Added 'loop header' field to basic blocks to ease Andre's computation of the cut set.

git-svn-id: http://lampsvn.epfl.ch/svn-repos/scala/scala/trunk@7089 5e8d7ff9-d8ef-0310-90f0-a4852d11357a

src/compiler/scala/tools/nsc/ast/parser/Parsers.scala

@@ -662,7 +662,7 @@ trait Parsers requires SyntaxAnalyzer {
           Try(body, catches, finalizer)
         }
       case WHILE =>
-        val lname: Name = unit.fresh.newName("label$");
+        val lname: Name = unit.fresh.newName("while$");
         val pos = in.skipToken();
         accept(LPAREN);
         val cond = expr();
@@ -671,7 +671,7 @@ trait Parsers requires SyntaxAnalyzer {
         val body = expr();
         atPos(pos) { makeWhile(lname, cond, body) }
       case DO =>
-        val lname: Name = unit.fresh.newName("label$");
+        val lname: Name = unit.fresh.newName("doWhile$");
         val pos = in.skipToken();
         val body = expr();
         if (in.token == SEMI || in.token == NEWLINE) in.nextToken();

src/compiler/scala/tools/nsc/backend/icode/BasicBlocks.scala

@@ -24,19 +24,16 @@ trait BasicBlocks requires ICodes {
         extends AnyRef 
         with ProgramPoint[BasicBlock] {
 
-    /** The type stack at the begining of the block */
-    var initialStack : TypeStack = null;
-
     /** The label of the block */
     val label = theLabel;
 
-    /** The stack at the end of the block */
-    var endStack : TypeStack = null;
-
     /** When set, the 'emit' methods will be ignored. */
     var ignore: Boolean = false;
 
     var preds: List[BasicBlock] = null;
+
+    /** Is this block the head of a while? */
+    var loopHeader = false;
     
     /** ICode instructions, used as temporary storage while emitting code.
      * Once closed is called, only the `instrs' array should be used.
@@ -85,14 +82,6 @@ trait BasicBlocks requires ICodes {
       else
         instructionList.length;
 
-    /** Initialize the stack of the block, must be done before evaluation 
-     *  the type stack  */
-    def initStack(stack : TypeStack) = {
-      if (initialStack == null) {
-        initialStack = stack;
-        endStack = null;
-      }
-    }
     
     ///////////////////// Substitutions ///////////////////////
 

src/compiler/scala/tools/nsc/backend/icode/GenICode.scala

@@ -336,6 +336,9 @@ abstract class GenICode extends SubComponent  {
       val resCtx: Context = tree match {
         case LabelDef(name, params, rhs) =>            
           val ctx1 = ctx.newBlock;
+          if (isLoopHeaderLabel(name))
+            ctx1.bb.loopHeader = true;
+
           ctx1.labels.get(tree.symbol) match {
             case Some(label) => 
               label.anchor(ctx1.bb);
@@ -1381,6 +1384,9 @@ abstract class GenICode extends SubComponent  {
       List.forall2(tree.params, ctx.defdef.vparamss.head)
         { (x, y) => x.symbol == y.symbol }
     );
+
+    def isLoopHeaderLabel(name: Name): Boolean = 
+      name.startsWith("while$") || name.startsWith("doWhile$");
     
 
     /////////////////////// Context ////////////////////////////////

src/compiler/scala/tools/nsc/backend/icode/Members.scala

@@ -35,8 +35,6 @@ trait Members requires ICodes {
 
     // Constructor code
     startBlock = newBlock;
-    startBlock.initStack(new TypeStack);
-
 
     def removeBlock(b: BasicBlock) = {
       if (settings.debug.value) {

src/compiler/scala/tools/nsc/backend/icode/Printers.scala

@@ -113,7 +113,9 @@ abstract class Printers {
     }
 
     def printBlock(bb: BasicBlock): Unit = {
-      print(bb.label); print(": "); indent; println;
+      print(bb.label);
+      if (bb.loopHeader) print("[loop header]");
+      print(": "); indent; println;
       bb.toList foreach printInstruction;
       undent; println;
     }