/*
* $Id$
*
* Copyright (C) 2003-2014 JNode.org
*
* This library is free software; you can redistribute it and/or modify it
* under the terms of the GNU Lesser General Public License as published
* by the Free Software Foundation; either version 2.1 of the License, or
* (at your option) any later version.
*
* This library 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 Lesser General Public
* License for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with this library; If not, write to the Free Software Foundation, Inc.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/
package org.jnode.vm.x86.compiler;
import org.jnode.assembler.ObjectResolver;
import org.jnode.assembler.x86.X86Assembler;
import org.jnode.assembler.x86.X86Register;
import org.jnode.util.LittleEndian;
import org.jnode.vm.classmgr.ObjectLayout;
import org.jnode.vm.classmgr.TIBLayout;
import org.jnode.vm.classmgr.VmArray;
import org.jnode.vm.classmgr.VmClassLoader;
import org.jnode.vm.classmgr.VmMethod;
import org.jnode.vm.compiler.CompiledIMT;
import org.jnode.vm.compiler.IMTCompiler;
import static org.jnode.vm.x86.compiler.X86CompilerConstants.BITS32;
/**
* @author Ewout Prangsma (epr@users.sourceforge.net)
*/
public final class X86IMTCompiler32 extends IMTCompiler {
/**
* Register that holds the selector
*/
public static final X86Register SELECTOR_REG = X86Register.EDX;
/**
* Size in bytes of an entry in the IMT jump table generated by this method.
*/
private static final int IMT_ENTRY_SIZE = 6;
/**
* Initialize this instance.
*/
public X86IMTCompiler32() {
}
/**
* Generate the actual invocation code of an interface method. Inputs: EDI
* statics table (EDI is preserved) EAX object to invoke method on (EAX is
* destroyed)
*
* @param os
* @param method
*/
public static void emitInvokeInterface(X86Assembler os, VmMethod method) {
final int selector = method.getSelector();
final int index = selector % ObjectLayout.IMT_LENGTH;
final int offset = (VmArray.DATA_OFFSET * 4) + (index * IMT_ENTRY_SIZE);
// For debugging only
// os.writeMOV_Const(Register.ESI, offset);
// Get tib into EAX
os.writeMOV(BITS32, X86Register.EAX, X86Register.EAX,
ObjectLayout.TIB_SLOT * 4);
// Get selector into EDX
os.writeMOV_Const(X86Register.EDX, selector);
// Get compiled IMT into EAX
os.writeMOV(BITS32, X86Register.EAX, X86Register.EAX,
(TIBLayout.COMPILED_IMT_INDEX + VmArray.DATA_OFFSET) * 4);
// Call to offset within compiled IMT
os.writeLEA(X86Register.EAX, X86Register.EAX, offset);
os.writeCALL(X86Register.EAX);
}
/**
* Initialize this compiler
*
* @param loader
*/
public void initialize(VmClassLoader loader) {
// Nothing to do
}
/**
* @see org.jnode.vm.compiler.IMTCompiler#compile(ObjectResolver, Object[],
* boolean[])
*/
public CompiledIMT compile(ObjectResolver resolver__, Object[] imt, boolean[] imtCollisions) {
final int imtLength = imt.length;
// Calculate size of code array
int size = imtLength * IMT_ENTRY_SIZE;
for (int i = 0; i < imtLength; i++) {
if (imtCollisions[i]) {
final Object[] arr = (Object[]) imt[i];
size += arr.length * 15;
}
}
final byte[] code = new byte[size];
// Create the jump table
int extraIndex = imtLength * IMT_ENTRY_SIZE;
for (int i = 0; i < imtLength; i++) {
final int ofsStart = i * IMT_ENTRY_SIZE;
int ofs = ofsStart;
if (imtCollisions[i]) {
// Complex route
final Object[] arr = (Object[]) imt[i];
final int arrLength = arr.length;
final int jmpEaxCodeOfs;
// JMP extraIndex
code[ofs++] = (byte) 0xE9;
LittleEndian.setInt32(code, ofs, (extraIndex - ofs) - 4);
ofs += 4;
// Create extra field
for (int k = 0; k < arrLength; k++) {
final VmMethod method = (VmMethod) arr[k];
if (k + 1 == arrLength) {
// Last entry, jump directly
// JMP [statics+method_statics_index]
extraIndex = genJmpStaticsCodeOfs(code, extraIndex,
method.getSharedStaticsIndex());
} else {
// Non-last entry, compare and jump of select match
// CMP selectorReg, imm32_selector
code[extraIndex++] = (byte) 0x81;
code[extraIndex++] = (byte) 0xFA;
LittleEndian.setInt32(code, extraIndex, method
.getSelector());
extraIndex += 4;
// JNE labelAfterJump
code[extraIndex++] = (byte) 0x75;
code[extraIndex++] = (byte) 0x06;
// JMP [statics+method_statics_index]
extraIndex = genJmpStaticsCodeOfs(code, extraIndex,
method.getSharedStaticsIndex());
}
}
} else if (imt[i] != null) {
// Simple route
// JMP [STATICS+staticsOfs]
final VmMethod method = (VmMethod) imt[i];
ofs = genJmpStaticsCodeOfs(code, ofs, method.getSharedStaticsIndex());
} else {
// Empty IMT slot
// INT ABSTRACT_METHOD
code[ofs++] = (byte) 0xCD;
code[ofs++] = (byte) X86CompilerConstants.ABSTRACT_METHOD_INTNO;
// Fill with NOP's
code[ofs++] = (byte) 0x90;
code[ofs++] = (byte) 0x90;
code[ofs++] = (byte) 0x90;
code[ofs++] = (byte) 0x90;
}
if (ofs > ofsStart + IMT_ENTRY_SIZE) {
throw new InternalError("Adjust IMT_ENTRY_SIZE to "
+ (ofs - ofsStart));
}
}
return new X86CompiledIMT(code);
}
/**
* Generate: JMP [STATICS+method.staticsOffset]
*
* @param code
* @param ofs
* @param staticsIndex
* @return the new offset
*/
private int genJmpStaticsCodeOfs(byte[] code, int ofs, int staticsIndex) {
final int offset = (staticsIndex + VmArray.DATA_OFFSET) * 4;
// JMP [EDI+codeOfs]
code[ofs++] = (byte) 0xFF;
code[ofs++] = (byte) 0xA7;
LittleEndian.setInt32(code, ofs, offset);
return ofs + 4;
}
}