/*
* Copyright (C) 2007 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.android.dx.dex.code;
import com.android.dx.rop.code.RegisterSpec;
import com.android.dx.rop.code.RegisterSpecList;
import com.android.dx.rop.code.SourcePosition;
import com.android.dx.util.AnnotatedOutput;
/**
* Combination instruction which turns into a variable number of {@code move*}
* instructions to move a set of registers into registers starting at {@code 0}
* sequentially. This is used in translating an instruction whose register
* requirements cannot be met using a straightforward choice of a single opcode.
*/
public final class HighRegisterPrefix extends VariableSizeInsn {
/** {@code null-ok;} cached instructions, if constructed */
private SimpleInsn[] insns;
/**
* Constructs an instance. The output address of this instance is initially
* unknown ({@code -1}).
*
* @param position
* {@code non-null;} source position
* @param registers
* {@code non-null;} source registers
*/
public HighRegisterPrefix(SourcePosition position,
RegisterSpecList registers) {
super(position, registers);
if (registers.size() == 0) {
throw new IllegalArgumentException("registers.size() == 0");
}
insns = null;
}
/** {@inheritDoc} */
@Override
public int codeSize() {
int result = 0;
calculateInsnsIfNecessary();
for (SimpleInsn insn : insns) {
result += insn.codeSize();
}
return result;
}
/** {@inheritDoc} */
@Override
public void writeTo(AnnotatedOutput out) {
calculateInsnsIfNecessary();
for (SimpleInsn insn : insns) {
insn.writeTo(out);
}
}
/**
* Helper for {@link #codeSize} and {@link #writeTo} which sets up
* {@link #insns} if not already done.
*/
private void calculateInsnsIfNecessary() {
if (insns != null) {
return;
}
RegisterSpecList registers = getRegisters();
int sz = registers.size();
insns = new SimpleInsn[sz];
for (int i = 0, outAt = 0; i < sz; i++) {
RegisterSpec src = registers.get(i);
insns[i] = moveInsnFor(src, outAt);
outAt += src.getCategory();
}
}
/** {@inheritDoc} */
@Override
public DalvInsn withRegisters(RegisterSpecList registers) {
return new HighRegisterPrefix(getPosition(), registers);
}
public SimpleInsn[] getMoveInstructions() {
RegisterSpecList registers = getRegisters();
int sz = registers.size();
SimpleInsn[] result = new SimpleInsn[sz];
for (int i = 0, outAt = 0; i < sz; i++) {
RegisterSpec src = registers.get(i);
result[i] = moveInsnFor(src, outAt);
outAt += src.getCategory();
}
return result;
}
/** {@inheritDoc} */
@Override
protected String argString() {
return null;
}
/** {@inheritDoc} */
@Override
protected String listingString0(boolean noteIndices) {
StringBuffer sb = new StringBuffer(100);
SimpleInsn[] insns = getMoveInstructions();
boolean first = true;
for (SimpleInsn insn : insns) {
if (!first) {
sb.append('\n');
}
first = false;
sb.append(insn.listingString0(noteIndices));
}
return sb.toString();
}
/**
* Returns the proper move instruction for the given source spec and
* destination index.
*
* @param src
* {@code non-null;} the source register spec
* @param destIndex
* {@code >= 0;} the destination register index
* @return {@code non-null;} the appropriate move instruction
*/
private static SimpleInsn moveInsnFor(RegisterSpec src, int destIndex) {
return DalvInsn.makeMove(SourcePosition.NO_INFO, RegisterSpec.make(
destIndex, src.getType()), src);
}
}