Open-source multiplayer game server compatible with the RuneScape client
https://www.openrs2.org/
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50 lines
1.6 KiB
50 lines
1.6 KiB
package dev.openrs2.deob.transform;
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import com.google.common.collect.ImmutableSet;
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import dev.openrs2.asm.InsnMatcher;
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import dev.openrs2.asm.InsnNodeUtils;
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import dev.openrs2.asm.classpath.ClassPath;
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import dev.openrs2.asm.classpath.Library;
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import dev.openrs2.asm.transform.Transformer;
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import org.objectweb.asm.Opcodes;
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import org.objectweb.asm.tree.ClassNode;
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import org.objectweb.asm.tree.MethodNode;
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import org.slf4j.Logger;
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import org.slf4j.LoggerFactory;
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public final class BitShiftTransformer extends Transformer {
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private static final Logger logger = LoggerFactory.getLogger(BitShiftTransformer.class);
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private static final InsnMatcher CONST_SHIFT_MATCHER = InsnMatcher.compile("(ICONST | BIPUSH | SIPUSH | LDC) (ISHL | ISHR | IUSHR | LSHL | LSHR | LUSHR)");
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private static final ImmutableSet<Integer> LONG_SHIFTS = ImmutableSet.of(Opcodes.LSHL, Opcodes.LSHR, Opcodes.LUSHR);
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private int simplified;
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@Override
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public void preTransform(ClassPath classPath) {
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simplified = 0;
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}
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@Override
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public boolean transformCode(ClassPath classPath, Library library, ClassNode clazz, MethodNode method) {
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CONST_SHIFT_MATCHER.match(method).forEach(match -> {
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var push = match.get(0);
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var bits = InsnNodeUtils.getIntConstant(push);
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var opcode = match.get(1).getOpcode();
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var simplifiedBits = bits & (LONG_SHIFTS.contains(opcode) ? 63 : 31);
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if (bits != simplifiedBits) {
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method.instructions.set(push, InsnNodeUtils.createIntConstant(simplifiedBits));
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simplified++;
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}
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});
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return false;
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}
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@Override
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public void postTransform(ClassPath classPath) {
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logger.info("Simplified {} bit shifts", simplified);
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}
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}
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