[llvm] [RISCV][GlobalISel] Legalize G_ADD, G_SUB, G_AND, G_OR, G_XOR on RISC-V Vector Extension (PR #71400)

[Jiahan Xie via llvm-commits]

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@@ -181,3 +181,330 @@ body:             |
     PseudoRET implicit $x10, implicit $x11, implicit $x12
 
 ...
+---
+name:  test_nxv1s8
+body:   |
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jiahanxie353 wrote:

I saw you reorganized the testing directory.

> I think I would prefer a separate test file in test/CodeGen/RISCV/GlobalISel/legalizer/rvv/ 

you mean I should create a new folder `rvv/` on top your recent commits?
I don't have a strong opinion regarding where to place vector tests, [AArch64 mixed scalar and vector together](https://github.com/llvm/llvm-project/blob/main/llvm/test/CodeGen/AArch64/GlobalISel/legalize-add.mir) by the way.

https://github.com/llvm/llvm-project/pull/71400