Command-line flag to control inlining heuristics

Introduces a stress-test mode "everything" in which the inliner tries
to inline every calliste that can be statically resolved.

4 files changed, 14 insertions, 2 deletions

diff --git a/src/compiler/scala/tools/nsc/backend/jvm/BTypes.scala b/src/compiler/scala/tools/nsc/backend/jvm/BTypes.scala
index d8a17e975e..74990fad02 100644
--- a/src/compiler/scala/tools/nsc/backend/jvm/BTypes.scala
+++ b/src/compiler/scala/tools/nsc/backend/jvm/BTypes.scala
@@ -57,6 +57,8 @@ abstract class BTypes {
   // Settings that define what kind of optimizer warnings are emitted.
   def warnSettings: WarnSettings
 
+  def inliningHeuristics: String
+
   /**
    * A map from internal names to ClassBTypes. Every ClassBType is added to this map on its
    * construction.
diff --git a/src/compiler/scala/tools/nsc/backend/jvm/BTypesFromSymbols.scala b/src/compiler/scala/tools/nsc/backend/jvm/BTypesFromSymbols.scala
index eeb6ed24a2..ad434889cf 100644
--- a/src/compiler/scala/tools/nsc/backend/jvm/BTypesFromSymbols.scala
+++ b/src/compiler/scala/tools/nsc/backend/jvm/BTypesFromSymbols.scala
@@ -63,6 +63,8 @@ class BTypesFromSymbols[G <: Global](val global: G) extends BTypes {
       settings.YoptWarnings.contains(c.noInlineMissingScalaInlineInfoAttr.name))
   }
 
+  def inliningHeuristics: String = settings.YoptInlineHeuristics.value
+
   // helpers that need access to global.
   // TODO @lry create a separate component, they don't belong to BTypesFromSymbols
 
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 e14e57d3ab..fbbb6bb5e0 100644
--- a/src/compiler/scala/tools/nsc/backend/jvm/opt/Inliner.scala
+++ b/src/compiler/scala/tools/nsc/backend/jvm/opt/Inliner.scala
@@ -106,7 +106,8 @@ class Inliner[BT <: BTypes](val btypes: BT) {
    */
   def doInlineCallsite(callsite: Callsite): Boolean = callsite match {
     case Callsite(_, _, _, Right(Callee(callee, calleeDeclClass, safeToInline, _, annotatedInline, _, warning)), _, _, pos) =>
-      annotatedInline && safeToInline
+      if (inliningHeuristics == "everything") safeToInline
+      else annotatedInline && safeToInline
 
     case _ => false
   }
diff --git a/src/compiler/scala/tools/nsc/settings/ScalaSettings.scala b/src/compiler/scala/tools/nsc/settings/ScalaSettings.scala
index d273995e6e..ee683418d9 100644
--- a/src/compiler/scala/tools/nsc/settings/ScalaSettings.scala
+++ b/src/compiler/scala/tools/nsc/settings/ScalaSettings.scala
@@ -256,6 +256,13 @@ trait ScalaSettings extends AbsScalaSettings
   def YoptInlineGlobal            = Yopt.contains(YoptChoices.inlineGlobal)
   def YoptInlinerEnabled          = YoptInlineProject || YoptInlineGlobal
 
+  val YoptInlineHeuristics = ChoiceSetting(
+    name = "-Yopt-inline-heuristics",
+    helpArg = "strategy",
+    descr = "Set the heuristics for inlining decisions.",
+    choices = List("at-inline-annotated", "everything"),
+    default = "at-inline-annotated")
+
   object YoptWarningsChoices extends MultiChoiceEnumeration {
     val none                               = Choice("none"                       , "No optimizer warnings.")
     val atInlineFailedSummary              = Choice("at-inline-failed-summary"   , "One-line summary if there were @inline method calls that could not be inlined.")
@@ -267,7 +274,7 @@ trait ScalaSettings extends AbsScalaSettings
 
   val YoptWarnings = MultiChoiceSetting(
     name = "-Yopt-warnings",
-    helpArg = "warnings",
+    helpArg = "warning",
     descr = "Enable optimizer warnings",
     domain = YoptWarningsChoices,
     default = Some(List(YoptWarningsChoices.atInlineFailed.name))) withPostSetHook (self => {