Add bytecode checking infrastructure

1 files changed, 256 insertions, 0 deletions

diff --git a/test/test/AsmConverters.scala b/test/test/AsmConverters.scala
new file mode 100644
index 000000000..a870b8fe7
--- /dev/null
+++ b/test/test/AsmConverters.scala
@@ -0,0 +1,256 @@
+package test
+
+import scala.tools.asm
+import asm._
+import asm.tree._
+import scala.collection.JavaConverters._
+
+/** Makes using ASM from ByteCodeTests more convenient.
+ *
+ * Wraps ASM instructions in case classes so that equals and toString work
+ * for the purpose of bytecode diffing and pretty printing.
+ */
+object ASMConverters {
+  import asm.{tree => t}
+
+  /**
+   * Transform the instructions of an ASM Method into a list of [[Instruction]]s.
+   */
+  def instructionsFromMethod(meth: t.MethodNode): List[Instruction] = new AsmToScala(meth).instructions
+
+  def convertMethod(meth: t.MethodNode): Method = new AsmToScala(meth).method
+
+  implicit class RichInstructionLists(val self: List[Instruction]) extends AnyVal {
+    def === (other: List[Instruction]) = equivalentBytecode(self, other)
+
+    def dropLinesFrames = self.filterNot(i => i.isInstanceOf[LineNumber] || i.isInstanceOf[FrameEntry])
+
+    private def referencedLabels(instruction: Instruction): Set[Instruction] = instruction match {
+      case Jump(op, label)                         => Set(label)
+      case LookupSwitch(op, dflt, keys, labels)    => (dflt :: labels).toSet
+      case TableSwitch(op, min, max, dflt, labels) => (dflt :: labels).toSet
+      case LineNumber(line, start)                 => Set(start)
+      case _ => Set.empty
+    }
+
+    def dropStaleLabels = {
+      val definedLabels: Set[Instruction] = self.filter(_.isInstanceOf[Label]).toSet
+      val usedLabels: Set[Instruction] = self.flatMap(referencedLabels)(collection.breakOut)
+      self.filterNot(definedLabels diff usedLabels)
+    }
+
+    def dropNonOp = dropLinesFrames.dropStaleLabels
+
+    def summary: List[Any] = dropNonOp map {
+      case i: Invoke => i.name
+      case i => i.opcode
+    }
+
+    def summaryText: String = {
+      def comment(i: Instruction) = i match {
+        case j: Jump => s" /*${j.label.offset}*/"
+        case l: Label => s" /*${l.offset}*/"
+        case _ => ""
+      }
+      dropNonOp.map({
+        case i: Invoke => s""""${i.name}""""
+        case ins => opcodeToString(ins.opcode, ins.opcode) + comment(ins)
+      }).mkString("List(", ", ", ")")
+    }
+  }
+
+  def opcodeToString(op: Int, default: Any = "?"): String = {
+    import scala.tools.asm.util.Printer.OPCODES
+    if (OPCODES.isDefinedAt(op)) OPCODES(op) else default.toString
+  }
+
+  sealed abstract class Instruction extends Product {
+    def opcode: Int
+
+    // toString such that the first field, "opcode: Int", is printed textually.
+    final override def toString() = {
+      val printOpcode = opcode != -1
+      productPrefix + (
+        if (printOpcode) Iterator(opcodeToString(opcode)) ++ productIterator.drop(1)
+        else productIterator
+      ).mkString("(", ", ", ")")
+    }
+  }
+
+  case class Method(instructions: List[Instruction], handlers: List[ExceptionHandler], localVars: List[LocalVariable])
+
+  case class Field        (opcode: Int, owner: String, name: String, desc: String)                            extends Instruction
+  case class Incr         (opcode: Int, `var`: Int, incr: Int)                                                extends Instruction
+  case class Op           (opcode: Int)                                                                       extends Instruction
+  case class IntOp        (opcode: Int, operand: Int)                                                         extends Instruction
+  case class Jump         (opcode: Int, label: Label)                                                         extends Instruction
+  case class Ldc          (opcode: Int, cst: Any)                                                             extends Instruction
+  case class LookupSwitch (opcode: Int, dflt: Label, keys: List[Int], labels: List[Label])                    extends Instruction
+  case class TableSwitch  (opcode: Int, min: Int, max: Int, dflt: Label, labels: List[Label])                 extends Instruction
+  case class Invoke       (opcode: Int, owner: String, name: String, desc: String, itf: Boolean)              extends Instruction
+  case class InvokeDynamic(opcode: Int, name: String, desc: String, bsm: MethodHandle, bsmArgs: List[AnyRef]) extends Instruction
+  case class NewArray     (opcode: Int, desc: String, dims: Int)                                              extends Instruction
+  case class TypeOp       (opcode: Int, desc: String)                                                         extends Instruction
+  case class VarOp        (opcode: Int, `var`: Int)                                                           extends Instruction
+  case class Label        (offset: Int)                                                                       extends Instruction { def opcode: Int = -1 }
+  case class FrameEntry   (`type`: Int, local: List[Any], stack: List[Any])                                   extends Instruction { def opcode: Int = -1 }
+  case class LineNumber   (line: Int, start: Label)                                                           extends Instruction { def opcode: Int = -1 }
+
+  case class MethodHandle(tag: Int, owner: String, name: String, desc: String)
+
+  case class ExceptionHandler(start: Label, end: Label, handler: Label, desc: Option[String])
+  case class LocalVariable(name: String, desc: String, signature: Option[String], start: Label, end: Label, index: Int)
+
+  class AsmToScala(asmMethod: t.MethodNode) {
+
+    def instructions: List[Instruction] = asmMethod.instructions.iterator.asScala.toList map apply
+
+    def method: Method = Method(instructions, convertHandlers(asmMethod), convertLocalVars(asmMethod))
+
+    private def labelIndex(l: t.LabelNode): Int = asmMethod.instructions.indexOf(l)
+
+    private def op(i: t.AbstractInsnNode): Int = i.getOpcode
+
+    private def lst[T](xs: java.util.List[T]): List[T] = if (xs == null) Nil else xs.asScala.toList
+
+    // Heterogeneous List[Any] is used in FrameNode: type information about locals / stack values
+    // are stored in a List[Any] (Integer, String or LabelNode), see Javadoc of MethodNode#visitFrame.
+    // Opcodes (eg Opcodes.INTEGER) and Reference types (eg "java/lang/Object") are returned unchanged,
+    // LabelNodes are mapped to their LabelEntry.
+    private def mapOverFrameTypes(is: List[Any]): List[Any] = is map {
+      case i: t.LabelNode => applyLabel(i)
+      case x => x
+    }
+
+    // avoids some casts
+    private def applyLabel(l: t.LabelNode) = this(l: t.AbstractInsnNode).asInstanceOf[Label]
+
+    private def apply(x: t.AbstractInsnNode): Instruction = x match {
+      case i: t.FieldInsnNode          => Field        (op(i), i.owner, i.name, i.desc)
+      case i: t.IincInsnNode           => Incr         (op(i), i.`var`, i.incr)
+      case i: t.InsnNode               => Op           (op(i))
+      case i: t.IntInsnNode            => IntOp        (op(i), i.operand)
+      case i: t.JumpInsnNode           => Jump         (op(i), applyLabel(i.label))
+      case i: t.LdcInsnNode            => Ldc          (op(i), i.cst: Any)
+      case i: t.LookupSwitchInsnNode   => LookupSwitch (op(i), applyLabel(i.dflt), lst(i.keys) map (x => x: Int), lst(i.labels) map applyLabel)
+      case i: t.TableSwitchInsnNode    => TableSwitch  (op(i), i.min, i.max, applyLabel(i.dflt), lst(i.labels) map applyLabel)
+      case i: t.MethodInsnNode         => Invoke       (op(i), i.owner, i.name, i.desc, i.itf)
+      case i: t.InvokeDynamicInsnNode  => InvokeDynamic(op(i), i.name, i.desc, convertMethodHandle(i.bsm), convertBsmArgs(i.bsmArgs))
+      case i: t.MultiANewArrayInsnNode => NewArray     (op(i), i.desc, i.dims)
+      case i: t.TypeInsnNode           => TypeOp       (op(i), i.desc)
+      case i: t.VarInsnNode            => VarOp        (op(i), i.`var`)
+      case i: t.LabelNode              => Label        (labelIndex(i))
+      case i: t.FrameNode              => FrameEntry   (i.`type`, mapOverFrameTypes(lst(i.local)), mapOverFrameTypes(lst(i.stack)))
+      case i: t.LineNumberNode         => LineNumber   (i.line, applyLabel(i.start))
+    }
+
+    private def convertBsmArgs(a: Array[Object]): List[Object] = a.map({
+      case h: asm.Handle => convertMethodHandle(h)
+      case _ => a // can be: Class, method Type, primitive constant
+    })(collection.breakOut)
+
+    private def convertMethodHandle(h: asm.Handle): MethodHandle = MethodHandle(h.getTag, h.getOwner, h.getName, h.getDesc)
+
+    private def convertHandlers(method: t.MethodNode): List[ExceptionHandler] = {
+      method.tryCatchBlocks.asScala.map(h => ExceptionHandler(applyLabel(h.start), applyLabel(h.end), applyLabel(h.handler), Option(h.`type`)))(collection.breakOut)
+    }
+
+    private def convertLocalVars(method: t.MethodNode): List[LocalVariable] = {
+      method.localVariables.asScala.map(v => LocalVariable(v.name, v.desc, Option(v.signature), applyLabel(v.start), applyLabel(v.end), v.index))(collection.breakOut)
+    }
+  }
+
+  import collection.mutable.{Map => MMap}
+
+  /**
+   * Bytecode is equal modulo local variable numbering and label numbering.
+   */
+  def equivalentBytecode(as: List[Instruction], bs: List[Instruction], varMap: MMap[Int, Int] = MMap(), labelMap: MMap[Int, Int] = MMap()): Boolean = {
+    def same(v1: Int, v2: Int, m: MMap[Int, Int]) = {
+      if (m contains v1) m(v1) == v2
+      else if (m.valuesIterator contains v2) false // v2 is already associated with some different value v1
+      else { m(v1) = v2; true }
+    }
+    def sameVar(v1: Int, v2: Int) = same(v1, v2, varMap)
+    def sameLabel(l1: Label, l2: Label) = same(l1.offset, l2.offset, labelMap)
+    def sameLabels(ls1: List[Label], ls2: List[Label]) = (ls1 corresponds ls2)(sameLabel)
+
+    def sameFrameTypes(ts1: List[Any], ts2: List[Any]) = (ts1 corresponds ts2) {
+      case (t1: Label, t2: Label) => sameLabel(t1, t2)
+      case (x, y) => x == y
+    }
+
+    if (as.isEmpty) bs.isEmpty
+    else if (bs.isEmpty) false
+    else ((as.head, bs.head) match {
+      case (VarOp(op1, v1), VarOp(op2, v2))           => op1 == op2 && sameVar(v1, v2)
+      case (Incr(op1, v1, inc1), Incr(op2, v2, inc2)) => op1 == op2 && sameVar(v1, v2) && inc1 == inc2
+
+      case (l1 @ Label(_), l2 @ Label(_))                                                 => sameLabel(l1, l2)
+      case (Jump(op1, l1), Jump(op2, l2))                                                 => op1 == op2 && sameLabel(l1, l2)
+      case (LookupSwitch(op1, l1, keys1, ls1), LookupSwitch(op2, l2, keys2, ls2))         => op1 == op2 && sameLabel(l1, l2) && keys1 == keys2 && sameLabels(ls1, ls2)
+      case (TableSwitch(op1, min1, max1, l1, ls1), TableSwitch(op2, min2, max2, l2, ls2)) => op1 == op2 && min1 == min2 && max1 == max2 && sameLabel(l1, l2) && sameLabels(ls1, ls2)
+      case (LineNumber(line1, l1), LineNumber(line2, l2))                                 => line1 == line2 && sameLabel(l1, l2)
+      case (FrameEntry(tp1, loc1, stk1), FrameEntry(tp2, loc2, stk2))                     => tp1 == tp2 && sameFrameTypes(loc1, loc2) && sameFrameTypes(stk1, stk2)
+
+      // this needs to go after the above. For example, Label(1) may not equal Label(1), if before
+      // the left 1 was associated with another right index.
+      case (a, b) if a == b => true
+
+      case _ => false
+    }) && equivalentBytecode(as.tail, bs.tail, varMap, labelMap)
+  }
+
+  def applyToMethod(method: t.MethodNode, instructions: List[Instruction]): Unit = {
+    val asmLabel = createLabelNodes(instructions)
+    instructions.foreach(visitMethod(method, _, asmLabel))
+  }
+
+  /**
+   * Convert back a [[Method]] to ASM land. The code is emitted into the parameter `asmMethod`.
+   */
+  def applyToMethod(asmMethod: t.MethodNode, method: Method): Unit = {
+    val asmLabel = createLabelNodes(method.instructions)
+    method.instructions.foreach(visitMethod(asmMethod, _, asmLabel))
+    method.handlers.foreach(h => asmMethod.visitTryCatchBlock(asmLabel(h.start), asmLabel(h.end), asmLabel(h.handler), h.desc.orNull))
+    method.localVars.foreach(v => asmMethod.visitLocalVariable(v.name, v.desc, v.signature.orNull, asmLabel(v.start), asmLabel(v.end), v.index))
+  }
+
+  private def createLabelNodes(instructions: List[Instruction]): Map[Label, asm.Label] = {
+    val labels = instructions collect {
+      case l: Label => l
+    }
+    assert(labels.distinct == labels, s"Duplicate labels in: $labels")
+    labels.map(l => (l, new asm.Label())).toMap
+  }
+
+  private def frameTypesToAsm(l: List[Any], asmLabel: Map[Label, asm.Label]): List[Object] = l map {
+    case l: Label => asmLabel(l)
+    case x => x.asInstanceOf[Object]
+  }
+
+  def unconvertMethodHandle(h: MethodHandle): asm.Handle = new asm.Handle(h.tag, h.owner, h.name, h.desc)
+  def unconvertBsmArgs(a: List[Object]): Array[Object] = a.map({
+    case h: MethodHandle => unconvertMethodHandle(h)
+    case o => o
+  })(collection.breakOut)
+
+  private def visitMethod(method: t.MethodNode, instruction: Instruction, asmLabel: Map[Label, asm.Label]): Unit = instruction match {
+    case Field(op, owner, name, desc)                => method.visitFieldInsn(op, owner, name, desc)
+    case Incr(op, vr, incr)                          => method.visitIincInsn(vr, incr)
+    case Op(op)                                      => method.visitInsn(op)
+    case IntOp(op, operand)                          => method.visitIntInsn(op, operand)
+    case Jump(op, label)                             => method.visitJumpInsn(op, asmLabel(label))
+    case Ldc(op, cst)                                => method.visitLdcInsn(cst)
+    case LookupSwitch(op, dflt, keys, labels)        => method.visitLookupSwitchInsn(asmLabel(dflt), keys.toArray, (labels map asmLabel).toArray)
+    case TableSwitch(op, min, max, dflt, labels)     => method.visitTableSwitchInsn(min, max, asmLabel(dflt), (labels map asmLabel).toArray: _*)
+    case Invoke(op, owner, name, desc, itf)          => method.visitMethodInsn(op, owner, name, desc, itf)
+    case InvokeDynamic(op, name, desc, bsm, bsmArgs) => method.visitInvokeDynamicInsn(name, desc, unconvertMethodHandle(bsm), unconvertBsmArgs(bsmArgs))
+    case NewArray(op, desc, dims)                    => method.visitMultiANewArrayInsn(desc, dims)
+    case TypeOp(op, desc)                            => method.visitTypeInsn(op, desc)
+    case VarOp(op, vr)                               => method.visitVarInsn(op, vr)
+    case l: Label                                    => method.visitLabel(asmLabel(l))
+    case FrameEntry(tp, local, stack)                => method.visitFrame(tp, local.length, frameTypesToAsm(local, asmLabel).toArray, stack.length, frameTypesToAsm(stack, asmLabel).toArray)
+    case LineNumber(line, start)                     => method.visitLineNumber(line, asmLabel(start))
+  }
+}