(Apparently) Inconsistent compiler flags in um7 package.py

[manodeep]

These lines do not contain the architecture flag - which is currently set to -xCORE-AVX512 in this line. However that {FARCH} line is used in the C compiler flag: here. Are these intentional and necessary choices?

Similarly, some places have -fp-model strict while others are -fp-model precise - is that intentional as well?

[penguian]

Being able to have different flags for different compilation units is considered to be a feature of fcm make. As to why these flags were used for these particular files, it may come down to working around bugs that existed at the time. Unfortunately, much of the Trac and Subversion history of ACCESS-ESM1.5 has been lost, due to the decommissioning of trac.nci.org.au and accessdev.nci.org.au. One relevant Accessdev Wiki page has been archived: https://github.com/ACCESS-NRI/accessdev-Trac-archive/wiki/access_build_oasis3

See also https://github.com/ACCESS-NRI/UM7/blob/dev-access-esm1.6/ummodel_hg3/cfg/bld-hadgem3-mct.cfg

In summary, the choices are historical and the reasoning is lost. You may experiment with it, but there is no guarantee that the built executable will remain bitwise compatible and bug-free.

[penguian]

@manodeep @harshula Can I close this issue as WONTFIX?