[llvm] [AArch64] Add lowering for `@llvm.experimental.vector.compress` (PR #101015)

[David Green via llvm-commits]

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@@ -6615,6 +6633,132 @@ SDValue AArch64TargetLowering::LowerLOAD(SDValue Op,
   return DAG.getMergeValues({Ext, Chain}, DL);
 }
 
+SDValue AArch64TargetLowering::LowerVECTOR_COMPRESS(SDValue Op,
+                                                    SelectionDAG &DAG) const {
+  SDLoc DL(Op);
+  SDValue Vec = Op.getOperand(0);
+  SDValue Mask = Op.getOperand(1);
+  SDValue Passthru = Op.getOperand(2);
+  EVT VecVT = Vec.getValueType();
+  EVT MaskVT = Mask.getValueType();
+  EVT ElmtVT = VecVT.getVectorElementType();
+  const bool IsFixedLength = VecVT.isFixedLengthVector();
+  const bool HasPassthru = !Passthru.isUndef();
+  unsigned MinElmts = VecVT.getVectorElementCount().getKnownMinValue();
+  EVT FixedVecVT = MVT::getVectorVT(ElmtVT.getSimpleVT(), MinElmts);
+
+  assert(VecVT.isVector() && "Input to VECTOR_COMPRESS must be vector.");
+
+  if (!Subtarget->hasSVE())
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davemgreen wrote:

isSVEAvailable() I think.

https://github.com/llvm/llvm-project/pull/101015