Construct ClassBTypes from parsed classfiles

This infrastructure is required for the inliner: when inlining code
from a classfile, the corresponding ClassBType is needed for various
things (eg access checks, InnerClass attribute).

The test creates two ClassBTypes for the same class: once using the
(unpickled) Symbol, once using the parsed ASM ClassNode, and verifies
that the two are the same.

There's a cleanup to the InnerClass attribute:

    object T { class Member; def foo = { class Local } }
    class T

For Java compatibility the InnerClass entry for Member says the class
is nested in T (not in the module class T$). We now make sure to add
that entry only to T, not to T$ (unless Member is actually referenced
in the classfile T$, in that case it will be added, as required).

1 files changed, 93 insertions, 0 deletions

diff --git a/src/compiler/scala/tools/nsc/backend/jvm/opt/CodeRepository.scala b/src/compiler/scala/tools/nsc/backend/jvm/opt/CodeRepository.scala
new file mode 100644
index 0000000000..285855d083
--- /dev/null
+++ b/src/compiler/scala/tools/nsc/backend/jvm/opt/CodeRepository.scala
@@ -0,0 +1,93 @@
+/* NSC -- new Scala compiler
+ * Copyright 2005-2014 LAMP/EPFL
+ * @author  Martin Odersky
+ */
+
+package scala.tools.nsc
+package backend.jvm
+package opt
+
+import scala.tools.asm
+import asm.tree._
+import scala.collection.convert.decorateAsScala._
+import scala.tools.nsc.io.AbstractFile
+import scala.tools.nsc.util.ClassFileLookup
+import OptimizerReporting._
+
+class CodeRepository(val classPath: ClassFileLookup[AbstractFile]) {
+  import BTypes.InternalName
+
+  /**
+   * Cache for parsed ClassNodes.
+   */
+  val classes: collection.concurrent.Map[InternalName, ClassNode] = collection.concurrent.TrieMap.empty[InternalName, ClassNode]
+
+  /**
+   * 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): ClassNode = {
+    classes.getOrElseUpdate(internalName, parseClass(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.
+   */
+  def fieldNode(classInternalName: InternalName, name: String, descriptor: String): Option[(FieldNode, InternalName)] = {
+    val c = classNode(classInternalName)
+    c.fields.asScala.find(f => f.name == name && f.desc == descriptor).map((_, classInternalName)) orElse {
+      Option(c.superName).flatMap(n => fieldNode(n, name, descriptor))
+    }
+  }
+
+  /**
+   * The method node for a method matching `name` and `descriptor`, accessed in class `classInternalName`.
+   * The declaration of the method may be in one of the parents.
+   *
+   * @return The [[MethodNode]] of the requested method and the [[InternalName]] of its declaring class.
+   */
+  def methodNode(classInternalName: InternalName, name: String, descriptor: String): Option[(MethodNode, InternalName)] = {
+    val c = classNode(classInternalName)
+    c.methods.asScala.find(m => m.name == name && m.desc == descriptor).map((_, classInternalName)) orElse {
+      val parents = Option(c.superName) ++ c.interfaces.asScala
+      // `view` to stop at the first result
+      parents.view.flatMap(methodNode(_, name, descriptor)).headOption
+    }
+  }
+
+  private def parseClass(internalName: InternalName): ClassNode = {
+    val fullName = internalName.replace('/', '.')
+    classPath.findClassFile(fullName) map { classFile =>
+      val classNode = new asm.tree.ClassNode()
+      val classReader = new asm.ClassReader(classFile.toByteArray)
+      // 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, 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.
+      //   http://docs.oracle.com/javase/specs/jvms/se7/html/jvms-4.html#jvms-4.7.11
+      //   https://jcp.org/aboutJava/communityprocess/final/jsr045/index.html
+      removeLineNumberNodes(classNode)
+      classes(internalName) = classNode
+      classNode
+    } getOrElse {
+      inlineFailure(s"Class file for class $fullName not found.")
+    }
+  }
+
+  private def removeLineNumberNodes(classNode: ClassNode): Unit = {
+    for (method <- classNode.methods.asScala) {
+      val iter = method.instructions.iterator()
+      while (iter.hasNext) iter.next() match {
+        case _: LineNumberNode => iter.remove()
+        case _ =>
+      }
+    }
+  }
+}