[llvm] [LLVM] Add `llvm.masked.compress` intrinsic (PR #92289)

[Kolya Panchenko via llvm-commits]

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@@ -24975,6 +24975,72 @@ The '``llvm.masked.compressstore``' intrinsic is designed for compressing data i
 
 Other targets may support this intrinsic differently, for example, by lowering it into a sequence of branches that guard scalar store operations.
 
+Masked Vector Compress Intrinsic
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nikolaypanchenko wrote:

Personally I find this hard to justify `masked` in just `compress` or `expand` intrinsics. Both of them do require mask to perform an operation and, like @lukel97 said, the mask is not used to read or write memory and in some sense it's similar to use of a mask in `select` instruction.
That's different to `masked.compressstore` or `masked.expandload` where mask is used to write or read memory

https://github.com/llvm/llvm-project/pull/92289