Open-source multiplayer game server compatible with the RuneScape client https://www.openrs2.org/
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openrs2/deob-bytecode/src/main/kotlin/org/openrs2/deob/bytecode/transform/MultipleAssignmentTransform...

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package org.openrs2.deob.bytecode.transform
import com.github.michaelbull.logging.InlineLogger
import jakarta.inject.Singleton
import org.objectweb.asm.Opcodes
import org.objectweb.asm.tree.ClassNode
import org.objectweb.asm.tree.FieldInsnNode
import org.objectweb.asm.tree.MethodNode
import org.openrs2.asm.InsnMatcher
import org.openrs2.asm.classpath.ClassPath
import org.openrs2.asm.classpath.Library
import org.openrs2.asm.transform.Transformer
import org.openrs2.deob.bytecode.remap.StaticFieldUnscrambler
/**
* A [Transformer] that splits multiple assignments to static fields in a
* single expression in `<clinit>` methods. For example, `a = b = new X()` is
* translated to `b = new X(); a = b`. This allows [StaticFieldUnscrambler] to
* move the fields independently.
*/
@Singleton
public class MultipleAssignmentTransformer : Transformer() {
private var assignments = 0
override fun preTransform(classPath: ClassPath) {
assignments = 0
}
override fun transformCode(classPath: ClassPath, library: Library, clazz: ClassNode, method: MethodNode): Boolean {
if (method.name != "<clinit>") {
return false
}
for (match in MATCHER.match(method)) {
for (i in 0 until match.size - 1 step 2) {
val dup = match[i]
val putstatic = match[i + 1] as FieldInsnNode
method.instructions.remove(dup)
method.instructions.insert(putstatic, FieldInsnNode(Opcodes.GETSTATIC, putstatic.owner, putstatic.name, putstatic.desc))
assignments++
}
}
return false
}
override fun postTransform(classPath: ClassPath) {
logger.info { "Split $assignments multiple assignment expressions into separate expressions" }
}
private companion object {
private val logger = InlineLogger()
private val MATCHER = InsnMatcher.compile("(DUP PUTSTATIC)+ PUTSTATIC")
}
}