[llvm] [GIsel][AArch64] Legalize <2 x i16> for G_INSERT_VECTOR_ELT (PR #65830)

[Amara Emerson via llvm-commits]

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@@ -155,3 +155,15 @@ bb:
   store i64 %tmp4, ptr %p
   ret i64 %out
 }
+
+define <2 x i16> @pr63826(<2 x i16> %vec) {
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aemerson wrote:

Yes, the test itself is a good idea. I think it can go into it's own test file if there's no existing IR test file you can find. Using PR number is also ok, like `AArch64/GlobalISel/insert-vector-elt-pr63826.ll`

https://github.com/llvm/llvm-project/pull/65830