[clang] [clang] [ARM] Explicitly enable NEON for Windows/Darwin targets (PR #122095)

[Martin Storsjö via cfe-commits]

mstorsjo wrote:

Admittedly, I'm not sure if this patch really is relevant for upstream or not, as it doesn't really affect observable behaviour much at all. The main observable difference on the clang driver level is that when compiling assembly, `-target-feature` arguments are now passed on the `-cc1as` command line while there previously weren't passed any (as the implicit default was correct); this is the same as the added tests in d0fbef9c753a78aa20d5a462b682bfaf83cc6e6e. However, if https://salsa.debian.org/pkg-llvm-team/llvm-toolchain/-/blob/19/debian/patches/clang-arm-default-vfp3-on-armv7a.patch is applied, like in downstream Debian/Ubuntu distributions, this patch restores functionality for Windows/Darwin targets.

If it isn't seemed relevant/suitable for upstream, I'd request @sylvestre to pick it up and integrate into that referenced patch for future Debian/Ubuntu releases. (But I'm not sure if there are other Linux Clang downstream distributions that apply similar patches?)

https://github.com/llvm/llvm-project/pull/122095