scala.tools.nsc.backend.jvm.opt.ByteCodeRepository.scala Maven / Gradle / Ivy
/*
* Scala (https://www.scala-lang.org)
*
* Copyright EPFL and Lightbend, Inc.
*
* Licensed under Apache License 2.0
* (http://www.apache.org/licenses/LICENSE-2.0).
*
* See the NOTICE file distributed with this work for
* additional information regarding copyright ownership.
*/
package scala.tools.nsc
package backend.jvm
package opt
import scala.annotation.nowarn
import scala.collection.{concurrent, mutable}
import scala.jdk.CollectionConverters._
import scala.reflect.internal.util.NoPosition
import scala.tools.asm
import scala.tools.asm.{Attribute, Type}
import scala.tools.asm.tree._
import scala.tools.nsc.backend.jvm.BTypes.InternalName
import scala.tools.nsc.backend.jvm.BackendReporting._
import scala.tools.nsc.backend.jvm.analysis.BackendUtils.LambdaMetaFactoryCall
import scala.tools.nsc.backend.jvm.opt.BytecodeUtils._
/**
* The ByteCodeRepository provides utilities to read the bytecode of classfiles from the compilation
* classpath. Parsed classes are cached in the `classes` map.
*/
abstract class ByteCodeRepository extends PerRunInit {
val postProcessor: PostProcessor
import postProcessor.{bTypes, bTypesFromClassfile}
import bTypes._
import frontendAccess.{backendReporting, backendClassPath, recordPerRunCache}
/**
* Contains ClassNodes and the canonical path of the source file path of classes being compiled in
* the current compilation run.
*/
val compilingClasses: concurrent.Map[InternalName, (ClassNode, String)] = recordPerRunCache(concurrent.TrieMap.empty)
/**
* Prevent the code repository from growing too large. Profiling reveals that the average size
* of a ClassNode is about 30 kb. I observed having 17k+ classes in the cache, i.e., 500 mb.
*/
private val maxCacheSize = 1500
/**
* Cache for parsed ClassNodes, an LRU or size maxCacheSize
* For Java classes in mixed compilation, the map contains an error message: no ClassNode is
* generated by the backend and also no classfile that could be parsed.
* Note - although this is typed a mutable.Map, individual simple get and put operations are threadsafe as the
* underlying data structure is synchronized.
*/
val parsedClasses: mutable.Map[InternalName, Either[ClassNotFound, ClassNode]] = recordPerRunCache(LruMap[InternalName, Either[ClassNotFound, ClassNode]](maxCacheSize, true))
/**
* Contains the internal names of all classes that are defined in Java source files of the current
* compilation run (mixed compilation). Used for more detailed error reporting.
*/
private lazy val javaDefinedClasses = perRunLazy(this)(frontendAccess.javaDefinedClasses)
def add(classNode: ClassNode, sourceFilePath: Option[String]) = sourceFilePath match {
case Some(path) if path != "" => compilingClasses(classNode.name) = (classNode, path)
case _ => parsedClasses(classNode.name) = Right(classNode)
}
private def parsedClassNode(internalName: InternalName): Either[ClassNotFound, ClassNode] = {
parsedClasses.getOrElseUpdate(internalName, parseClass(internalName))
}
/**
* The class node and source file path (if the class is being compiled) for an internal name. If
* the class node is not yet available, it is parsed from the classfile on the compile classpath.
*/
def classNodeAndSourceFilePath(internalName: InternalName): Either[ClassNotFound, (ClassNode, Option[String])] = {
compilingClasses.get(internalName) match {
case Some((c, p)) => Right((c, Some(p)))
case _ => parsedClassNode(internalName).map((_, None))
}
}
/**
* The class node for an internal name. If the class node is not yet available, it is parsed from
* the classfile on the compile classpath.
*/
def classNode(internalName: InternalName): Either[ClassNotFound, ClassNode] = {
compilingClasses.get(internalName) match {
case Some((c, _)) => Right(c)
case None => parsedClassNode(internalName)
}
}
/**
* The field node for a field matching `name` and `descriptor`, accessed in class `classInternalName`.
* The declaration of the field may be in one of the superclasses.
*
* @return The [[FieldNode]] of the requested field and the [[InternalName]] of its declaring
* class, or an error message if the field could not be found
*/
def fieldNode(classInternalName: InternalName, name: String, descriptor: String): Either[FieldNotFound, (FieldNode, InternalName)] = {
def fieldNodeImpl(parent: InternalName): Either[FieldNotFound, (FieldNode, InternalName)] = {
classNode(parent) match {
case Left(e) => Left(FieldNotFound(name, descriptor, classInternalName, Some(e)))
case Right(c) =>
c.fields.asScala.find(f => f.name == name && f.desc == descriptor) match {
case Some(f) => Right((f, parent))
case None =>
if (c.superName == null) Left(FieldNotFound(name, descriptor, classInternalName, None))
else fieldNode(c.superName, name, descriptor)
}
}
}
fieldNodeImpl(classInternalName)
}
/**
* The method node for a method matching `name` and `descriptor`, accessed in class `ownerInternalNameOrArrayDescriptor`.
* The declaration of the method may be in one of the parents.
*
* Note that the JVM spec performs method lookup in two steps: resolution and selection.
*
* Method resolution, defined in jvms-5.4.3.3 and jvms-5.4.3.4, is the first step and is identical
* for all invocation styles (virtual, interface, special, static). If C is the receiver class
* in the invocation instruction:
* 1 find a matching method (name and descriptor) in C
* 2 then in C's superclasses
* 3 then find the maximally-specific matching superinterface methods, succeed if there's a
* single non-abstract one. static and private methods in superinterfaces are not considered.
* 4 then pick a random non-static, non-private superinterface method.
* 5 then fail.
*
* Note that for an `invokestatic` instruction, a method reference `B.m` may resolve to `A.m`, if
* class `B` doesn't specify a matching method `m`, but the parent `A` does.
*
* Selection depends on the invocation style and is defined in jvms-6.5.
* - invokestatic: invokes the resolved method
* - invokevirtual / invokeinterface: searches for an override of the resolved method starting
* at the dynamic receiver type. the search procedure is basically the same as in resolution,
* but it fails at 4 instead of picking a superinterface method at random.
* - invokespecial: if C is the receiver in the invocation instruction, searches for an override
* of the resolved method starting at
* - the superclass of the current class, if C is a superclass of the current class
* - C otherwise
* again, the search procedure is the same.
*
* In the method here we implement method *resolution*. Whether or not the returned method is
* actually invoked at runtime depends on the invocation instruction and the class hierarchy, so
* the users (e.g. the inliner) have to be aware of method selection.
*
* Note that the returned method may be abstract (ACC_ABSTRACT), native (ACC_NATIVE) or signature
* polymorphic (methods `invoke` and `invokeExact` in class `MethodHandles`).
*
* @return The [[MethodNode]] of the requested method and the [[InternalName]] of its declaring
* class, or an error message if the method could not be found. An error message is also
* returned if method resolution results in multiple default methods.
*/
def methodNode(ownerInternalNameOrArrayDescriptor: String, name: String, descriptor: String): Either[MethodNotFound, (MethodNode, InternalName)] = {
def findMethod(c: ClassNode): Option[MethodNode] = c.methods.asScala.find(m => m.name == name && m.desc == descriptor)
// https://docs.oracle.com/javase/specs/jvms/se11/html/jvms-2.html#jvms-2.9.3
def findSignaturePolymorphic(owner: ClassNode): Option[MethodNode] = {
def hasObjectArrayParam(m: MethodNode) = Type.getArgumentTypes(m.desc) match {
case Array(pt) => pt.getDimensions == 1 && pt.getElementType.getInternalName == coreBTypes.ObjectRef.internalName
case _ => false
}
// Don't try to build a BType for `VarHandle`, it doesn't exist on JDK 8
if (owner.name == coreBTypes.jliMethodHandleRef.internalName || owner.name == "java/lang/invoke/VarHandle")
owner.methods.asScala.find(m =>
m.name == name &&
isNativeMethod(m) &&
isVarargsMethod(m) &&
hasObjectArrayParam(m))
else None
}
// Note: if `owner` is an interface, in the first iteration we search for a matching member in the interface itself.
// If that fails, the recursive invocation checks in the superclass (which is Object) with `publicInstanceOnly == true`.
// This is specified in jvms-5.4.3.4: interface method resolution only returns public, non-static methods of Object.
def findInSuperClasses(owner: ClassNode, publicInstanceOnly: Boolean = false): Either[ClassNotFound, Option[(MethodNode, InternalName)]] = {
findMethod(owner) match {
case Some(m) if !publicInstanceOnly || (isPublicMethod(m) && !isStaticMethod(m)) => Right(Some((m, owner.name)))
case _ =>
findSignaturePolymorphic(owner) match {
case Some(m) => Right(Some((m, owner.name)))
case _ =>
if (owner.superName == null) Right(None)
else classNode(owner.superName).flatMap(findInSuperClasses(_, publicInstanceOnly = isInterface(owner)))
}
}
}
def findInInterfaces(initialOwner: ClassNode): Either[ClassNotFound, Option[(MethodNode, InternalName)]] = {
val visited = mutable.Set.empty[InternalName]
val found = mutable.ListBuffer.empty[(MethodNode, ClassNode)]
@nowarn("cat=lint-nonlocal-return")
def findIn(owner: ClassNode): Option[ClassNotFound] = {
for (i <- owner.interfaces.asScala if !visited(i)) classNode(i) match {
case Left(e) => return Some(e)
case Right(c) =>
visited += i
// abstract and static methods are excluded, see jvms-5.4.3.3
for (m <- findMethod(c) if !isPrivateMethod(m) && !isStaticMethod(m)) found += ((m, c))
val recursionResult = findIn(c)
if (recursionResult.isDefined) return recursionResult
}
None
}
findIn(initialOwner)
val result =
if (found.size <= 1) found.headOption
else {
val maxSpecific = found.filterNot({
case (method, owner) =>
isAbstractMethod(method) || {
val ownerTp = bTypesFromClassfile.classBTypeFromClassNode(owner)
found exists {
case (other, otherOwner) =>
(other ne method) && {
val otherTp = bTypesFromClassfile.classBTypeFromClassNode(otherOwner)
otherTp.isSubtypeOf(ownerTp).get
}
}
}
})
// (*) note that if there's no single, non-abstract, maximally-specific method, the jvm
// method resolution (jvms-5.4.3.3) returns any of the non-private, non-static parent
// methods at random (abstract or concrete).
// we chose not to do this here, to prevent the inliner from potentially inlining the
// wrong method. in other words, we guarantee that a concrete method is only returned if
// it resolves deterministically.
// however, there may be multiple abstract methods inherited. in this case we *do* want
// to return a result to allow performing accessibility checks in the inliner. note that
// for accessibility it does not matter which of these methods is return, as they are all
// non-private (i.e., public, protected is not possible, jvms-4.1).
// the remaining case (when there's no max-specific method, but some non-abstract one)
// does not occur in bytecode generated by scalac or javac. we return no result in this
// case. this may at worst prevent some optimizations from happening.
if (maxSpecific.size == 1) maxSpecific.headOption
else if (found.forall(p => isAbstractMethod(p._1))) found.headOption // (*)
else None
}
Right(result.map(p => (p._1, p._2.name)))
}
// In a MethodInsnNode, the `owner` field may be an array descriptor, for example when invoking `clone`. We don't have a method node to return in this case.
if (ownerInternalNameOrArrayDescriptor.charAt(0) == '[') {
Left(MethodNotFound(name, descriptor, ownerInternalNameOrArrayDescriptor, None))
} else {
def notFound(cnf: Option[ClassNotFound]) = Left(MethodNotFound(name, descriptor, ownerInternalNameOrArrayDescriptor, cnf))
val res: Either[ClassNotFound, Option[(MethodNode, InternalName)]] = classNode(ownerInternalNameOrArrayDescriptor).flatMap(c =>
findInSuperClasses(c) flatMap {
case None => findInInterfaces(c)
case res => Right(res)
}
)
res match {
case Left(e) => notFound(Some(e))
case Right(None) => notFound(None)
case Right(Some(res)) => Right(res)
}
}
}
private def removeLineNumbersAndAddLMFImplMethods(classNode: ClassNode): Unit = {
for (m <- classNode.methods.asScala) {
val iter = m.instructions.iterator
while (iter.hasNext) {
val insn = iter.next()
insn.getType match {
case AbstractInsnNode.LINE =>
iter.remove()
case AbstractInsnNode.INVOKE_DYNAMIC_INSN => insn match {
case LambdaMetaFactoryCall(indy, _, implMethod, _, _) =>
postProcessor.backendUtils.addIndyLambdaImplMethod(classNode.name, m, indy, implMethod)
case _ =>
}
case _ =>
}
}
}
}
private def parseClass(internalName: InternalName): Either[ClassNotFound, ClassNode] = {
val fullName = internalName.replace('/', '.')
backendClassPath.findClassFile(fullName).flatMap { classFile =>
val classNode = new ClassNode1
val classReader = new asm.ClassReader(classFile.toByteArray)
try {
// Passing the InlineInfoAttributePrototype makes the ClassReader invoke the specific `read`
// method of the InlineInfoAttribute class, instead of putting the byte array into a generic
// Attribute.
// We don't need frames when inlining, but we want to keep the local variable table, so we
// don't use SKIP_DEBUG.
classReader.accept(classNode, Array[Attribute](InlineInfoAttributePrototype), asm.ClassReader.SKIP_FRAMES)
// SKIP_FRAMES leaves line number nodes. Remove them because they are not correct after
// inlining.
// TODO: we need to remove them also for classes that are not parsed from classfiles, why not simplify and do it once when inlining?
// OR: instead of skipping line numbers for inlined code, use write a SourceDebugExtension
// attribute that contains JSR-45 data that encodes debugging info.
// https://docs.oracle.com/javase/specs/jvms/se7/html/jvms-4.html#jvms-4.7.11
// https://jcp.org/aboutJava/communityprocess/final/jsr045/index.html
removeLineNumbersAndAddLMFImplMethods(classNode)
Some(classNode)
} catch {
case ex: Exception =>
if (frontendAccess.compilerSettings.debug) ex.printStackTrace()
backendReporting.warning(NoPosition, s"Error while reading InlineInfoAttribute from ${fullName}\n${ex.getMessage}")
None
}
} match {
case Some(node) => Right(node)
case None => Left(ClassNotFound(internalName, javaDefinedClasses.get(internalName)))
}
}
}
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