Merge pull request #5412 from retronym/ticket/SD-226

Be lazier in Fields info transform for better performance

Fix scala-dev#226

2 files changed, 19 insertions, 1 deletions

diff --git a/src/compiler/scala/tools/nsc/transform/Fields.scala b/src/compiler/scala/tools/nsc/transform/Fields.scala
index f75e6f5efa..6cf6a5abce 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 classNeedsInfoTransform(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 !classNeedsInfoTransform(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..106b076eef 100644
--- a/src/compiler/scala/tools/nsc/typechecker/RefChecks.scala
+++ b/src/compiler/scala/tools/nsc/typechecker/RefChecks.scala
@@ -95,6 +95,15 @@ abstract class RefChecks extends Transform {
       )
   }
 
+  private val separatelyCompiledScalaSuperclass = perRunCaches.newAnyRefMap[Symbol, Unit]()
+  final def isSeparatelyCompiledScalaSuperclass(sym: Symbol) = if (globalPhase.refChecked){
+    separatelyCompiledScalaSuperclass.contains(sym)
+  } else {
+    // conservative approximation in case someone in pre-refchecks phase asks for `exitingFields(someClass.info)`
+    // and we haven't run the refchecks tree transform which populates `separatelyCompiledScalaSuperclass`
+    false
+  }
+
   class RefCheckTransformer(unit: CompilationUnit) extends Transformer {
 
     var localTyper: analyzer.Typer = typer
@@ -854,6 +863,8 @@ 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)))