FMS 2025.03 built with oneAPI@2025.{2,3}.1 ifx optimizes code to create a divide by zero error

[rickgrubin-noaa]

Description

For spack-stack@2.x / FMS@2025.03 (see configs/common/packages.yaml), ifx will optimize away a check for dividing by zero.

To Reproduce

See the reproducer code in the issue noted above.

Expected behavior

ifx does not optimize away checks for division by zero.

System, compiler, code, ...

• All RDHPCS hosts
• ifx@2025.{2,3}.1

Additional context

This is not a bug with spack / spack-stack per se, noting it here for the sake of completeness.

This may solved by adding the following stanza to configs/common/packages.yaml for package fms

      - any_of:
        - 'fflags="-fp-speculation=safe"'
        when: '%oneapi'
        message: Reduce aggressive speculative optimization for ifx

Note that any_of could also be one_of

[climbfuji]

Are you planning to fix this in the release/2.1 branch for 2.1.1? Since the release is only being deployed on NOAA systems, that wouldn't be a problem (bug fix PR --> retag --> reinstall).

[rickgrubin-noaa]

Are you planning to fix this in the release/2.1 branch for 2.1.1? Since the release is only being deployed on NOAA systems, that wouldn't be a problem (bug fix PR --> retag --> reinstall).

Testing the fix; awaiting commentary from Dusan.

[rickgrubin-noaa]

Are you planning to fix this in the release/2.1 branch for 2.1.1? Since the release is only being deployed on NOAA systems, that wouldn't be a problem (bug fix PR --> retag --> reinstall).

That is the plan, assuming the (temporary) fix works. This issue is blocking full successful regression testing for UFS WM and thus blocking a move to spack-stack@2.x

This would be in advance of a root fix in FMS code, and could be removed at a later date given that fix.