[FIRRTL][LowerLayers] Update rwprobe operations if possible.

Fixes first example in llvm#7365 .

lib/Dialect/FIRRTL/Transforms/LowerLayers.cpp

@@ -430,6 +430,7 @@ void LowerLayersPass::runOnModuleBody(FModuleOp moduleOp,
     };
 
     SmallVector<hw::InnerSymAttr> innerSyms;
+    SmallVector<RWProbeOp> rwprobes;
     for (auto &op : llvm::make_early_inc_range(*body)) {
       // Record any operations inside the layer block which have inner symbols.
       // Theses may have symbol users which need to be updated.
@@ -475,6 +476,11 @@ void LowerLayersPass::runOnModuleBody(FModuleOp moduleOp,
         continue;
       }
 
+      if (auto rwprobe = dyn_cast<RWProbeOp>(op)) {
+        rwprobes.push_back(rwprobe);
+        continue;
+      }
+
       if (auto connect = dyn_cast<FConnectLike>(op)) {
         auto src = connect.getSrc();
         auto dst = connect.getDest();
@@ -589,6 +595,25 @@ void LowerLayersPass::runOnModuleBody(FModuleOp moduleOp,
                               << splice.second << "\n";);
     }
 
+    // Update RWProbe operations.
+    if (!rwprobes.empty()) {
+      for (auto rwprobe : rwprobes) {
+        auto target = rwprobe.getTarget();
+        auto mapped = innerRefMap.find(target);
+        // This should be diagnosed, need to add error reporting path for that,
+        // though.
+        if (mapped == innerRefMap.end())
+          llvm::report_fatal_error(
+              "rwprobe target not moved (not part of this block?)");
+
+        if (mapped->second.second != newModule.getModuleNameAttr())
+          llvm::report_fatal_error("inner ref mapped to different module");
+
+        rwprobe.setTargetAttr(
+            hw::InnerRefAttr::get(mapped->second.second, target.getName()));
+      }
+    }
+
     // Connect instance ports to values.
     assert(ports.size() == connectValues.size() &&
            "the number of instance ports and values to connect to them must be "