src/hotspot/share/prims/jvm.cpp

rev 54124 : 8218628: Add detailed message to NullPointerException describing what is null.

*** 35,44 ****
--- 35,45 ----
  #include "classfile/stringTable.hpp"
  #include "classfile/systemDictionary.hpp"
  #include "classfile/vmSymbols.hpp"
  #include "gc/shared/collectedHeap.inline.hpp"
  #include "interpreter/bytecode.hpp"
+ #include "interpreter/bytecodeUtils.hpp"
  #include "jfr/jfrEvents.hpp"
  #include "logging/log.hpp"
  #include "memory/heapShared.hpp"
  #include "memory/oopFactory.hpp"
  #include "memory/referenceType.hpp"
*** 532,548 ****
  
  
  
  // java.lang.Throwable //////////////////////////////////////////////////////
  
- 
  JVM_ENTRY(void, JVM_FillInStackTrace(JNIEnv *env, jobject receiver))
    JVMWrapper("JVM_FillInStackTrace");
    Handle exception(thread, JNIHandles::resolve_non_null(receiver));
    java_lang_Throwable::fill_in_stack_trace(exception);
  JVM_END
  
  
  // java.lang.StackTraceElement //////////////////////////////////////////////
  
  
  JVM_ENTRY(void, JVM_InitStackTraceElementArray(JNIEnv *env, jobjectArray elements, jobject throwable))
--- 533,593 ----
  
  
  
  // java.lang.Throwable //////////////////////////////////////////////////////
  
  JVM_ENTRY(void, JVM_FillInStackTrace(JNIEnv *env, jobject receiver))
    JVMWrapper("JVM_FillInStackTrace");
    Handle exception(thread, JNIHandles::resolve_non_null(receiver));
    java_lang_Throwable::fill_in_stack_trace(exception);
  JVM_END
  
+ // java.lang.NullPointerException ///////////////////////////////////////////
+ 
+ JVM_ENTRY(jstring, JVM_GetExtendedNPEMessage(JNIEnv *env, jthrowable throwable))
+   oop exc = JNIHandles::resolve_non_null(throwable);
+ 
+   Method* method;
+   int bci;
+   if (!java_lang_Throwable::get_method_and_bci(exc, &method, &bci)) {
+     return NULL;
+   }
+   if (method->is_native()) {
+     return NULL;
+   }
+ 
+   ResourceMark rm(THREAD);
+   TrackingStackCreator stc(method, bci);
+   char const* reason;
+   int slot = stc.get_null_pointer_slot(bci, &reason);
+ 
+   // Build the message.
+   stringStream ss;
+   if (slot == -2) {
+     return NULL;
+   } else if (slot == -1) {
+     ss.print("There cannot be a NullPointerException at bci %d of method %s",
+              bci, method->name_and_sig_as_C_string());
+   } else if (reason == NULL) {
+     ss.print("Cannot get the reason for the NullPointerException at bci %d of method %s",
+              bci, method->name_and_sig_as_C_string());
+   } else {
+     TrackingStackSource source = stc.get_source(bci, slot, 5);
+     if (source.get_type() != TrackingStackSource::INVALID) {
+       const char *msg = source.as_string();
+       if (strncmp("The return value of", msg, strlen("The return value of")) == 0) {
+         ss.print("%s is null. ", msg);
+       } else {
+         ss.print("'%s' is null. ", msg);
+       }
+     }
+     ss.print("%s", reason);
+   }
+ 
+   oop result = java_lang_String::create_oop_from_str(ss.as_string(), CHECK_0);
+   return (jstring) JNIHandles::make_local(env, result);
+ JVM_END
  
  // java.lang.StackTraceElement //////////////////////////////////////////////
  
  
  JVM_ENTRY(void, JVM_InitStackTraceElementArray(JNIEnv *env, jobjectArray elements, jobject throwable))