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 /*

  * Copyright (c) 2010, 2011, 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

  * under the terms of the GNU General Public License version 2 only, as

  * published by the Free Software Foundation.

  *

  * This code is distributed in the hope that it will be useful, but WITHOUT

  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

  * version 2 for more details (a copy is included in the LICENSE file that

  * accompanied this code).

  *

  * You should have received a copy of the GNU General Public License version

  * 2 along with this work; if not, write to the Free Software Foundation,

  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

  *

  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

  * or visit www.oracle.com if you need additional information or have any

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  */

 // Platform-specific definitions for method handles.

 // These definitions are inlined into class MethodHandles.

 public:

 // The stack just after the recursive call from a ricochet frame

 // looks something like this.  Offsets are marked in words, not bytes.

 // rsi (r13 on LP64) is part of the interpreter calling sequence

 // which tells the callee where is my real rsp (for frame walking).

 // (...lower memory addresses)

 // rsp:     [ return pc                 ]   always the global RicochetBlob::bounce_addr

 // rsp+1:   [ recursive arg N           ]

 // rsp+2:   [ recursive arg N-1         ]

 // ...

 // rsp+N:   [ recursive arg 1           ]

 // rsp+N+1: [ recursive method handle   ]

 // ...

 // rbp-6:   [ cleanup continuation pc   ]   <-- (struct RicochetFrame)

 // rbp-5:   [ saved target MH           ]   the MH we will call on the saved args

 // rbp-4:   [ saved args layout oop     ]   an int[] array which describes argument layout

 // rbp-3:   [ saved args pointer        ]   address of transformed adapter arg M (slot 0)

 // rbp-2:   [ conversion                ]   information about how the return value is used

 // rbp-1:   [ exact sender sp           ]   exact TOS (rsi/r13) of original sender frame

 // rbp+0:   [ saved sender fp           ]   (for original sender of AMH)

 // rbp+1:   [ saved sender pc           ]   (back to original sender of AMH)

 // rbp+2:   [ transformed adapter arg M ]   <-- (extended TOS of original sender)

 // rbp+3:   [ transformed adapter arg M-1]

 // ...

 // rbp+M+1: [ transformed adapter arg 1 ]

 // rbp+M+2: [ padding                   ] <-- (rbp + saved args base offset)

 // ...      [ optional padding]

 // (higher memory addresses...)

 //

 // The arguments originally passed by the original sender

 // are lost, and arbitrary amounts of stack motion might have

 // happened due to argument transformation.

 // (This is done by C2I/I2C adapters and non-direct method handles.)

 // This is why there is an unpredictable amount of memory between

 // the extended and exact TOS of the sender.

 // The ricochet adapter itself will also (in general) perform

 // transformations before the recursive call.

 //

 // The transformed and saved arguments, immediately above the saved

 // return PC, are a well-formed method handle invocation ready to execute.

 // When the GC needs to walk the stack, these arguments are described

 // via the saved arg types oop, an int[] array with a private format.

 // This array is derived from the type of the transformed adapter

 // method handle, which also sits at the base of the saved argument

 // bundle.  Since the GC may not be able to fish out the int[]

 // array, so it is pushed explicitly on the stack.  This may be

 // an unnecessary expense.

 //

 // The following register conventions are significant at this point:

 // rsp       the thread stack, as always; preserved by caller

 // rsi/r13   exact TOS of recursive frame (contents of [rbp-2])

 // rcx       recursive method handle (contents of [rsp+N+1])

 // rbp       preserved by caller (not used by caller)

 // Unless otherwise specified, all registers can be blown by the call.

 //

 // If this frame must be walked, the transformed adapter arguments

 // will be found with the help of the saved arguments descriptor.

 //

 // Therefore, the descriptor must match the referenced arguments.

 // The arguments must be followed by at least one word of padding,

 // which will be necessary to complete the final method handle call.

 // That word is not treated as holding an oop.  Neither is the word

 //

 // The word pointed to by the return argument pointer is not

 // treated as an oop, even if points to a saved argument.

 // This allows the saved argument list to have a "hole" in it

 // to receive an oop from the recursive call.

 // (The hole might temporarily contain RETURN_VALUE_PLACEHOLDER.)

 //

 // When the recursive callee returns, RicochetBlob::bounce_addr will

 // immediately jump to the continuation stored in the RF.

 // This continuation will merge the recursive return value

 // into the saved argument list.  At that point, the original

 // rsi, rbp, and rsp will be reloaded, the ricochet frame will

 // disappear, and the final target of the adapter method handle

 // will be invoked on the transformed argument list.

 class RicochetFrame {

   friend class MethodHandles;

  private:

   intptr_t* _continuation;          // what to do when control gets back here

   oopDesc*  _saved_target;          // target method handle to invoke on saved_args

   oopDesc*  _saved_args_layout;     // caching point for MethodTypeForm.vmlayout cookie

   intptr_t* _saved_args_base;       // base of pushed arguments (slot 0, arg N) (-3)

   intptr_t  _conversion;            // misc. information from original AdapterMethodHandle (-2)

   intptr_t* _exact_sender_sp;       // parallel to interpreter_frame_sender_sp (-1)

   intptr_t* _sender_link;           // *must* coincide with frame::link_offset (0)

   address   _sender_pc;             // *must* coincide with frame::return_addr_offset (1)

  public:

   intptr_t* continuation() const        { return _continuation; }

   oop       saved_target() const        { return _saved_target; }

   oop       saved_args_layout() const   { return _saved_args_layout; }

   intptr_t* saved_args_base() const     { return _saved_args_base; }

   intptr_t  conversion() const          { return _conversion; }

   intptr_t* exact_sender_sp() const     { return _exact_sender_sp; }

   intptr_t* sender_link() const         { return _sender_link; }

   address   sender_pc() const           { return _sender_pc; }

   intptr_t* extended_sender_sp() const  { return saved_args_base(); }

   intptr_t  return_value_slot_number() const {

     return adapter_conversion_vminfo(conversion());

   }

   BasicType return_value_type() const {

     return adapter_conversion_dest_type(conversion());

   }

   bool has_return_value_slot() const {

     return return_value_type() != T_VOID;

   }

   intptr_t* return_value_slot_addr() const {

     assert(has_return_value_slot(), "");

     return saved_arg_slot_addr(return_value_slot_number());

   }

   intptr_t* saved_target_slot_addr() const {

     return saved_arg_slot_addr(saved_args_length());

   }

   intptr_t* saved_arg_slot_addr(int slot) const {

     assert(slot >= 0, "");

     return (intptr_t*)( (address)saved_args_base() + (slot * Interpreter::stackElementSize) );

   }

   jint      saved_args_length() const;

   jint      saved_arg_offset(int arg) const;

   // GC interface

   oop*  saved_target_addr()                     { return (oop*)&_saved_target; }

   oop*  saved_args_layout_addr()                { return (oop*)&_saved_args_layout; }

   oop  compute_saved_args_layout(bool read_cache, bool write_cache);

   // Compiler/assembler interface.

   static int continuation_offset_in_bytes()     { return offset_of(RicochetFrame, _continuation); }

   static int saved_target_offset_in_bytes()     { return offset_of(RicochetFrame, _saved_target); }

   static int saved_args_layout_offset_in_bytes(){ return offset_of(RicochetFrame, _saved_args_layout); }

   static int saved_args_base_offset_in_bytes()  { return offset_of(RicochetFrame, _saved_args_base); }

   static int conversion_offset_in_bytes()       { return offset_of(RicochetFrame, _conversion); }

   static int exact_sender_sp_offset_in_bytes()  { return offset_of(RicochetFrame, _exact_sender_sp); }

   static int sender_link_offset_in_bytes()      { return offset_of(RicochetFrame, _sender_link); }

   static int sender_pc_offset_in_bytes()        { return offset_of(RicochetFrame, _sender_pc); }

   // This value is not used for much, but it apparently must be nonzero.

   static int frame_size_in_bytes()              { return sender_link_offset_in_bytes(); }

 #ifdef ASSERT

   // The magic number is supposed to help find ricochet frames within the bytes of stack dumps.

   enum { MAGIC_NUMBER_1 = 0xFEED03E, MAGIC_NUMBER_2 = 0xBEEF03E };

   static int magic_number_1_offset_in_bytes()   { return -wordSize; }

   static int magic_number_2_offset_in_bytes()   { return sizeof(RicochetFrame); }

   intptr_t magic_number_1() const               { return *(intptr_t*)((address)this + magic_number_1_offset_in_bytes()); };

   intptr_t magic_number_2() const               { return *(intptr_t*)((address)this + magic_number_2_offset_in_bytes()); };

 #endif //ASSERT

   enum { RETURN_VALUE_PLACEHOLDER = (NOT_DEBUG(0) DEBUG_ONLY(42)) };

   static void verify_offsets() NOT_DEBUG_RETURN;

   void verify() const NOT_DEBUG_RETURN; // check for MAGIC_NUMBER, etc.

   void zap_arguments() NOT_DEBUG_RETURN;

   static void generate_ricochet_blob(MacroAssembler* _masm,

                                      // output params:

                                      int* frame_size_in_words, int* bounce_offset, int* exception_offset);

   static void enter_ricochet_frame(MacroAssembler* _masm,

                                    Register rcx_recv,

                                    Register rax_argv,

                                    address return_handler,

                                    Register rbx_temp);

   static void leave_ricochet_frame(MacroAssembler* _masm,

                                    Register rcx_recv,

                                    Register new_sp_reg,

                                    Register sender_pc_reg);

   static Address frame_address(int offset = 0) {

     // The RicochetFrame is found by subtracting a constant offset from rbp.

     return Address(rbp, - sender_link_offset_in_bytes() + offset);

   }

   static RicochetFrame* from_frame(const frame& fr) {

     address bp = (address) fr.fp();

     RicochetFrame* rf = (RicochetFrame*)(bp - sender_link_offset_in_bytes());

     rf->verify();

     return rf;

   }

   static void verify_clean(MacroAssembler* _masm) NOT_DEBUG_RETURN;

 };

 // Additional helper methods for MethodHandles code generation:

 public:

   static void load_klass_from_Class(MacroAssembler* _masm, Register klass_reg);

   static void load_conversion_vminfo(MacroAssembler* _masm, Register reg, Address conversion_field_addr);

   static void load_conversion_dest_type(MacroAssembler* _masm, Register reg, Address conversion_field_addr);

   static void load_stack_move(MacroAssembler* _masm,

                               Register rdi_stack_move,

                               Register rcx_amh,

                               bool might_be_negative);

   static void insert_arg_slots(MacroAssembler* _masm,

                                RegisterOrConstant arg_slots,

                                Register rax_argslot,

                                Register rbx_temp, Register rdx_temp);

   static void remove_arg_slots(MacroAssembler* _masm,

                                RegisterOrConstant arg_slots,

                                Register rax_argslot,

                                Register rbx_temp, Register rdx_temp);

   static void push_arg_slots(MacroAssembler* _masm,

                                    Register rax_argslot,

                                    RegisterOrConstant slot_count,

                                    int skip_words_count,

                                    Register rbx_temp, Register rdx_temp);

   static void move_arg_slots_up(MacroAssembler* _masm,

                                 Register rbx_bottom,  // invariant

                                 Address  top_addr,    // can use rax_temp

                                 RegisterOrConstant positive_distance_in_slots,

                                 Register rax_temp, Register rdx_temp);

   static void move_arg_slots_down(MacroAssembler* _masm,

                                   Address  bottom_addr,  // can use rax_temp

                                   Register rbx_top,      // invariant

                                   RegisterOrConstant negative_distance_in_slots,

                                   Register rax_temp, Register rdx_temp);

   static void move_typed_arg(MacroAssembler* _masm,

                              BasicType type, bool is_element,

                              Address slot_dest, Address value_src,

                              Register rbx_temp, Register rdx_temp);

   static void move_return_value(MacroAssembler* _masm, BasicType type,

                                 Address return_slot);

   static void verify_argslot(MacroAssembler* _masm, Register argslot_reg,

                              const char* error_message) NOT_DEBUG_RETURN;

   static void verify_argslots(MacroAssembler* _masm,

                               RegisterOrConstant argslot_count,

                               Register argslot_reg,

                               bool negate_argslot,

                               const char* error_message) NOT_DEBUG_RETURN;

   static void verify_stack_move(MacroAssembler* _masm,

                                 RegisterOrConstant arg_slots,

                                 int direction) NOT_DEBUG_RETURN;

   static void verify_klass(MacroAssembler* _masm,

                            Register obj, KlassHandle klass,

                            const char* error_message = "wrong klass") NOT_DEBUG_RETURN;

   static void verify_method_handle(MacroAssembler* _masm, Register mh_reg) {

     verify_klass(_masm, mh_reg, SystemDictionaryHandles::MethodHandle_klass(),

                  "reference is a MH");

   }

   static void trace_method_handle(MacroAssembler* _masm, const char* adaptername) PRODUCT_RETURN;

   static Register saved_last_sp_register() {

     // Should be in sharedRuntime, not here.

     return LP64_ONLY(r13) NOT_LP64(rsi);

   }