[clang] [llvm] [Clang][AArch64] Implement widening FMMLA intrinsics (PR #165282)

[Eli Friedman via llvm-commits]

efriedma-quic wrote:

See https://reviews.llvm.org/D113439 for similar discussion we had for RISC-V intrinsics.  Basically the same issues apply here.  The end result was that the intrinsics were reworked into their current form: the intrinsics take the mode as an argument, and an MIR pass converts the mode operand into explicit instructions to set the mode.

https://github.com/llvm/llvm-project/pull/165282