The initial limitation preventing from using -ffast-math, worked around
in 09df1f4caf, got fixed upstream in LLVM
and the fix is part of current DPC++ compiler:
63ecd2a725
We're now able to go back to using -ffast-math, which helps simplifying
the set of compiler flags.
No performance nor conformance change is expected from this change (most
of the gain is achieved already with the use of -cl-fast-relaxed-math
since 284b89a0a3) and this has been
verified on Arc B580 under Windows.
c4cf399755