Automerge: [X86] EltsFromConsecutiveLoads - add recursion depth limiter (#168694)

EltsFromConsecutiveLoads can be recursively called - ensure we limit the recursion depth.

Author: RKSimon

llvm/lib/Target/X86/X86ISelLowering.cpp

@@ -7281,7 +7281,10 @@ static bool findEltLoadSrc(SDValue Elt, LoadSDNode *&Ld, int64_t &ByteOffset) {
 static SDValue EltsFromConsecutiveLoads(EVT VT, ArrayRef<SDValue> Elts,
                                         const SDLoc &DL, SelectionDAG &DAG,
                                         const X86Subtarget &Subtarget,
-                                        bool IsAfterLegalize) {
+                                        bool IsAfterLegalize,
+                                        unsigned Depth = 0) {
+  if (Depth >= SelectionDAG::MaxRecursionDepth)
+    return SDValue(); // Limit search depth.
   if ((VT.getScalarSizeInBits() % 8) != 0)
     return SDValue();
 
@@ -7455,7 +7458,7 @@ static SDValue EltsFromConsecutiveLoads(EVT VT, ArrayRef<SDValue> Elts,
           EVT::getVectorVT(*DAG.getContext(), VT.getScalarType(), HalfNumElems);
       SDValue HalfLD =
           EltsFromConsecutiveLoads(HalfVT, Elts.drop_back(HalfNumElems), DL,
-                                   DAG, Subtarget, IsAfterLegalize);
+                                   DAG, Subtarget, IsAfterLegalize, Depth + 1);
       if (HalfLD)
         return DAG.getNode(ISD::INSERT_SUBVECTOR, DL, VT, DAG.getUNDEF(VT),
                            HalfLD, DAG.getVectorIdxConstant(0, DL));
@@ -7532,7 +7535,8 @@ static SDValue EltsFromConsecutiveLoads(EVT VT, ArrayRef<SDValue> Elts,
                            VT.getSizeInBits() / ScalarSize);
       if (TLI.isTypeLegal(BroadcastVT)) {
         if (SDValue RepeatLoad = EltsFromConsecutiveLoads(
-                RepeatVT, RepeatedLoads, DL, DAG, Subtarget, IsAfterLegalize)) {
+                RepeatVT, RepeatedLoads, DL, DAG, Subtarget, IsAfterLegalize,
+                Depth + 1)) {
           SDValue Broadcast = RepeatLoad;
           if (RepeatSize > ScalarSize) {
             while (Broadcast.getValueSizeInBits() < VT.getSizeInBits())