1 #ifdef USE_PRAGMA_IDENT_SRC
   2 #pragma ident "@(#)dump_x86_64.cpp      1.13 07/09/17 09:25:59 JVM"
   3 #endif
   4 /*
   5  * Copyright 2004-2007 Sun Microsystems, Inc.  All Rights Reserved.
   6  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   7  *
   8  * This code is free software; you can redistribute it and/or modify it
   9  * under the terms of the GNU General Public License version 2 only, as
  10  * published by the Free Software Foundation.
  11  *
  12  * This code is distributed in the hope that it will be useful, but WITHOUT
  13  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  14  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  15  * version 2 for more details (a copy is included in the LICENSE file that
  16  * accompanied this code).
  17  *
  18  * You should have received a copy of the GNU General Public License version
  19  * 2 along with this work; if not, write to the Free Software Foundation,
  20  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  21  *
  22  * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
  23  * CA 95054 USA or visit www.sun.com if you need additional information or
  24  * have any questions.
  25  *  
  26  */
  27 
  28 # include "incls/_precompiled.incl"
  29 # include "incls/_dump_x86_64.cpp.incl"
  30 
  31 
  32 
  33 // Generate the self-patching vtable method:
  34 //
  35 // This method will be called (as any other Klass virtual method) with
  36 // the Klass itself as the first argument.  Example:
  37 //
  38 //      oop obj;
  39 //      int size = obj->klass()->klass_part()->oop_size(this);
  40 //
  41 // for which the virtual method call is Klass::oop_size();
  42 //
  43 // The dummy method is called with the Klass object as the first
  44 // operand, and an object as the second argument.
  45 //
  46 
  47 //=====================================================================
  48 
  49 // All of the dummy methods in the vtable are essentially identical,
  50 // differing only by an ordinal constant, and they bear no releationship
  51 // to the original method which the caller intended. Also, there needs
  52 // to be 'vtbl_list_size' instances of the vtable in order to
  53 // differentiate between the 'vtable_list_size' original Klass objects.
  54 
  55 #define __ masm->
  56 
  57 void CompactingPermGenGen::generate_vtable_methods(void** vtbl_list,
  58                                                    void** vtable,
  59                                                    char** md_top,
  60                                                    char* md_end,
  61                                                    char** mc_top,
  62                                                    char* mc_end) {
  63 
  64   intptr_t vtable_bytes = (num_virtuals * vtbl_list_size) * sizeof(void*);
  65   *(intptr_t *)(*md_top) = vtable_bytes;
  66   *md_top += sizeof(intptr_t);
  67   void** dummy_vtable = (void**)*md_top;
  68   *vtable = dummy_vtable;
  69   *md_top += vtable_bytes;
  70 
  71   // Get ready to generate dummy methods.
  72 
  73   CodeBuffer cb((unsigned char*)*mc_top, mc_end - *mc_top);
  74   MacroAssembler* masm = new MacroAssembler(&cb);
  75 
  76   Label common_code;
  77   for (int i = 0; i < vtbl_list_size; ++i) {
  78     for (int j = 0; j < num_virtuals; ++j) {
  79       dummy_vtable[num_virtuals * i + j] = (void*)masm->pc();
  80 
  81       // Load eax with a value indicating vtable/offset pair.
  82       // -- bits[ 7..0]  (8 bits) which virtual method in table?
  83       // -- bits[12..8]  (5 bits) which virtual method table?
  84       // -- must fit in 13-bit instruction immediate field.
  85       __ movl(rax, (i << 8) + j);
  86       __ jmp(common_code);
  87     }
  88   }
  89 
  90   __ bind(common_code);
  91 
  92   // Expecting to be called with "thiscall" convections -- the arguments
  93   // are on the stack and the "this" pointer is in c_rarg0. In addition, rax
  94   // was set (above) to the offset of the method in the table.
  95 
  96   __ pushq(c_rarg1);                    // save & free register
  97   __ pushq(c_rarg0);                    // save "this"
  98   __ movq(c_rarg0, rax);
  99   __ shrq(c_rarg0, 8);                  // isolate vtable identifier.
 100   __ shlq(c_rarg0, LogBytesPerWord);
 101   __ lea(c_rarg1, ExternalAddress((address)vtbl_list)); // ptr to correct vtable list.
 102   __ addq(c_rarg1, c_rarg0);            // ptr to list entry.
 103   __ movq(c_rarg1, Address(c_rarg1, 0));        // get correct vtable address.
 104   __ popq(c_rarg0);                     // restore "this"
 105   __ movq(Address(c_rarg0, 0), c_rarg1);        // update vtable pointer.
 106 
 107   __ andq(rax, 0x00ff);                 // isolate vtable method index
 108   __ shlq(rax, LogBytesPerWord);
 109   __ addq(rax, c_rarg1);                // address of real method pointer.
 110   __ popq(c_rarg1);                     // restore register.
 111   __ movq(rax, Address(rax, 0));        // get real method pointer.
 112   __ jmp(rax);                          // jump to the real method.
 113 
 114   __ flush();
 115 
 116   *mc_top = (char*)__ pc();
 117 }
 118