[PATCH 4/13] AArch64: Cleanup fenv implementation

[Wilco Dijkstra]

> Carlos O'Donell wrote:
> > ---
> >  sysdeps/aarch64/fpu/fclrexcpt.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/sysdeps/aarch64/fpu/fclrexcpt.c b/sysdeps/aarch64/fpu/fclrexcpt.c
> > index b24f0ff..4471373 100644
> > --- a/sysdeps/aarch64/fpu/fclrexcpt.c
> > +++ b/sysdeps/aarch64/fpu/fclrexcpt.c
> > @@ -28,7 +28,7 @@ feclearexcept (int excepts)
> >    excepts &= FE_ALL_EXCEPT;
> >
> >    _FPU_GETFPSR (fpsr);
> > -  fpsr_new = (fpsr & ~FE_ALL_EXCEPT) | (fpsr & FE_ALL_EXCEPT & ~excepts);
> > +  fpsr_new = fpsr & ~excepts;
> 
> OK.
> 
> The logic does seem to collapse down nicely. No need to assembly the final
> fpsr_new from the two halves.
> 
> Is the generated code better?

Absolutely - it saves 3 instructions. GCC understands ((X & ~Y) | (X & Y)) == X,
but it doesn't do (X & ~Y) | (X & Y & Z) -> X & (Z | ~Y). In any case the new
version is much easier to understand as you no longer have to figure out what
it is trying to achieve!

Thanks for the link btw, I know what to do in the future for trivial patches.
Patch 1-4 have been committed.

Wilco