[clang] [llvm] [ARM][Clang] Make `+nosimd` functional for AArch32 Targets (PR #130623)

[David Green via llvm-commits]

davemgreen wrote:

NEON is never mandatory AFAIU in the architecture (FP too). We might assume it to be present though, as I believe it comes from the default -mfpu. (For example FK_CRYPTO_NEON_FP_ARMV8 from armv8-a).

Using something like this: https://godbolt.org/z/EKEMsaMdW. If I take this patch and remove the ARM::AEK_SIMD from the ARM_ARCH and ARM_CPU_NAME definitions it still seems to do OK. Is there some other reason that AEK_SIMD needs to be added to them? I tried some combinations of -march=..[+[no]fp] and -mfpu=... but they seemed OK and the tests passed. ARM::getFPUFeatures gets used in quite a few places though so something else might be going wrong.

https://github.com/llvm/llvm-project/pull/130623