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Word-by-word card table scanning #5860

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31 changes: 20 additions & 11 deletions ...ore.genscavenge/src/com/oracle/svm/core/genscavenge/remset/AlignedChunkRememberedSet.java
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Original file line number Diff line number Diff line change
Expand Up @@ -54,6 +54,11 @@ final class AlignedChunkRememberedSet {
private AlignedChunkRememberedSet() {
}

@Fold
public static int wordSize() {
return ConfigurationValues.getTarget().wordSize;
}

@Fold
public static UnsignedWord getHeaderSize() {
UnsignedWord headerSize = getFirstObjectTableLimitOffset();
Expand Down Expand Up @@ -133,19 +138,23 @@ public static void walkDirtyObjects(AlignedHeader chunk, GreyToBlackObjectVisito
UnsignedWord memorySize = objectsLimit.subtract(objectsStart);
UnsignedWord indexLimit = CardTable.indexLimitForMemorySize(memorySize);

for (UnsignedWord index = WordFactory.zero(); index.belowThan(indexLimit); index = index.add(1)) {
if (CardTable.isDirty(cardTableStart, index)) {
for (UnsignedWord index = WordFactory.zero(); index.belowThan(indexLimit); index = index.add(wordSize())) {
UnsignedWord value = CardTable.readWord(cardTableStart, index);
if (value.notEqual(CardTable.CLEAN_WORD)) {
if (clean) {
CardTable.setClean(cardTableStart, index);
CardTable.cleanWord(cardTableStart, index);
}

Pointer ptr = FirstObjectTable.getFirstObjectImprecise(fotStart, objectsStart, objectsLimit, index);
Pointer cardLimit = CardTable.indexToMemoryPointer(objectsStart, index.add(1));
Pointer walkLimit = PointerUtils.min(cardLimit, objectsLimit);
while (ptr.belowThan(walkLimit)) {
Object obj = ptr.toObject();
visitor.visitObjectInline(obj);
ptr = LayoutEncoding.getObjectEndInline(obj);
for (int i = 0; i < wordSize(); i++) {
if (value.unsignedShiftRight(i * 8).and(0xFF).equal(CardTable.DIRTY_ENTRY)) {
Pointer ptr = FirstObjectTable.getFirstObjectImprecise(fotStart, objectsStart, objectsLimit, index.add(i));
Pointer cardLimit = CardTable.indexToMemoryPointer(objectsStart, index.add(i + 1));
Pointer walkLimit = PointerUtils.min(cardLimit, objectsLimit);
while (ptr.belowThan(walkLimit)) {
Object obj = ptr.toObject();
visitor.visitObjectInline(obj);
ptr = LayoutEncoding.getObjectEndInline(obj);
}
}
}
}
}
Expand Down
15 changes: 12 additions & 3 deletions ...com.oracle.svm.core.genscavenge/src/com/oracle/svm/core/genscavenge/remset/CardTable.java
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Original file line number Diff line number Diff line change
Expand Up @@ -74,10 +74,11 @@
final class CardTable {
public static final int BYTES_COVERED_BY_ENTRY = 512;

private static final int ENTRY_SIZE_BYTES = 1;
static final int DIRTY_ENTRY = 0;
static final int CLEAN_ENTRY = 1;
static final UnsignedWord CLEAN_WORD = WordFactory.unsigned(0x0101010101010101L);

private static final int DIRTY_ENTRY = 0;
private static final int CLEAN_ENTRY = 1;
private static final int ENTRY_SIZE_BYTES = 1;

private static final CardTableVerificationVisitor CARD_TABLE_VERIFICATION_VISITOR = new CardTableVerificationVisitor();

Expand Down Expand Up @@ -112,6 +113,14 @@ private static boolean isClean(Pointer table, UnsignedWord index) {
return entry == CLEAN_ENTRY;
}

public static UnsignedWord readWord(Pointer table, UnsignedWord index) {
return table.readWord(indexToTableOffset(index));
}

public static void cleanWord(Pointer table, UnsignedWord index) {
table.writeWord(indexToTableOffset(index), CLEAN_WORD, BarrierSnippets.CARD_REMEMBERED_SET_LOCATION);
}

private static int readEntry(Pointer table, UnsignedWord index) {
return table.readByte(indexToTableOffset(index));
}
Expand Down