The Cortex-M7 has 3 options for it's FPU: none, FPv5-SP-D16 and FPv5-DP-D16. FPv5 has the same instructions as FP-ARMv8, so it can be modelled using the same target feature, and all double-precision operations are already disabled by the fp-only-sp target features.
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It's not a full NEON, is it? The M7 page only talks about 8/16-bit DSP related SIMD.