[rbi] Fix an iterator invalidation issue.

Due to compile time issues, I added a cache into
getUnderlyingTrackedValue(). This caused an iterator invalidation issue when we
recursed in the case when we had an underlying object since we would recurse
into getUnderlyingTrackedValue() instead of getUnderlyingTrackedValueHelper()
potentially causing us to cache another value and thus causing the underlying
DenseMap to expand. Now we instead just call getUnderlyingTrackedValueHelper()
so that we avoid the invalidation issue. This may cause us to use slightly more
compile time but we are still only ever going to compute the underlying value
once for any specific value.

Author: gottesmm

lib/SILOptimizer/Analysis/RegionAnalysis.cpp

@@ -874,11 +874,13 @@ RegionAnalysisValueMap::getUnderlyingTrackedValueHelper(SILValue value) const {
 
   // If we have an object base...
   if (base->getType().isObject()) {
-    // ... we purposely recurse into the cached version of our computation
-    // rather than recurse into getUnderlyingTrackedObjectValueHelper. This is
-    // safe since we know that value was previously an address so if our base is
-    // an object, it cannot be the same object.
-    return UnderlyingTrackedValueInfo(getUnderlyingTrackedValue(base).value);
+    // Recurse.
+    //
+    // NOTE: We purposely recurse into getUnderlyingTrackedValueHelper instead
+    // of getUnderlyingTrackedValue since we could cause an invalidation to
+    // occur in the underlying DenseMap that backs getUnderlyingTrackedValue()
+    // if we insert another entry into the DenseMap.
+    return UnderlyingTrackedValueInfo(getUnderlyingTrackedValueHelper(base));
   }
 
   // Otherwise, we return the actorIsolation that our visitor found.