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

[Sam Tebbs via llvm-commits]

================
@@ -23911,6 +23911,87 @@ Examples:
       %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_loop_dependence_war_mask:
+.. _int_experimental_loop_dependence_raw_mask:
+
+'``llvm.experimental.loop.dependence.raw.mask.*``' and '``llvm.experimental.loop.dependence.war.mask.*``' Intrinsics
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+Syntax:
+"""""""
+This is an overloaded intrinsic.
+
+::
+
+      declare <4 x i1> @llvm.experimental.loop.dependence.raw.mask.v4i1(ptr %ptrA, ptr %ptrB, i64 immarg %elementSize)
+      declare <8 x i1> @llvm.experimental.loop.dependence.war.mask.v8i1(ptr %ptrA, ptr %ptrB, i64 immarg %elementSize)
+      declare <16 x i1> @llvm.experimental.loop.dependence.raw.mask.v16i1(ptr %ptrA, ptr %ptrB, i64 immarg %elementSize)
+      declare <vscale x 16 x i1> @llvm.experimental.loop.dependence.war.mask.nxv16i1(ptr %ptrA, ptr %ptrB, i64 immarg %elementSize)
+
+
+Overview:
+"""""""""
+
+Create a mask enabling lanes that do not overlap between two pointers
+across one vector loop iteration.
+
+
+Arguments:
+""""""""""
+
+The first two arguments are pointers and the last argument is an immediate.
+The result is a vector with the i1 element type.
+
+Semantics:
+""""""""""
+
+``%elementSize`` is the size of the accessed elements in bytes.
+The intrinsic will return poison if ``%ptrA`` and ``%ptrB`` are within
+VF * ``%elementSize`` of each other and ``%ptrA`` + VF * ``%elementSize`` wraps.
+The '``llvm.experimental.loop.dependence.war.mask*``' intrinsics are semantically
+equivalent to:
+
+::
+
+      %diff = (%ptrB - %ptrA) / %elementSize
+      %m[i] = (icmp ult i, %diff) || (%diff <= 0)
----------------
SamTebbs33 wrote:

Done, do let me know if I missed anything. Thanks.

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