Switch-implementation.

frog/leg/ssa/codegen.dart

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 class SsaCodeGeneratorTask extends CompilerTask {
   SsaCodeGeneratorTask(Compiler compiler) : super(compiler);
   String get name() => 'SSA code generator';
 
   String generate(WorkItem work, HGraph graph) {
     return measure(() {
@@ skipping 197 matching lines @@
   /**
     * Only visits the arguments starting at inputs[HInvoke.ARGUMENTS_OFFSET].
     */
   void visitArguments(List<HInstruction> inputs) {
     assert(inputs.length >= HInvoke.ARGUMENTS_OFFSET);
     buffer.add('(');
     for (int i = HInvoke.ARGUMENTS_OFFSET; i < inputs.length; i++) {
       if (i != HInvoke.ARGUMENTS_OFFSET) buffer.add(', ');
       use(inputs[i], JSPrecedence.ASSIGNMENT_PRECEDENCE);
     }
-    buffer.add(")");
+    buffer.add(')');
   }
 
   void define(HInstruction instruction) {
     buffer.add('var ${temporary(instruction)} = ');
     visit(instruction, JSPrecedence.ASSIGNMENT_PRECEDENCE);
   }
 
   void use(HInstruction argument, int expectedPrecedence) {
     if (argument.generateAtUseSite()) {
       visit(argument, expectedPrecedence);
     } else {
       buffer.add(temporary(argument));
     }
   }
 
   visit(HInstruction node, int expectedPrecedence) {
     int oldPrecedence = this.expectedPrecedence;
     this.expectedPrecedence = expectedPrecedence;
     node.accept(this);
     this.expectedPrecedence = oldPrecedence;
   }
 
   void handleLabeledBlock(HLabeledBlockInformation labeledBlockInfo) {
     addIndentation();
-    for (SourceString label in labeledBlockInfo.labels) {
+    for (LabelElement label in labeledBlockInfo.labels) {
       addLabel(label);
-      buffer.add(":");
+      buffer.add(':');
     }
-    buffer.add("{\n");
+    String implicitLabel = labeledBlockInfo.target.implicitLabel();
+    if (implicitLabel !== null) {
+      buffer.add(@'$');
+      buffer.add(implicitLabel);
+      buffer.add(@':');
+    }
+    buffer.add('{\n');
     indent++;
 
     visitSubGraph(labeledBlockInfo.body);
 
     indent--;
     addIndentation();
-    buffer.add("}\n");
+    buffer.add('}\n');
 
-    visitBasicBlock(labeledBlockInfo.joinBlock);
+    if (labeledBlockInfo.joinBlock !== null) {
+      visitBasicBlock(labeledBlockInfo.joinBlock);
+    }
   }
 
 
   visitBasicBlock(HBasicBlock node) {
     // Abort traversal if we are leaving the currently active sub-graph.
     if (!subGraph.contains(node)) return;
 
     // If this node has special behavior attached, handle it.
     // If we reach here again while handling the attached information,
     // e.g., because we call visitSubGraph on a subgraph starting here,
@@ skipping 148 matching lines @@
     if (dominated.length == 2 && currentBlock !== currentGraph.entry) {
       unreachable();
     }
     assert(dominated[0] == currentBlock.successors[0]);
     visitBasicBlock(dominated[0]);
   }
 
   // Used to write the name of labels.
   // The default implementation uses the unmodified Dart label name.
   // Specializations might change this.
-  void addLabel(SourceString label) {
-    buffer.add(label.slowToString());
+  void addLabel(LabelElement label) {
+    buffer.add(@'$');
+    buffer.add(label.labelName);
   }
 
   visitBreak(HBreak node) {
     assert(currentBlock.successors.length == 1);
-    // No block finishing with a 'break' can have more than
-    // one dominated block (since it has only one successor).
-    // If the successor is dominated by another block, then the other block
-    // is responsible for visiting the successor.
-    List<HBasicBlock> dominated = currentBlock.dominatedBlocks;
-    assert(dominated.isEmpty());
-    // Otherwise we would have bailed out in the builder.
     addIndentation();
     buffer.add("break");
     if (node.label !== null) {
       buffer.add(" ");
       addLabel(node.label);
+    } else {
+      StatementElement target = node.target;
+      String implicitLabel = target.implicitLabel();
+      if (implicitLabel !== null) {
+        buffer.add(@' $');
+        buffer.add(implicitLabel);
+      }
     }
     buffer.add(";\n");
+    // We never follow the break to its target, even if it dominates the
+    // break target block. That block is always handled by the structure
+    // that introduced the break.
   }
 
   visitTry(HTry node) {
     addIndentation();
     buffer.add('try {\n');
     indent++;
     List<HBasicBlock> successors = node.block.successors;
     visitBasicBlock(successors[0]);
     indent--;
 
@@ skipping 700 matching lines @@
       checkArray(input, '!==');
       buffer.add(')) ');
       bailout(node, 'Not a string or array');
     } else {
       unreachable();
     }
   }
 
   void beginLoop(HBasicBlock block) {
     addIndentation();
-    for (SourceString label in block.loopInformation.labels) {
-      buffer.add("${label.slowToString()}:");
+    for (LabelElement label in block.loopInformation.labels) {
+      addLabel(label);
+      buffer.add(":");
     }
     buffer.add('while (true) {\n');
     indent++;
   }
 
   void endLoop(HBasicBlock block) {
     indent--;
     addIndentation();
     buffer.add('}\n');  // Close 'while' loop.
   }
@@ skipping 145 matching lines @@
   void endBailoutSwitch() {
     indent--; // Close 'case'.
     indent--;
     addIndentation();
     buffer.add('}\n');  // Close 'switch'.
   }
 
   // Adds a "$" in front of names of labels from the original source.
   // This avoids conflicts with labels introduced by bailouts, which
   // starts with a non-"$" character.
-  void addLabel(SourceString label) {
-    buffer.add("\$$label");
+  void addLabel(LabelElement label) {
+    buffer.add("\$${label.labelName}");
   }
 
   void beginLoop(HBasicBlock block) {
     // TODO(ngeoffray): Don't put labels on loops that don't bailout.
     String newLabel = pushLabel();
     if (block.hasBailouts()) {
       startBailoutCase(block.bailouts, const <HBailoutTarget>[]);
     }
 
     addIndentation();
-    for (SourceString label in block.loopInformation.labels) {
+    for (LabelElement label in block.loopInformation.labels) {
       addLabel(label);
       buffer.add(":");
     }
     buffer.add('$newLabel: while (true) {\n');
     indent++;
 
     if (block.hasBailouts()) {
       startBailoutSwitch();
     }
   }
@@ skipping 72 matching lines @@
       startBailoutSwitch();
     }
   }
 
   void endElse(HIf node) {
     if (node.elseBlock.hasBailouts()) {
       endBailoutSwitch();
     }
   }
 }