The ARM Runtime ABI document (IHI0043) defines the AEABI floating point helper functions in section 4.1.2 The floating-point helper functions.
The functions listed in this section must always use the base AAPCS calling convention.
This test generates calls to all the helper functions that llvm supports and checks that the base AAPCS calling convention has been used. We test the equivalent of -mfloat-abi=soft, -mfloat-abi=softfp, -mfloat-abi=hardfp with an FPU that supports single and double precision, and one that only supports double precision.
This additional test has been added as a part of a change to clang under D35538
This test isn't really great... I mean, you checking for the presence of the important instruction, but you aren't checking for the lack of other instructions. Maybe use CHECK-NEXT to explicitly check the entire body? (You can use utils/update_llc_test_checks.py to do this automatically.)