Remove stackWalks for LUDCL outside of resolveClass

There exist different points where LUDCL is refreshed by a stackWalk
where it's not needed, this commit removes these cases and stackWalking
only when it needs to.

Signed-off-by: Abdulrahman Alattas <[email protected]>

Author: rmnattas

src/java.base/share/classes/java/io/ObjectInputStream.java

@@ -568,18 +568,18 @@ private final Object readObject(Class<?> type, Class<?> caller)
 
         if (((null == curContext) || refreshLudcl) && isClassCachingEnabled) {
             oldCachedLudcl = cachedLudcl;
+            setCached = true;
 
             // If caller is not provided, follow the standard path to get the cachedLudcl.
             // Otherwise use the class loader provided by JIT as the cachedLudcl.
 
             if (caller == null) {
-                 cachedLudcl = latestUserDefinedLoader();
+                 refreshLudcl = true;
             } else {
                  cachedLudcl = caller.getClassLoader();
+                 refreshLudcl = false;
             }
 
-            setCached = true;
-            refreshLudcl = false;
             if (null == startingLudclObject) {
                 startingLudclObject = this;
             }
@@ -694,9 +694,8 @@ public Object readUnshared() throws IOException, ClassNotFoundException {
 
         if (((null == curContext) || refreshLudcl) && isClassCachingEnabled) {
             oldCachedLudcl = cachedLudcl;
-            cachedLudcl = latestUserDefinedLoader();
             setCached = true;
-            refreshLudcl = false;
+            refreshLudcl = true;
             if (null == startingLudclObject) {
                 startingLudclObject = this;
             }