JVM_IR more compact safe call chains (almost as old BE)
This commit is contained in:
Dmitry Petrov
committed by
teamcityserver
teamcityserver
parent
f4eaf611c8
commit
0a67ab54fe
+177
@@ -6,6 +6,7 @@
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package org.jetbrains.kotlin.codegen.optimization.temporaryVals
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import org.jetbrains.kotlin.codegen.optimization.common.InsnSequence
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import org.jetbrains.kotlin.codegen.optimization.common.isMeaningful
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import org.jetbrains.kotlin.codegen.optimization.common.removeUnusedLocalVariables
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import org.jetbrains.kotlin.codegen.optimization.transformer.MethodTransformer
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import org.jetbrains.kotlin.codegen.state.GenerationState
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@@ -21,6 +22,8 @@ class TemporaryVariablesEliminationTransformer(private val state: GenerationStat
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override fun transform(internalClassName: String, methodNode: MethodNode) {
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if (!state.isIrBackend) return
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simplifyTrivialInstructions(methodNode)
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val cfg = ControlFlowGraph(methodNode)
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processLabels(cfg)
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@@ -35,6 +38,42 @@ class TemporaryVariablesEliminationTransformer(private val state: GenerationStat
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}
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private fun simplifyTrivialInstructions(methodNode: MethodNode) {
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val insnList = methodNode.instructions
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for (insn in insnList.toArray()) {
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when {
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insn.matchOpcodes(Opcodes.ILOAD, Opcodes.POP) ||
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insn.matchOpcodes(Opcodes.FLOAD, Opcodes.POP) ||
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insn.matchOpcodes(Opcodes.ALOAD, Opcodes.POP) -> {
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// Remove size 1 LOAD immediately followed by a POP
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val popInsn = insn.next
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insnList.insert(insn, InsnNode(Opcodes.NOP))
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insnList.remove(insn)
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insnList.remove(popInsn)
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}
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insn.matchOpcodes(Opcodes.DLOAD, Opcodes.POP2) ||
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insn.matchOpcodes(Opcodes.LLOAD, Opcodes.POP2) -> {
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// Remove size 2 LOAD immediately followed by a POP2
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val pop2Insn = insn.next
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insnList.insert(insn, InsnNode(Opcodes.NOP))
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insnList.remove(insn)
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insnList.remove(pop2Insn)
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}
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}
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}
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for (insn in insnList.toArray()) {
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// Remove NOPs immediately preceded or immediately followed by an instruction that does something
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// - not a LINENUMBER, not a LABEL, and not a FRAME.
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if (insn.opcode == Opcodes.NOP) {
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val next = insn.next
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val prev = insn.previous
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if (next != null && next.isMeaningful || prev != null && prev.isMeaningful) {
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insnList.remove(insn)
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}
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}
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}
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}
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private class ControlFlowGraph(val methodNode: MethodNode) {
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private val nonTrivialPredecessors = HashMap<LabelNode, MutableList<AbstractInsnNode>>()
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@@ -49,6 +88,22 @@ class TemporaryVariablesEliminationTransformer(private val state: GenerationStat
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fun hasNonTrivialPredecessors(label: LabelNode) =
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nonTrivialPredecessors.containsKey(label)
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fun getAllPredecessors(label: LabelNode): List<AbstractInsnNode> {
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val result = ArrayList<AbstractInsnNode>()
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val trivialPredecessor = label.previous
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if (trivialPredecessor.opcode != Opcodes.GOTO &&
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trivialPredecessor.opcode !in Opcodes.IRETURN..Opcodes.RETURN &&
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trivialPredecessor.opcode != Opcodes.ATHROW
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) {
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result.add(trivialPredecessor)
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}
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result.addAll(nonTrivialPredecessors[label] ?: emptyList())
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return result
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}
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fun hasSinglePredecessor(label: LabelNode, expectedPredecessor: AbstractInsnNode): Boolean {
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var trivialPredecessor = label.previous
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if (trivialPredecessor.opcode == Opcodes.GOTO ||
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@@ -334,12 +389,134 @@ class TemporaryVariablesEliminationTransformer(private val state: GenerationStat
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continue
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}
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}
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} else if (insn.matchOpcodes(Opcodes.ALOAD, Opcodes.IFNULL)) {
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// This looks like a start of some safe call chain:
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// { ... evaluate receiver ... }
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// ASTORE v1
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// ALOAD v1 << insn
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// IFNULL L
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// [ possible first receiver - ALOAD or GETSTATIC ]
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// ALOAD v1
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// { ... call-1 ... }
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// ASTORE v2
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// ALOAD v2
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// IFNULL L
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// [ possible first receiver - ALOAD or GETSTATIC ]
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// ALOAD v2
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// { ... call-2 ... }
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// ...
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// ASTORE vN
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// ALOAD vN
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// IFNULL L
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// [ possible first receiver - ALOAD or GETSTATIC ]
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// ALOAD vN
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// { ... call-N ... }
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// L:
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// { ... if null ... }
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val ifNull1 = insn.next as JumpInsnNode
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val ifNullLabel = ifNull1.label
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val predecessors = cfg.getAllPredecessors(ifNullLabel)
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if (predecessors.all { isRewritableSafeCallPart(it) }) {
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predecessors.forEach { rewriteSafeCallPart(it, insnList) }
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insnList.insert(ifNullLabel, InsnNode(Opcodes.POP))
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maxStackIncrement = max(maxStackIncrement, 1)
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continue
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}
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}
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}
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cfg.methodNode.maxStack += maxStackIncrement
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}
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private fun isRewritableSafeCallPart(branchInsn: AbstractInsnNode): Boolean {
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val start = branchInsn.previous ?: return false
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// ALOAD v1 << start
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// IFNULL L
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// [ possible first receiver - ALOAD or GETSTATIC ]
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// ALOAD v1
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if (start.matchOpcodes(Opcodes.ALOAD, Opcodes.IFNULL)) {
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val aLoad1 = start as VarInsnNode
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val ifNull = start.next as JumpInsnNode
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val ifNullNext = ifNull.next
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if (ifNullNext.opcode == Opcodes.ALOAD) {
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val aLoad2 = ifNullNext as VarInsnNode
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if (aLoad2.`var` == aLoad1.`var`) return true
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val aLoad2Next = aLoad2.next
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if (aLoad2Next.opcode == Opcodes.ALOAD) {
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val aLoad3 = aLoad2Next as VarInsnNode
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if (aLoad3.`var` == aLoad1.`var`) return true
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}
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} else if (ifNullNext.matchOpcodes(Opcodes.GETSTATIC, Opcodes.ALOAD)) {
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val getStaticInsn = ifNullNext as FieldInsnNode
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if (Type.getType(getStaticInsn.desc).size != 1) return false
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val aLoad2 = getStaticInsn.next as VarInsnNode
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if (aLoad2.`var` == aLoad1.`var`) return true
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}
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}
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return false
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}
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private fun rewriteSafeCallPart(branchInsn: AbstractInsnNode, insnList: InsnList) {
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val start = branchInsn.previous
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// ALOAD v1 << start
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// IFNULL L
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// [ possible first receiver - ALOAD or GETSTATIC ]
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// ALOAD v1
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val aLoad1 = start as VarInsnNode
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val ifNull = start.next as JumpInsnNode
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val ifNullNext = ifNull.next
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if (ifNullNext.opcode == Opcodes.ALOAD) {
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val aLoad2 = ifNullNext as VarInsnNode
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if (aLoad2.`var` == aLoad1.`var`) {
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// Rewrite
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// ALOAD v1
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// IFNULL L
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// ALOAD v1
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// to
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// ALOAD v1
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// DUP
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// IFNULL L
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insnList.insertBefore(ifNull, InsnNode(Opcodes.DUP))
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insnList.remove(aLoad2)
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return
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} else {
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val aLoad3 = aLoad2.next as VarInsnNode
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// Rewrite
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// ALOAD v1
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// IFNULL L
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// ALOAD x
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// ALOAD v1
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// to
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// ALOAD v1
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// DUP
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// IFNULL L
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// ALOAD x
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// SWAP
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insnList.insertBefore(ifNull, InsnNode(Opcodes.DUP))
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insnList.remove(aLoad3)
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insnList.insert(aLoad2, InsnNode(Opcodes.SWAP))
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return
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}
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} else {
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// Rewrite
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// ALOAD v1
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// IFNULL L
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// GETSTATIC s
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// ALOAD v1
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// to
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// ALOAD v1
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// DUP
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// IFNULL L
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// GETSTATIC s
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// SWAP
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val aLoad2 = ifNullNext.next
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insnList.insertBefore(ifNull, InsnNode(Opcodes.DUP))
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insnList.remove(aLoad2)
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insnList.insert(ifNullNext, InsnNode(Opcodes.SWAP))
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}
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}
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private fun AbstractInsnNode.matchOpcodes(vararg opcodes: Int): Boolean {
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var insn = this
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for (i in opcodes.indices) {
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