[RISCV] Add intrinsics support for RISCV XTHeadVdot Extension

[JojoR]

Summary

This patch adds clang support for XTHeadVdot extension,
which is documented here, it's based on standard vector extension v1.0:

https://github.com/T-head-Semi/thead-extension-spec

[jrtc27]

clang/include/clang/Basic/riscv_vector.td

2384

This is an ugly name that isn't consistent with anything...

clang/test/CodeGen/RISCV/rvv-intrinsics-overloaded/xtheadvdot-vmaqa.c

5 ↗

(On Diff #487648)

Still not sure if these should be in riscv_vector.h or not... probably makes sense but a part of me says no

[JojoR]

clang/test/CodeGen/RISCV/rvv-intrinsics-overloaded/xtheadvdot-vmaqa.c

5 ↗

(On Diff #487648)

Any suggestions ?

[kito-cheng]

clang/test/CodeGen/RISCV/rvv-intrinsics-overloaded/xtheadvdot-vmaqa.c

5 ↗

(On Diff #487648)

Separated header file would be better, maybe thead_vector.h, and also extend the pragma syntax to #pragma clang riscv intrinsic thead-vector.

so the content of thead_vector.h only need header guard #pragma clang riscv intrinsic thead-vector.

[JojoR]

clang/test/CodeGen/RISCV/rvv-intrinsics-overloaded/xtheadvdot-vmaqa.c

5 ↗

(On Diff #487648)

Ok & thanks, I will update later :)

[JojoR]

Separated header file would be better, maybe thead_vector.h, and also extend the pragma syntax to #pragma clang riscv intrinsic thead-vector.
so the content of thead_vector.h only need header guard #pragma clang riscv intrinsic thead-vector.

@kito-cheng From RVV pragma implementation, the 'xtheadvdot' intrinsics could been filtered out according to command line.
Of course I could add thead_vector.h and include vector.h, but is it really necessary ?

[JojoR]

@craig.topper
@kito-cheng
@asb
@eopXD
@jrtc27

Any comments or suggestions ?

[JojoR]

In D141346#4157530, @JojoR wrote:

Separated header file would be better, maybe thead_vector.h, and also extend the pragma syntax to #pragma clang riscv intrinsic thead-vector.
so the content of thead_vector.h only need header guard #pragma clang riscv intrinsic thead-vector.

@kito-cheng From RVV pragma implementation, the 'xtheadvdot' intrinsics could been filtered out according to command line.
Of course I could add thead_vector.h and include vector.h, but is it really necessary ?

@kito-cheng Ping ...

[kito-cheng]

FYI: https://reviews.llvm.org/D148308, this patch has implemented a new pragma, you can reference that to separated t-head stuffs from riscv_vector.h

[eopXD]

Unit tests?