From cb95310d8689cb78b783b13222996938f39cb8ee Mon Sep 17 00:00:00 2001
From: Iulian Dragos <jaguarul@gmail.com>
Date: Fri, 23 Sep 2005 16:04:36 +0000
Subject: Initial commit.

---
 .../tools/nsc/backend/icode/Linearizers.scala      | 71 ++++++++++++++++++++++
 1 file changed, 71 insertions(+)
 create mode 100644 sources/scala/tools/nsc/backend/icode/Linearizers.scala

diff --git a/sources/scala/tools/nsc/backend/icode/Linearizers.scala b/sources/scala/tools/nsc/backend/icode/Linearizers.scala
new file mode 100644
index 0000000000..be6e9548f2
--- /dev/null
+++ b/sources/scala/tools/nsc/backend/icode/Linearizers.scala
@@ -0,0 +1,71 @@
+/* NSC -- new scala compiler
+ * Copyright 2005 LAMP/EPFL
+ * @author  Martin Odersky
+ */
+
+// $Id$
+
+package scala.tools.nsc.backend.icode;
+
+import scala.tools.nsc.ast._;
+import scala.collection.mutable.Queue;
+
+trait Linearizers: ICodes {
+  import opcodes._;
+
+  trait Linearizer {
+    def linearize(c: Code): List[BasicBlock];
+  }
+
+  /**
+   * A simple linearizer which predicts all branches to
+   * take the 'success' branch and tries to schedule those
+   * blocks immediately after the test. This is in sync with
+   * how 'while' statements are translated (if the test is
+   * 'true', the loop continues).
+   */
+  class NormalLinearizer extends Linearizer with WorklistAlgorithm {
+    type Elem = BasicBlock;
+    val worklist: Queue[Elem] = new Queue();
+
+    var blocks: List[BasicBlock] = Nil;
+
+    def linearize(c: Code): List[BasicBlock] = {
+      val b = c.startBlock;
+      blocks = b :: Nil;
+
+      run( { worklist.enqueue(b); } );
+      blocks.reverse;
+    }
+
+    def processElement(b: BasicBlock) =
+      b.lastInstruction match {
+        case JUMP(where) =>
+          add(where);
+        case CJUMP(success, failure, _, _) =>
+          add(success);
+          add(failure);
+        case CZJUMP(success, failure, _, _) =>
+          add(success);
+          add(failure);
+        case SWITCH(_, labels) =>
+          add(labels);
+        case RETURN() =>
+          ()
+      }
+
+    /**
+     * Prepend b to the list, if not already scheduled.
+     * TODO: use better test than linear search
+     */
+    def add(b: BasicBlock) =
+      if (blocks.contains(b))
+        ()
+      else {
+        blocks = b :: blocks;
+        worklist enqueue b;
+      }
+
+    def add(bs: List[BasicBlock]): Unit = bs foreach add;
+  }
+}
-- 
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