Merge pull request #3445 from retronym/topic/opt7

Grab bag of compiler optimizations

5 files changed, 19 insertions, 15 deletions

diff --git a/src/compiler/scala/tools/nsc/transform/Erasure.scala b/src/compiler/scala/tools/nsc/transform/Erasure.scala
index 0a013995b6..a60310f900 100644
--- a/src/compiler/scala/tools/nsc/transform/Erasure.scala
+++ b/src/compiler/scala/tools/nsc/transform/Erasure.scala
@@ -522,6 +522,8 @@ abstract class Erasure extends AddInterfaces
   class Eraser(_context: Context) extends Typer(_context) with TypeAdapter {
     val typer = this.asInstanceOf[analyzer.Typer]
 
+    override protected def stabilize(tree: Tree, pre: Type, mode: Mode, pt: Type): Tree = tree
+
     /**  Replace member references as follows:
      *
      *   - `x == y` for == in class Any becomes `x equals y` with equals in class Object.
diff --git a/src/compiler/scala/tools/nsc/typechecker/Implicits.scala b/src/compiler/scala/tools/nsc/typechecker/Implicits.scala
index 847211945c..776920ed42 100644
--- a/src/compiler/scala/tools/nsc/typechecker/Implicits.scala
+++ b/src/compiler/scala/tools/nsc/typechecker/Implicits.scala
@@ -788,7 +788,7 @@ trait Implicits {
         final class LocalShadower extends Shadower {
           val shadowed = util.HashSet[Name](512)
           def addInfos(infos: Infos) {
-            shadowed addEntries infos.map(_.name)
+            infos.foreach(i => shadowed.addEntry(i.name))
           }
           def isShadowed(name: Name) = shadowed(name)
         }
@@ -805,7 +805,6 @@ trait Implicits {
       private def isIneligible(info: ImplicitInfo) = (
            info.isCyclicOrErroneous
         || isView && (info.sym eq Predef_conforms)
-        || shadower.isShadowed(info.name)
         || (!context.macrosEnabled && info.sym.isTermMacro)
       )
 
@@ -814,6 +813,7 @@ trait Implicits {
       def survives(info: ImplicitInfo) = (
            !isIneligible(info)                      // cyclic, erroneous, shadowed, or specially excluded
         && isPlausiblyCompatible(info.tpe, wildPt)  // optimization to avoid matchesPt
+        && !shadower.isShadowed(info.name)          // OPT rare, only check for plausible candidates
         && matchesPt(info)                          // stable and matches expected type
       )
       /** The implicits that are not valid because they come later in the source and
diff --git a/src/compiler/scala/tools/nsc/typechecker/Namers.scala b/src/compiler/scala/tools/nsc/typechecker/Namers.scala
index 27e8698676..645f267a21 100644
--- a/src/compiler/scala/tools/nsc/typechecker/Namers.scala
+++ b/src/compiler/scala/tools/nsc/typechecker/Namers.scala
@@ -1069,8 +1069,9 @@ trait Namers extends MethodSynthesis {
       }
 
       def overriddenSymbol(resTp: Type) = {
+        lazy val schema: Type = methodTypeSchema(resTp) // OPT create once. Must be lazy to avoid cycles in neg/t5093.scala
         intersectionType(methOwner.info.parents).nonPrivateMember(meth.name).filter { sym =>
-          sym != NoSymbol && (site.memberType(sym) matches methodTypeSchema(resTp))
+          sym != NoSymbol && (site.memberType(sym) matches schema)
         }
       }
       // TODO: see whether this or something similar would work instead:
diff --git a/src/compiler/scala/tools/nsc/typechecker/StdAttachments.scala b/src/compiler/scala/tools/nsc/typechecker/StdAttachments.scala
index 995f98cc2c..57f27a05fd 100644
--- a/src/compiler/scala/tools/nsc/typechecker/StdAttachments.scala
+++ b/src/compiler/scala/tools/nsc/typechecker/StdAttachments.scala
@@ -46,7 +46,7 @@ trait StdAttachments {
    *  The parameter is of type `Any`, because macros can expand both into trees and into annotations.
    */
   def hasMacroExpansionAttachment(any: Any): Boolean = any match {
-    case tree: Tree => tree.attachments.get[MacroExpansionAttachment].isDefined
+    case tree: Tree => tree.hasAttachment[MacroExpansionAttachment]
     case _ => false
   }
 
@@ -96,7 +96,7 @@ trait StdAttachments {
    */
   def isMacroExpansionSuppressed(tree: Tree): Boolean =
     (  settings.Ymacroexpand.value == settings.MacroExpand.None // SI-6812
-    || tree.attachments.get[SuppressMacroExpansionAttachment.type].isDefined
+    || tree.hasAttachment[SuppressMacroExpansionAttachment.type]
     || (tree match {
         // we have to account for the fact that during typechecking an expandee might become wrapped,
         // i.e. surrounded by an inferred implicit argument application or by an inferred type argument application.
@@ -150,7 +150,7 @@ trait StdAttachments {
   /** Determines whether a tree should or should not be adapted,
    *  because someone has put MacroImplRefAttachment on it.
    */
-  def isMacroImplRef(tree: Tree): Boolean = tree.attachments.get[MacroImplRefAttachment.type].isDefined
+  def isMacroImplRef(tree: Tree): Boolean = tree.hasAttachment[MacroImplRefAttachment.type]
 
   /** Since mkInvoke, the applyDynamic/selectDynamic/etc desugarer, is disconnected
    *  from typedNamedApply, the applyDynamicNamed argument rewriter, the latter
diff --git a/src/compiler/scala/tools/nsc/typechecker/Typers.scala b/src/compiler/scala/tools/nsc/typechecker/Typers.scala
index b44375e8c4..101e1526fe 100644
--- a/src/compiler/scala/tools/nsc/typechecker/Typers.scala
+++ b/src/compiler/scala/tools/nsc/typechecker/Typers.scala
@@ -579,7 +579,8 @@ trait Typers extends Adaptations with Tags with TypersTracking with PatternTyper
      *  3. Turn tree type into stable type if possible and required by context.
      *  4. Give getClass calls a more precise type based on the type of the target of the call.
      */
-    private def stabilize(tree: Tree, pre: Type, mode: Mode, pt: Type): Tree = {
+    protected def stabilize(tree: Tree, pre: Type, mode: Mode, pt: Type): Tree = {
+
       // Side effect time! Don't be an idiot like me and think you
       // can move "val sym = tree.symbol" before this line, because
       // inferExprAlternative side-effects the tree's symbol.
@@ -992,7 +993,7 @@ trait Typers extends Adaptations with Tags with TypersTracking with PatternTyper
       def adaptMismatchedSkolems() = {
         def canIgnoreMismatch = (
              !context.reportErrors && isPastTyper
-          || tree.attachments.get[MacroExpansionAttachment].isDefined
+          || tree.hasAttachment[MacroExpansionAttachment]
         )
         def bound = pt match {
           case ExistentialType(qs, _) => qs
@@ -2232,14 +2233,14 @@ trait Typers extends Adaptations with Tags with TypersTracking with PatternTyper
               DeprecatedParamNameError(p, n)
           }
         }
-      }
-      if (meth.isStructuralRefinementMember)
-        checkMethodStructuralCompatible(ddef)
+        if (meth.isStructuralRefinementMember)
+          checkMethodStructuralCompatible(ddef)
 
-      if (meth.isImplicit && !meth.isSynthetic) meth.info.paramss match {
-        case List(param) :: _ if !param.isImplicit =>
-          checkFeature(ddef.pos, ImplicitConversionsFeature, meth.toString)
-        case _ =>
+        if (meth.isImplicit && !meth.isSynthetic) meth.info.paramss match {
+          case List(param) :: _ if !param.isImplicit =>
+            checkFeature(ddef.pos, ImplicitConversionsFeature, meth.toString)
+          case _ =>
+        }
       }
 
       treeCopy.DefDef(ddef, typedMods, ddef.name, tparams1, vparamss1, tpt1, rhs1) setType NoType