Bug#1031414: clinfo breaks libgpuarray autopkgtest on i386: numerical deltas

[Adrian Bunk]

On Thu, Feb 16, 2023 at 11:34:32PM +0100, Andreas Beckmann wrote:
>...
> On Thu, 16 Feb 2023 21:46:31 +0000 "Rebecca N. Palmer"
> <rebecca_palmer at zoho.com> wrote:
> > The trigger is probably pocl, not clinfo.  I don't yet know whether the
> > bug is in pocl or libgpuarray.
> or llvm-15
> 
> pocl/sid is built against llvm-15, pocl/testing against llvm-14
> 
> This also causes a test regression in pyopencl due to numerical differences
> (#1030298). This was attempted to be fixed in pyopencl upstream by requiring
> the numerical difference to be below some tolerance level instead of
> requiring equality, but the numerical delta is too large to hide behind that
> ...
>...

FYI:

$ clang-15 -march=i686 -O2 test_fmod.c -lm && ./a.out
a=0 b=0.1 c=0 d=0 abserr=0 relerr=0
a=0.1 b=0.1221239 c=0.1 d=0.1 abserr=0 relerr=0
a=0.2 b=0.14424779 c=0.055752218 d=0.055752214 abserr=-3.72529e-09 relerr=-2.58256e-08
a=0.3 b=0.16637169 c=0.13362832 d=0.13362831 abserr=-1.49012e-08 relerr=-8.95655e-08
a=0.4 b=0.18849558 c=0.023008853 d=0.023008848 abserr=-5.58794e-09 relerr=-2.96449e-08
a=0.5 b=0.21061946 c=0.078761071 d=0.078761071 abserr=0 relerr=0
a=0.6 b=0.23274337 c=0.13451329 d=0.13451326 abserr=-2.98023e-08 relerr=-1.28048e-07 FAIL
a=0.7 b=0.25486726 c=0.19026548 d=0.19026549 abserr=1.49012e-08 relerr=5.84664e-08
a=0.8 b=0.27699116 c=0.24601769 d=0.24601768 abserr=-1.49012e-08 relerr=-5.37965e-08
a=0.9 b=0.29911503 c=0.0026548803 d=0.002654904 abserr=2.37487e-08 relerr=7.93966e-08
$ clang-15 -march=i686 -O2 test_fmod.c -lm -frounding-math  && ./a.out
a=0 b=0.1 c=0 d=0 abserr=0 relerr=0
a=0.1 b=0.1221239 c=0.1 d=0.1 abserr=0 relerr=0
a=0.2 b=0.14424779 c=0.055752218 d=0.055752218 abserr=0 relerr=0
a=0.3 b=0.16637169 c=0.13362832 d=0.13362832 abserr=0 relerr=0
a=0.4 b=0.18849558 c=0.023008853 d=0.023008853 abserr=0 relerr=0
a=0.5 b=0.21061946 c=0.078761071 d=0.078761071 abserr=0 relerr=0
a=0.6 b=0.23274337 c=0.13451329 d=0.13451329 abserr=0 relerr=0
a=0.7 b=0.25486726 c=0.19026548 d=0.19026548 abserr=0 relerr=0
a=0.8 b=0.27699116 c=0.24601769 d=0.24601769 abserr=0 relerr=0
a=0.9 b=0.29911503 c=0.0026548803 d=0.0026548803 abserr=0 relerr=0
$ clang-15 -march=i686 -O2 test_fmod.c -lm -ffp-model=strict  && ./a.out
a=0 b=0.1 c=0 d=0 abserr=0 relerr=0
a=0.1 b=0.1221239 c=0.1 d=0.1 abserr=0 relerr=0
a=0.2 b=0.14424779 c=0.055752218 d=0.055752218 abserr=0 relerr=0
a=0.3 b=0.16637169 c=0.13362832 d=0.13362832 abserr=0 relerr=0
a=0.4 b=0.18849558 c=0.023008853 d=0.023008853 abserr=0 relerr=0
a=0.5 b=0.21061946 c=0.078761071 d=0.078761071 abserr=0 relerr=0
a=0.6 b=0.23274337 c=0.13451329 d=0.13451329 abserr=0 relerr=0
a=0.7 b=0.25486726 c=0.19026548 d=0.19026548 abserr=0 relerr=0
a=0.8 b=0.27699116 c=0.24601769 d=0.24601769 abserr=0 relerr=0
a=0.9 b=0.29911503 c=0.0026548803 d=0.0026548803 abserr=0 relerr=0
$ 


(-ffp-model=strict is a superset of -frounding-math)


> Andreas

cu
Adrian