This patch adds fp8 variants to existing intrinsics, whose operation
doesn't depend on arguments being a specific type.
It also changes mfloat8 type representation in memory from `i8` to
`<1xi8>`
Reimplement Neon FP8 vector types using attribute `neon_vector_type`
instead of having them as builtin types.
This allows to implement FP8 Neon intrinsics without the need to add
special cases for these types when using `__builtin_shufflevector`
or bitcast (using C-style cast operator) between vectors, both
extensively used in the generated code in `arm_neon.h`.
The scalar __mfp8 type has the wrong name and mangle name in
AArch64SVEACLETypes.def
According to the ACLE[1] the name should be __mfp8
This patch fixes this problem by replacing
the Name __MFloat8_t by __mfp8
and
the Mangle Name __MFloat8_t by u6__mfp8
And we revert the incorrect typedef in NeonEmitter.
[1]https://github.com/ARM-software/acle
ARM ACLE PR#323[1] adds new modal types for 8-bit floating point
intrinsic.
From the PR#323:
```
ACLE defines the `__mfp8` type, which can be used for the E5M2 and E4M3
8-bit floating-point formats. It is a storage and interchange only type
with no arithmetic operations other than intrinsic calls.
````
The type should be an opaque type and its format in undefined in Clang.
Only defined in the backend by a status/format register, for AArch64 the
FPMR.
This patch is an attempt to the add the mfloat8_t scalar type. It has a
parser and codegen for the new scalar type.
The patch it is lowering to and 8bit unsigned as it has no format. But
maybe we should add another opaque type.
[1] https://github.com/ARM-software/acle/pull/323
