Optimization: Specialize ==, != on value classes

Without the optimization a comparison of value classes always boxing, since
the rhs operand is cast to Any. Most likely these are eliminated by escape
analysis, but by specializing here we make the job of the JOT compiler easier.

Author: odersky

compiler/src/dotty/tools/dotc/core/Mode.scala

@@ -12,6 +12,9 @@ case class Mode(val bits: Int) extends AnyVal {
 
   override def toString: String =
     (0 until 31).filter(i => (bits & (1 << i)) != 0).map(modeName).mkString("Mode(", ",", ")")
+
+  def ==(that: Mode): Boolean = this.bits == that.bits
+  def !=(that: Mode): Boolean = this.bits != that.bits
 }
 
 object Mode {

compiler/src/dotty/tools/dotc/core/Periods.scala

@@ -123,6 +123,9 @@ object Periods {
           this.lastPhaseId max that.lastPhaseId)
 
     override def toString: String = s"Period($firstPhaseId..$lastPhaseId, run = $runId)"
+
+    def ==(that: Period): Boolean = this.code == that.code
+    def !=(that: Period): Boolean = this.code != that.code
   }
 
   object Period {

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

@@ -20,6 +20,9 @@ object TastyBuffer {
     def + (delta: Int): Addr = Addr(this.index + delta)
 
     def relativeTo(base: Addr): Addr = this - base.index - AddrWidth
+
+    def ==(that: Addr): Boolean = this.index == that.index
+    def !=(that: Addr): Boolean = this.index != that.index
   }
 
   val NoAddr: Addr = Addr(-1)

compiler/src/dotty/tools/dotc/util/Spans.scala

@@ -127,6 +127,9 @@ object Spans {
       else
         s"${left}no position${right}"
     }
+
+    def ==(that: Span): Boolean = this.coords == that.coords
+    def !=(that: Span): Boolean = this.coords != that.coords
   }
 
   private def fromOffsets(start: Int, end: Int, pointDelta: Int) = {