org.jetbrains.kotlin.codegen.optimization.common.backwardAnalysis.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.common
import org.jetbrains.org.objectweb.asm.tree.AbstractInsnNode
import org.jetbrains.org.objectweb.asm.tree.MethodNode
interface VarFrame> {
fun mergeFrom(other: F)
override fun equals(other: Any?): Boolean
override fun hashCode(): Int
}
interface BackwardAnalysisInterpreter> {
fun newFrame(maxLocals: Int): F
fun def(frame: F, insn: AbstractInsnNode)
fun use(frame: F, insn: AbstractInsnNode)
}
fun > analyze(node: MethodNode, interpreter: BackwardAnalysisInterpreter): List {
val graph = ControlFlowGraph.build(node)
val insnList = node.instructions
val frames = (1..insnList.size()).map { interpreter.newFrame(node.maxLocals) }.toMutableList()
val insnArray = insnList.toArray()
// see Figure 9.16 from Dragon book
var wereChanges: Boolean
do {
wereChanges = false
for (insn in insnArray) {
val index = insnList.indexOf(insn)
val newFrame = interpreter.newFrame(node.maxLocals)
for (successorIndex in graph.getSuccessorsIndices(insn)) {
newFrame.mergeFrom(frames[successorIndex])
}
interpreter.def(newFrame, insn)
interpreter.use(newFrame, insn)
if (frames[index] != newFrame) {
frames[index] = newFrame
wereChanges = true
}
}
} while (wereChanges)
return frames
}