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/* NSC -- new Scala compiler
* Copyright 2005-2014 LAMP/EPFL
* @author Martin Odersky
*/
package scala.tools.nsc
package backend.jvm
package opt
import scala.annotation.{tailrec, switch}
import scala.collection.mutable
import scala.reflect.internal.util.Collections._
import scala.tools.asm.Opcodes
import scala.tools.asm.tree._
import scala.collection.convert.decorateAsScala._
object BytecodeUtils {
object Goto {
def unapply(instruction: AbstractInsnNode): Option[JumpInsnNode] = {
if (instruction.getOpcode == Opcodes.GOTO) Some(instruction.asInstanceOf[JumpInsnNode])
else None
}
}
object JumpNonJsr {
def unapply(instruction: AbstractInsnNode): Option[JumpInsnNode] = {
if (isJumpNonJsr(instruction)) Some(instruction.asInstanceOf[JumpInsnNode])
else None
}
}
object ConditionalJump {
def unapply(instruction: AbstractInsnNode): Option[JumpInsnNode] = {
if (isConditionalJump(instruction)) Some(instruction.asInstanceOf[JumpInsnNode])
else None
}
}
object VarInstruction {
def unapply(instruction: AbstractInsnNode): Option[VarInsnNode] = {
if (isVarInstruction(instruction)) Some(instruction.asInstanceOf[VarInsnNode])
else None
}
}
def isJumpNonJsr(instruction: AbstractInsnNode): Boolean = {
val op = instruction.getOpcode
// JSR is deprecated in classfile version 50, disallowed in 51. historically, it was used to implement finally.
op == Opcodes.GOTO || isConditionalJump(instruction)
}
def isConditionalJump(instruction: AbstractInsnNode): Boolean = {
val op = instruction.getOpcode
(op >= Opcodes.IFEQ && op <= Opcodes.IF_ACMPNE) || op == Opcodes.IFNULL || op == Opcodes.IFNONNULL
}
def isReturn(instruction: AbstractInsnNode): Boolean = {
val op = instruction.getOpcode
op >= Opcodes.IRETURN && op <= Opcodes.RETURN
}
def isVarInstruction(instruction: AbstractInsnNode): Boolean = {
val op = instruction.getOpcode
(op >= Opcodes.ILOAD && op <= Opcodes.ALOAD) || (op >= Opcodes.ISTORE && op <= Opcodes.ASTORE)
}
def isExecutable(instruction: AbstractInsnNode): Boolean = instruction.getOpcode >= 0
def nextExecutableInstruction(instruction: AbstractInsnNode, alsoKeep: AbstractInsnNode => Boolean = Set()): Option[AbstractInsnNode] = {
var result = instruction
do { result = result.getNext }
while (result != null && !isExecutable(result) && !alsoKeep(result))
Option(result)
}
def sameTargetExecutableInstruction(a: JumpInsnNode, b: JumpInsnNode): Boolean = {
// Compare next executable instead of the the labels. Identifies a, b as the same target:
// LabelNode(a)
// LabelNode(b)
// Instr
nextExecutableInstruction(a.label) == nextExecutableInstruction(b.label)
}
def removeJumpAndAdjustStack(method: MethodNode, jump: JumpInsnNode) {
val instructions = method.instructions
val op = jump.getOpcode
if ((op >= Opcodes.IFEQ && op <= Opcodes.IFGE) || op == Opcodes.IFNULL || op == Opcodes.IFNONNULL) {
instructions.insert(jump, getPop(1))
} else if ((op >= Opcodes.IF_ICMPEQ && op <= Opcodes.IF_ICMPLE) || op == Opcodes.IF_ACMPEQ || op == Opcodes.IF_ACMPNE) {
instructions.insert(jump, getPop(1))
instructions.insert(jump, getPop(1))
} else {
// we can't remove JSR: its execution does not only jump, it also adds a return address to the stack
assert(jump.getOpcode == Opcodes.GOTO)
}
instructions.remove(jump)
}
def finalJumpTarget(source: JumpInsnNode): LabelNode = {
@tailrec def followGoto(label: LabelNode, seenLabels: Set[LabelNode]): LabelNode = nextExecutableInstruction(label) match {
case Some(Goto(dest)) =>
if (seenLabels(dest.label)) dest.label
else followGoto(dest.label, seenLabels + dest.label)
case _ => label
}
followGoto(source.label, Set(source.label))
}
def negateJumpOpcode(jumpOpcode: Int): Int = (jumpOpcode: @switch) match {
case Opcodes.IFEQ => Opcodes.IFNE
case Opcodes.IFNE => Opcodes.IFEQ
case Opcodes.IFLT => Opcodes.IFGE
case Opcodes.IFGE => Opcodes.IFLT
case Opcodes.IFGT => Opcodes.IFLE
case Opcodes.IFLE => Opcodes.IFGT
case Opcodes.IF_ICMPEQ => Opcodes.IF_ICMPNE
case Opcodes.IF_ICMPNE => Opcodes.IF_ICMPEQ
case Opcodes.IF_ICMPLT => Opcodes.IF_ICMPGE
case Opcodes.IF_ICMPGE => Opcodes.IF_ICMPLT
case Opcodes.IF_ICMPGT => Opcodes.IF_ICMPLE
case Opcodes.IF_ICMPLE => Opcodes.IF_ICMPGT
case Opcodes.IF_ACMPEQ => Opcodes.IF_ACMPNE
case Opcodes.IF_ACMPNE => Opcodes.IF_ACMPEQ
case Opcodes.IFNULL => Opcodes.IFNONNULL
case Opcodes.IFNONNULL => Opcodes.IFNULL
}
def getPop(size: Int): InsnNode = {
val op = if (size == 1) Opcodes.POP else Opcodes.POP2
new InsnNode(op)
}
def labelReferences(method: MethodNode): Map[LabelNode, Set[AnyRef]] = {
val res = mutable.Map.empty[LabelNode, Set[AnyRef]]
def add(l: LabelNode, ref: AnyRef) = if (res contains l) res(l) = res(l) + ref else res(l) = Set(ref)
method.instructions.iterator().asScala foreach {
case jump: JumpInsnNode => add(jump.label, jump)
case line: LineNumberNode => add(line.start, line)
case switch: LookupSwitchInsnNode => switch.labels.asScala.foreach(add(_, switch)); add(switch.dflt, switch)
case switch: TableSwitchInsnNode => switch.labels.asScala.foreach(add(_, switch)); add(switch.dflt, switch)
case _ =>
}
if (method.localVariables != null) {
method.localVariables.iterator().asScala.foreach(l => { add(l.start, l); add(l.end, l) })
}
if (method.tryCatchBlocks != null) {
method.tryCatchBlocks.iterator().asScala.foreach(l => { add(l.start, l); add(l.handler, l); add(l.end, l) })
}
res.toMap
}
def substituteLabel(reference: AnyRef, from: LabelNode, to: LabelNode): Unit = {
def substList(list: java.util.List[LabelNode]) = {
foreachWithIndex(list.asScala.toList) { case (l, i) =>
if (l == from) list.set(i, to)
}
}
reference match {
case jump: JumpInsnNode => jump.label = to
case line: LineNumberNode => line.start = to
case switch: LookupSwitchInsnNode => substList(switch.labels); if (switch.dflt == from) switch.dflt = to
case switch: TableSwitchInsnNode => substList(switch.labels); if (switch.dflt == from) switch.dflt = to
case local: LocalVariableNode =>
if (local.start == from) local.start = to
if (local.end == from) local.end = to
case handler: TryCatchBlockNode =>
if (handler.start == from) handler.start = to
if (handler.handler == from) handler.handler = to
if (handler.end == from) handler.end = to
}
}
}
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