[backport] Fix unsafe array opt. / opt. primitive Array(...)

SI-6611, SI-6247 (partial fix)

The original commits on master were a bit circuitous, this
is squashed to a neat little package.

I had to add type arguments to the Array.apply calls in the
test case, they are inferred on master.

commit 41ff05dfdbcf032157b3509ace633f2e7a12295c
Author: Jason Zaugg <jzaugg@gmail.com>
Date:   Sun Nov 4 14:44:59 2012 +0100

    Refactor guards checking for a particular overload of Array.apply.
    (cherry picked from commit 092345a24c22a821204fb358d33272ae8f7353be)

commit 1e5c942deccaf64f8d57bd8891b912381d7f220a
Author: Jason Zaugg <jzaugg@gmail.com>
Date:   Sun Nov 4 14:17:25 2012 +0100

    Expand optimization of Array(e1, ..., en) to primitive arrays.
    (cherry picked from commit 8265175ecc42293997d59049f430396c77a2b891)

commit ab1bf77e39f2dfeacf3fc107ccb2907a1867f04c
Author: Jason Zaugg <jzaugg@gmail.com>
Date:   Sat Nov 3 13:34:20 2012 +0100

    SI-6611 Tighten up an unsafe array optimization

    The net was cast too wide and was unsafely optimizing away array
    copies.
    (cherry picked from commit dad886659faca4fba2d4937c9bc6780591b02c27)

And also:

Optimize primitive Array(e1, ..., en)

Expands an existing optimization for reference arrays to
apply to primitives, as well.

Fixes one aspect of SI-6247.
(cherry picked from commit cac5a08611f9511ba4d94b99db630404efae190a)

Conflicts:
	src/compiler/scala/tools/nsc/transform/CleanUp.scala

More principled tree copying.

Canonical > home-spun.

Conflicts:
	src/compiler/scala/tools/nsc/transform/CleanUp.scala

2 files changed, 23 insertions, 6 deletions

diff --git a/src/reflect/scala/reflect/internal/Definitions.scala b/src/reflect/scala/reflect/internal/Definitions.scala
index 2a7b55cb5a..f28b3567a2 100644
--- a/src/reflect/scala/reflect/internal/Definitions.scala
+++ b/src/reflect/scala/reflect/internal/Definitions.scala
@@ -337,12 +337,13 @@ trait Definitions extends api.StandardDefinitions {
     lazy val PredefModule      = requiredModule[scala.Predef.type]
     lazy val PredefModuleClass = PredefModule.moduleClass
 
-      def Predef_classOf      = getMemberMethod(PredefModule, nme.classOf)
-      def Predef_identity     = getMemberMethod(PredefModule, nme.identity)
-      def Predef_conforms     = getMemberMethod(PredefModule, nme.conforms)
-      def Predef_wrapRefArray = getMemberMethod(PredefModule, nme.wrapRefArray)
-      def Predef_???          = getMemberMethod(PredefModule, nme.???)
-      def Predef_implicitly   = getMemberMethod(PredefModule, nme.implicitly)
+      def Predef_classOf             = getMemberMethod(PredefModule, nme.classOf)
+      def Predef_identity            = getMemberMethod(PredefModule, nme.identity)
+      def Predef_conforms            = getMemberMethod(PredefModule, nme.conforms)
+    def Predef_wrapRefArray        = getMemberMethod(PredefModule, nme.wrapRefArray)
+    def Predef_wrapArray(tp: Type) = getMemberMethod(PredefModule, wrapArrayMethodName(tp))
+    def Predef_???                 = getMemberMethod(PredefModule, nme.???)
+    def Predef_implicitly          = getMemberMethod(PredefModule, nme.implicitly)
 
     /** Is `sym` a member of Predef with the given name?
      *  Note: DON't replace this by sym == Predef_conforms/etc, as Predef_conforms is a `def`
@@ -466,6 +467,8 @@ trait Definitions extends api.StandardDefinitions {
     // arrays and their members
     lazy val ArrayModule                   = requiredModule[scala.Array.type]
       lazy val ArrayModule_overloadedApply = getMemberMethod(ArrayModule, nme.apply)
+           def ArrayModule_genericApply    = ArrayModule_overloadedApply.suchThat(_.paramss.flatten.last.tpe.typeSymbol == ClassTagClass) // [T: ClassTag](xs: T*): Array[T]
+           def ArrayModule_apply(tp: Type) = ArrayModule_overloadedApply.suchThat(_.tpe.resultType =:= arrayType(tp)) // (p1: AnyVal1, ps: AnyVal1*): Array[AnyVal1]
     lazy val ArrayClass                    = getRequiredClass("scala.Array") // requiredClass[scala.Array[_]]
       lazy val Array_apply                 = getMemberMethod(ArrayClass, nme.apply)
       lazy val Array_update                = getMemberMethod(ArrayClass, nme.update)
diff --git a/src/reflect/scala/reflect/internal/TreeInfo.scala b/src/reflect/scala/reflect/internal/TreeInfo.scala
index 8908036442..e1a18570b2 100644
--- a/src/reflect/scala/reflect/internal/TreeInfo.scala
+++ b/src/reflect/scala/reflect/internal/TreeInfo.scala
@@ -234,6 +234,20 @@ abstract class TreeInfo {
       tree
   }
 
+  /** Strips layers of `.asInstanceOf[T]` / `_.$asInstanceOf[T]()` from an expression */
+  def stripCast(tree: Tree): Tree = tree match {
+    case TypeApply(sel @ Select(inner, _), _) if isCastSymbol(sel.symbol) =>
+      stripCast(inner)
+    case Apply(TypeApply(sel @ Select(inner, _), _), Nil) if isCastSymbol(sel.symbol) =>
+      stripCast(inner)
+    case t =>
+      t
+  }
+
+  object StripCast {
+    def unapply(tree: Tree): Some[Tree] = Some(stripCast(tree))
+  }
+
   /** Is tree a self or super constructor call? */
   def isSelfOrSuperConstrCall(tree: Tree) = {
     // stripNamedApply for SI-3584: adaptToImplicitMethod in Typers creates a special context