Remove dead code in the optimizer related to trait impl classes

7 files changed, 41 insertions, 188 deletions

diff --git a/src/compiler/scala/tools/nsc/backend/jvm/BCodeHelpers.scala b/src/compiler/scala/tools/nsc/backend/jvm/BCodeHelpers.scala
index a2ccce9d21..271146f623 100644
--- a/src/compiler/scala/tools/nsc/backend/jvm/BCodeHelpers.scala
+++ b/src/compiler/scala/tools/nsc/backend/jvm/BCodeHelpers.scala
@@ -247,14 +247,6 @@ abstract class BCodeHelpers extends BCodeIdiomatic with BytecodeWriters {
    * Build the [[InlineInfo]] for a class symbol.
    */
   def buildInlineInfoFromClassSymbol(classSym: Symbol, classSymToInternalName: Symbol => InternalName, methodSymToDescriptor: Symbol => String): InlineInfo = {
-    val traitSelfType = if (classSym.isTrait) {
-      // The mixin phase uses typeOfThis for the self parameter in implementation class methods.
-      val selfSym = classSym.typeOfThis.typeSymbol
-      if (selfSym != classSym) Some(classSymToInternalName(selfSym)) else None
-    } else {
-      None
-    }
-
     val isEffectivelyFinal = classSym.isEffectivelyFinal
 
     val sam = {
@@ -291,7 +283,6 @@ abstract class BCodeHelpers extends BCodeIdiomatic with BytecodeWriters {
 
           val info = MethodInlineInfo(
             effectivelyFinal                    = effectivelyFinal,
-            traitMethodWithStaticImplementation = false,
             annotatedInline                     = methodSym.hasAnnotation(ScalaInlineClass),
             annotatedNoInline                   = methodSym.hasAnnotation(ScalaNoInlineClass)
           )
@@ -299,7 +290,7 @@ abstract class BCodeHelpers extends BCodeIdiomatic with BytecodeWriters {
         }
     }).toMap
 
-    InlineInfo(traitSelfType, isEffectivelyFinal, sam, methodInlineInfos, warning)
+    InlineInfo(isEffectivelyFinal, sam, methodInlineInfos, warning)
   }
 
   /*
diff --git a/src/compiler/scala/tools/nsc/backend/jvm/BTypes.scala b/src/compiler/scala/tools/nsc/backend/jvm/BTypes.scala
index c3f6399901..192c2ee14e 100644
--- a/src/compiler/scala/tools/nsc/backend/jvm/BTypes.scala
+++ b/src/compiler/scala/tools/nsc/backend/jvm/BTypes.scala
@@ -255,13 +255,11 @@ abstract class BTypes {
       val methodInfos = classNode.methods.asScala.map(methodNode => {
         val info = MethodInlineInfo(
           effectivelyFinal                    = BytecodeUtils.isFinalMethod(methodNode),
-          traitMethodWithStaticImplementation = false,
           annotatedInline                     = false,
           annotatedNoInline                   = false)
         (methodNode.name + methodNode.desc, info)
       }).toMap
       InlineInfo(
-        traitImplClassSelfType = None,
         isEffectivelyFinal = BytecodeUtils.isFinalClass(classNode),
         sam = inlinerHeuristics.javaSam(classNode.name),
         methodInfos = methodInfos,
@@ -1139,22 +1137,8 @@ object BTypes {
    * Note that this class should contain information that can only be obtained from the ClassSymbol.
    * Information that can be computed from the ClassNode should be added to the call graph instead.
    *
-   * @param traitImplClassSelfType `Some(tp)` if this InlineInfo describes a trait, and the `self`
-   *                               parameter type of the methods in the implementation class is not
-   *                               the trait itself. Example:
-   *                                 trait T { self: U => def f = 1 }
-   *                               Generates something like:
-   *                                 class T$class { static def f(self: U) = 1 }
-   *
-   *                               In order to inline a trat method call, the INVOKEINTERFACE is
-   *                               rewritten to an INVOKESTATIC of the impl class, so we need the
-   *                               self type (U) to get the right signature.
-   *
-   *                               `None` if the self type is the interface type, or if this
-   *                               InlineInfo does not describe a trait.
-   *
    * @param isEffectivelyFinal     True if the class cannot have subclasses: final classes, module
-   *                               classes, trait impl classes.
+   *                               classes.
    *
    * @param sam                    If this class is a SAM type, the SAM's "$name$descriptor".
    *
@@ -1166,26 +1150,21 @@ object BTypes {
    *                               InlineInfo, for example if some classfile could not be found on
    *                               the classpath. This warning can be reported later by the inliner.
    */
-  final case class InlineInfo(traitImplClassSelfType: Option[InternalName],
-                              isEffectivelyFinal: Boolean,
+  final case class InlineInfo(isEffectivelyFinal: Boolean,
                               sam: Option[String],
                               methodInfos: Map[String, MethodInlineInfo],
                               warning: Option[ClassInlineInfoWarning])
 
-  val EmptyInlineInfo = InlineInfo(None, false, None, Map.empty, None)
+  val EmptyInlineInfo = InlineInfo(false, None, Map.empty, None)
 
   /**
    * Metadata about a method, used by the inliner.
    *
    * @param effectivelyFinal                    True if the method cannot be overridden (in Scala)
-   * @param traitMethodWithStaticImplementation True if the method is an interface method method of
-   *                                            a trait method and has a static counterpart in the
-   *                                            implementation class.
    * @param annotatedInline                     True if the method is annotated `@inline`
    * @param annotatedNoInline                   True if the method is annotated `@noinline`
    */
   final case class MethodInlineInfo(effectivelyFinal: Boolean,
-                                    traitMethodWithStaticImplementation: Boolean,
                                     annotatedInline: Boolean,
                                     annotatedNoInline: Boolean)
 
diff --git a/src/compiler/scala/tools/nsc/backend/jvm/opt/CallGraph.scala b/src/compiler/scala/tools/nsc/backend/jvm/opt/CallGraph.scala
index 3267b9b5df..5f06e13560 100644
--- a/src/compiler/scala/tools/nsc/backend/jvm/opt/CallGraph.scala
+++ b/src/compiler/scala/tools/nsc/backend/jvm/opt/CallGraph.scala
@@ -132,16 +132,16 @@ class CallGraph[BT <: BTypes](val btypes: BT) {
               (declarationClassNode, source) <- byteCodeRepository.classNodeAndSource(declarationClass): Either[OptimizerWarning, (ClassNode, Source)]
             } yield {
                 val declarationClassBType = classBTypeFromClassNode(declarationClassNode)
-                val CallsiteInfo(safeToInline, safeToRewrite, canInlineFromSource, annotatedInline, annotatedNoInline, samParamTypes, warning) = analyzeCallsite(method, declarationClassBType, call, source)
+                val info = analyzeCallsite(method, declarationClassBType, call, source)
+                import info._
                 Callee(
                   callee = method,
                   calleeDeclarationClass = declarationClassBType,
                   safeToInline = safeToInline,
-                  safeToRewrite = false,
                   canInlineFromSource = canInlineFromSource,
                   annotatedInline = annotatedInline,
                   annotatedNoInline = annotatedNoInline,
-                  samParamTypes = samParamTypes,
+                  samParamTypes = info.samParamTypes,
                   calleeInfoWarning = warning)
               }
 
@@ -256,7 +256,7 @@ class CallGraph[BT <: BTypes](val btypes: BT) {
   /**
    * Just a named tuple used as return type of `analyzeCallsite`.
    */
-  private case class CallsiteInfo(safeToInline: Boolean, safeToRewrite: Boolean, canInlineFromSource: Boolean,
+  private case class CallsiteInfo(safeToInline: Boolean, canInlineFromSource: Boolean,
                                   annotatedInline: Boolean, annotatedNoInline: Boolean,
                                   samParamTypes: IntMap[ClassBType],
                                   warning: Option[CalleeInfoWarning])
@@ -300,16 +300,12 @@ class CallGraph[BT <: BTypes](val btypes: BT) {
               receiverType.info.orThrow.inlineInfo.isEffectivelyFinal // (1)
           }
 
-          val isRewritableTraitCall = false
-
           val warning = calleeDeclarationClassBType.info.orThrow.inlineInfo.warning.map(
             MethodInlineInfoIncomplete(calleeDeclarationClassBType.internalName, calleeMethodNode.name, calleeMethodNode.desc, _))
 
           // (1) For invocations of final trait methods, the callee isStaticallyResolved but also
           //     abstract. Such a callee is not safe to inline - it needs to be re-written to the
           //     static impl method first (safeToRewrite).
-          // (2) Final trait methods can be rewritten from the interface to the static implementation
-          //     method to enable inlining.
           CallsiteInfo(
             safeToInline      =
               canInlineFromSource &&
@@ -318,7 +314,6 @@ class CallGraph[BT <: BTypes](val btypes: BT) {
                 !BytecodeUtils.isConstructor(calleeMethodNode) &&
                 !BytecodeUtils.isNativeMethod(calleeMethodNode) &&
                 !BytecodeUtils.hasCallerSensitiveAnnotation(calleeMethodNode),
-            safeToRewrite       = canInlineFromSource && isRewritableTraitCall, // (2)
             canInlineFromSource = canInlineFromSource,
             annotatedInline     = methodInlineInfo.annotatedInline,
             annotatedNoInline   = methodInlineInfo.annotatedNoInline,
@@ -327,12 +322,12 @@ class CallGraph[BT <: BTypes](val btypes: BT) {
 
         case None =>
           val warning = MethodInlineInfoMissing(calleeDeclarationClassBType.internalName, calleeMethodNode.name, calleeMethodNode.desc, calleeDeclarationClassBType.info.orThrow.inlineInfo.warning)
-          CallsiteInfo(false, false, false, false, false, IntMap.empty, Some(warning))
+          CallsiteInfo(false, false, false, false, IntMap.empty, Some(warning))
       }
     } catch {
       case Invalid(noInfo: NoClassBTypeInfo) =>
         val warning = MethodInlineInfoError(calleeDeclarationClassBType.internalName, calleeMethodNode.name, calleeMethodNode.desc, noInfo)
-        CallsiteInfo(false, false, false, false, false, IntMap.empty, Some(warning))
+        CallsiteInfo(false, false, false, false, IntMap.empty, Some(warning))
     }
   }
 
@@ -387,20 +382,18 @@ class CallGraph[BT <: BTypes](val btypes: BT) {
    * @param calleeDeclarationClass The class in which the callee is declared
    * @param safeToInline           True if the callee can be safely inlined: it cannot be overridden,
    *                               and the inliner settings (project / global) allow inlining it.
-   * @param safeToRewrite          True if the callee is the interface method of a concrete trait method
-   *                               that can be safely re-written to the static implementation method.
    * @param annotatedInline        True if the callee is annotated @inline
    * @param annotatedNoInline      True if the callee is annotated @noinline
    * @param samParamTypes          A map from parameter positions to SAM parameter types
    * @param calleeInfoWarning      An inliner warning if some information was not available while
    *                               gathering the information about this callee.
    */
-  final case class Callee(callee: MethodNode, calleeDeclarationClass: ClassBType,
-                          safeToInline: Boolean, safeToRewrite: Boolean, canInlineFromSource: Boolean,
-                          annotatedInline: Boolean, annotatedNoInline: Boolean,
-                          samParamTypes: IntMap[ClassBType],
-                          calleeInfoWarning: Option[CalleeInfoWarning]) {
-    assert(!(safeToInline && safeToRewrite), s"A callee of ${callee.name} can be either safeToInline or safeToRewrite, but not both.")
+  final case class Callee(
+                           callee: MethodNode, calleeDeclarationClass: btypes.ClassBType,
+                           safeToInline: Boolean, canInlineFromSource: Boolean,
+                           annotatedInline: Boolean, annotatedNoInline: Boolean,
+                           samParamTypes: IntMap[btypes.ClassBType],
+                           calleeInfoWarning: Option[CalleeInfoWarning]) {
     override def toString = s"Callee($calleeDeclarationClass.${callee.name})"
   }
 
diff --git a/src/compiler/scala/tools/nsc/backend/jvm/opt/ClosureOptimizer.scala b/src/compiler/scala/tools/nsc/backend/jvm/opt/ClosureOptimizer.scala
index 4935b9d1a0..fef15bcf9a 100644
--- a/src/compiler/scala/tools/nsc/backend/jvm/opt/ClosureOptimizer.scala
+++ b/src/compiler/scala/tools/nsc/backend/jvm/opt/ClosureOptimizer.scala
@@ -363,7 +363,6 @@ class ClosureOptimizer[BT <: BTypes](val btypes: BT) {
           callee = bodyMethodNode,
           calleeDeclarationClass = bodyDeclClassType,
           safeToInline = canInlineFromSource,
-          safeToRewrite = false, // the lambda body method is not a trait interface method
           canInlineFromSource = canInlineFromSource,
           annotatedInline = false,
           annotatedNoInline = false,
diff --git a/src/compiler/scala/tools/nsc/backend/jvm/opt/InlineInfoAttribute.scala b/src/compiler/scala/tools/nsc/backend/jvm/opt/InlineInfoAttribute.scala
index c885a29e16..079a9eec9b 100644
--- a/src/compiler/scala/tools/nsc/backend/jvm/opt/InlineInfoAttribute.scala
+++ b/src/compiler/scala/tools/nsc/backend/jvm/opt/InlineInfoAttribute.scala
@@ -27,7 +27,7 @@ import scala.tools.nsc.backend.jvm.BackendReporting.UnknownScalaInlineInfoVersio
  * In principle we could encode the InlineInfo into a Java annotation (instead of a classfile attribute).
  * However, an attribute allows us to save many bits. In particular, note that the strings in an
  * InlineInfo are serialized as references to constants in the constant pool, and those strings
- * (traitImplClassSelfType, method names, method signatures) would exist in there anyway. So the
+ * (method names, method signatures) would exist in there anyway. So the
  * ScalaInlineAttribute remains relatively compact.
  */
 case class InlineInfoAttribute(inlineInfo: InlineInfo) extends Attribute(InlineInfoAttribute.attributeName) {
@@ -48,15 +48,11 @@ case class InlineInfoAttribute(inlineInfo: InlineInfo) extends Attribute(InlineI
     result.putByte(InlineInfoAttribute.VERSION)
 
     var finalSelfSam = 0
-    if (inlineInfo.isEffectivelyFinal)               finalSelfSam |= 1
-    if (inlineInfo.traitImplClassSelfType.isDefined) finalSelfSam |= 2
-    if (inlineInfo.sam.isDefined)                    finalSelfSam |= 4
+    if (inlineInfo.isEffectivelyFinal) finalSelfSam |= 1
+    //                                 finalSelfSam |= 2 // no longer written
+    if (inlineInfo.sam.isDefined)      finalSelfSam |= 4
     result.putByte(finalSelfSam)
 
-    for (selfInternalName <- inlineInfo.traitImplClassSelfType) {
-      result.putShort(cw.newUTF8(selfInternalName))
-    }
-
     for (samNameDesc <- inlineInfo.sam) {
       val (name, desc) = samNameDesc.span(_ != '(')
       result.putShort(cw.newUTF8(name))
@@ -75,10 +71,10 @@ case class InlineInfoAttribute(inlineInfo: InlineInfo) extends Attribute(InlineI
       result.putShort(cw.newUTF8(desc))
 
       var inlineInfo = 0
-      if (info.effectivelyFinal)                    inlineInfo |= 1
-      if (info.traitMethodWithStaticImplementation) inlineInfo |= 2
-      if (info.annotatedInline)                     inlineInfo |= 4
-      if (info.annotatedNoInline)                   inlineInfo |= 8
+      if (info.effectivelyFinal)  inlineInfo |= 1
+      //                          inlineInfo |= 2 // no longer written
+      if (info.annotatedInline)   inlineInfo |= 4
+      if (info.annotatedNoInline) inlineInfo |= 8
       result.putByte(inlineInfo)
     }
 
@@ -106,10 +102,7 @@ case class InlineInfoAttribute(inlineInfo: InlineInfo) extends Attribute(InlineI
       val hasSelf = (finalSelfSam & 2) != 0
       val hasSam  = (finalSelfSam & 4) != 0
 
-      val self = if (!hasSelf) None else {
-        val selfName = nextUTF8()
-        Some(selfName)
-      }
+      if (hasSelf) nextUTF8() // no longer used
 
       val sam = if (!hasSam) None else {
         val name = nextUTF8()
@@ -123,14 +116,14 @@ case class InlineInfoAttribute(inlineInfo: InlineInfo) extends Attribute(InlineI
         val desc = nextUTF8()
 
         val inlineInfo = nextByte()
-        val isFinal                             = (inlineInfo & 1) != 0
-        val traitMethodWithStaticImplementation = (inlineInfo & 2) != 0
-        val isInline                            = (inlineInfo & 4) != 0
-        val isNoInline                          = (inlineInfo & 8) != 0
-        (name + desc, MethodInlineInfo(isFinal, traitMethodWithStaticImplementation, isInline, isNoInline))
+        val isFinal                                = (inlineInfo & 1) != 0
+        // val traitMethodWithStaticImplementation = (inlineInfo & 2) != 0 // no longer used
+        val isInline                               = (inlineInfo & 4) != 0
+        val isNoInline                             = (inlineInfo & 8) != 0
+        (name + desc, MethodInlineInfo(isFinal, isInline, isNoInline))
       }).toMap
 
-      InlineInfoAttribute(InlineInfo(self, isFinal, sam, infos, None))
+      InlineInfoAttribute(InlineInfo(isFinal, sam, infos, None))
     } else {
       val msg = UnknownScalaInlineInfoVersion(cr.getClassName, version)
       InlineInfoAttribute(BTypes.EmptyInlineInfo.copy(warning = Some(msg)))
@@ -140,6 +133,13 @@ case class InlineInfoAttribute(inlineInfo: InlineInfo) extends Attribute(InlineI
 
 object InlineInfoAttribute {
   /**
+   * Notes:
+   *  - `traitImplClassSelfType` is no longer emitted, `hasTraitImplClassSelfType` is always emitted
+   *    as 0. Similarly, `traitMethodWithStaticImplementation` is always emitted 0.
+   *  - When reading an existing attribute where `hasTraitImplClassSelfType` is 1, the
+   *    `traitImplClassSelfType` is ignored. Also the value of `traitMethodWithStaticImplementation`
+   *    is ignored.
+   *
    * [u1]    version
    * [u1]    isEffectivelyFinal (<< 0), hasTraitImplClassSelfType (<< 1), hasSam (<< 2)
    * [u2]?   traitImplClassSelfType (reference)
@@ -159,4 +159,4 @@ object InlineInfoAttribute {
  * In order to instruct the ASM framework to de-serialize the ScalaInlineInfo attribute, we need
  * to pass a prototype instance when running the class reader.
  */
-object InlineInfoAttributePrototype extends InlineInfoAttribute(InlineInfo(null, false, null, null, null))
+object InlineInfoAttributePrototype extends InlineInfoAttribute(InlineInfo(false, null, null, null))
diff --git a/src/compiler/scala/tools/nsc/backend/jvm/opt/Inliner.scala b/src/compiler/scala/tools/nsc/backend/jvm/opt/Inliner.scala
index 32106614e3..a0ef74b46a 100644
--- a/src/compiler/scala/tools/nsc/backend/jvm/opt/Inliner.scala
+++ b/src/compiler/scala/tools/nsc/backend/jvm/opt/Inliner.scala
@@ -27,8 +27,6 @@ class Inliner[BT <: BTypes](val btypes: BT) {
   import backendUtils._
 
   def runInliner(): Unit = {
-//    rewriteFinalTraitMethodInvocations()
-
     for (request <- collectAndOrderInlineRequests) {
       val Right(callee) = request.callsite.callee // collectAndOrderInlineRequests returns callsites with a known callee
 
@@ -70,111 +68,6 @@ class Inliner[BT <: BTypes](val btypes: BT) {
     }
   }
 
-  // Rewriting final trait method callsites to the implementation class enables inlining.
-  def rewriteFinalTraitMethodInvocations(): Unit = {
-    // Collect callsites to rewrite before actually rewriting anything. This prevents changing the
-    // `callsties` map while iterating it.
-    val toRewrite = mutable.ArrayBuffer.empty[Callsite]
-    for (css <- callsites.valuesIterator; cs <- css.valuesIterator if doRewriteTraitCallsite(cs)) toRewrite += cs
-    toRewrite foreach rewriteFinalTraitMethodInvocation
-  }
-
-  /**
-   * True for statically resolved trait callsites that should be rewritten to the static implementation method.
-   */
-  def doRewriteTraitCallsite(callsite: Callsite) = callsite.callee match {
-    case Right(callee) => callee.safeToRewrite
-    case _ => false
-  }
-
-  /**
-   * Rewrite the INVOKEINTERFACE callsite of a final trait method invocation to INVOKESTATIC of the
-   * corresponding method in the implementation class. This enables inlining final trait methods.
-   *
-   * In a final trait method callsite, the callee is safeToInline and the callee method is abstract
-   * (the receiver type is the interface, so the method is abstract).
-   */
-  def rewriteFinalTraitMethodInvocation(callsite: Callsite): Unit = {
-    // The analyzer used below needs to have a non-null frame for the callsite instruction
-    localOpt.minimalRemoveUnreachableCode(callsite.callsiteMethod, callsite.callsiteClass.internalName)
-
-    // If the callsite was eliminated by DCE, do nothing.
-    if (!callGraph.containsCallsite(callsite)) return
-
-    val Right(Callee(callee, calleeDeclarationClass, _, _, canInlineFromSource, annotatedInline, annotatedNoInline, samParamTypes, infoWarning)) = callsite.callee
-
-    val traitMethodArgumentTypes = asm.Type.getArgumentTypes(callee.desc)
-
-    val implClassInternalName = calleeDeclarationClass.internalName + "$class"
-
-    val selfParamTypeV: Either[OptimizerWarning, ClassBType] = calleeDeclarationClass.info.map(_.inlineInfo.traitImplClassSelfType match {
-      case Some(internalName) => classBTypeFromParsedClassfile(internalName)
-      case None               => calleeDeclarationClass
-    })
-
-    def implClassMethodV(implMethodDescriptor: String): Either[OptimizerWarning, MethodNode] = {
-      byteCodeRepository.methodNode(implClassInternalName, callee.name, implMethodDescriptor).map(_._1)
-    }
-
-    // The rewrite reading the implementation class and the implementation method from the bytecode
-    // repository. If either of the two fails, the rewrite is not performed.
-    val res = for {
-      selfParamType        <- selfParamTypeV
-      implMethodDescriptor =  asm.Type.getMethodDescriptor(asm.Type.getReturnType(callee.desc), selfParamType.toASMType +: traitMethodArgumentTypes: _*)
-      implClassMethod      <- implClassMethodV(implMethodDescriptor)
-      implClassBType       =  classBTypeFromParsedClassfile(implClassInternalName)
-      selfTypeOk           <- calleeDeclarationClass.isSubtypeOf(selfParamType)
-    } yield {
-
-      // The self parameter type may be incompatible with the trait type.
-      //   trait T { self: S => def foo = 1 }
-      // The $self parameter type of T$class.foo is S, which may be unrelated to T. If we re-write
-      // a call to T.foo to T$class.foo, we need to cast the receiver to S, otherwise we get a
-      // VerifyError. We run a `SourceInterpreter` to find all producer instructions of the
-      // receiver value and add a cast to the self type after each.
-      if (!selfTypeOk) {
-        // We don't need to worry about the method being too large for running an analysis.
-        // Callsites of large methods are not added to the call graph.
-        val analyzer = new AsmAnalyzer(callsite.callsiteMethod, callsite.callsiteClass.internalName, new Analyzer(new SourceInterpreter))
-        val receiverValue = analyzer.frameAt(callsite.callsiteInstruction).peekStack(traitMethodArgumentTypes.length)
-        for (i <- receiverValue.insns.asScala) {
-          val cast = new TypeInsnNode(CHECKCAST, selfParamType.internalName)
-          callsite.callsiteMethod.instructions.insert(i, cast)
-        }
-      }
-
-      val newCallsiteInstruction = new MethodInsnNode(INVOKESTATIC, implClassInternalName, callee.name, implMethodDescriptor, false)
-      callsite.callsiteMethod.instructions.insert(callsite.callsiteInstruction, newCallsiteInstruction)
-      callsite.callsiteMethod.instructions.remove(callsite.callsiteInstruction)
-
-      callGraph.removeCallsite(callsite.callsiteInstruction, callsite.callsiteMethod)
-      val staticCallSamParamTypes = {
-        if (selfParamType.info.get.inlineInfo.sam.isEmpty) samParamTypes - 0
-        else samParamTypes.updated(0, selfParamType)
-      }
-      val staticCallsite = callsite.copy(
-        callsiteInstruction = newCallsiteInstruction,
-        callee              = Right(Callee(
-          callee                 = implClassMethod,
-          calleeDeclarationClass = implClassBType,
-          safeToInline           = true,
-          safeToRewrite          = false,
-          canInlineFromSource    = canInlineFromSource,
-          annotatedInline        = annotatedInline,
-          annotatedNoInline      = annotatedNoInline,
-          samParamTypes          = staticCallSamParamTypes,
-          calleeInfoWarning      = infoWarning))
-      )
-      callGraph.addCallsite(staticCallsite)
-    }
-
-    for (warning <- res.left) {
-      val Right(callee) = callsite.callee
-      val newCallee = callee.copy(calleeInfoWarning = Some(RewriteTraitCallToStaticImplMethodFailed(calleeDeclarationClass.internalName, callee.callee.name, callee.callee.desc, warning)))
-      callGraph.addCallsite(callsite.copy(callee = Right(newCallee)))
-    }
-  }
-
   /**
    * Returns the callsites that can be inlined. Ensures that the returned inline request graph does
    * not contain cycles.
diff --git a/src/compiler/scala/tools/nsc/backend/jvm/opt/InlinerHeuristics.scala b/src/compiler/scala/tools/nsc/backend/jvm/opt/InlinerHeuristics.scala
index 7e35d0e7f0..35735794b1 100644
--- a/src/compiler/scala/tools/nsc/backend/jvm/opt/InlinerHeuristics.scala
+++ b/src/compiler/scala/tools/nsc/backend/jvm/opt/InlinerHeuristics.scala
@@ -41,7 +41,7 @@ class InlinerHeuristics[BT <: BTypes](val bTypes: BT) {
     compilingMethods.map(methodNode => {
       var requests = Set.empty[InlineRequest]
       callGraph.callsites(methodNode).valuesIterator foreach {
-        case callsite @ Callsite(_, _, _, Right(Callee(callee, calleeDeclClass, safeToInline, _, canInlineFromSource, calleeAnnotatedInline, _, _, callsiteWarning)), _, _, _, pos, _, _) =>
+        case callsite @ Callsite(_, _, _, Right(Callee(callee, calleeDeclClass, safeToInline, canInlineFromSource, calleeAnnotatedInline, _, _, callsiteWarning)), _, _, _, pos, _, _) =>
           inlineRequest(callsite) match {
             case Some(Right(req)) => requests += req
             case Some(Left(w))    =>
@@ -57,9 +57,7 @@ class InlinerHeuristics[BT <: BTypes](val bTypes: BT) {
                 // reason is, for example, mixed compilation (which has a separate -Yopt-warning flag).
                 def initMsg = s"${BackendReporting.methodSignature(calleeDeclClass.internalName, callee)} is annotated @inline but cannot be inlined"
                 def warnMsg = callsiteWarning.map(" Possible reason:\n" + _).getOrElse("")
-                if (doRewriteTraitCallsite(callsite))
-                  backendReporting.inlinerWarning(pos, s"$initMsg: the trait method call could not be rewritten to the static implementation method." + warnMsg)
-                else if (!safeToInline)
+                if (!safeToInline)
                   backendReporting.inlinerWarning(pos, s"$initMsg: the method is not final and may be overridden." + warnMsg)
                 else
                   backendReporting.inlinerWarning(pos, s"$initMsg." + warnMsg)