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

[Lawrence Benson via llvm-commits]

================
@@ -19197,6 +19197,71 @@ the follow sequence of operations:
 
 The ``mask`` operand will apply to at least the gather and scatter operations.
 
+
+.. _int_masked_compress:
+
+'``llvm.masked.compress.*``' Intrinsics
----------------
lawben wrote:

I do not know what the convention is for adding this in experimental or not. Would the flow be to have it experimental for a release or two and then make it "normal"? I don't have an opinion on this, so I'm happy to follow whatever the recommended way is.

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