From 288b9749671eff98ac170fad35052e95e968c0ef Mon Sep 17 00:00:00 2001
From: Miguel Garcia <miguelalfredo.garcia@epfl.ch>
Date: Thu, 31 May 2012 13:46:44 +0200
Subject: skipping unnecessary work in GenASM when emitting 1.5 classfiles

---
 src/compiler/scala/tools/nsc/backend/jvm/GenASM.scala | 11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/src/compiler/scala/tools/nsc/backend/jvm/GenASM.scala b/src/compiler/scala/tools/nsc/backend/jvm/GenASM.scala
index 99832d1327..b8cf4eca9f 100644
--- a/src/compiler/scala/tools/nsc/backend/jvm/GenASM.scala
+++ b/src/compiler/scala/tools/nsc/backend/jvm/GenASM.scala
@@ -433,10 +433,11 @@ abstract class GenASM extends SubComponent with BytecodeWriters {
   }
 
   private val majorVersion: Int = (classfileVersion & 0xFF)
+  private val emitStackMapFrame = (majorVersion >= 50)
 
   private val extraProc: Int = mkFlags(
     asm.ClassWriter.COMPUTE_MAXS,
-    if(majorVersion >= 50) asm.ClassWriter.COMPUTE_FRAMES else 0
+    if(emitStackMapFrame) asm.ClassWriter.COMPUTE_FRAMES else 0
   )
 
   val JAVA_LANG_OBJECT = asm.Type.getObjectType("java/lang/Object")
@@ -580,14 +581,14 @@ abstract class GenASM extends SubComponent with BytecodeWriters {
         else                 { sym.javaSimpleName }
       })
 
-      if(hasInternalName) {
+      if(emitStackMapFrame && hasInternalName) {
         val internalName = cachedJN.toString()
         val trackedSym = jsymbol(sym)
         reverseJavaName.get(internalName) match {
           case None         =>
             reverseJavaName.put(internalName, trackedSym)
           case Some(oldsym) =>
-            assert((oldsym == trackedSym) || List(RuntimeNothingClass, RuntimeNullClass).contains(oldsym), // NothingClass, NullClass,
+            assert((oldsym == trackedSym) || (oldsym == RuntimeNothingClass) || (oldsym == RuntimeNullClass), // In contrast, neither NothingClass nor NullClass show up bytecode-level.
                    "how can getCommonSuperclass() do its job if different class symbols get the same bytecode-level internal name.")
         }
       }
@@ -2728,7 +2729,7 @@ abstract class GenASM extends SubComponent with BytecodeWriters {
           // TODO Logical's 2nd elem should be declared ValueTypeKind, to better approximate its allowed values (isIntSized, its comments appears to convey)
           // TODO GenICode uses `toTypeKind` to define that elem, `toValueTypeKind` would be needed instead.
           // TODO How about adding some asserts to Logical and similar ones to capture the remaining constraint (UNIT not allowed).
-          case Logical(op, kind) => (op, kind) match {
+          case Logical(op, kind) => ((op, kind): @unchecked) match {
             case (AND, LONG) => emit(Opcodes.LAND)
             case (AND, INT)  => emit(Opcodes.IAND)
             case (AND, _)    =>
@@ -2748,7 +2749,7 @@ abstract class GenASM extends SubComponent with BytecodeWriters {
               if (kind != BOOL) { emitT2T(INT, kind) }
           }
 
-          case Shift(op, kind) => (op, kind) match {
+          case Shift(op, kind) => ((op, kind): @unchecked) match {
             case (LSL, LONG) => emit(Opcodes.LSHL)
             case (LSL, INT)  => emit(Opcodes.ISHL)
             case (LSL, _) =>
-- 
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