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/* Package information */
package depgraph
/* Simple import of data structures and IO */
import scala.collection.mutable.{HashSet,HashMap}
import java.io.{BufferedWriter,FileWriter}
/* Class made to model the internal compiler phases
*
* All internal phases inherits from SubComponent
*/
abstract class SubComponent {
val phaseName: String
val runsAfter: List[String]
val runsRightAfter: Option[String]
val internal: Boolean = true
}
/*
*
*/
class Global extends Plugins with PhaseAssembly {
/* Simple option value to hold the compiler phase chain */
private var phasesCache : Option[List[SubComponent]] = None
/* The set of phase objects that is the basis for the compiler phase chain */
protected val phasesSet : HashSet[SubComponent] = new HashSet[SubComponent]
/* All the internal phase objects
*
*/
object parser extends {
val phaseName = "nsc::parser"
val runsAfter = List[String]()
val runsRightAfter = None
} with SubComponent
object typer extends {
val phaseName = "nsc::typer"
val runsAfter = List[String]("nsc::parser")
val runsRightAfter = None
} with SubComponent
object pickler extends {
val phaseName = "nsc::pickler"
val runsAfter = List[String]("nsc::typer")
val runsRightAfter = None
} with SubComponent
object liftcode extends {
val phaseName = "nsc::liftcode"
val runsAfter = List[String]("nsc::pickler")
val runsRightAfter = None
} with SubComponent
object tailcalls extends {
val phaseName = "nsc::tailcalls"
val runsAfter = List[String]("nsc::pickler","nsc::liftcode")
val runsRightAfter = None
} with SubComponent
object erasure extends {
val phaseName = "nsc::erasure"
val runsAfter = List[String]()
val runsRightAfter = Some("nsc::tailcalls")
} with SubComponent
object cleanup extends {
val phaseName = "nsc::cleanup"
val runsAfter = List[String]("nsc::erasure")
val runsRightAfter = None
} with SubComponent
object jvm extends {
val phaseName = "nsc::jvm"
val runsAfter = List[String]("nsc::cleanup")
val runsRightAfter = None
} with SubComponent
object terminal extends {
val phaseName = "nsc::terminal"
val runsAfter = List[String]("nsc::jvm","nsc::msil")
val runsRightAfter = None
} with SubComponent
/* Helper method
*/
private def computePhaseDescriptors: List[SubComponent] = {
computeInternalPhases() // Global.scala
computePluginPhases() // plugins/Plugins.scala
buildCompilerFromPhasesSet() // PhaseAssembly.scala
}
/* Will add the internal compiler phases to the phases set
*/
protected def computeInternalPhases() {
phasesSet += parser
phasesSet += typer
phasesSet += pickler
phasesSet += liftcode
phasesSet += tailcalls
phasesSet += erasure
phasesSet += cleanup
phasesSet += jvm
phasesSet += terminal
}
/* Getter method for the compiler phases chain
*/
def phaseDescriptors : List[SubComponent] = {
if (phasesCache.isEmpty) {
phasesCache = Some(computePhaseDescriptors)
}
phasesCache.get
}
}
/* Class make to model the Plug-in supplied phases
*
* All external phases inherits from PluginComponent
*/
abstract class PluginComponent extends SubComponent {
override val internal = false
val runsRightAfter: Option[String] = None
}
/* Trait made to model the behavior of the plugins
*
*/
trait Plugins { self: Global =>
/* Example plugin phases
*
*/
object plugin1 extends {
val phaseName = "plug1::optimization1"
val runsAfter = List[String]("nsc::typer")
} with PluginComponent
object plugin2 extends {
val phaseName = "plug2::optimization1"
val runsAfter = List[String]("nsc::liftcode")
} with PluginComponent
object plugin3 extends {
val phaseName = "plug2::optimization2"
val runsAfter = List[String]("plug2::optimization1","nsc::cleanup")
} with PluginComponent
/* Add plug-in supplied phase objects to the phases set
*/
def computePluginPhases() {
phasesSet += plugin1
phasesSet += plugin2
phasesSet += plugin3
}
}
/* Trait made to seperate the constraint solving from the rest of the compiler
*
*/
trait PhaseAssembly { self: Global =>
/* Aux datastructure for solving the constraint system
* Simple edge with to and from refs
*/
class Edge(f: Node, t: Node, h: Boolean) {
var frm = f
var to = t
var hard = h
}
/* Aux datastructure for solving the constraint system
* Simple node with name and object ref for the phase object,
* also sets of in and out going dependencies
*/
class Node(phs:SubComponent, name:String) {
var phasename: String = name
var phaseobj: SubComponent = phs
var after: HashSet[Edge] = new HashSet[Edge]()
var deps: HashSet[Edge] = new HashSet[Edge]()
}
/* Aux datastructure for solving the constraint system
* The depency graph container with helper methods for node and edge creation
*/
class DependencyGraph {
val nodes = new HashMap[String,Node]()
val edges = new HashSet[Edge]()
/* Given a phase object, get the node for this phase object. If the
* node object does not exist, then create it.
*/
def getNodeByPhase(phs : SubComponent) : Node = {
var node : Node = getNodeByPhase(phs.phaseName)
if (node.phaseobj == null) {
node.phaseobj = phs
}
node
}
/* Given the name of a phase object, get the node for that name. If the
* node object does not exits, then create it.
*/
def getNodeByPhase(name : String) : Node = {
var node : Node = null
this.nodes.get(name) match {
case None =>
node = new Node(null,name)
nodes += (name->node)
case Some(n) =>
node = n
}
node
}
/* Connect the frm and to nodes with an edge and make it soft.
* Also add the edge object to the set of edges, and to the dependency
* list of the nodes
*/
def softConnectNodes(frm: Node, to: Node) {
var e = new Edge(frm, to, false)
this.edges += e
frm.after += e
to.deps += e
}
/* Connect the frm and to nodes with an edge and make it hard.
* Also add the edge object to the set of edges, and to the dependency
* list of the nodes
*/
def hardConnectNodes(frm: Node, to: Node) {
var e = new Edge(frm, to, true)
this.edges += e
frm.after += e
to.deps += e
}
}
/* This method will simplify the graph, by removing unneeded edges and turning the graph into
* a tree.
*/
private def simplifyGraphFromNode(node : Node, graph : DependencyGraph) : Unit = {
var removal : List[Edge] = Nil
for(edge <- node.deps) {
if (edge.frm.after.size > 1)
removal = edge :: removal
}
for(edge <- removal) {
println("[removing edge: " + edge.frm.phasename + " => " + edge.to.phasename + "]")
node.deps -= edge
edge.frm.after -= edge
graph.edges -= edge
}
var nodes = dependencyOrder(node.deps)
for(nd <- nodes) {
simplifyGraphFromNode(nd, graph)
}
}
/* This is a simple method that tests for cycles in the graph. If a cycle is found, a fatal error
* will be produced.
*/
private def testForCycles(node : Node, names : HashSet[String]) : Unit = {
if (names.contains( node.phasename ) ) {
println("There is a cycle in this graph! The algorithm was able to reach the node " + node.phasename + " twice!")
System.exit(1)
}
names += node.phasename
var nodes = dependencyOrder(node.deps)
for(nd <- nodes) {
testForCycles(nd, names)
}
names -= node.phasename
}
/* Given the dependency list of a node, return a list so that first come the reversed
* external phases sorted alphabetically, followed by the internal phase
*/
private def dependencyOrder(deps : HashSet[Edge]) : List[Node] = {
var external = deps.filter(e => (! e.frm.phaseobj.internal))
var internal = deps.filter(e => e.frm.phaseobj.internal)
var extnodes = (Nil ++ external.map(e => e.frm)).sort((n1,n2) => (n1.phasename compareTo n2.phasename) < 0)
extnodes = extnodes.reverse
var nodes = Nil ++ internal.map(e => e.frm) ++ extnodes
nodes = nodes.reverse
return nodes
}
/* Find all edges in the given graph that are hard links. For each hard link we
* need to check that its the only dependency. If not, then we will promote the
* other dependencies down
*/
private def enforceHardlinks(graph : DependencyGraph) : Unit = {
var rerun = true
while(rerun) {
rerun = false
var hardlinks = graph.edges.filter(e => e.hard)
for(hl <- hardlinks) {
var sanity = Nil ++ hl.to.deps.filter(e => e.hard)
if (sanity.length == 0) {
println("This is not supposed to happen!")
System.exit(1)
// throw new FataError()
} else if (sanity.length > 1) {
println("Multiple phases want to run right after the same phase")
println("Phases:")
for (edge <- sanity) {
println(" - " + edge.frm.phasename)
}
System.exit(1)
} else {
var promote = hl.to.deps.filter(e => (!e.hard))
hl.to.deps.clear
sanity foreach (edge => hl.to.deps += edge)
for (edge <- promote) {
rerun = true
println("[promote the dependency of " + edge.frm.phasename + ": " + edge.to.phasename + " => " + hl.frm.phasename + "]")
edge.to = hl.frm
hl.frm.deps += edge
}
}
}
}
}
/* Remove all nodes in the given graph, that have no phase object
* Make sure to clean up all edges when removing the node object
*/
private def removeDanglingNodes(graph : DependencyGraph) : Unit = {
var dnodes = graph.nodes.values.filter(n => (n.phaseobj == null))
for(node <- dnodes) {
println("[dropping depend on node with no phase: " + node.phasename + "]")
graph.nodes -= node.phasename
for(edge <- node.deps) {
graph.edges -= edge
edge.frm.after -= edge
}
}
}
/* This is a helper method, that given a dependency graph will generate a graphviz dot
* file showing its structure.
* Plug-in supplied phases are marked as green nodes and hard links are marked as blue edges.
*/
private def graphToDotFile(graph : DependencyGraph, filename : String) : Unit = {
var sbuf = new StringBuffer()
var extnodes = new HashSet[Node]()
sbuf.append("digraph G {\n")
for(edge <- graph.edges) {
sbuf.append("\"" + edge.frm.phasename + "\"->\"" + edge.to.phasename + "\"")
if (! edge.frm.phaseobj.internal) {
extnodes += edge.frm
}
if (edge.hard) {
sbuf.append(" [color=\"#0000ff\"]\n")
} else {
sbuf.append(" [color=\"#000000\"]\n")
}
}
for(node <- extnodes) {
sbuf.append("\"" + node.phasename + "\" [color=\"#00ff00\"]\n")
}
sbuf.append("}\n")
var out = new BufferedWriter(new FileWriter(filename))
out.write(sbuf.toString)
out.flush()
out.close()
}
/* Given the phases set, will build a dependency graph from the phases set
* Using the aux. method of the DependencyGraph to create nodes and egdes
*/
private def phasesSetToDepGraph(phsSet : HashSet[SubComponent]) : DependencyGraph = {
val graph = new DependencyGraph()
for(phs <- phsSet) {
var fromnode = graph.getNodeByPhase(phs)
phs.runsRightAfter match {
case None =>
for(phsname <- phs.runsAfter) {
if (! (phsname equals "terminal")) {
var tonode = graph.getNodeByPhase(phsname)
graph.softConnectNodes(fromnode, tonode)
} else {
println("[depends on terminal not allowed, dropping depend: " + fromnode.phasename + " => "+ phsname +"]")
}
}
case Some(phsname) =>
if (! (phsname equals "terminal")) {
var tonode = graph.getNodeByPhase(phsname)
graph.hardConnectNodes(fromnode, tonode)
} else {
println("[depends on terminal not allowed, dropping depend: " + fromnode.phasename + " => "+ phsname +"]")
}
}
}
return graph
}
/* Simple transformation function, that given a dependency graph transforms it into a dependency tree
* Will return the root of the tree
*/
private def depGraphToDepTree(graph : DependencyGraph) : Node = {
graphToDotFile(graph, "depgraph1.dot")
// Remove nodes without phaseobj
removeDanglingNodes(graph)
graphToDotFile(graph, "depgraph2.dot")
// Enforce hardlinks / runsRightAfter and promote nodes down the tree
enforceHardlinks(graph)
graphToDotFile(graph, "depgraph3.dot")
var root = graph.getNodeByPhase("nsc::parser")
// Test for cycles in graph, if found will generate fatal error
testForCycles(root, new HashSet[String]())
// Simplify graph by removing edges starting from the root
simplifyGraphFromNode(root, graph)
graphToDotFile(graph, "depgraph4.dot")
root
}
/* Given a node and a list of phases, it will traverse the dependencies of the node object and
* call itself recursively
*
*/
private def depTree2CompilerPhaseList(node : Node, pchain : List[SubComponent]) : List[SubComponent] = {
var chain : List[SubComponent] = pchain
chain = chain ::: List(node.phaseobj)
if (node.deps.size == 0)
return chain
else if (node.deps.size == 1) {
for(edge <- node.deps)
chain = depTree2CompilerPhaseList(edge.frm, chain)
return chain
} else {
var nodes = dependencyOrder(node.deps)
for(nd <- nodes) {
chain = depTree2CompilerPhaseList(nd, chain)
}
return chain
}
}
/* Method called from computePhaseDescriptors in class Global
* This method will call three aux. methods to convert the phases set into a dependency graph
* Convert the dependency graph into a dependency tree and return the root of the tree
* Assemble the compiler phase chain from the root of the dependency tree
*/
def buildCompilerFromPhasesSet() : List[SubComponent] = {
// Add all phases in the set to the graph
val graph = phasesSetToDepGraph(phasesSet)
val root = depGraphToDepTree(graph)
return depTree2CompilerPhaseList(root, Nil)
}
}
/**
* Test object that will create a new object from the Global class
* and call the method phaseDescriptors to get the list of phase objects
* and print the phase names to stdout
*
*/
object DepGraphTest extends Application {
val global = new Global()
var compilerchain = global.phaseDescriptors
for(phase <- compilerchain) {
println(" - " + phase.phaseName)
}
}
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