aoqi@0: /*
aoqi@0:  * Copyright (c) 2004, 2012, Oracle and/or its affiliates. All rights reserved.
aoqi@0:  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
aoqi@0:  *
aoqi@0:  * This code is free software; you can redistribute it and/or modify it
aoqi@0:  * under the terms of the GNU General Public License version 2 only, as
aoqi@0:  * published by the Free Software Foundation.
aoqi@0:  *
aoqi@0:  * This code is distributed in the hope that it will be useful, but WITHOUT
aoqi@0:  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
aoqi@0:  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
aoqi@0:  * version 2 for more details (a copy is included in the LICENSE file that
aoqi@0:  * accompanied this code).
aoqi@0:  *
aoqi@0:  * You should have received a copy of the GNU General Public License version
aoqi@0:  * 2 along with this work; if not, write to the Free Software Foundation,
aoqi@0:  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
aoqi@0:  *
aoqi@0:  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
aoqi@0:  * or visit www.oracle.com if you need additional information or have any
aoqi@0:  * questions.
aoqi@0:  *
aoqi@0:  */
aoqi@0: 
aoqi@0: #include "precompiled.hpp"
aoqi@0: #include "asm/macroAssembler.hpp"
aoqi@0: #include "asm/codeBuffer.hpp"
aoqi@0: #include "memory/metaspaceShared.hpp"
aoqi@0: 
aoqi@0: // Generate the self-patching vtable method:
aoqi@0: //
aoqi@0: // This method will be called (as any other Klass virtual method) with
aoqi@0: // the Klass itself as the first argument.  Example:
aoqi@0: //
aoqi@0: //      oop obj;
aoqi@0: //      int size = obj->klass()->oop_size(this);
aoqi@0: //
aoqi@0: // for which the virtual method call is Klass::oop_size();
aoqi@0: //
aoqi@0: // The dummy method is called with the Klass object as the first
aoqi@0: // operand, and an object as the second argument.
aoqi@0: //
aoqi@0: 
aoqi@0: //=====================================================================
aoqi@0: 
aoqi@0: // All of the dummy methods in the vtable are essentially identical,
aoqi@0: // differing only by an ordinal constant, and they bear no relationship
aoqi@0: // to the original method which the caller intended. Also, there needs
aoqi@0: // to be 'vtbl_list_size' instances of the vtable in order to
aoqi@0: // differentiate between the 'vtable_list_size' original Klass objects.
aoqi@0: 
aoqi@0: #define __ masm->
aoqi@0: 
aoqi@0: void MetaspaceShared::generate_vtable_methods(void** vtbl_list,
aoqi@0:                                                    void** vtable,
aoqi@0:                                                    char** md_top,
aoqi@0:                                                    char* md_end,
aoqi@0:                                                    char** mc_top,
aoqi@0:                                                    char* mc_end) {
aoqi@0: 
aoqi@0:   intptr_t vtable_bytes = (num_virtuals * vtbl_list_size) * sizeof(void*);
aoqi@0:   *(intptr_t *)(*md_top) = vtable_bytes;
aoqi@0:   *md_top += sizeof(intptr_t);
aoqi@0:   void** dummy_vtable = (void**)*md_top;
aoqi@0:   *vtable = dummy_vtable;
aoqi@0:   *md_top += vtable_bytes;
aoqi@0: 
aoqi@0:   // Get ready to generate dummy methods.
aoqi@0: 
aoqi@0:   CodeBuffer cb((unsigned char*)*mc_top, mc_end - *mc_top);
aoqi@0:   MacroAssembler* masm = new MacroAssembler(&cb);
aoqi@0: 
aoqi@0:   Label common_code;
aoqi@0:   for (int i = 0; i < vtbl_list_size; ++i) {
aoqi@0:     for (int j = 0; j < num_virtuals; ++j) {
aoqi@0:       dummy_vtable[num_virtuals * i + j] = (void*)masm->pc();
aoqi@0: 
aoqi@0:       // Load eax with a value indicating vtable/offset pair.
aoqi@0:       // -- bits[ 7..0]  (8 bits) which virtual method in table?
aoqi@0:       // -- bits[12..8]  (5 bits) which virtual method table?
aoqi@0:       // -- must fit in 13-bit instruction immediate field.
aoqi@0:       __ movl(rax, (i << 8) + j);
aoqi@0:       __ jmp(common_code);
aoqi@0:     }
aoqi@0:   }
aoqi@0: 
aoqi@0:   __ bind(common_code);
aoqi@0: 
aoqi@0:   // Expecting to be called with "thiscall" convections -- the arguments
aoqi@0:   // are on the stack and the "this" pointer is in c_rarg0. In addition, rax
aoqi@0:   // was set (above) to the offset of the method in the table.
aoqi@0: 
aoqi@0:   __ push(c_rarg1);                     // save & free register
aoqi@0:   __ push(c_rarg0);                     // save "this"
aoqi@0:   __ mov(c_rarg0, rax);
aoqi@0:   __ shrptr(c_rarg0, 8);                // isolate vtable identifier.
aoqi@0:   __ shlptr(c_rarg0, LogBytesPerWord);
aoqi@0:   __ lea(c_rarg1, ExternalAddress((address)vtbl_list)); // ptr to correct vtable list.
aoqi@0:   __ addptr(c_rarg1, c_rarg0);          // ptr to list entry.
aoqi@0:   __ movptr(c_rarg1, Address(c_rarg1, 0));      // get correct vtable address.
aoqi@0:   __ pop(c_rarg0);                      // restore "this"
aoqi@0:   __ movptr(Address(c_rarg0, 0), c_rarg1);      // update vtable pointer.
aoqi@0: 
aoqi@0:   __ andptr(rax, 0x00ff);                       // isolate vtable method index
aoqi@0:   __ shlptr(rax, LogBytesPerWord);
aoqi@0:   __ addptr(rax, c_rarg1);              // address of real method pointer.
aoqi@0:   __ pop(c_rarg1);                      // restore register.
aoqi@0:   __ movptr(rax, Address(rax, 0));      // get real method pointer.
aoqi@0:   __ jmp(rax);                          // jump to the real method.
aoqi@0: 
aoqi@0:   __ flush();
aoqi@0: 
aoqi@0:   *mc_top = (char*)__ pc();
aoqi@0: }