org.jetbrains.kotlin.codegen.optimization.common.ControlFlowGraph.kt Maven / Gradle / Ivy

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/*
 * Copyright 2010-2019 JetBrains s.r.o. and Kotlin Programming Language contributors.
 * Use of this source code is governed by the Apache 2.0 license that can be found in the license/LICENSE.txt file.
 */

package org.jetbrains.kotlin.codegen.optimization.common

import org.jetbrains.org.objectweb.asm.tree.AbstractInsnNode
import org.jetbrains.org.objectweb.asm.tree.InsnList
import org.jetbrains.org.objectweb.asm.tree.MethodNode
import org.jetbrains.org.objectweb.asm.tree.analysis.BasicValue


class ControlFlowGraph private constructor(private val insns: InsnList) {
    private val edges: Array> = Array(insns.size()) { arrayListOf() }
    private val backwardEdges: Array> = Array(insns.size()) { arrayListOf() }

    fun getSuccessorsIndices(insn: AbstractInsnNode): List = getSuccessorsIndices(insns.indexOf(insn))
    fun getSuccessorsIndices(index: Int): List = edges[index]
    fun getPredecessorsIndices(insn: AbstractInsnNode): List = getPredecessorsIndices(insns.indexOf(insn))
    fun getPredecessorsIndices(index: Int): List = backwardEdges[index]

    companion object {
        @JvmStatic
        fun build(node: MethodNode, followExceptions: Boolean = true): ControlFlowGraph {
            val graph = ControlFlowGraph(node.instructions)

            fun addEdge(from: Int, to: Int) {
                graph.edges[from].add(to)
                graph.backwardEdges[to].add(from)
            }

            object : MethodAnalyzer("fake", node, OptimizationBasicInterpreter()) {
                override fun visitControlFlowEdge(insn: Int, successor: Int): Boolean {
                    addEdge(insn, successor)
                    return true
                }

                override fun visitControlFlowExceptionEdge(insn: Int, successor: Int): Boolean {
                    if (followExceptions) {
                        addEdge(insn, successor)
                    }
                    return true
                }
            }.analyze()

            return graph
        }
    }
}