/dalvik/dx/src/com/android/dx/ssa/back/RegisterAllocator.java
Java | 197 lines | 81 code | 31 blank | 85 comment | 11 complexity | de159c6a890c6c1fdd97567e95c034ba MD5 | raw file
- /*
- * 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.ssa.back;
- import com.android.dx.rop.code.RegOps;
- import com.android.dx.rop.code.RegisterSpec;
- import com.android.dx.rop.code.PlainInsn;
- import com.android.dx.rop.code.Rops;
- import com.android.dx.rop.code.SourcePosition;
- import com.android.dx.rop.code.RegisterSpecList;
- import com.android.dx.ssa.NormalSsaInsn;
- import com.android.dx.ssa.RegisterMapper;
- import com.android.dx.ssa.SsaInsn;
- import com.android.dx.ssa.SsaMethod;
- import com.android.dx.ssa.SsaBasicBlock;
- import com.android.dx.util.IntSet;
- import com.android.dx.util.IntIterator;
- import java.util.BitSet;
- import java.util.ArrayList;
- /**
- * Base class of all register allocators.
- */
- public abstract class RegisterAllocator {
- /** method being processed */
- protected final SsaMethod ssaMeth;
- /** interference graph, indexed by register in both dimensions */
- protected final InterferenceGraph interference;
- /**
- * Creates an instance. Call {@code allocateRegisters} to run.
- * @param ssaMeth method to process.
- * @param interference Interference graph, indexed by register in both
- * dimensions.
- */
- public RegisterAllocator(SsaMethod ssaMeth,
- InterferenceGraph interference) {
- this.ssaMeth = ssaMeth;
- this.interference = interference;
- }
- /**
- * Indicates whether the method params were allocated at the bottom
- * of the namespace, and thus should be moved up to the top of the
- * namespace after phi removal.
- *
- * @return {@code true} if params should be moved from low to high
- */
- public abstract boolean wantsParamsMovedHigh();
- /**
- * Runs the algorithm.
- *
- * @return a register mapper to apply to the {@code SsaMethod}
- */
- public abstract RegisterMapper allocateRegisters();
- /**
- * Returns the category (width) of the definition site of the register.
- * Returns {@code 1} for undefined registers.
- *
- * @param reg register
- * @return {@code 1..2}
- */
- protected final int getCategoryForSsaReg(int reg) {
- SsaInsn definition = ssaMeth.getDefinitionForRegister(reg);
- if (definition == null) {
- // an undefined reg
- return 1;
- } else {
- return definition.getResult().getCategory();
- }
- }
- /**
- * Returns the RegisterSpec of the definition of the register.
- *
- * @param reg {@code >= 0;} SSA register
- * @return definition spec of the register or null if it is never defined
- * (for the case of "version 0" SSA registers)
- */
- protected final RegisterSpec getDefinitionSpecForSsaReg(int reg) {
- SsaInsn definition = ssaMeth.getDefinitionForRegister(reg);
- return definition == null ? null : definition.getResult();
- }
- /**
- * Returns true if the definition site of this register is a
- * move-param (ie, this is a method parameter).
- *
- * @param reg register in question
- * @return {@code true} if this is a method parameter
- */
- protected boolean isDefinitionMoveParam(int reg) {
- SsaInsn defInsn = ssaMeth.getDefinitionForRegister(reg);
- if (defInsn instanceof NormalSsaInsn) {
- NormalSsaInsn ndefInsn = (NormalSsaInsn) defInsn;
- return ndefInsn.getOpcode().getOpcode() == RegOps.MOVE_PARAM;
- }
- return false;
- }
- /**
- * Inserts a move instruction for a specified SSA register before a
- * specified instruction, creating a new SSA register and adjusting the
- * interference graph in the process. The insn currently must be the
- * last insn in a block.
- *
- * @param insn {@code non-null;} insn to insert move before, must
- * be last insn in block
- * @param reg {@code non-null;} SSA register to duplicate
- * @return {@code non-null;} spec of new SSA register created by move
- */
- protected final RegisterSpec insertMoveBefore(SsaInsn insn,
- RegisterSpec reg) {
- SsaBasicBlock block = insn.getBlock();
- ArrayList<SsaInsn> insns = block.getInsns();
- int insnIndex = insns.indexOf(insn);
- if (insnIndex < 0) {
- throw new IllegalArgumentException (
- "specified insn is not in this block");
- }
- if (insnIndex != insns.size() - 1) {
- /*
- * Presently, the interference updater only works when
- * adding before the last insn, and the last insn must have no
- * result
- */
- throw new IllegalArgumentException(
- "Adding move here not supported:" + insn.toHuman());
- }
- /*
- * Get new register and make new move instruction.
- */
- // The new result must not have an associated local variable.
- RegisterSpec newRegSpec = RegisterSpec.make(ssaMeth.makeNewSsaReg(),
- reg.getTypeBearer());
- SsaInsn toAdd = SsaInsn.makeFromRop(
- new PlainInsn(Rops.opMove(newRegSpec.getType()),
- SourcePosition.NO_INFO, newRegSpec,
- RegisterSpecList.make(reg)), block);
- insns.add(insnIndex, toAdd);
- int newReg = newRegSpec.getReg();
- /*
- * Adjust interference graph based on what's live out of the current
- * block and what's used by the final instruction.
- */
- IntSet liveOut = block.getLiveOutRegs();
- IntIterator liveOutIter = liveOut.iterator();
- while (liveOutIter.hasNext()) {
- interference.add(newReg, liveOutIter.next());
- }
- // Everything that's a source in the last insn interferes.
- RegisterSpecList sources = insn.getSources();
- int szSources = sources.size();
- for (int i = 0; i < szSources; i++) {
- interference.add(newReg, sources.get(i).getReg());
- }
- ssaMeth.onInsnsChanged();
- return newRegSpec;
- }
- }