[Bug libfortran/68743] [6 Regression] FAIL: gfortran.dg/aint_anint_1.f90 -O0 execution test

[sgk at troutmask dot apl.washington.edu]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=68743

--- Comment #21 from Steve Kargl <sgk at troutmask dot apl.washington.edu> ---
On Tue, Dec 15, 2015 at 08:58:23PM +0000, danglin at gcc dot gnu.org wrote:
> 
> The -fno-builtin option works and gives the best code:
> 
>         stw %r2,-20(%r30)
>         ldo 64(%r30),%r30
>         .CALL ARGW0=FR,ARGW1=FU
>         bl floor,%r2
>         fcnvff,sgl,dbl %fr4L,%fr5
>         fcnvff,dbl,sgl %fr4,%fr4L
>         ldw -84(%r30),%r2
>         bv %r0(%r2)
>         ldo -64(%r30),%r30

-fno-builtin would apply to the whole file, and may then
be a pessimization for other functions in c99_functions.c.

> The first approach in #16 can be made to work but one needs to assign
> x to a volatile double instead of retval.  The code isn't too bad but
> it introduces an unnecessary store/load pair:
> 
> float
> floorf (float x)
> {
>   volatile double y = x;
>   return (float) floor(y);
> }
> 
> gives
> 
>         stw %r2,-20(%r30)
>         fcnvff,sgl,dbl %fr4L,%fr4
>         ldo 64(%r30),%r30
>         ldo -64(%r30),%r28
>         fstds %fr4,8(%r28)
>         fldds 8(%r28),%fr5
>         .CALL ARGW0=FR,ARGW1=FU
>         bl floor,%r2
>         nop
> 

I suspect that this is the option that should be committed.
It fixes the problem and localizes the store/load penalty 
to only floorf.  If you want to commit the above fix, it's
ok with me.