Clean up the way compiler settings are accessed in the backend.

Many backend components don't have access to the compiler instance
holding the settings.

Before this change, individual settings required in these parts of the
backend were made available as members of trait BTypes, implemented
in the subclass BTypesFromSymbols (which has access to global).

This change exposes a single value of type ScalaSettings in the super
trait BTypes, which gives access to all compiler settings.

1 files changed, 14 insertions, 9 deletions

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 fb5cfeb167..5f51a94673 100644
--- a/src/compiler/scala/tools/nsc/backend/jvm/opt/LocalOpt.scala
+++ b/src/compiler/scala/tools/nsc/backend/jvm/opt/LocalOpt.scala
@@ -14,7 +14,6 @@ import scala.tools.asm.tree._
 import scala.collection.convert.decorateAsScala._
 import scala.tools.nsc.backend.jvm.BTypes.InternalName
 import scala.tools.nsc.backend.jvm.opt.BytecodeUtils._
-import scala.tools.nsc.settings.ScalaSettings
 
 /**
  * Optimizations within a single method.
@@ -47,7 +46,10 @@ import scala.tools.nsc.settings.ScalaSettings
  * stale labels
  *   - eliminate labels that are not referenced, merge sequences of label definitions.
  */
-class LocalOpt(settings: ScalaSettings, unreachableCodeEliminated: collection.mutable.Set[MethodNode]) {
+class LocalOpt[BT <: BTypes](val btypes: BT) {
+  import LocalOptImpls._
+  import btypes._
+
   /**
    * Remove unreachable code from a method.
    *
@@ -88,7 +90,7 @@ class LocalOpt(settings: ScalaSettings, unreachableCodeEliminated: collection.mu
    * @return      `true` if unreachable code was eliminated in some method, `false` otherwise.
    */
   def methodOptimizations(clazz: ClassNode): Boolean = {
-    !settings.YoptNone && clazz.methods.asScala.foldLeft(false) {
+    !compilerSettings.YoptNone && clazz.methods.asScala.foldLeft(false) {
       case (changed, method) => methodOptimizations(method, clazz.name) || changed
     }
   }
@@ -137,7 +139,7 @@ class LocalOpt(settings: ScalaSettings, unreachableCodeEliminated: collection.mu
 
     def removalRound(): Boolean = {
       // unreachable-code, empty-handlers and simplify-jumps run until reaching a fixpoint (see doc on class LocalOpt)
-      val (codeRemoved, handlersRemoved, liveHandlerRemoved) = if (settings.YoptUnreachableCode) {
+      val (codeRemoved, handlersRemoved, liveHandlerRemoved) = if (compilerSettings.YoptUnreachableCode) {
         val (removedInstructions, liveLabels) = removeUnreachableCodeImpl(method, ownerClassName)
         val removedHandlers = removeEmptyExceptionHandlers(method)
         (removedInstructions.nonEmpty, removedHandlers.nonEmpty, removedHandlers.exists(h => liveLabels(h.start)))
@@ -145,7 +147,7 @@ class LocalOpt(settings: ScalaSettings, unreachableCodeEliminated: collection.mu
         (false, false, false)
       }
 
-      val jumpsChanged = if (settings.YoptSimplifyJumps) simplifyJumps(method) else false
+      val jumpsChanged = if (compilerSettings.YoptSimplifyJumps) simplifyJumps(method) else false
 
       // Eliminating live handlers and simplifying jump instructions may render more code
       // unreachable, so we need to run another round.
@@ -158,13 +160,13 @@ class LocalOpt(settings: ScalaSettings, unreachableCodeEliminated: collection.mu
 
     // (*) Removing stale local variable descriptors is required for correctness of unreachable-code
     val localsRemoved =
-      if (settings.YoptCompactLocals) compactLocalVariables(method) // also removes unused
-      else if (settings.YoptUnreachableCode) removeUnusedLocalVariableNodes(method)() // (*)
+      if (compilerSettings.YoptCompactLocals) compactLocalVariables(method) // also removes unused
+      else if (compilerSettings.YoptUnreachableCode) removeUnusedLocalVariableNodes(method)() // (*)
       else false
 
-    val lineNumbersRemoved = if (settings.YoptEmptyLineNumbers) removeEmptyLineNumbers(method) else false
+    val lineNumbersRemoved = if (compilerSettings.YoptEmptyLineNumbers) removeEmptyLineNumbers(method) else false
 
-    val labelsRemoved = if (settings.YoptEmptyLabels) removeEmptyLabelNodes(method) else false
+    val labelsRemoved = if (compilerSettings.YoptEmptyLabels) 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.
@@ -177,6 +179,9 @@ class LocalOpt(settings: ScalaSettings, unreachableCodeEliminated: collection.mu
     codeHandlersOrJumpsChanged || localsRemoved || lineNumbersRemoved || labelsRemoved
   }
 
+}
+
+object LocalOptImpls {
   /**
    * Removes unreachable basic blocks.
    *