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org.jetbrains.kotlin.codegen.optimization.boxing.PopBackwardPropagationTransformer.kt Maven / Gradle / Ivy
/*
* Copyright 2010-2016 JetBrains s.r.o.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.jetbrains.kotlin.codegen.optimization.boxing
import org.jetbrains.kotlin.codegen.optimization.OptimizationMethodVisitor
import org.jetbrains.kotlin.codegen.optimization.common.isLoadOperation
import org.jetbrains.kotlin.codegen.optimization.common.isMeaningful
import org.jetbrains.kotlin.codegen.optimization.fixStack.top
import org.jetbrains.kotlin.codegen.optimization.removeNodeGetNext
import org.jetbrains.kotlin.codegen.optimization.transformer.MethodTransformer
import org.jetbrains.org.objectweb.asm.Opcodes
import org.jetbrains.org.objectweb.asm.tree.*
import org.jetbrains.org.objectweb.asm.tree.analysis.Analyzer
import org.jetbrains.org.objectweb.asm.tree.analysis.Frame
import org.jetbrains.org.objectweb.asm.tree.analysis.SourceInterpreter
import org.jetbrains.org.objectweb.asm.tree.analysis.SourceValue
import java.util.*
class PopBackwardPropagationTransformer : MethodTransformer() {
override fun transform(internalClassName: String, methodNode: MethodNode) {
if (!OptimizationMethodVisitor.canBeOptimizedUsingSourceInterpreter(methodNode)) return
Transformer(methodNode).transform()
}
private class Transformer(val methodNode: MethodNode) {
private interface Transformation {
fun apply(insn: AbstractInsnNode)
}
private inline fun Transformation(crossinline body: (AbstractInsnNode) -> Unit): Transformation =
object : Transformation {
override fun apply(insn: AbstractInsnNode) {
body(insn)
}
}
private val REPLACE_WITH_NOP = Transformation { insnList.set(it, createRemovableNopInsn()) }
private val REPLACE_WITH_POP1 = Transformation { insnList.set(it, InsnNode(Opcodes.POP)) }
private val REPLACE_WITH_POP2 = Transformation { insnList.set(it, InsnNode(Opcodes.POP2)) }
private val INSERT_POP1_AFTER = Transformation { insnList.insert(it, InsnNode(Opcodes.POP)) }
private val INSERT_POP2_AFTER = Transformation { insnList.insert(it, InsnNode(Opcodes.POP2)) }
private val insnList = methodNode.instructions
private val insns = insnList.toArray()
private val dontTouchInsnIndices = BitSet(insns.size)
private val transformations = hashMapOf()
private val removableNops = hashSetOf()
private val frames by lazy { analyzeMethodBody() }
fun transform() {
if (insns.none { it.isPop() || it.isPurePush() }) return
computeTransformations()
for ((insn, transformation) in transformations.entries) {
transformation.apply(insn)
}
postprocessNops()
}
private fun analyzeMethodBody(): Array?> =
Analyzer(object : SourceInterpreter() {
override fun naryOperation(insn: AbstractInsnNode, values: MutableList): SourceValue {
for (value in values) {
value.insns.markAsDontTouch()
}
return super.naryOperation(insn, values)
}
override fun copyOperation(insn: AbstractInsnNode, value: SourceValue): SourceValue {
value.insns.markAsDontTouch()
return super.copyOperation(insn, value)
}
override fun unaryOperation(insn: AbstractInsnNode, value: SourceValue): SourceValue {
if (insn.opcode != Opcodes.CHECKCAST && !insn.isPrimitiveTypeConversion()) {
value.insns.markAsDontTouch()
}
return super.unaryOperation(insn, value)
}
override fun binaryOperation(insn: AbstractInsnNode, value1: SourceValue, value2: SourceValue): SourceValue {
value1.insns.markAsDontTouch()
value2.insns.markAsDontTouch()
return super.binaryOperation(insn, value1, value2)
}
override fun ternaryOperation(insn: AbstractInsnNode, value1: SourceValue, value2: SourceValue, value3: SourceValue): SourceValue {
value1.insns.markAsDontTouch()
value2.insns.markAsDontTouch()
value3.insns.markAsDontTouch()
return super.ternaryOperation(insn, value1, value2, value3)
}
private fun Collection.markAsDontTouch() {
forEach {
dontTouchInsnIndices[insnList.indexOf(it)] = true
}
}
}).analyze("fake", methodNode)
private fun computeTransformations() {
transformations.clear()
for (i in insns.indices) {
if (frames[i] == null) continue
val insn = insns[i]
if (insn.opcode == Opcodes.POP) {
propagatePopBackwards(insn, 0)
}
}
}
private fun propagatePopBackwards(insn: AbstractInsnNode, poppedValueSize: Int) {
if (transformations.containsKey(insn)) return
when {
insn.opcode == Opcodes.POP -> {
val inputTop = getInputTop(insn)
val sources = inputTop.insns
if (sources.all { !isDontTouch(it) } && sources.any { isTransformablePopOperand(it) }) {
transformations[insn] = replaceWithNopTransformation()
sources.forEach { propagatePopBackwards(it, inputTop.size) }
}
}
insn.opcode == Opcodes.CHECKCAST -> {
val inputTop = getInputTop(insn)
val sources = inputTop.insns
val resultType = (insn as TypeInsnNode).desc
if (sources.all { !isDontTouch(it) } && sources.any { isTransformableCheckcastOperand(it, resultType) }) {
transformations[insn] = replaceWithNopTransformation()
sources.forEach { propagatePopBackwards(it, inputTop.size) }
}
else {
transformations[insn] = insertPopAfterTransformation(poppedValueSize)
}
}
insn.isPrimitiveBoxing() -> {
val boxedValueSize = getInputTop(insn).size
transformations[insn] = replaceWithPopTransformation(boxedValueSize)
}
insn.isPurePush() -> {
transformations[insn] = replaceWithNopTransformation()
}
insn.isPrimitiveTypeConversion() -> {
val inputTop = getInputTop(insn)
val sources = inputTop.insns
if (sources.all { !isDontTouch(it) }) {
transformations[insn] = replaceWithNopTransformation()
sources.forEach { propagatePopBackwards(it, inputTop.size) }
}
else {
transformations[insn] = replaceWithPopTransformation(poppedValueSize)
}
}
else -> {
transformations[insn] = insertPopAfterTransformation(poppedValueSize)
}
}
}
private fun postprocessNops() {
var node: AbstractInsnNode? = insnList.first
var hasRemovableNops = false
while (node != null) {
node = node.next
val begin = node ?: break
while (node != null && node !is LabelNode) {
if (node in removableNops) {
hasRemovableNops = true
}
node = node.next
}
val end = node
if (hasRemovableNops) {
removeUnneededNopsInRange(begin, end)
}
hasRemovableNops = false
}
}
private fun removeUnneededNopsInRange(begin: AbstractInsnNode, end: AbstractInsnNode?) {
var node: AbstractInsnNode? = begin
var keepNop = true
while (node != null && node != end) {
if (node in removableNops && !keepNop) {
node = insnList.removeNodeGetNext(node)
}
else {
if (node.isMeaningful) keepNop = false
node = node.next
}
}
}
private fun replaceWithPopTransformation(size: Int): Transformation =
when (size) {
1 -> REPLACE_WITH_POP1
2 -> REPLACE_WITH_POP2
else -> throw AssertionError("Unexpected pop value size: $size")
}
private fun insertPopAfterTransformation(size: Int): Transformation =
when (size) {
1 -> INSERT_POP1_AFTER
2 -> INSERT_POP2_AFTER
else -> throw AssertionError("Unexpected pop value size: $size")
}
private fun replaceWithNopTransformation(): Transformation =
REPLACE_WITH_NOP
private fun createRemovableNopInsn() =
InsnNode(Opcodes.NOP).apply { removableNops.add(this) }
private fun getInputTop(insn: AbstractInsnNode): SourceValue {
val i = insnList.indexOf(insn)
val frame = frames[i] ?: throw AssertionError("Unexpected dead instruction #$i")
return frame.top() ?: throw AssertionError("Instruction #$i has empty stack on input")
}
private fun isTransformableCheckcastOperand(it: AbstractInsnNode, resultType: String) =
it.isPrimitiveBoxing() && (it as MethodInsnNode).owner == resultType
private fun isTransformablePopOperand(insn: AbstractInsnNode) =
insn.opcode == Opcodes.CHECKCAST || insn.isPrimitiveBoxing() || insn.isPurePush()
private fun isDontTouch(insn: AbstractInsnNode) =
dontTouchInsnIndices[insnList.indexOf(insn)]
}
}
fun AbstractInsnNode.isPurePush() =
isLoadOperation() ||
opcode in Opcodes.ACONST_NULL .. Opcodes.LDC + 2 ||
isUnitInstance()
fun AbstractInsnNode.isPop() =
opcode == Opcodes.POP || opcode == Opcodes.POP2
fun AbstractInsnNode.isUnitInstance() =
opcode == Opcodes.GETSTATIC &&
this is FieldInsnNode && owner == "kotlin/Unit" && name == "INSTANCE"
fun AbstractInsnNode.isPrimitiveTypeConversion() =
opcode in Opcodes.I2L .. Opcodes.I2S
