[llvm] [Intrinsics][AArch64] Add intrinsic to mask off aliasing vector lanes (PR #117007)

[Sam Tebbs via llvm-commits]

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@@ -23624,6 +23624,90 @@ Examples:
       %active.lane.mask = call <4 x i1> @llvm.get.active.lane.mask.v4i1.i64(i64 %elem0, i64 429)
       %wide.masked.load = call <4 x i32> @llvm.masked.load.v4i32.p0v4i32(<4 x i32>* %3, i32 4, <4 x i1> %active.lane.mask, <4 x i32> poison)
 
+.. _int_experimental_get_alias_lane_mask:
+
+'``llvm.experimental.get.alias.lane.mask.*``' Intrinsics
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+Syntax:
+"""""""
+This is an overloaded intrinsic.
+
+::
+
+      declare <4 x i1> @llvm.experimental.get.alias.lane.mask.v4i1.i64.i64(i64 %ptrA, i64 %ptrB, i64 immarg %elementSize, i1 immarg %writeAfterRead)
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SamTebbs33 wrote:

I originally chose for it to be overloaded so that targets could choose the type based on what the instruction it gets lowered to supports. But it probably makes sense to always have it be a ptr.

https://github.com/llvm/llvm-project/pull/117007