Revert "Refactoring if block-information."

lib/compiler/implementation/ssa/codegen.dart

Index: lib/compiler/implementation/ssa/codegen.dart
diff --git a/lib/compiler/implementation/ssa/codegen.dart b/lib/compiler/implementation/ssa/codegen.dart
index c7a7b9679817f748e3e8e61d639fee5a8f67fc95..67774ca552f11613bb09748c48bc90608e9c06e8 100644
--- a/lib/compiler/implementation/ssa/codegen.dart
+++ b/lib/compiler/implementation/ssa/codegen.dart
@@ -15,7 +15,7 @@ class SsaCodeGeneratorTask extends CompilerTask {
       SsaOptimizedCodeGenerator codegen = new SsaOptimizedCodeGenerator(
           compiler, work, parameters, parameterNames);
       codegen.visitGraph(graph);
-
+      
       FunctionElement element = work.element;
       String code;
       if (element.isInstanceMember()
@@ -80,7 +80,7 @@ class SsaCodeGeneratorTask extends CompilerTask {
 
 typedef void ElementAction(Element element);
 
-class SsaCodeGenerator implements HVisitor, HBlockInformationVisitor {
+class SsaCodeGenerator implements HVisitor {
   /**
    * Current state for generating simple (non-local-control) code.
    * It is generated as either statements (indented and ';'-terminated),
@@ -413,114 +413,7 @@ class SsaCodeGenerator implements HVisitor, HBlockInformationVisitor {
     buffer.add(";\n");
   }
 
-  bool visitIfInfo(HIfBlockInformation info) {
-    return false;
-  }
-
-  bool visitAndOrInfo(HAndOrBlockInformation info) {
-    return false;
-  }
-
-  bool visitLoopInfo(HLoopInformation info) {
-    SubExpression condition = info.condition;
-    void visitBodyIgnoreLabels() {
-      if (info.body.start.isLabeledBlock()) {
-        HBlockInformation oldInfo = currentBlockInformation;
-        currentBlockInformation = info.body.start.blockInformation;
-        visitSubGraph(info.body);
-        currentBlockInformation = oldInfo;
-      } else {
-        visitSubGraph(info.body);
-      }
-    }
-
-    if (!isCondition(condition)) {
-      return false;
-    }
-    switch (info.kind) {
-      case HLoopInformation.WHILE_LOOP:
-      case HLoopInformation.FOR_IN_LOOP: {
-        addIndentation();
-        for (LabelElement label in info.labels) {
-          writeLabel(label);
-          buffer.add(":");
-        }
-        bool inlineUpdates =
-            info.updates !== null && isExpression(info.updates);
-        if (inlineUpdates) {
-          buffer.add("for (; ");
-          visitConditionGraph(condition);
-          buffer.add("; ");
-          visitExpressionGraph(info.updates);
-          buffer.add(") {\n");
-          indent++;
-          // The body might be labeled. Ignore this when recursing on the
-          // subgraph.
-          // TODO(lrn): Remove this extra labeling when handling all loops
-          // using subgraphs.
-          visitBodyIgnoreLabels();
-
-          indent--;
-        } else {
-          buffer.add("while (");
-          visitConditionGraph(condition);
-          buffer.add(") {\n");
-          indent++;
-          wrapLoopBodyForContinue(info);
-          if (info.updates !== null) visitSubGraph(info.updates);
-          indent--;
-        }
-        addIndentation();
-        buffer.add("}\n");
-        break;
-      }
-      case HLoopInformation.FOR_LOOP: {
-        // TODO(lrn): Find a way to put initialization into the for.
-        // It's currently handled before we reach the [HLoopInformation].
-        addIndentation();
-        for (LabelElement label in info.labels) {
-          if (label.isTarget) {
-            writeLabel(label);
-            buffer.add(":");
-          }
-        }
-        buffer.add("for(;");
-        visitConditionGraph(info.condition);
-        buffer.add(";");
-        if (isExpression(info.updates)) {
-          visitExpressionGraph(info.updates);
-          buffer.add(") {\n");
-          indent++;
-
-          visitBodyIgnoreLabels();
-
-          indent--;
-          addIndentation();
-          buffer.add("}\n");
-        } else {
-          addIndentation();
-          buffer.add(") {\n");
-          indent++;
-          wrapLoopBodyForContinue(info);
-          visitSubGraph(info.updates);
-          indent--;
-          buffer.add("}\n");
-        }
-        break;
-      }
-      case HLoopInformation.DO_WHILE_LOOP:
-        // Currently unhandled.
-        return false;
-      default:
-        compiler.internalError(
-          'Unexpected loop kind: ${info.kind}',
-          instruction: condition.expression);
-    }
-    visitBasicBlock(info.joinBlock);
-    return true;
-  }
-
-  bool visitLabeledBlockInfo(HLabeledBlockInformation labeledBlockInfo) {
+  void handleLabeledBlock(HLabeledBlockInformation labeledBlockInfo) {
     addIndentation();
     Link<Element> continueOverrides = const EmptyLink<Element>();
     // If [labeledBlockInfo.isContinue], the block is an artificial
@@ -581,7 +474,6 @@ class SsaCodeGenerator implements HVisitor, HBlockInformationVisitor {
     } else {
       breakAction.remove(labeledBlockInfo.target);
     }
-    return true;
   }
 
   void emitLogicalOperation(HPhi node, String operation) {
@@ -627,6 +519,99 @@ class SsaCodeGenerator implements HVisitor, HBlockInformationVisitor {
     }
   }
 
+  bool handleLoop(HBasicBlock node) {
+    bool success = false;
+    assert(node.isLoopHeader());
+    HLoopInformation info = node.loopInformation;
+    SubExpression condition = info.condition;
+    if (isCondition(condition)) {
+      switch (info.type) {
+        case HLoopInformation.WHILE_LOOP:
+        case HLoopInformation.FOR_IN_LOOP: {
+          addIndentation();
+          for (LabelElement label in info.labels) {
+            writeLabel(label);
+            buffer.add(":");
+          }
+          bool inlineUpdates =
+              info.updates !== null && isExpression(info.updates);
+          if (inlineUpdates) {
+            buffer.add("for (; ");
+            visitConditionGraph(condition);
+            buffer.add("; ");
+            visitExpressionGraph(info.updates);
+            buffer.add(") {\n");
+            indent++;
+            // The body might be labeled. Ignore this when recursing on the
+            // subgraph.
+            // TODO(lrn): Remove this extra labeling when handling all loops
+            // using subgraphs.
+            HBlockInformation oldInfo = currentBlockInformation;
+            currentBlockInformation = info.body.start.labeledBlockInformation;
+            visitSubGraph(info.body);
+            currentBlockInformation = oldInfo;
+
+            indent--;
+          } else {
+            buffer.add("while (");
+            visitConditionGraph(condition);
+            buffer.add(") {\n");
+            indent++;
+            wrapLoopBodyForContinue(info);
+            if (info.updates !== null) visitSubGraph(info.updates);
+            indent--;
+          }
+          addIndentation();
+          buffer.add("}\n");
+          success = true;
+          break;
+        }
+        case HLoopInformation.FOR_LOOP: {
+          // TODO(lrn): Find a way to put initialization into the for.
+          // It's currently handled before we reach the [HLoopInformation].
+          addIndentation();
+          for (LabelElement label in info.labels) {
+            if (label.isTarget) {
+              writeLabel(label);
+              buffer.add(":");
+            }
+          }
+          buffer.add("for(;");
+          visitConditionGraph(info.condition);
+          buffer.add(";");
+          if (isExpression(info.updates)) {
+            visitExpressionGraph(info.updates);
+            buffer.add(") {\n");
+            indent++;
+
+            HBlockInformation oldInfo = currentBlockInformation;
+            currentBlockInformation = info.body.start.labeledBlockInformation;
+            visitSubGraph(info.body);
+            currentBlockInformation = oldInfo;
+
+            indent--;
+            addIndentation();
+            buffer.add("}\n");
+          } else {
+            addIndentation();
+            buffer.add(") {\n");
+            indent++;
+            wrapLoopBodyForContinue(info);
+            visitSubGraph(info.updates);
+            indent--;
+            buffer.add("}\n");
+          }
+          success = true;
+          break;
+        }
+        case HLoopInformation.DO_WHILE_LOOP:
+          // Currently unhandled.
+        default:
+      }
+    }
+    return success;
+  }
+
   void visitBasicBlock(HBasicBlock node) {
     // Abort traversal if we are leaving the currently active sub-graph.
     if (!subGraph.contains(node)) return;
@@ -635,20 +620,28 @@ class SsaCodeGenerator implements HVisitor, HBlockInformationVisitor {
     // If we reach here again while handling the attached information,
     // e.g., because we call visitSubGraph on a subgraph starting here,
     // don't handle it again.
-    if (node.blockInformation !== null &&
-        node.blockInformation !== currentBlockInformation) {
+    if (node.hasLabeledBlockInformation() &&
+        node.labeledBlockInformation !== currentBlockInformation) {
       HBlockInformation oldBlockInformation = currentBlockInformation;
-      currentBlockInformation = node.blockInformation;
-      bool success = currentBlockInformation.accept(this);
+      currentBlockInformation = node.labeledBlockInformation;
+      handleLabeledBlock(currentBlockInformation);
       currentBlockInformation = oldBlockInformation;
-      if (success) return;
+      return;
+    }
 
-      // If our special handling didn't succeed, we have to emit a generic
-      // version. This still requires special handling for loop-blocks
-      if (node.isLoopHeader()) {
-        beginLoop(node);
+    if (node.isLoopHeader() &&
+        node.loopInformation !== currentBlockInformation) {
+      HBlockInformation oldBlockInformation = currentBlockInformation;
+      currentBlockInformation = node.loopInformation;
+      bool prettyLoop = handleLoop(node);
+      currentBlockInformation = oldBlockInformation;
+      if (prettyLoop) {
+        visitBasicBlock(node.loopInformation.joinBlock);
+        return;
       }
+      beginLoop(node);
     }
+
     iterateBasicBlock(node);
   }
 
@@ -1621,7 +1614,7 @@ class SsaOptimizedCodeGenerator extends SsaCodeGenerator {
       buffer.add('||');
       checkImmutableArray(input);
       buffer.add(') ');
-      bailout(node, 'Not a mutable array');
+      bailout(node, 'Not a mutable array');      
     } else if (node.isArray()) {
       buffer.add('if (');
       checkObject(input, '!==');
@@ -1646,8 +1639,7 @@ class SsaOptimizedCodeGenerator extends SsaCodeGenerator {
 
   void beginLoop(HBasicBlock block) {
     addIndentation();
-    HLoopInformation info = block.blockInformation;
-    for (LabelElement label in info.labels) {
+    for (LabelElement label in block.loopInformation.labels) {
       writeLabel(label);
       buffer.add(":");
     }
@@ -1766,7 +1758,7 @@ class SsaUnoptimizedCodeGenerator extends SsaCodeGenerator {
     }
   }
 
-  bool visitLoopInfo(HLoopInformation info) => false;
+  bool handleLoop(HBasicBlock node) => false;
 
   void visitTypeGuard(HTypeGuard node) {
     indent--;
@@ -1818,6 +1810,7 @@ class SsaUnoptimizedCodeGenerator extends SsaCodeGenerator {
     buffer.add('}\n');  // Close 'switch'.
   }
 
+
   void beginLoop(HBasicBlock block) {
     // TODO(ngeoffray): Don't put labels on loops that don't bailout.
     String newLabel = pushLabel();
@@ -1826,8 +1819,7 @@ class SsaUnoptimizedCodeGenerator extends SsaCodeGenerator {
     }
 
     addIndentation();
-    HLoopInformation loopInformation = block.blockInformation;
-    for (LabelElement label in loopInformation.labels) {
+    for (LabelElement label in block.loopInformation.labels) {
       writeLabel(label);
       buffer.add(":");
     }