[llvm] [NVPTX] Add intrinsics and codegen for tensormap.replace (PR #172458)

[Durgadoss R via llvm-commits]

================
@@ -2746,6 +2746,64 @@ lowerTcgen05Ld(SDNode *N, SelectionDAG &DAG, bool HasOffset = false) {
   return {{BuildVector, Chain}};
 }
 
+static SDValue lowerTensormapReplaceElemtype(SDValue Op, SelectionDAG &DAG) {
+  SDNode *N = Op.getNode();
+  SDLoc DL(N);
+  unsigned Val = N->getConstantOperandVal(3);
+
+  if (!DAG.getSubtarget<NVPTXSubtarget>().hasTensormapReplaceElemtypeSupport(
+          Val)) {
+    const Function &Fn = DAG.getMachineFunction().getFunction();
+
+    unsigned AS = 0;
+    if (auto *MemN = dyn_cast<MemIntrinsicSDNode>(N)) {
+      AS = MemN->getAddressSpace();
+    }
+    Type *PtrTy = PointerType::get(*DAG.getContext(), AS);
+    Module *M = DAG.getMachineFunction().getFunction().getParent();
+
+    DAG.getContext()->diagnose(DiagnosticInfoUnsupported(
+        Fn,
+        "Intrinsic " +
+            Intrinsic::getName(N->getConstantOperandVal(1), {PtrTy}, M) +
+            " with elemtype " + Twine(Val) +
+            " is not supported on the given target.",
+        DL.getDebugLoc()));
+    return Op.getOperand(0);
+  }
+
+  return Op;
+}
+
+static SDValue lowerTensormapReplaceSwizzleMode(SDValue Op, SelectionDAG &DAG) {
+  SDNode *N = Op.getNode();
+  SDLoc DL(N);
+  unsigned Val = N->getConstantOperandVal(3);
+
+  if (!DAG.getSubtarget<NVPTXSubtarget>().hasTensormapReplaceSwizzleModeSupport(
+          Val)) {
----------------
durga4github wrote:

After this check happens, the following part seems similar across both functions.
Can we refactor them into a common function to simplify these?

Eventually, we can try and find a way to get this work within tablegen itself
(i.e. including the nice diagnostic this provides)

https://github.com/llvm/llvm-project/pull/172458