SD-226 Be lazier in Fields info transform for better performance

Only mixin fields + accessors into class infos of classes that are
either in the current run, or appear in a superclass chain of a class
in the current run.

This is analagous to what happens in the mixin phase.

2 files changed, 13 insertions, 1 deletions

diff --git a/src/compiler/scala/tools/nsc/transform/Fields.scala b/src/compiler/scala/tools/nsc/transform/Fields.scala
index 894d0a1701..c39491cf9e 100644
--- a/src/compiler/scala/tools/nsc/transform/Fields.scala
+++ b/src/compiler/scala/tools/nsc/transform/Fields.scala
@@ -305,6 +305,10 @@ abstract class Fields extends InfoTransform with ast.TreeDSL with TypingTransfor
       lazyCallingSuper setInfo tp
     }
 
+    private def needsMixin(cls: Symbol): Boolean = {
+      !(cls.isPackageClass || cls.isJavaDefined) && (currentRun.compiles(cls) || refChecks.isSeparatelyCompiledScalaSuperclass(cls))
+    }
+
     def apply(tp0: Type): Type = tp0 match {
       // TODO: make less destructive (name changes, decl additions, flag setting --
       // none of this is actually undone when travelling back in time using atPhase)
@@ -360,9 +364,12 @@ abstract class Fields extends InfoTransform with ast.TreeDSL with TypingTransfor
           ClassInfoType(parents, allDecls, clazz)
         } else tp
 
+
+      case tp@ClassInfoType(parents, oldDecls, clazz) if !needsMixin(clazz) => tp
+
       // mix in fields & accessors for all mixed in traits
+      case tp@ClassInfoType(parents, oldDecls, clazz) =>
 
-      case tp@ClassInfoType(parents, oldDecls, clazz) if !clazz.isPackageClass =>
         val site = clazz.thisType
 
         // setter conflicts cannot arise independently from a getter conflict, since a setter without a getter does not a val definition make
diff --git a/src/compiler/scala/tools/nsc/typechecker/RefChecks.scala b/src/compiler/scala/tools/nsc/typechecker/RefChecks.scala
index 8034d056d7..24b4334ec4 100644
--- a/src/compiler/scala/tools/nsc/typechecker/RefChecks.scala
+++ b/src/compiler/scala/tools/nsc/typechecker/RefChecks.scala
@@ -95,6 +95,9 @@ abstract class RefChecks extends Transform {
       )
   }
 
+  private val separatelyCompiledScalaSuperclass = perRunCaches.newAnyRefMap[Symbol, Unit]()
+  final def isSeparatelyCompiledScalaSuperclass(sym: Symbol) = separatelyCompiledScalaSuperclass.contains(sym)
+
   class RefCheckTransformer(unit: CompilationUnit) extends Transformer {
 
     var localTyper: analyzer.Typer = typer
@@ -854,6 +857,8 @@ abstract class RefChecks extends Transform {
 //            println("validate base type "+tp)
         val baseClass = tp.typeSymbol
         if (baseClass.isClass) {
+          if (!baseClass.isTrait && !baseClass.isJavaDefined && !currentRun.compiles(baseClass) && !separatelyCompiledScalaSuperclass.contains(baseClass))
+            separatelyCompiledScalaSuperclass.update(baseClass, ())
           val index = clazz.info.baseTypeIndex(baseClass)
           if (index >= 0) {
             if (seenTypes(index) forall (tp1 => !(tp1 <:< tp)))