Added 'loop header' field to basic blocks to ea...

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

5 files changed, 14 insertions, 19 deletions

diff --git a/src/compiler/scala/tools/nsc/ast/parser/Parsers.scala b/src/compiler/scala/tools/nsc/ast/parser/Parsers.scala
index 5ad34ef612..1d73da9005 100644
--- a/src/compiler/scala/tools/nsc/ast/parser/Parsers.scala
+++ b/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();
diff --git a/src/compiler/scala/tools/nsc/backend/icode/BasicBlocks.scala b/src/compiler/scala/tools/nsc/backend/icode/BasicBlocks.scala
index 59e3aa5d6d..7bb3d9c8d2 100644
--- a/src/compiler/scala/tools/nsc/backend/icode/BasicBlocks.scala
+++ b/src/compiler/scala/tools/nsc/backend/icode/BasicBlocks.scala
@@ -24,20 +24,17 @@ 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 ///////////////////////
 
diff --git a/src/compiler/scala/tools/nsc/backend/icode/GenICode.scala b/src/compiler/scala/tools/nsc/backend/icode/GenICode.scala
index 95909722ce..fd82a4f0d6 100644
--- a/src/compiler/scala/tools/nsc/backend/icode/GenICode.scala
+++ b/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);
@@ -1382,6 +1385,9 @@ abstract class GenICode extends SubComponent  {
         { (x, y) => x.symbol == y.symbol }
     );
 
+    def isLoopHeaderLabel(name: Name): Boolean =
+      name.startsWith("while$") || name.startsWith("doWhile$");
+
 
     /////////////////////// Context ////////////////////////////////
 
diff --git a/src/compiler/scala/tools/nsc/backend/icode/Members.scala b/src/compiler/scala/tools/nsc/backend/icode/Members.scala
index 6eb47ac8f7..c93d318d5a 100644
--- a/src/compiler/scala/tools/nsc/backend/icode/Members.scala
+++ b/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) {
diff --git a/src/compiler/scala/tools/nsc/backend/icode/Printers.scala b/src/compiler/scala/tools/nsc/backend/icode/Printers.scala
index bc0104ce78..5e249cf17f 100644
--- a/src/compiler/scala/tools/nsc/backend/icode/Printers.scala
+++ b/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;
     }