Clean up optimizer settings.

3 files changed, 19 insertions, 23 deletions

diff --git a/src/compiler/scala/tools/nsc/backend/jvm/GenBCode.scala b/src/compiler/scala/tools/nsc/backend/jvm/GenBCode.scala
index 35e4db33bc..b0ec37db97 100644
--- a/src/compiler/scala/tools/nsc/backend/jvm/GenBCode.scala
+++ b/src/compiler/scala/tools/nsc/backend/jvm/GenBCode.scala
@@ -237,7 +237,7 @@ abstract class GenBCode extends BCodeSyncAndTry {
         }
         if (settings.YoptInlinerEnabled)
           bTypes.inliner.runInliner()
-        if (settings.YoptClosureElimination)
+        if (settings.YoptClosureInvocations)
           closureOptimizer.rewriteClosureApplyInvocations()
       }
 
diff --git a/src/compiler/scala/tools/nsc/backend/jvm/opt/LocalOpt.scala b/src/compiler/scala/tools/nsc/backend/jvm/opt/LocalOpt.scala
index 5ad6910d5e..b4868a03ef 100644
--- a/src/compiler/scala/tools/nsc/backend/jvm/opt/LocalOpt.scala
+++ b/src/compiler/scala/tools/nsc/backend/jvm/opt/LocalOpt.scala
@@ -198,14 +198,14 @@ class LocalOpt[BT <: BTypes](val btypes: BT) {
     def removalRound(runDCE: Boolean, runCopyProp: Boolean, maxRecursion: Int = 10): Boolean = {
       if (maxRecursion == 0) return false
 
-      val (codeRemoved, liveLabels) = if (runDCE) removeUnreachableCodeImpl(method, ownerClassName) else (false, Set.empty[LabelNode])
+      // Both AliasingAnalyzer (used in copyProp) and ProdConsAnalyzer (used in eliminateStaleStores)
+      // require not having unreachable instructions (null frames).
+      val dceRequired = runDCE || compilerSettings.YoptCopyPropagation
+      val (codeRemoved, liveLabels) = if (dceRequired) removeUnreachableCodeImpl(method, ownerClassName) else (false, Set.empty[LabelNode])
 
       // runCopyProp is only true in the first iteration; there's no optimization below that enables
       // further copy propagation. it is still part of the fixpoint loop because it needs to run after DCE.
-      val copyPropChanged = if (runCopyProp) {
-        if (!runDCE) minimalRemoveUnreachableCode(method, ownerClassName) // copyProp (AliasingAnalyzer) requires DCE
-        copyProp(method, ownerClassName)
-      } else false
+      val copyPropChanged = if (runCopyProp) copyProp(method, ownerClassName) else false
 
       val storesRemoved = if (compilerSettings.YoptCopyPropagation) eliminateStaleStores(method, ownerClassName) else false
 
@@ -213,7 +213,7 @@ class LocalOpt[BT <: BTypes](val btypes: BT) {
 
       val storeLoadRemoved = if (compilerSettings.YoptCopyPropagation) eliminateStoreLoad(method) else false
 
-      val removedHandlers = if (runDCE) removeEmptyExceptionHandlers(method) else Set.empty[TryCatchBlockNode]
+      val removedHandlers = if (dceRequired) removeEmptyExceptionHandlers(method) else Set.empty[TryCatchBlockNode]
       val handlersRemoved = removedHandlers.nonEmpty
       val liveHandlerRemoved = removedHandlers.exists(h => liveLabels(h.start))
 
@@ -233,7 +233,7 @@ class LocalOpt[BT <: BTypes](val btypes: BT) {
 
     val dceCopyPropHandlersOrJumpsChanged = if (AsmAnalyzer.sizeOKForBasicValue(method)) {
       // we run DCE even if the method is already in the `unreachableCodeEliminated` map: the DCE
-      // here is more thorough than `minimalRemoveUnreachableCode`
+      // here is more thorough than `minimalRemoveUnreachableCode` that run before inlining.
       val r = removalRound(
         runDCE = compilerSettings.YoptUnreachableCode,
         runCopyProp = compilerSettings.YoptCopyPropagation)
@@ -247,9 +247,9 @@ class LocalOpt[BT <: BTypes](val btypes: BT) {
       else if (compilerSettings.YoptUnreachableCode) removeUnusedLocalVariableNodes(method)() // (*)
       else false
 
-    val lineNumbersRemoved = if (compilerSettings.YoptEmptyLineNumbers) removeEmptyLineNumbers(method) else false
+    val lineNumbersRemoved = if (compilerSettings.YoptUnreachableCode) removeEmptyLineNumbers(method) else false
 
-    val labelsRemoved = if (compilerSettings.YoptEmptyLabels) removeEmptyLabelNodes(method) else false
+    val labelsRemoved = if (compilerSettings.YoptUnreachableCode) removeEmptyLabelNodes(method) else false
 
     // assert that local variable annotations are empty (we don't emit them) - otherwise we'd have
     // to eliminate those covering an empty range, similar to removeUnusedLocalVariableNodes.
diff --git a/src/compiler/scala/tools/nsc/settings/ScalaSettings.scala b/src/compiler/scala/tools/nsc/settings/ScalaSettings.scala
index cbd9ee1a55..794c0ba324 100644
--- a/src/compiler/scala/tools/nsc/settings/ScalaSettings.scala
+++ b/src/compiler/scala/tools/nsc/settings/ScalaSettings.scala
@@ -225,23 +225,21 @@ trait ScalaSettings extends AbsScalaSettings
   val YskipInlineInfoAttribute = BooleanSetting("-Yskip-inline-info-attribute", "Do not add the ScalaInlineInfo attribute to classfiles generated by -Ybackend:GenASM")
 
   object YoptChoices extends MultiChoiceEnumeration {
-    val unreachableCode         = Choice("unreachable-code",          "Eliminate unreachable code, exception handlers protecting no instructions, debug information of eliminated variables.")
+    val unreachableCode         = Choice("unreachable-code",          "Eliminate unreachable code, exception handlers guarding no instructions, redundant metadata (debug information, line numbers).")
     val simplifyJumps           = Choice("simplify-jumps",            "Simplify branching instructions, eliminate unnecessary ones.")
-    val emptyLineNumbers        = Choice("empty-line-numbers",        "Eliminate unnecessary line number information.")
-    val emptyLabels             = Choice("empty-labels",              "Eliminate and collapse redundant labels in the bytecode.")
     val compactLocals           = Choice("compact-locals",            "Eliminate empty slots in the sequence of local variables.")
-    val copyPropagation         = Choice("copy-propagation",          "Eliminate redundant local variables (locals that are copies of others).")
+    val copyPropagation         = Choice("copy-propagation",          "Eliminate redundant local variables and unused values (including closures). Enables unreachable-code.")
     val nullnessTracking        = Choice("nullness-tracking",         "Track nullness / non-nullness of local variables and apply optimizations.")
-    val closureElimination      = Choice("closure-elimination" ,      "Rewrite closure invocations to the implementation method and eliminate closures.")
-    val inlineProject           = Choice("inline-project",            "Inline only methods defined in the files being compiled.")
-    val inlineGlobal            = Choice("inline-global",             "Inline methods from any source, including classfiles on the compile classpath.")
+    val closureInvocations      = Choice("closure-invocations" ,      "Rewrite closure invocations to the implementation method.")
+    val inlineProject           = Choice("inline-project",            "Inline only methods defined in the files being compiled. Enables unreachable-code.")
+    val inlineGlobal            = Choice("inline-global",             "Inline methods from any source, including classfiles on the compile classpath. Enables unreachable-code.")
 
     val lNone           = Choice("l:none",      "Don't enable any optimizations.")
 
     private val defaultChoices = List(unreachableCode)
     val lDefault        = Choice("l:default",   "Enable default optimizations: "+ defaultChoices.mkString(","),                                    expandsTo = defaultChoices)
 
-    private val methodChoices = List(unreachableCode, simplifyJumps, emptyLineNumbers, emptyLabels, compactLocals, copyPropagation, nullnessTracking, closureElimination)
+    private val methodChoices = List(unreachableCode, simplifyJumps, compactLocals, copyPropagation, nullnessTracking, closureInvocations)
     val lMethod         = Choice("l:method",    "Enable intra-method optimizations: "+ methodChoices.mkString(","),                                expandsTo = methodChoices)
 
     private val projectChoices = List(lMethod, inlineProject)
@@ -260,19 +258,17 @@ trait ScalaSettings extends AbsScalaSettings
   def YoptNone                    = Yopt.isSetByUser && Yopt.value.isEmpty
   def YoptUnreachableCode         = !Yopt.isSetByUser || Yopt.contains(YoptChoices.unreachableCode)
   def YoptSimplifyJumps           = Yopt.contains(YoptChoices.simplifyJumps)
-  def YoptEmptyLineNumbers        = Yopt.contains(YoptChoices.emptyLineNumbers)
-  def YoptEmptyLabels             = Yopt.contains(YoptChoices.emptyLabels)
   def YoptCompactLocals           = Yopt.contains(YoptChoices.compactLocals)
   def YoptCopyPropagation         = Yopt.contains(YoptChoices.copyPropagation)
   def YoptNullnessTracking        = Yopt.contains(YoptChoices.nullnessTracking)
-  def YoptClosureElimination      = Yopt.contains(YoptChoices.closureElimination)
+  def YoptClosureInvocations      = Yopt.contains(YoptChoices.closureInvocations)
 
   def YoptInlineProject           = Yopt.contains(YoptChoices.inlineProject)
   def YoptInlineGlobal            = Yopt.contains(YoptChoices.inlineGlobal)
   def YoptInlinerEnabled          = YoptInlineProject || YoptInlineGlobal
 
-  def YoptBuildCallGraph          = YoptInlinerEnabled || YoptClosureElimination
-  def YoptAddToBytecodeRepository = YoptBuildCallGraph || YoptInlinerEnabled || YoptClosureElimination
+  def YoptBuildCallGraph          = YoptInlinerEnabled || YoptClosureInvocations
+  def YoptAddToBytecodeRepository = YoptBuildCallGraph || YoptInlinerEnabled || YoptClosureInvocations
 
   val YoptInlineHeuristics = ChoiceSetting(
     name = "-Yopt-inline-heuristics",