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8339492: StackMapDecoder::writeFrames makes lots of allocations

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Reviewed-by: liach, redestad, jwaters, asotona
This commit is contained in:
David M. Lloyd 2024-09-04 16:46:44 +00:00 • committed by Chen Liang
parent ef96a7b014
commit 433f6d8a06
1 changed files with 16 additions and 9 deletions
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25
src/java.base/share/classes/jdk/internal/classfile/impl/StackMapDecoder.java
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@ -35,9 +35,10 @@ import java.lang.classfile.constantpool.ClassEntry;
import java.lang.constant.ConstantDescs;
import java.lang.constant.MethodTypeDesc;
import java.lang.reflect.AccessFlag;
import java.util.Arrays;
import java.util.Comparator;
import java.util.List;
import java.util.Objects;
import java.util.TreeMap;
import static java.lang.classfile.ClassFile.*;
@ -46,6 +47,7 @@ public class StackMapDecoder {
private static final int
SAME_LOCALS_1_STACK_ITEM_EXTENDED = 247,
SAME_EXTENDED = 251;
private static final StackMapFrameInfo[] NO_STACK_FRAME_INFOS = new StackMapFrameInfo[0];
private final ClassReader classReader;
private final int pos;
@ -103,15 +105,20 @@ public class StackMapDecoder {
mi.methodTypeSymbol(),
(mi.methodFlags() & ACC_STATIC) != 0);
int prevOffset = -1;
var map = new TreeMap<Integer, StackMapFrameInfo>();
// avoid using method handles due to early bootstrap
StackMapFrameInfo[] infos = entries.toArray(NO_STACK_FRAME_INFOS);
//sort by resolved label offsets first to allow unordered entries
for (var fr : entries) {
map.put(dcb.labelToBci(fr.target()), fr);
}
b.writeU2(map.size());
for (var me : map.entrySet()) {
int offset = me.getKey();
var fr = me.getValue();
Arrays.sort(infos, new Comparator<StackMapFrameInfo>() {
public int compare(final StackMapFrameInfo o1, final StackMapFrameInfo o2) {
return Integer.compare(dcb.labelToBci(o1.target()), dcb.labelToBci(o2.target()));
}
});
b.writeU2(infos.length);
for (var fr : infos) {
int offset = dcb.labelToBci(fr.target());
if (offset == prevOffset) {
throw new IllegalArgumentException("Duplicated stack frame bytecode index: " + offset);
}
writeFrame(buf, offset - prevOffset - 1, prevLocals, fr);
prevOffset = offset;
prevLocals = fr.locals();