Mercurial > hg > graal-jvmci-8
view graal/com.oracle.max.graal.compiler/src/com/oracle/max/graal/compiler/alloc/ComputeLinearScanOrder.java @ 3529:d683f8a40c05
Second round of refactoring.
author | Thomas Wuerthinger <thomas@wuerthinger.net> |
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date | Wed, 10 Aug 2011 00:34:29 +0200 |
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/* * Copyright (c) 2009, 2011, Oracle and/or its affiliates. All rights reserved. * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. * * This code is free software; you can redistribute it and/or modify it * under the terms of the GNU General Public License version 2 only, as * published by the Free Software Foundation. * * This code 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 General Public License * version 2 for more details (a copy is included in the LICENSE file that * accompanied this code). * * You should have received a copy of the GNU General Public License version * 2 along with this work; if not, write to the Free Software Foundation, * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. * * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA * or visit www.oracle.com if you need additional information or have any * questions. */ package com.oracle.max.graal.compiler.alloc; import java.util.*; import com.oracle.max.graal.compiler.*; import com.oracle.max.graal.compiler.debug.*; import com.oracle.max.graal.compiler.lir.*; import com.oracle.max.graal.graph.*; public final class ComputeLinearScanOrder { private final int maxBlockId; // the highest blockId of a block private int numBlocks; // total number of blocks (smaller than maxBlockId) List<LIRBlock> linearScanOrder; // the resulting list of blocks in correct order List<LIRBlock> codeEmittingOrder; final BitMap visitedBlocks; // used for recursive processing of blocks final BitMap activeBlocks; // used for recursive processing of blocks final BitMap dominatorBlocks; // temporary BitMap used for computation of dominator final int[] forwardBranches; // number of incoming forward branches for each block final List<LIRBlock> workList; // temporary list (used in markLoops and computeOrder) final LIRBlock[] loopHeaders; // accessors for visitedBlocks and activeBlocks void initVisited() { activeBlocks.clearAll(); visitedBlocks.clearAll(); } boolean isVisited(LIRBlock b) { return visitedBlocks.get(b.blockID()); } boolean isActive(LIRBlock b) { return activeBlocks.get(b.blockID()); } void setVisited(LIRBlock b) { assert !isVisited(b) : "already set"; visitedBlocks.set(b.blockID()); } void setActive(LIRBlock b) { assert !isActive(b) : "already set"; activeBlocks.set(b.blockID()); } void clearActive(LIRBlock b) { assert isActive(b) : "not already"; activeBlocks.clear(b.blockID()); } // accessors for forwardBranches void incForwardBranches(LIRBlock b) { forwardBranches[b.blockID()]++; } int decForwardBranches(LIRBlock b) { return --forwardBranches[b.blockID()]; } // accessors for final result public List<LIRBlock> linearScanOrder() { return linearScanOrder; } public ComputeLinearScanOrder(int maxBlockId, int loopCount, LIRBlock startBlock) { loopHeaders = new LIRBlock[loopCount]; this.maxBlockId = maxBlockId; visitedBlocks = new BitMap(maxBlockId); activeBlocks = new BitMap(maxBlockId); dominatorBlocks = new BitMap(maxBlockId); forwardBranches = new int[maxBlockId]; workList = new ArrayList<LIRBlock>(8); countEdges(startBlock, null); computeOrder(startBlock); printBlocks(); } /** * Traverses the CFG to analyze block and edge info. The analysis performed is: * * 1. Count of total number of blocks. * 2. Count of all incoming edges and backward incoming edges. * 3. Number loop header blocks. * 4. Create a list with all loop end blocks. */ void countEdges(LIRBlock cur, LIRBlock parent) { if (GraalOptions.TraceLinearScanLevel >= 3) { TTY.println("Counting edges for block B%d%s", cur.blockID(), parent == null ? "" : " coming from B" + parent.blockID()); } if (isActive(cur)) { return; } // increment number of incoming forward branches incForwardBranches(cur); if (isVisited(cur)) { if (GraalOptions.TraceLinearScanLevel >= 3) { TTY.println("block already visited"); } return; } numBlocks++; setVisited(cur); setActive(cur); // recursive call for all successors int i; for (i = cur.numberOfSux() - 1; i >= 0; i--) { countEdges(cur.suxAt(i), cur); } clearActive(cur); if (GraalOptions.TraceLinearScanLevel >= 3) { TTY.println("Finished counting edges for block B%d", cur.blockID()); } } int computeWeight(LIRBlock cur) { // limit loop-depth to 15 bit (only for security reason, it will never be so big) int weight = (cur.loopDepth() & 0x7FFF) << 16; int curBit = 15; // this is necessary for the (very rare) case that two successive blocks have // the same loop depth, but a different loop index (can happen for endless loops // with exception handlers) // if (!cur.isLinearScanLoopHeader()) { // weight |= 1 << curBit; // } // curBit--; // loop end blocks (blocks that end with a backward branch) are added // after all other blocks of the loop. if (!cur.isLinearScanLoopEnd()) { weight |= 1 << curBit; } curBit--; // critical edge split blocks are preferred because then they have a greater // probability to be completely empty //if (cur.isCriticalEdgeSplit()) { // weight |= 1 << curBit; //} //curBit--; // exceptions should not be thrown in normal control flow, so these blocks // are added as late as possible // if (!(cur.end() instanceof Throw) && (singleSux == null || !(singleSux.end() instanceof Throw))) { // weight |= 1 << curBit; // } // curBit--; // if (!(cur.end() instanceof Return) && (singleSux == null || !(singleSux.end() instanceof Return))) { // weight |= 1 << curBit; // } // curBit--; // exceptions handlers are added as late as possible if (!cur.isExceptionEntry()) { weight |= 1 << curBit; } curBit--; // guarantee that weight is > 0 weight |= 1; assert curBit >= 0 : "too many flags"; assert weight > 0 : "weight cannot become negative"; return weight; } private boolean readyForProcessing(LIRBlock cur) { // Discount the edge just traveled. // When the number drops to zero, all forward branches were processed if (decForwardBranches(cur) != 0) { return false; } assert !linearScanOrder.contains(cur) : "block already processed (block can be ready only once)"; assert !workList.contains(cur) : "block already in work-list (block can be ready only once)"; return true; } private void sortIntoWorkList(LIRBlock cur) { assert !workList.contains(cur) : "block already in work list"; int curWeight = computeWeight(cur); // the linearScanNumber is used to cache the weight of a block cur.setLinearScanNumber(curWeight); if (GraalOptions.StressLinearScan) { workList.add(0, cur); return; } workList.add(null); // provide space for new element int insertIdx = workList.size() - 1; while (insertIdx > 0 && workList.get(insertIdx - 1).linearScanNumber() > curWeight) { workList.set(insertIdx, workList.get(insertIdx - 1)); insertIdx--; } workList.set(insertIdx, cur); if (GraalOptions.TraceLinearScanLevel >= 3) { TTY.println("Sorted B%d into worklist. new worklist:", cur.blockID()); for (int i = 0; i < workList.size(); i++) { TTY.println(String.format("%8d B%02d weight:%6x", i, workList.get(i).blockID(), workList.get(i).linearScanNumber())); } } for (int i = 0; i < workList.size(); i++) { assert workList.get(i).linearScanNumber() > 0 : "weight not set"; assert i == 0 || workList.get(i - 1).linearScanNumber() <= workList.get(i).linearScanNumber() : "incorrect order in worklist"; } } private void appendBlock(LIRBlock cur) { if (GraalOptions.TraceLinearScanLevel >= 3) { TTY.println("appending block B%d (weight 0x%06x) to linear-scan order", cur.blockID(), cur.linearScanNumber()); } assert !linearScanOrder.contains(cur) : "cannot add the same block twice"; // currently, the linear scan order and code emit order are equal. // therefore the linearScanNumber and the weight of a block must also // be equal. cur.setLinearScanNumber(linearScanOrder.size()); linearScanOrder.add(cur); if (!cur.isLinearScanLoopHeader() || !GraalOptions.OptReorderLoops) { codeEmittingOrder.add(cur); if (cur.isLinearScanLoopEnd() && GraalOptions.OptReorderLoops) { LIRBlock loopHeader = loopHeaders[cur.loopIndex()]; assert loopHeader != null; codeEmittingOrder.add(loopHeader); for (LIRBlock succ : loopHeader.blockSuccessors()) { if (succ.loopDepth() == loopHeader.loopDepth()) { succ.setAlign(true); } } } } else { loopHeaders[cur.loopIndex()] = cur; } } private void computeOrder(LIRBlock startBlock) { if (GraalOptions.TraceLinearScanLevel >= 3) { TTY.println("----- computing final block order"); } // the start block is always the first block in the linear scan order linearScanOrder = new ArrayList<LIRBlock>(numBlocks); codeEmittingOrder = new ArrayList<LIRBlock>(numBlocks); // start processing with standard entry block assert workList.isEmpty() : "list must be empty before processing"; assert readyForProcessing(startBlock); sortIntoWorkList(startBlock); do { LIRBlock cur = workList.remove(workList.size() - 1); appendBlock(cur); int i; int numSux = cur.numberOfSux(); // changed loop order to get "intuitive" order of if- and else-blocks for (i = 0; i < numSux; i++) { LIRBlock sux = cur.suxAt(i); if (readyForProcessing(sux)) { sortIntoWorkList(sux); } } } while (workList.size() > 0); } public void printBlocks() { if (GraalOptions.TraceLinearScanLevel >= 2) { TTY.println("----- loop information:"); for (LIRBlock cur : linearScanOrder) { TTY.print(String.format("%4d: B%02d: ", cur.linearScanNumber(), cur.blockID())); TTY.println(String.format(" . loopIndex: %2d, loopDepth: %2d", cur.loopIndex(), cur.loopDepth())); } } if (GraalOptions.TraceLinearScanLevel >= 1) { TTY.println("----- linear-scan block order:"); for (LIRBlock cur : linearScanOrder) { TTY.print(String.format("%4d: B%02d loop: %2d depth: %2d", cur.linearScanNumber(), cur.blockID(), cur.loopIndex(), cur.loopDepth())); TTY.print(cur.isLinearScanLoopHeader() ? " lh" : " "); TTY.print(cur.isLinearScanLoopEnd() ? " le" : " "); TTY.print(" dom: null "); if (cur.numberOfPreds() > 0) { TTY.print(" preds: "); for (int j = 0; j < cur.numberOfPreds(); j++) { LIRBlock pred = cur.predAt(j); TTY.print("B%d ", pred.blockID()); } } if (cur.numberOfSux() > 0) { TTY.print(" sux: "); for (int j = 0; j < cur.numberOfSux(); j++) { LIRBlock sux = cur.suxAt(j); TTY.print("B%d ", sux.blockID()); } } TTY.println(); } } } public List<LIRBlock> codeEmittingOrder() { return codeEmittingOrder; } }