[llvm] [X86] matchAddressRecursively - move ZERO_EXTEND patterns into matchIndexRecursively (PR #85081)

[Simon Pilgrim via llvm-commits]

================
@@ -2278,18 +2278,27 @@ static bool foldMaskedShiftToBEXTR(SelectionDAG &DAG, SDValue N,
   return false;
 }
 
-// Attempt to peek further into a scaled index register, collecting additional
-// extensions / offsets / etc. Returns /p N if we can't peek any further.
-SDValue X86DAGToDAGISel::matchIndexRecursively(SDValue N,
-                                               X86ISelAddressMode &AM,
-                                               unsigned Depth) {
+// Change the return type of matchIndexRecursively to std::optional<SDValue> to
+// make it easier for caller to tell whether the match is successful. Attempt to
+// peek further into a scaled index register, collecting additional extensions /
+// offsets / etc. Returns /p N if we can't peek any further.
+std::optional<SDValue>
+X86DAGToDAGISel::matchIndexRecursively(SDValue N, X86ISelAddressMode &AM,
+                                       unsigned Depth) {
   assert(AM.IndexReg.getNode() == nullptr && "IndexReg already matched");
   assert((AM.Scale == 1 || AM.Scale == 2 || AM.Scale == 4 || AM.Scale == 8) &&
          "Illegal index scale");
 
+  auto adapter = [this, &AM, &Depth](SDValue N) -> SDValue {
+    auto ret_val = matchIndexRecursively(N, AM, Depth + 1);
+    if (ret_val)
+      return ret_val.value();
+    return N;
----------------
RKSimon wrote:

this can all be reduced to
```
return matchIndexRecursively(N, AM, Depth + 1).value_or(N);
```

https://github.com/llvm/llvm-project/pull/85081