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

[Matt Arsenault via llvm-commits]

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@@ -1500,6 +1500,13 @@ def G_SPLAT_VECTOR: GenericInstruction {
   let hasSideEffects = false;
 }
 
+// Generic masked compress.
+def G_MCOMPRESS: GenericInstruction {
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arsenm wrote:

Should match the IR operation name and spill out the masked_compress 

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