[llvm] [LLVM][CodeGen][AArch64] Implement expansion for fixed-length get.active.lane.mask. (PR #225459)

[Luke Lau via llvm-commits]

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@@ -1737,6 +1743,47 @@ SDValue VectorLegalizer::ExpandVP_REM(SDNode *Node) {
   return DAG.getNode(ISD::SUB, DL, VT, Dividend, Mul);
 }
 
+SDValue VectorLegalizer::ExpandGET_ACTIVE_LANE_MASK(SDNode *N) {
+  SDLoc DL(N);
+
+  SDValue Start = N->getOperand(0);
+  SDValue End = N->getOperand(1);
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lukel97 wrote:

Nit, the langref calls these "Base" and "N", should we be consistent? Start and End FWIW are a bit more clear to me, we could equally update the terminology in the LangRef

https://github.com/llvm/llvm-project/pull/225459