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