loongarch: Use intrinsics::simd for vadda

[heiher]

No description provided.

[heiher]

Ref:

• lsx_vadda_b
• lsx_vadda_h
• lsx_vadda_w
• lsx_vadda_d
• lasx_xvadda_b
• lasx_xvadda_h
• lasx_xvadda_w
• lasx_xvadda_d

[rustbot]

r? @sayantn

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• Owners of files modified in this PR: @Amanieu, @folkertdev, @sayantn
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[sayantn]

LGTM, just one query. The reference doesn't specify what happens, e.g. for xvadda_b(-128, -128). The implementation suggests it is wrapping to 0, just making sure that it is the correct behavior

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[heiher]

LGTM, just one query. The reference doesn't specify what happens, e.g. for xvadda_b(-128, -128). The implementation suggests it is wrapping to 0, just making sure that it is the correct behavior

Yeah, I made sure that it uses wrapping addition. Thanks