grt: add comment + small refactor

Signed-off-by: Eder Monteiro <[email protected]>

Author: eder-matheus

src/grt/src/GlobalRouter.cpp

@@ -937,6 +937,8 @@ bool GlobalRouter::findPinAccessPointPositions(
   } else if (pin.isCorePin()) {
     access_points = pin.getITerm()->getPrefAccessPoints();
   } else {
+    // For non-core cells, DRT does not assign preferred APs.
+    // Use all APs to ensure the guides covering at least one AP.
     for (const auto& [pin, aps] : pin.getITerm()->getAccessPoints()) {
       access_points.insert(access_points.end(), aps.begin(), aps.end());
     }

src/grt/src/Pin.cpp

@@ -187,11 +187,7 @@ odb::Point Pin::getPositionNearInstEdge(const odb::Rect& pin_box,
 
 bool Pin::isCorePin() const
 {
-  if (is_port_) {
-    return false;
-  }
-
-  if (connected_to_pad_or_macro_) {
+  if (iterm == nullptr) {
     return false;
   }