1 /*
   2  * Copyright (c) 1997, 2017, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  *
  23  */
  24 
  25 #ifndef SHARE_VM_RUNTIME_JAVACALLS_HPP
  26 #define SHARE_VM_RUNTIME_JAVACALLS_HPP
  27 
  28 #include "memory/allocation.hpp"
  29 #include "oops/method.hpp"
  30 #include "runtime/handles.hpp"
  31 #include "runtime/javaFrameAnchor.hpp"
  32 #include "runtime/thread.hpp"
  33 #include "runtime/vmThread.hpp"
  34 #include "utilities/macros.hpp"
  35 
  36 #include CPU_HEADER(jniTypes)
  37 
  38 // A JavaCallWrapper is constructed before each JavaCall and destructed after the call.
  39 // Its purpose is to allocate/deallocate a new handle block and to save/restore the last
  40 // Java fp/sp. A pointer to the JavaCallWrapper is stored on the stack.
  41 
  42 class JavaCallWrapper: StackObj {
  43   friend class VMStructs;
  44  private:
  45   JavaThread*      _thread;                 // the thread to which this call belongs
  46   JNIHandleBlock*  _handles;                // the saved handle block
  47   Method*          _callee_method;          // to be able to collect arguments if entry frame is top frame
  48   oop              _receiver;               // the receiver of the call (if a non-static call)
  49 
  50   JavaFrameAnchor  _anchor;                 // last thread anchor state that we must restore
  51 
  52   JavaValue*       _result;                 // result value
  53 
  54  public:
  55   // Construction/destruction
  56    JavaCallWrapper(const methodHandle& callee_method, Handle receiver, JavaValue* result, TRAPS);
  57   ~JavaCallWrapper();
  58 
  59   // Accessors
  60   JavaThread*      thread() const           { return _thread; }
  61   JNIHandleBlock*  handles() const          { return _handles; }
  62 
  63   JavaFrameAnchor* anchor(void)             { return &_anchor; }
  64 
  65   JavaValue*       result() const           { return _result; }
  66   // GC support
  67   Method*          callee_method()          { return _callee_method; }
  68   oop              receiver()               { return _receiver; }
  69   void             oops_do(OopClosure* f);
  70 
  71   bool             is_first_frame() const   { return _anchor.last_Java_sp() == NULL; }
  72 
  73 };
  74 
  75 
  76 // Encapsulates arguments to a JavaCall (faster, safer, and more convenient than using var-args)
  77 class JavaCallArguments : public StackObj {
  78  private:
  79   enum Constants {
  80    _default_size = 8    // Must be at least # of arguments in JavaCalls methods
  81   };
  82 
  83   intptr_t    _value_buffer      [_default_size + 1];
  84   u_char      _value_state_buffer[_default_size + 1];
  85 
  86   intptr_t*   _value;
  87   u_char*     _value_state;
  88   int         _size;
  89   int         _max_size;
  90   bool        _start_at_zero;      // Support late setting of receiver
  91   JVMCI_ONLY(nmethod*    _alternative_target;) // Nmethod that should be called instead of normal target
  92 
  93   void initialize() {
  94     // Starts at first element to support set_receiver.
  95     _value       = &_value_buffer[1];
  96     _value_state = &_value_state_buffer[1];
  97 
  98     _max_size = _default_size;
  99     _size = 0;
 100     _start_at_zero = false;
 101     JVMCI_ONLY(_alternative_target = NULL;)
 102   }
 103 
 104   // Helper for push_oop and the like.  The value argument is a
 105   // "handle" that refers to an oop.  We record the address of the
 106   // handle rather than the designated oop.  The handle is later
 107   // resolved to the oop by parameters().  This delays the exposure of
 108   // naked oops until it is GC-safe.
 109   template<typename T>
 110   inline int push_oop_impl(T handle, int size) {
 111     // JNITypes::put_obj expects an oop value, so we play fast and
 112     // loose with the type system.  The cast from handle type to oop
 113     // *must* use a C-style cast.  In a product build it performs a
 114     // reinterpret_cast. In a debug build (more accurately, in a
 115     // CHECK_UNHANDLED_OOPS build) it performs a static_cast, invoking
 116     // the debug-only oop class's conversion from void* constructor.
 117     JNITypes::put_obj((oop)handle, _value, size); // Updates size.
 118     return size;                // Return the updated size.
 119   }
 120 
 121  public:
 122   JavaCallArguments() { initialize(); }
 123 
 124   JavaCallArguments(Handle receiver) {
 125     initialize();
 126     push_oop(receiver);
 127   }
 128 
 129   JavaCallArguments(int max_size) {
 130     if (max_size > _default_size) {
 131       _value = NEW_RESOURCE_ARRAY(intptr_t, max_size + 1);
 132       _value_state = NEW_RESOURCE_ARRAY(u_char, max_size + 1);
 133 
 134       // Reserve room for potential receiver in value and state
 135       _value++;
 136       _value_state++;
 137 
 138       _max_size = max_size;
 139       _size = 0;
 140       _start_at_zero = false;
 141       JVMCI_ONLY(_alternative_target = NULL;)
 142     } else {
 143       initialize();
 144     }
 145   }
 146 
 147 #if INCLUDE_JVMCI
 148   void set_alternative_target(nmethod* target) {
 149     _alternative_target = target;
 150   }
 151 
 152   nmethod* alternative_target() {
 153     return _alternative_target;
 154   }
 155 #endif
 156 
 157   // The possible values for _value_state elements.
 158   enum {
 159     value_state_primitive,
 160     value_state_oop,
 161     value_state_handle,
 162     value_state_jobject,
 163     value_state_limit
 164   };
 165 
 166   inline void push_oop(Handle h) {
 167     _value_state[_size] = value_state_handle;
 168     _size = push_oop_impl(h.raw_value(), _size);
 169   }
 170 
 171   inline void push_jobject(jobject h) {
 172     _value_state[_size] = value_state_jobject;
 173     _size = push_oop_impl(h, _size);
 174   }
 175 
 176   inline void push_int(int i) {
 177     _value_state[_size] = value_state_primitive;
 178     JNITypes::put_int(i, _value, _size);
 179   }
 180 
 181   inline void push_double(double d) {
 182     _value_state[_size] = value_state_primitive;
 183     _value_state[_size + 1] = value_state_primitive;
 184     JNITypes::put_double(d, _value, _size);
 185   }
 186 
 187   inline void push_long(jlong l) {
 188     _value_state[_size] = value_state_primitive;
 189     _value_state[_size + 1] = value_state_primitive;
 190     JNITypes::put_long(l, _value, _size);
 191   }
 192 
 193   inline void push_float(float f) {
 194     _value_state[_size] = value_state_primitive;
 195     JNITypes::put_float(f, _value, _size);
 196   }
 197 
 198   // receiver
 199   Handle receiver() {
 200     assert(_size > 0, "must at least be one argument");
 201     assert(_value_state[0] == value_state_handle,
 202            "first argument must be an oop");
 203     assert(_value[0] != 0, "receiver must be not-null");
 204     return Handle((oop*)_value[0], false);
 205   }
 206 
 207   void set_receiver(Handle h) {
 208     assert(_start_at_zero == false, "can only be called once");
 209     _start_at_zero = true;
 210     _value_state--;
 211     _value--;
 212     _size++;
 213     _value_state[0] = value_state_handle;
 214     push_oop_impl(h.raw_value(), 0);
 215   }
 216 
 217   // Converts all Handles to oops, and returns a reference to parameter vector
 218   intptr_t* parameters() ;
 219   int   size_of_parameters() const { return _size; }
 220 
 221   // Verify that pushed arguments fits a given method
 222   void verify(const methodHandle& method, BasicType return_type);
 223 };
 224 
 225 // All calls to Java have to go via JavaCalls. Sets up the stack frame
 226 // and makes sure that the last_Java_frame pointers are chained correctly.
 227 //
 228 
 229 class JavaCalls: AllStatic {
 230   static void call_helper(JavaValue* result, const methodHandle& method, JavaCallArguments* args, TRAPS);
 231  public:
 232   // call_special
 233   // ------------
 234   // The receiver must be first oop in argument list
 235   static void call_special(JavaValue* result, Klass* klass, Symbol* name, Symbol* signature, JavaCallArguments* args, TRAPS);
 236 
 237   static void call_special(JavaValue* result, Handle receiver, Klass* klass, Symbol* name, Symbol* signature, TRAPS); // No args
 238   static void call_special(JavaValue* result, Handle receiver, Klass* klass, Symbol* name, Symbol* signature, Handle arg1, TRAPS);
 239   static void call_special(JavaValue* result, Handle receiver, Klass* klass, Symbol* name, Symbol* signature, Handle arg1, Handle arg2, TRAPS);
 240 
 241   // virtual call
 242   // ------------
 243 
 244   // The receiver must be first oop in argument list
 245   static void call_virtual(JavaValue* result, Klass* spec_klass, Symbol* name, Symbol* signature, JavaCallArguments* args, TRAPS);
 246 
 247   static void call_virtual(JavaValue* result, Handle receiver, Klass* spec_klass, Symbol* name, Symbol* signature, TRAPS); // No args
 248   static void call_virtual(JavaValue* result, Handle receiver, Klass* spec_klass, Symbol* name, Symbol* signature, Handle arg1, TRAPS);
 249   static void call_virtual(JavaValue* result, Handle receiver, Klass* spec_klass, Symbol* name, Symbol* signature, Handle arg1, Handle arg2, TRAPS);
 250 
 251   // Static call
 252   // -----------
 253   static void call_static(JavaValue* result, Klass* klass, Symbol* name, Symbol* signature, JavaCallArguments* args, TRAPS);
 254 
 255   static void call_static(JavaValue* result, Klass* klass, Symbol* name, Symbol* signature, TRAPS);
 256   static void call_static(JavaValue* result, Klass* klass, Symbol* name, Symbol* signature, Handle arg1, TRAPS);
 257   static void call_static(JavaValue* result, Klass* klass, Symbol* name, Symbol* signature, Handle arg1, Handle arg2, TRAPS);
 258   static void call_static(JavaValue* result, Klass* klass, Symbol* name, Symbol* signature, Handle arg1, Handle arg2, Handle arg3, TRAPS);
 259 
 260   // Low-level interface
 261   static void call(JavaValue* result, const methodHandle& method, JavaCallArguments* args, TRAPS);
 262 };
 263 
 264 #endif // SHARE_VM_RUNTIME_JAVACALLS_HPP