From 52fbbcc82470e100d95ac9cdb468060620f1e29e Mon Sep 17 00:00:00 2001
From: Martin Odersky <odersky@gmail.com>
Date: Tue, 19 Apr 2011 10:56:58 +0000
Subject: Further optimizations of implicits.

---
 .../scala/tools/nsc/typechecker/Implicits.scala         | 17 ++++++++++++++---
 src/compiler/scala/tools/nsc/util/Statistics.scala      |  2 ++
 2 files changed, 16 insertions(+), 3 deletions(-)

(limited to 'src')

diff --git a/src/compiler/scala/tools/nsc/typechecker/Implicits.scala b/src/compiler/scala/tools/nsc/typechecker/Implicits.scala
index 647bbd01ab..a05aefe1fa 100644
--- a/src/compiler/scala/tools/nsc/typechecker/Implicits.scala
+++ b/src/compiler/scala/tools/nsc/typechecker/Implicits.scala
@@ -13,7 +13,7 @@ package typechecker
 
 import annotation.tailrec
 import scala.collection.{ mutable, immutable }
-import mutable.{ LinkedHashMap, ListBuffer }
+import mutable.{ HashMap, LinkedHashMap, ListBuffer }
 import scala.util.matching.Regex
 import symtab.Flags._
 import util.Statistics._
@@ -71,10 +71,12 @@ trait Implicits {
   private type InfoMap = LinkedHashMap[Symbol, List[ImplicitInfo]]
   private val implicitsCache = new LinkedHashMap[Type, Infoss]
   private val infoMapCache = new LinkedHashMap[Symbol, InfoMap]
+  private val improvesCache = new HashMap[(ImplicitInfo, ImplicitInfo), Boolean]
 
   def resetImplicits() {
     implicitsCache.clear()
     infoMapCache.clear()
+    improvesCache.clear()
   }
 
   private val ManifestSymbols = Set(PartialManifestClass, FullManifestClass, OptManifestClass)
@@ -229,8 +231,17 @@ trait Implicits {
     def improves(info1: ImplicitInfo, info2: ImplicitInfo) = {
       incCounter(improvesCount)
       (info2 == NoImplicitInfo) ||
-      (info1 != NoImplicitInfo) &&
-      isStrictlyMoreSpecific(info1.tpe, info2.tpe, info1.sym, info2.sym)
+      (info1 != NoImplicitInfo) && {
+        if (info1.sym.isStatic && info2.sym.isStatic) {
+          improvesCache get (info1, info2) match {
+            case Some(b) => incCounter(improvesCachedCount); b
+            case None =>
+              val result = isStrictlyMoreSpecific(info1.tpe, info2.tpe, info1.sym, info2.sym)
+              improvesCache((info1, info2)) = result
+              result
+          }
+        } else isStrictlyMoreSpecific(info1.tpe, info2.tpe, info1.sym, info2.sym)
+      }
     }
 
     /** Map all type params in given list to WildcardType
diff --git a/src/compiler/scala/tools/nsc/util/Statistics.scala b/src/compiler/scala/tools/nsc/util/Statistics.scala
index 86b9ca5cda..b6e61a4014 100644
--- a/src/compiler/scala/tools/nsc/util/Statistics.scala
+++ b/src/compiler/scala/tools/nsc/util/Statistics.scala
@@ -159,6 +159,7 @@ object Statistics {
   val implicitCacheHits = new Counter
   val implicitCacheMisses = new Counter
   val improvesCount = new Counter
+  val improvesCachedCount = new Counter
   val subtypeAppInfos = new SubCounter(subtypeCount)
   val subtypeImprovCount = new SubCounter(subtypeCount)
   val subtypeETNanos = new Timer
@@ -260,6 +261,7 @@ abstract class Statistics {
         inform("#implicit searches       : " + implicitSearchCount)
         inform("#tried, plausible, matching, typed, found implicits: "+triedImplicits+", "+plausiblyCompatibleImplicits+", "+matchingImplicits+", "+typedImplicits+", "+foundImplicits)
         inform("#implicit improves tests : " + improvesCount)
+        inform("#implicit improves cached: " + improvesCachedCount)
         inform("#implicit inscope hits   : " + inscopeImplicitHits)
         inform("#implicit oftype hits    : " + oftypeImplicitHits)
       }
-- 
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