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[GR-71328] Avoid VarHandle dispatch in interpreter loop for opcode fetch #12545

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[GR-71328] Avoid VarHandle dispatch in interpreter loop for opcode fetch #12545

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3 changes: 3 additions & 0 deletions substratevm/mx.substratevm/suite.py
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Original file line number Diff line number Diff line change
Expand Up @@ -1640,6 +1640,9 @@
"com.oracle.graal.pointsto",
],
"requiresConcealed" : {
"java.base" : [
"jdk.internal.misc", # Unsafe
],
"jdk.internal.vm.ci" : [
"jdk.vm.ci.meta",
"jdk.vm.ci.meta.annotation",
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16 changes: 9 additions & 7 deletions ...om.oracle.svm.interpreter.metadata/src/com/oracle/svm/interpreter/metadata/ByteUtils.java
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Original file line number Diff line number Diff line change
Expand Up @@ -25,15 +25,17 @@

package com.oracle.svm.interpreter.metadata;

import java.lang.invoke.MethodHandles;
import java.lang.invoke.VarHandle;
import jdk.internal.misc.Unsafe;

/**
* A collection of utility methods for dealing with bytes, particularly in byte arrays.
*/
public final class ByteUtils {
private static final Unsafe UNSAFE = Unsafe.getUnsafe();

private static final VarHandle BYTE_ARRAY_VARHANDLE = MethodHandles.arrayElementVarHandle(byte[].class);
private static long offsetFor(int index) {
return Unsafe.ARRAY_BYTE_BASE_OFFSET + ((long) index * Unsafe.ARRAY_BYTE_INDEX_SCALE);
}

/**
* Gets a signed 1-byte value.
Expand Down Expand Up @@ -76,7 +78,7 @@ public static int beU1(byte[] data, int bci) {
* @return the unsigned 1-byte value at index {@code bci} in array {@code data}
*/
public static int volatileBeU1(byte[] data, int bci) {
return ((byte) BYTE_ARRAY_VARHANDLE.getVolatile(data, bci)) & 0xff;
return UNSAFE.getByteVolatile(data, offsetFor(bci)) & 0xff;
}

/**
Expand All @@ -87,7 +89,7 @@ public static int volatileBeU1(byte[] data, int bci) {
* @return the unsigned 1-byte value at index {@code bci} in array {@code data}
*/
public static int opaqueBeU1(byte[] data, int bci) {
return ((byte) BYTE_ARRAY_VARHANDLE.getOpaque(data, bci)) & 0xff;
return UNSAFE.getByteOpaque(data, offsetFor(bci)) & 0xff;
}

/**
Expand Down Expand Up @@ -128,7 +130,7 @@ public static int beSVar(byte[] data, int bci, boolean fourByte) {
}
}

public static void opaqueWrite(byte[] array, int index, byte value) {
BYTE_ARRAY_VARHANDLE.setOpaque(array, index, value);
public static void opaqueWrite(byte[] data, int bci, byte value) {
UNSAFE.putByteOpaque(data, offsetFor(bci), value);
}
}