--- old/src/share/vm/runtime/javaCalls.hpp	2019-04-11 21:28:19.901991213 +0000
+++ new/src/share/vm/runtime/javaCalls.hpp	2019-04-11 21:28:19.791990513 +0000
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 1997, 2013, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 1997, 2017, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -92,25 +92,42 @@
    _default_size = 8    // Must be at least # of arguments in JavaCalls methods
   };
 
-  intptr_t    _value_buffer [_default_size + 1];
-  bool        _is_oop_buffer[_default_size + 1];
+  intptr_t    _value_buffer      [_default_size + 1];
+  u_char      _value_state_buffer[_default_size + 1];
 
   intptr_t*   _value;
-  bool*       _is_oop;
+  u_char*     _value_state;
   int         _size;
   int         _max_size;
   bool        _start_at_zero;      // Support late setting of receiver
 
   void initialize() {
     // Starts at first element to support set_receiver.
-    _value    = &_value_buffer[1];
-    _is_oop   = &_is_oop_buffer[1];
+    _value       = &_value_buffer[1];
+    _value_state = &_value_state_buffer[1];
 
     _max_size = _default_size;
     _size = 0;
     _start_at_zero = false;
   }
 
+  // Helper for push_oop and the like.  The value argument is a
+  // "handle" that refers to an oop.  We record the address of the
+  // handle rather than the designated oop.  The handle is later
+  // resolved to the oop by parameters().  This delays the exposure of
+  // naked oops until it is GC-safe.
+  template<typename T>
+  inline int push_oop_impl(T handle, int size) {
+    // JNITypes::put_obj expects an oop value, so we play fast and
+    // loose with the type system.  The cast from handle type to oop
+    // *must* use a C-style cast.  In a product build it performs a
+    // reinterpret_cast. In a debug build (more accurately, in a
+    // CHECK_UNHANDLED_OOPS build) it performs a static_cast, invoking
+    // the debug-only oop class's conversion from void* constructor.
+    JNITypes::put_obj((oop)handle, _value, size); // Updates size.
+    return size;                // Return the updated size.
+  }
+
  public:
   JavaCallArguments() { initialize(); }
 
@@ -121,11 +138,12 @@
 
   JavaCallArguments(int max_size) {
     if (max_size > _default_size) {
-      _value  = NEW_RESOURCE_ARRAY(intptr_t, max_size + 1);
-      _is_oop = NEW_RESOURCE_ARRAY(bool, max_size + 1);
+      _value = NEW_RESOURCE_ARRAY(intptr_t, max_size + 1);
+      _value_state = NEW_RESOURCE_ARRAY(u_char, max_size + 1);
 
-      // Reserve room for potential receiver in value and is_oop
-      _value++; _is_oop++;
+      // Reserve room for potential receiver in value and state
+      _value++;
+      _value_state++;
 
       _max_size = max_size;
       _size = 0;
@@ -135,25 +153,52 @@
     }
   }
 
-  inline void push_oop(Handle h)    { _is_oop[_size] = true;
-                               JNITypes::put_obj((oop)h.raw_value(), _value, _size); }
+  // The possible values for _value_state elements.
+  enum {
+    value_state_primitive,
+    value_state_oop,
+    value_state_handle,
+    value_state_jobject,
+    value_state_limit
+  };
 
-  inline void push_int(int i)       { _is_oop[_size] = false;
-                               JNITypes::put_int(i, _value, _size); }
+  inline void push_oop(Handle h) {
+    _value_state[_size] = value_state_handle;
+    _size = push_oop_impl(h.raw_value(), _size);
+  }
 
-  inline void push_double(double d) { _is_oop[_size] = false; _is_oop[_size + 1] = false;
-                               JNITypes::put_double(d, _value, _size); }
+  inline void push_jobject(jobject h) {
+    _value_state[_size] = value_state_jobject;
+    _size = push_oop_impl(h, _size);
+  }
 
-  inline void push_long(jlong l)    { _is_oop[_size] = false; _is_oop[_size + 1] = false;
-                               JNITypes::put_long(l, _value, _size); }
+  inline void push_int(int i) {
+    _value_state[_size] = value_state_primitive;
+    JNITypes::put_int(i, _value, _size);
+  }
 
-  inline void push_float(float f)   { _is_oop[_size] = false;
-                               JNITypes::put_float(f, _value, _size); }
+  inline void push_double(double d) {
+    _value_state[_size] = value_state_primitive;
+    _value_state[_size + 1] = value_state_primitive;
+    JNITypes::put_double(d, _value, _size);
+  }
+
+  inline void push_long(jlong l) {
+    _value_state[_size] = value_state_primitive;
+    _value_state[_size + 1] = value_state_primitive;
+    JNITypes::put_long(l, _value, _size);
+  }
+
+  inline void push_float(float f) {
+    _value_state[_size] = value_state_primitive;
+    JNITypes::put_float(f, _value, _size);
+  }
 
   // receiver
   Handle receiver() {
     assert(_size > 0, "must at least be one argument");
-    assert(_is_oop[0], "first argument must be an oop");
+    assert(_value_state[0] == value_state_handle,
+           "first argument must be an oop");
     assert(_value[0] != 0, "receiver must be not-null");
     return Handle((oop*)_value[0], false);
   }
@@ -161,11 +206,11 @@
   void set_receiver(Handle h) {
     assert(_start_at_zero == false, "can only be called once");
     _start_at_zero = true;
-    _is_oop--;
+    _value_state--;
     _value--;
     _size++;
-    _is_oop[0] = true;
-    _value[0] = (intptr_t)h.raw_value();
+    _value_state[0] = value_state_handle;
+    push_oop_impl(h.raw_value(), 0);
   }
 
   // Converts all Handles to oops, and returns a reference to parameter vector
@@ -173,7 +218,7 @@
   int   size_of_parameters() const { return _size; }
 
   // Verify that pushed arguments fits a given method
-  void verify(methodHandle method, BasicType return_type, Thread *thread);
+  void verify(methodHandle method, BasicType return_type);
 };
 
 // All calls to Java have to go via JavaCalls. Sets up the stack frame