Do not pickle number of lines

Author: nicolasstucki

compiler/src/dotty/tools/dotc/core/tasty/LineSizesPickler.scala

@@ -22,20 +22,14 @@ class LineSizesPickler(pickler: TastyPickler) {
   val buf: TastyBuffer = new TastyBuffer(5000)
   pickler.newSection("LineSizes", buf)
 
-  def pickleLineNumbers(source: SourceFile): Unit = {
+  def pickleLineNumbers(source: SourceFile): Unit =
     val content = source.content()
-
-    val numLines = content.count(_ == '\n')
-    buf.writeInt(numLines + 1)
-
     var lastIndex = content.indexOf('\n', 0)
     buf.writeInt(lastIndex) // size of first line
     while lastIndex != -1 do
       val nextIndex = content.indexOf('\n', lastIndex + 1)
-      if nextIndex != -1 then
-        buf.writeInt(nextIndex - lastIndex - 1) // size of the next line
-      else
-        buf.writeInt(content.length - 1 - lastIndex) // size of the last line
+      val end = if nextIndex != -1 then nextIndex else content.length
+      buf.writeInt(end - lastIndex - 1) // size of the next line
       lastIndex = nextIndex
-  }
+
 }

compiler/src/dotty/tools/dotc/core/tasty/LineSizesUnpickler.scala

@@ -15,23 +15,18 @@ import Names.TermName
 class LineSizesUnpickler(reader: TastyReader) {
   import reader._
 
-  private var myLines: Int = _
   private var mySizes: Array[Int] = _
   private var isDefined = false
 
-  def ensureDefined(): Unit = {
-    if (!isDefined) {
-      myLines = readInt()
-      mySizes = new Array(myLines)
-      for i <- 0 until myLines do
-        mySizes(i) = readInt()
+  def ensureDefined(): Unit =
+    if !isDefined then
+      val sizeBuf = Array.newBuilder[Int]
+      // Number of lines if all lines are 127 characters or less
+      var lowSizeBound = endAddr.index - currentAddr.index
+      sizeBuf.sizeHint(lowSizeBound)
+      while !isAtEnd do sizeBuf += readInt()
+      mySizes = sizeBuf.result()
       isDefined = true
-    }
-  }
-
-  private[tasty] def lines: Int =
-    ensureDefined()
-    myLines
 
   private[tasty] def sizes: Array[Int] =
     ensureDefined()

compiler/src/dotty/tools/dotc/core/tasty/TastyPrinter.scala

@@ -163,7 +163,6 @@ class TastyPrinter(bytes: Array[Byte]) {
       sb.append(" ").append(reader.endAddr.index - reader.currentAddr.index)
       sb.append(" line sizes bytes:\n")
       val lineSizes = new LineSizesUnpickler(reader)
-      sb.append("   lines: ").append(lineSizes.lines).append("\n")
       sb.append("   sizes: ")
       sb.append(lineSizes.sizes.mkString(", "))
       sb.result