Re: [PATCH v2 00/14] GLIBC LoongArch PATCHES

[Xi Ruoyao <xry111@mengyan1223.wang>]

On Tue, 2022-01-04 at 13:27 +0000, Adhemerval Zanella via Libc-alpha wrote:
> On 31/12/2021 03:44, caiyinyu wrote:

/* snip */

> > FAIL: math/test-double-acos
> > FAIL: math/test-double-asin
> > FAIL: math/test-float32x-acos
> > FAIL: math/test-float32x-asin
> > FAIL: math/test-float64-acos
> > FAIL: math/test-float64-asin
> > 
> > These fails are caused by gcc optimizations. if we use -O0 options, these fails
> > will pass.

/* snip */

> > 338       else {
> > 339         u.i[HIGH_HALF]=0x7ff00000;
> > 340         v.i[HIGH_HALF]=0x7ff00000;
> > 341         u.i[LOW_HALF]=0;
> > 342         v.i[LOW_HALF]=0;
> > 343         return u.x/v.x;                     /////////  optimized out
> > 
> >    0x00007ffff7f4dad8 <+1432>:  pcaddu12i       $t0, 63(0x3f)
> >    0x00007ffff7f4dadc <+1436>:  addi.d          $t0, $t0, -1248(0xb20)
> >    0x00007ffff7f4dae0 <+1440>:  fld.d           $fa0, $t0, 0
> >    0x00007ffff7f4dae4 <+1444>:  b               -812(0xffffcd4) # 0x7ffff7f4d7b8 <__ieee754_acos+632>

/* snip */

> Is this being tracked by a GCC bug report? We need to understand if we
> require to use math_force_eval to avoid such issue on other ports as
> well.

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95115

This one has been haunting RISC-V for a while.
-- 
Xi Ruoyao <xry111@mengyan1223.wang>
School of Aerospace Science and Technology, Xidian University