[llvm] [AArch64][SVE] Rework VECTOR_COMPRESS lowering (PR #171162)

[Benjamin Maxwell via llvm-commits]

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@@ -263,13 +255,12 @@ define <4 x double> @test_compress_v4f64_with_sve(<4 x double> %vec, <4 x i1> %m
 define <2 x i16> @test_compress_v2i16_with_sve(<2 x i16> %vec, <2 x i1> %mask) {
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MacDue wrote:

There's no cost model at all for `vector_compress` (and AFAIK nothing emits it right now, other than compresstore, but that's not emitted automatically yet, and we don't support i16 for it). 

https://github.com/llvm/llvm-project/pull/171162