Tale as old as the world - there's an ABI mismatch:
https://github.com/rust-lang/compiler-builtins/pull/527
Fortunately, newest GCCs (from v11, it seems) actually provide most of
those intrinsics (even for f64!), so that's pretty cool.
(the only intrinsics not provided by GCC are `__powisf2` & `__powidf2`,
but our codegen for AVR doesn't emit those anyway.)
Fixes https://github.com/rust-lang/rust/issues/118079.
Here using `"C"` the compiler will use `"aapcs"` or `"aapcs-vfp"`
depending on target configuration.
Of course this translates in a call to `__aeabi_fdiv` / `__aeabi_fmul`
on non-HF targets.
On `eabi` targets with +vfpv2/vfpv3 LLVM generate:
vmov s0, r1
vmov s2, r0
vdiv.f32 s0, s2, s0
vmov r0, s0
bx lr
On `eabihf` targets with +vfpv3-d16/d32/f32 +fp-only-sp LLVM generate:
vdiv.f32 s0, s0, s1
bx lr
That's exactly what We need for [div/mul][s/d]f3vfp.S
