Likewise.
> >         (nearbyintf): Likewise.
> >         (ceil): Likewise.
> >         (ceilf): Likewise.
> >         (floor): Likewise.
> >         (floorf): Likewise.
>
> So what happens if I call lrint but compile with -fno-builtins?


After the change:
The same as if you compile with -D__NO_MATH_INLINES: no inlining occurs.

But this is fine, the functions are optimizations that were added when 
gcc was not able to do them. The change for x86-64 reflects changes done 
for the i386 code in sysdeps/i386/fpu/bits/mathinline.h already.

Still the i386 code could use more of the gcc builtins, there's further 
cleanup needed...

Andreas
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