Optimize tail calls to avoid findMember calls

Cache the member symbols for `Boolean.{||, &&}` per-run, rather
than look them up repeatedly.

Based on profiling the tail calls phase in the program below, which
was distilled by @rmacleod2 from the code generated by macros in
https://github.com/paytronix/utils-open/tree/release/2014/ernststavrosgrouper

Wall clock time went from 12s to 6.5s.

```scala
object Test {
    def a(): Option[String] = Some("a")

    def main(args: Array[String]) {
        a() match {
            case Some(b1) =>
        a() match {
            case Some(b2) =>
        a() match {
            case Some(b3) =>
        a() match {
            case Some(b4) =>
        a() match {
            case Some(b5) =>
        a() match {
            case Some(b6) =>
        a() match {
            case Some(b7) =>
        a() match {
            case Some(b8) =>
        a() match {
            case Some(b9) =>
        a() match {
            case Some(b10) =>
        a() match {
            case Some(b11) =>
        a() match {
            case Some(b12) =>
        a() match {
            case Some(b13) =>
        a() match {
            case Some(b14) =>
        a() match {
            case Some(b15) =>
        a() match {
            case Some(b16) =>
        a() match {
            case Some(b17) =>
        a() match {
            case Some(b18) =>
        a() match {
            case Some(b19) =>
        a() match {
            case Some(b20) =>
                println("yay")
            case None => None
        }
            case None => None
        }
            case None => None
        }
            case None => None
        }
            case None => None
        }
            case None => None
        }
            case None => None
        }
            case None => None
        }
            case None => None
        }
            case None => None
        }
            case None => None
        }
            case None => None
        }
            case None => None
        }
            case None => None
        }
            case None => None
        }
            case None => None
        }
            case None => None
        }
            case None => None
        }
            case None => None
        }
            case None => None
        }
    }
}
```

1 files changed, 8 insertions, 0 deletions

diff --git a/src/compiler/scala/tools/nsc/transform/TailCalls.scala b/src/compiler/scala/tools/nsc/transform/TailCalls.scala
index ef534f70fd..93a343675b 100644
--- a/src/compiler/scala/tools/nsc/transform/TailCalls.scala
+++ b/src/compiler/scala/tools/nsc/transform/TailCalls.scala
@@ -265,6 +265,10 @@ abstract class TailCalls extends Transform {
         !(sym.hasAccessorFlag || sym.isConstructor)
       }
 
+      // intentionally shadowing imports from definitions for performance
+      val runDefinitions = currentRun.runDefinitions
+      import runDefinitions.{Boolean_or, Boolean_and}
+
       tree match {
         case ValDef(_, _, _, _) =>
           if (tree.symbol.isLazy && tree.symbol.hasAnnotation(TailrecClass))
@@ -421,6 +425,10 @@ abstract class TailCalls extends Transform {
     def traverseNoTail(tree: Tree) = traverse(tree, maybeTailNew = false)
     def traverseTreesNoTail(trees: List[Tree]) = trees foreach traverseNoTail
 
+    // intentionally shadowing imports from definitions for performance
+    private val runDefinitions = currentRun.runDefinitions
+    import runDefinitions.{Boolean_or, Boolean_and}
+
     override def traverse(tree: Tree) = tree match {
       // we're looking for label(x){x} in tail position, since that means `a` is in tail position in a call `label(a)`
       case LabelDef(_, List(arg), body@Ident(_)) if arg.symbol == body.symbol =>