DelayFreeUses wrt CndSel node

wrap in TARGET_ARM64

Author: kunalspathak

src/coreclr/jit/lsra.h

@@ -1991,6 +1991,9 @@ class LinearScan : public LinearScanInterface
                             GenTree*         rmwNode        = nullptr,
                             SingleTypeRegSet candidates     = RBM_NONE,
                             RefPosition**    useRefPosition = nullptr);
+#ifdef TARGET_ARM64
+    int BuildDelayFreeUses(GenTree* node, GenTree* rmwNode1, GenTree* rmwNode2, SingleTypeRegSet candidates = RBM_NONE);
+#endif
     int  BuildIndirUses(GenTreeIndir* indirTree, SingleTypeRegSet candidates = RBM_NONE);
     int  BuildAddrUses(GenTree* addr, SingleTypeRegSet candidates = RBM_NONE);
 

src/coreclr/jit/lsraarm64.cpp

@@ -1979,9 +1979,9 @@ int LinearScan::BuildHWIntrinsic(GenTreeHWIntrinsic* intrinsicTree, int* pDstCou
 
             tgtPrefUse = BuildUse(emitOp1);
             srcCount += 1;
-            srcCount += BuildDelayFreeUses(emitOp2, emitOp1);
-            srcCount += BuildDelayFreeUses(emitOp3, emitOp1);
-            srcCount += BuildDelayFreeUses(intrin.op3, emitOp1);
+            srcCount += BuildDelayFreeUses(emitOp2, emitOp1, intrinsicTree);
+            srcCount += BuildDelayFreeUses(emitOp3, emitOp1, intrinsicTree);
+            srcCount += BuildDelayFreeUses(intrin.op3, emitOp1, intrinsicTree);
         }
         else
         {

src/coreclr/jit/lsrabuild.cpp

@@ -3878,6 +3878,35 @@ int LinearScan::BuildDelayFreeUses(GenTree*         node,
     return srcCount;
 }
 
+#ifdef TARGET_ARM64
+//------------------------------------------------------------------------
+// BuildDelayFreeUses: Build Use RefPositions for an operand that might be contained,
+//                     and which may need to be marked delayRegFree with respect to
+//                     two RMW nodes.
+//
+// Arguments:
+//    node              - The node of interest
+//    rmwNode1          - The node that has RMW semantics (if applicable)
+//    rmwNode2          - The node that has RMW semantics (if applicable)
+//    candidates        - The set of candidates for the uses
+//
+// Return Value:
+//    The number of source registers used by the *parent* of this node.
+//
+int LinearScan::BuildDelayFreeUses(GenTree* node, GenTree* rmwNode1, GenTree* rmwNode2, SingleTypeRegSet candidates)
+{
+    RefPosition* useRefPosition = nullptr;
+    int srcCount = BuildDelayFreeUses(node, rmwNode1, candidates, &useRefPosition);
+
+    if ((useRefPosition != nullptr) && !useRefPosition->delayRegFree)
+    {
+        AddDelayFreeUses(useRefPosition, rmwNode2);
+    }
+
+    return srcCount;
+}
+#endif // TARGET_ARM64
+
 //------------------------------------------------------------------------
 // BuildBinaryUses: Get the RefInfoListNodes for the operands of the
 //                  given node, and build uses for them.