/*
* 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
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*/
package com.sun.c1x.ir;
import java.util.*;
import com.sun.c1x.*;
import com.oracle.max.criutils.*;
import com.sun.c1x.util.*;
import com.sun.cri.ci.*;
public final class ComputeLinearScanOrder {
private final int maxBlockId; // the highest blockId of a block
private int numBlocks; // total number of blocks (smaller than maxBlockId)
private int numLoops; // total number of loops
private boolean iterativeDominators; // method requires iterative computation of dominators
List<BlockBegin> linearScanOrder; // the resulting list of blocks in correct order
final CiBitMap visitedBlocks; // used for recursive processing of blocks
final CiBitMap activeBlocks; // used for recursive processing of blocks
final CiBitMap dominatorBlocks; // temporary BitMap used for computation of dominator
final int[] forwardBranches; // number of incoming forward branches for each block
final List<BlockBegin> loopEndBlocks; // list of all loop end blocks collected during countEdges
BitMap2D loopMap; // two-dimensional bit set: a bit is set if a block is contained in a loop
final List<BlockBegin> workList; // temporary list (used in markLoops and computeOrder)
// accessors for visitedBlocks and activeBlocks
void initVisited() {
activeBlocks.clearAll();
visitedBlocks.clearAll();
}
boolean isVisited(BlockBegin b) {
return visitedBlocks.get(b.blockID);
}
boolean isActive(BlockBegin b) {
return activeBlocks.get(b.blockID);
}
void setVisited(BlockBegin b) {
assert !isVisited(b) : "already set";
visitedBlocks.set(b.blockID);
}
void setActive(BlockBegin b) {
assert !isActive(b) : "already set";
activeBlocks.set(b.blockID);
}
void clearActive(BlockBegin b) {
assert isActive(b) : "not already";
activeBlocks.clear(b.blockID);
}
// accessors for forwardBranches
void incForwardBranches(BlockBegin b) {
forwardBranches[b.blockID]++;
}
int decForwardBranches(BlockBegin b) {
return --forwardBranches[b.blockID];
}
// accessors for loopMap
boolean isBlockInLoop(int loopIdx, BlockBegin b) {
return loopMap.at(loopIdx, b.blockID);
}
void setBlockInLoop(int loopIdx, BlockBegin b) {
loopMap.setBit(loopIdx, b.blockID);
}
void clearBlockInLoop(int loopIdx, int blockId) {
loopMap.clearBit(loopIdx, blockId);
}
// accessors for final result
public List<BlockBegin> linearScanOrder() {
return linearScanOrder;
}
public int numLoops() {
return numLoops;
}
public ComputeLinearScanOrder(int maxBlockId, BlockBegin startBlock) {
this.maxBlockId = maxBlockId;
visitedBlocks = new CiBitMap(maxBlockId);
activeBlocks = new CiBitMap(maxBlockId);
dominatorBlocks = new CiBitMap(maxBlockId);
forwardBranches = new int[maxBlockId];
loopEndBlocks = new ArrayList<BlockBegin>(8);
workList = new ArrayList<BlockBegin>(8);
splitCriticalEdges();
countEdges(startBlock, null);
if (numLoops > 0) {
markLoops();
clearNonNaturalLoops(startBlock);
assignLoopDepth(startBlock);
}
computeOrder(startBlock);
computeDominators();
printBlocks();
assert verify();
}
void splitCriticalEdges() {
// TODO: move critical edge splitting from IR to here
}
/**
* 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(BlockBegin cur, BlockBegin parent) {
if (C1XOptions.TraceLinearScanLevel >= 3) {
TTY.println("Counting edges for block B%d%s", cur.blockID, parent == null ? "" : " coming from B" + parent.blockID);
}
assert cur.dominator() == null : "dominator already initialized";
if (isActive(cur)) {
if (C1XOptions.TraceLinearScanLevel >= 3) {
TTY.println("backward branch");
}
assert isVisited(cur) : "block must be visited when block is active";
assert parent != null : "must have parent";
cur.setBlockFlag(BlockBegin.BlockFlag.LinearScanLoopHeader);
cur.setBlockFlag(BlockBegin.BlockFlag.BackwardBranchTarget);
parent.setBlockFlag(BlockBegin.BlockFlag.LinearScanLoopEnd);
// When a loop header is also the start of an exception handler, then the backward branch is
// an exception edge. Because such edges are usually critical edges which cannot be split, the
// loop must be excluded here from processing.
if (cur.checkBlockFlag(BlockBegin.BlockFlag.ExceptionEntry)) {
// Make sure that dominators are correct in this weird situation
iterativeDominators = true;
return;
}
// assert parent.numberOfSux() == 1 && parent.suxAt(0) == cur : "loop end blocks must have one successor (critical edges are split)";
loopEndBlocks.add(parent);
return;
}
// increment number of incoming forward branches
incForwardBranches(cur);
if (isVisited(cur)) {
if (C1XOptions.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);
}
for (i = cur.numberOfExceptionHandlers() - 1; i >= 0; i--) {
countEdges(cur.exceptionHandlerAt(i), cur);
}
clearActive(cur);
// Each loop has a unique number.
// When multiple loops are nested, assignLoopDepth assumes that the
// innermost loop has the lowest number. This is guaranteed by setting
// the loop number after the recursive calls for the successors above
// have returned.
if (cur.checkBlockFlag(BlockBegin.BlockFlag.LinearScanLoopHeader)) {
assert cur.loopIndex() == -1 : "cannot set loop-index twice";
if (C1XOptions.TraceLinearScanLevel >= 3) {
TTY.println("Block B%d is loop header of loop %d", cur.blockID, numLoops);
}
cur.setLoopIndex(numLoops);
numLoops++;
}
if (C1XOptions.TraceLinearScanLevel >= 3) {
TTY.println("Finished counting edges for block B%d", cur.blockID);
}
}
void markLoops() {
if (C1XOptions.TraceLinearScanLevel >= 3) {
TTY.println("----- marking loops");
}
loopMap = new BitMap2D(numLoops, maxBlockId);
for (int i = loopEndBlocks.size() - 1; i >= 0; i--) {
BlockBegin loopEnd = loopEndBlocks.get(i);
BlockBegin loopStart = loopEnd.suxAt(0);
int loopIdx = loopStart.loopIndex();
if (C1XOptions.TraceLinearScanLevel >= 3) {
TTY.println("Processing loop from B%d to B%d (loop %d):", loopStart.blockID, loopEnd.blockID, loopIdx);
}
assert loopEnd.checkBlockFlag(BlockBegin.BlockFlag.LinearScanLoopEnd) : "loop end flag must be set";
// assert loopEnd.numberOfSux() == 1 : "incorrect number of successors";
assert loopStart.checkBlockFlag(BlockBegin.BlockFlag.LinearScanLoopHeader) : "loop header flag must be set";
assert loopIdx >= 0 && loopIdx < numLoops : "loop index not set";
assert workList.isEmpty() : "work list must be empty before processing";
// add the end-block of the loop to the working list
workList.add(loopEnd);
setBlockInLoop(loopIdx, loopEnd);
do {
BlockBegin cur = workList.remove(workList.size() - 1);
if (C1XOptions.TraceLinearScanLevel >= 3) {
TTY.println(" processing B%d", cur.blockID);
}
assert isBlockInLoop(loopIdx, cur) : "bit in loop map must be set when block is in work list";
// recursive processing of all predecessors ends when start block of loop is reached
if (cur != loopStart && !cur.checkBlockFlag(BlockBegin.BlockFlag.OsrEntry)) {
for (int j = cur.numberOfPreds() - 1; j >= 0; j--) {
BlockBegin pred = cur.predAt(j);
if (!isBlockInLoop(loopIdx, pred)) {
// this predecessor has not been processed yet, so add it to work list
if (C1XOptions.TraceLinearScanLevel >= 3) {
TTY.println(" pushing B%d", pred.blockID);
}
workList.add(pred);
setBlockInLoop(loopIdx, pred);
}
}
}
} while (!workList.isEmpty());
}
}
// check for non-natural loops (loops where the loop header does not dominate
// all other loop blocks = loops with multiple entries).
// such loops are ignored
void clearNonNaturalLoops(BlockBegin startBlock) {
for (int i = numLoops - 1; i >= 0; i--) {
if (isBlockInLoop(i, startBlock)) {
// loop i contains the entry block of the method.
// this is not a natural loop, so ignore it
if (C1XOptions.TraceLinearScanLevel >= 2) {
TTY.println("Loop %d is non-natural, so it is ignored", i);
}
for (int blockId = maxBlockId - 1; blockId >= 0; blockId--) {
clearBlockInLoop(i, blockId);
}
iterativeDominators = true;
}
}
}
void assignLoopDepth(BlockBegin startBlock) {
if (C1XOptions.TraceLinearScanLevel >= 3) {
TTY.println("----- computing loop-depth and weight");
}
initVisited();
assert workList.isEmpty() : "work list must be empty before processing";
workList.add(startBlock);
do {
BlockBegin cur = workList.remove(workList.size() - 1);
if (!isVisited(cur)) {
setVisited(cur);
if (C1XOptions.TraceLinearScanLevel >= 4) {
TTY.println("Computing loop depth for block B%d", cur.blockID);
}
// compute loop-depth and loop-index for the block
assert cur.loopDepth() == 0 : "cannot set loop-depth twice";
int i;
int loopDepth = 0;
int minLoopIdx = -1;
for (i = numLoops - 1; i >= 0; i--) {
if (isBlockInLoop(i, cur)) {
loopDepth++;
minLoopIdx = i;
}
}
cur.setLoopDepth(loopDepth);
cur.setLoopIndex(minLoopIdx);
// append all unvisited successors to work list
for (i = cur.numberOfSux() - 1; i >= 0; i--) {
workList.add(cur.suxAt(i));
}
for (i = cur.numberOfExceptionHandlers() - 1; i >= 0; i--) {
workList.add(cur.exceptionHandlerAt(i));
}
}
} while (!workList.isEmpty());
}
BlockBegin commonDominator(BlockBegin a, BlockBegin b) {
assert a != null && b != null : "must have input blocks";
dominatorBlocks.clearAll();
while (a != null) {
dominatorBlocks.set(a.blockID);
assert a.dominator() != null || a == linearScanOrder.get(0) : "dominator must be initialized";
a = a.dominator();
}
while (b != null && !dominatorBlocks.get(b.blockID)) {
assert b.dominator() != null || b == linearScanOrder.get(0) : "dominator must be initialized";
b = b.dominator();
}
assert b != null : "could not find dominator";
return b;
}
void computeDominator(BlockBegin cur, BlockBegin parent) {
if (cur.dominator() == null) {
if (C1XOptions.TraceLinearScanLevel >= 4) {
TTY.println("DOM: initializing dominator of B%d to B%d", cur.blockID, parent.blockID);
}
if (cur.isExceptionEntry()) {
assert parent.dominator() != null;
cur.setDominator(parent.dominator());
} else {
cur.setDominator(parent);
}
} else if (!(cur.checkBlockFlag(BlockBegin.BlockFlag.LinearScanLoopHeader) && parent.checkBlockFlag(BlockBegin.BlockFlag.LinearScanLoopEnd))) {
if (C1XOptions.TraceLinearScanLevel >= 4) {
TTY.println("DOM: computing dominator of B%d: common dominator of B%d and B%d is B%d", cur.blockID, parent.blockID, cur.dominator().blockID, commonDominator(cur.dominator(), parent).blockID);
}
assert cur.numberOfPreds() > 1 : "";
cur.setDominator(commonDominator(cur.dominator(), parent));
}
}
int computeWeight(BlockBegin cur) {
BlockBegin singleSux = null;
if (cur.numberOfSux() == 1) {
singleSux = cur.suxAt(0);
}
// 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.checkBlockFlag(BlockBegin.BlockFlag.LinearScanLoopHeader)) {
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.checkBlockFlag(BlockBegin.BlockFlag.LinearScanLoopEnd)) {
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.checkBlockFlag(BlockBegin.BlockFlag.ExceptionEntry)) {
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;
}
boolean readyForProcessing(BlockBegin 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;
}
void sortIntoWorkList(BlockBegin 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 (C1XOptions.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 (C1XOptions.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";
}
}
void appendBlock(BlockBegin cur) {
if (C1XOptions.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);
}
void computeOrder(BlockBegin startBlock) {
if (C1XOptions.TraceLinearScanLevel >= 3) {
TTY.println("----- computing final block order");
}
// the start block is always the first block in the linear scan order
linearScanOrder = new ArrayList<BlockBegin>(numBlocks);
appendBlock(startBlock);
assert startBlock.end() instanceof Base : "start block must end with Base-instruction";
BlockBegin stdEntry = ((Base) startBlock.end()).standardEntry();
BlockBegin osrEntry = ((Base) startBlock.end()).osrEntry();
BlockBegin suxOfOsrEntry = null;
if (osrEntry != null) {
// special handling for osr entry:
// ignore the edge between the osr entry and its successor for processing
// the osr entry block is added manually below
assert osrEntry.numberOfSux() == 1 : "osr entry must have exactly one successor";
assert osrEntry.suxAt(0).numberOfPreds() >= 2 : "sucessor of osr entry must have two predecessors (otherwise it is not present in normal control flow)";
suxOfOsrEntry = osrEntry.suxAt(0);
decForwardBranches(suxOfOsrEntry);
computeDominator(osrEntry, startBlock);
iterativeDominators = true;
}
computeDominator(stdEntry, startBlock);
// start processing with standard entry block
assert workList.isEmpty() : "list must be empty before processing";
if (readyForProcessing(stdEntry)) {
sortIntoWorkList(stdEntry);
} else {
throw new CiBailout("the stdEntry must be ready for processing (otherwise, the method has no start block)");
}
do {
BlockBegin cur = workList.remove(workList.size() - 1);
if (cur == suxOfOsrEntry) {
// the osr entry block is ignored in normal processing : it is never added to the
// work list. Instead : it is added as late as possible manually here.
appendBlock(osrEntry);
computeDominator(cur, osrEntry);
}
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++) {
BlockBegin sux = cur.suxAt(i);
computeDominator(sux, cur);
if (readyForProcessing(sux)) {
sortIntoWorkList(sux);
}
}
numSux = cur.numberOfExceptionHandlers();
for (i = 0; i < numSux; i++) {
BlockBegin sux = cur.exceptionHandlerAt(i);
computeDominator(sux, cur);
if (readyForProcessing(sux)) {
sortIntoWorkList(sux);
}
}
} while (workList.size() > 0);
}
boolean computeDominatorsIter() {
boolean changed = false;
int numBlocks = linearScanOrder.size();
assert linearScanOrder.get(0).dominator() == null : "must not have dominator";
assert linearScanOrder.get(0).numberOfPreds() == 0 : "must not have predecessors";
for (int i = 1; i < numBlocks; i++) {
BlockBegin block = linearScanOrder.get(i);
assert block.numberOfPreds() > 0;
BlockBegin dominator = block.predAt(0);
if (block.isExceptionEntry()) {
dominator = dominator.dominator();
}
int numPreds = block.numberOfPreds();
for (int j = 1; j < numPreds; j++) {
BlockBegin curPred = block.predAt(j);
if (block.isExceptionEntry()) {
curPred = curPred.dominator();
}
dominator = commonDominator(dominator, curPred);
}
if (dominator != block.dominator()) {
if (C1XOptions.TraceLinearScanLevel >= 4) {
TTY.println("DOM: updating dominator of B%d from B%d to B%d", block.blockID, block.dominator().blockID, dominator.blockID);
}
block.setDominator(dominator);
changed = true;
}
}
return changed;
}
void computeDominators() {
if (C1XOptions.TraceLinearScanLevel >= 3) {
TTY.println("----- computing dominators (iterative computation reqired: %b)", iterativeDominators);
}
// iterative computation of dominators is only required for methods with non-natural loops
// and OSR-methods. For all other methods : the dominators computed when generating the
// linear scan block order are correct.
if (iterativeDominators) {
do {
if (C1XOptions.TraceLinearScanLevel >= 1) {
TTY.println("DOM: next iteration of fix-point calculation");
}
} while (computeDominatorsIter());
}
// check that dominators are correct
assert !computeDominatorsIter() : "fix point not reached";
}
public void printBlocks() {
if (C1XOptions.TraceLinearScanLevel >= 2) {
TTY.println("----- loop information:");
for (BlockBegin cur : linearScanOrder) {
TTY.print(String.format("%4d: B%02d: ", cur.linearScanNumber(), cur.blockID));
for (int loopIdx = 0; loopIdx < numLoops; loopIdx++) {
TTY.print(String.format("%d = %b ", loopIdx, isBlockInLoop(loopIdx, cur)));
}
TTY.println(String.format(" . loopIndex: %2d, loopDepth: %2d", cur.loopIndex(), cur.loopDepth()));
}
}
if (C1XOptions.TraceLinearScanLevel >= 1) {
TTY.println("----- linear-scan block order:");
for (BlockBegin cur : linearScanOrder) {
TTY.print(String.format("%4d: B%02d loop: %2d depth: %2d", cur.linearScanNumber(), cur.blockID, cur.loopIndex(), cur.loopDepth()));
TTY.print(cur.isExceptionEntry() ? " ex" : " ");
TTY.print(cur.isCriticalEdgeSplit() ? " ce" : " ");
TTY.print(cur.checkBlockFlag(BlockBegin.BlockFlag.LinearScanLoopHeader) ? " lh" : " ");
TTY.print(cur.checkBlockFlag(BlockBegin.BlockFlag.LinearScanLoopEnd) ? " le" : " ");
if (cur.dominator() != null) {
TTY.print(" dom: B%d ", cur.dominator().blockID);
} else {
TTY.print(" dom: null ");
}
if (cur.numberOfPreds() > 0) {
TTY.print(" preds: ");
for (int j = 0; j < cur.numberOfPreds(); j++) {
BlockBegin 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++) {
BlockBegin sux = cur.suxAt(j);
TTY.print("B%d ", sux.blockID);
}
}
if (cur.numberOfExceptionHandlers() > 0) {
TTY.print(" ex: ");
for (int j = 0; j < cur.numberOfExceptionHandlers(); j++) {
BlockBegin ex = cur.exceptionHandlerAt(j);
TTY.print("B%d ", ex.blockID);
}
}
TTY.println();
}
}
}
boolean verify() {
assert linearScanOrder.size() == numBlocks : "wrong number of blocks in list";
if (C1XOptions.StressLinearScan) {
// blocks are scrambled when StressLinearScan is used
return true;
}
// check that all successors of a block have a higher linear-scan-number
// and that all predecessors of a block have a lower linear-scan-number
// (only backward branches of loops are ignored)
int i;
for (i = 0; i < linearScanOrder.size(); i++) {
BlockBegin cur = linearScanOrder.get(i);
assert cur.linearScanNumber() == i : "incorrect linearScanNumber";
assert cur.linearScanNumber() >= 0 && cur.linearScanNumber() == linearScanOrder.indexOf(cur) : "incorrect linearScanNumber";
for (BlockBegin sux : cur.end().successors()) {
assert sux.linearScanNumber() >= 0 && sux.linearScanNumber() == linearScanOrder.indexOf(sux) : "incorrect linearScanNumber";
if (!cur.checkBlockFlag(BlockBegin.BlockFlag.LinearScanLoopEnd)) {
assert cur.linearScanNumber() < sux.linearScanNumber() : "invalid order";
}
if (cur.loopDepth() == sux.loopDepth()) {
assert cur.loopIndex() == sux.loopIndex() || sux.checkBlockFlag(BlockBegin.BlockFlag.LinearScanLoopHeader) : "successing blocks with same loop depth must have same loop index";
}
}
for (BlockBegin pred : cur.predecessors()) {
assert pred.linearScanNumber() >= 0 && pred.linearScanNumber() == linearScanOrder.indexOf(pred) : "incorrect linearScanNumber";
if (!cur.checkBlockFlag(BlockBegin.BlockFlag.LinearScanLoopHeader)) {
assert cur.linearScanNumber() > pred.linearScanNumber() : "invalid order";
}
if (cur.loopDepth() == pred.loopDepth()) {
assert cur.loopIndex() == pred.loopIndex() || cur.checkBlockFlag(BlockBegin.BlockFlag.LinearScanLoopHeader) : "successing blocks with same loop depth must have same loop index";
}
assert cur.dominator().linearScanNumber() <= pred.linearScanNumber() : "dominator must be before predecessors";
}
// check dominator
if (i == 0) {
assert cur.dominator() == null : "first block has no dominator";
} else {
assert cur.dominator() != null : "all but first block must have dominator";
}
assert cur.numberOfPreds() != 1 || cur.dominator() == cur.predAt(0) || cur.isExceptionEntry() : "Single predecessor must also be dominator";
}
// check that all loops are continuous
for (int loopIdx = 0; loopIdx < numLoops; loopIdx++) {
int blockIdx = 0;
assert !isBlockInLoop(loopIdx, linearScanOrder.get(blockIdx)) : "the first block must not be present in any loop";
// skip blocks before the loop
while (blockIdx < numBlocks && !isBlockInLoop(loopIdx, linearScanOrder.get(blockIdx))) {
blockIdx++;
}
// skip blocks of loop
while (blockIdx < numBlocks && isBlockInLoop(loopIdx, linearScanOrder.get(blockIdx))) {
blockIdx++;
}
// after the first non-loop block : there must not be another loop-block
while (blockIdx < numBlocks) {
assert !isBlockInLoop(loopIdx, linearScanOrder.get(blockIdx)) : "loop not continuous in linear-scan order";
blockIdx++;
}
}
return true;
}
}