Continue for simple loops (while/for).

frog/leg/ssa/codegen.dart

Index: frog/leg/ssa/codegen.dart
diff --git a/frog/leg/ssa/codegen.dart b/frog/leg/ssa/codegen.dart
index 957f323e3b23d09d2cf2a6b85a1e072f17fd657f..d089e1612fde49d4bfae17a1c7b57bc3425b53d3 100644
--- a/frog/leg/ssa/codegen.dart
+++ b/frog/leg/ssa/codegen.dart
@@ -247,14 +247,22 @@ class SsaCodeGenerator implements HVisitor {
   void handleLabeledBlock(HLabeledBlockInformation labeledBlockInfo) {
     addIndentation();
     for (LabelElement label in labeledBlockInfo.labels) {
-      addLabel(label);
+      if (labeledBlockInfo.isContinue) {
+        addContinueLabel(label);
+      } else {
+        addBreakLabel(label);
+      }
       buffer.add(':');
     }

[ngeoffray, 2012/03/19 11:42:06]

Shouldn't you do: if !(labeledBlockInfo.labels.isEmpty()) ?

[Lasse Reichstein Nielsen, 2012/03/19 12:13:58]

It's never empty, so no.

     TargetElement target = labeledBlockInfo.target;
     if (target.isSwitch) {
-      addImplicitLabel(target);
+      addImplicitBreakLabel(target);
       buffer.add(@':');
     }
+    if (labeledBlockInfo.isContinue) {
+      addImplicitContinueLabel(target);
+      buffer.add(':');
+    }
     buffer.add('{\n');
     indent++;
 
@@ -433,15 +441,24 @@ class SsaCodeGenerator implements HVisitor {
   }
 
   // Used to write the name of labels.
-  // The default implementation uses the unmodified Dart label name.
-  // Specializations might change this.
-  void addLabel(LabelElement label) {
+  void addBreakLabel(LabelElement label) {
     buffer.add(@'$');
     buffer.add(label.labelName);
   }
 
-  void addImplicitLabel(TargetElement target) {
-    buffer.add('\$${target.nestingLevel}');
+  void addContinueLabel(LabelElement label) {
+    buffer.add(@'c$');
+    buffer.add(label.labelName);
+  }
+
+  void addImplicitBreakLabel(TargetElement target) {
+    buffer.add(@'$');
+    buffer.add('${target.nestingLevel}');
+  }
+
+  void addImplicitContinueLabel(TargetElement target) {
+    buffer.add(@'c$');
+    buffer.add('${target.nestingLevel}');
   }
 
   visitBreak(HBreak node) {
@@ -450,15 +467,33 @@ class SsaCodeGenerator implements HVisitor {
     buffer.add("break");
     if (node.label !== null) {
       buffer.add(" ");
-      addLabel(node.label);
+      addBreakLabel(node.label);
     } else {
       TargetElement target = node.target;
       if (target.isSwitch) {

[ngeoffray, 2012/03/19 11:42:06]

Please add a comment that since we're generating switch as a loop, we must break
from that loop.

[Lasse Reichstein Nielsen, 2012/03/19 12:13:58]

Done.

         buffer.add(@' ');
-        addImplicitLabel(target);
+        addImplicitBreakLabel(target);
       }
     }
     buffer.add(";\n");
+  }
+
+  visitContinue(HContinue node) {
+    assert(currentBlock.successors.length == 1);
+    // No block finishing with a 'break' can have more than

[ngeoffray, 2012/03/19 11:42:06]

break -> continue

+    // one dominated block (since it has only one successor).

[ngeoffray, 2012/03/19 11:42:06]

more than one -> a ? You're checking that dominatedBlock.isEmpty.

+    // If the successor is dominated by another block, then the other block
+    // is responsible for visiting the successor.
+    assert(currentBlock.dominatedBlocks.isEmpty());
+    // Otherwise we would have bailed out in the builder.

[ngeoffray, 2012/03/19 11:42:06]

Should that comment be one line above?

[Lasse Reichstein Nielsen, 2012/03/19 12:13:58]

These comments should all go away, just as they did for break in the "switch"
CL.

+    addIndentation();
+    buffer.add("break ");

[ngeoffray, 2012/03/19 11:42:06]

Please add a comment on why this isn't 'continue'.

[Lasse Reichstein Nielsen, 2012/03/19 12:13:58]

Done.

+    if (node.label !== null) {
+      addContinueLabel(node.label);
+    } else {
+      addImplicitContinueLabel(node.target);
+    }
+    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.
@@ -1179,7 +1214,7 @@ class SsaOptimizedCodeGenerator extends SsaCodeGenerator {
   void beginLoop(HBasicBlock block) {
     addIndentation();
     for (LabelElement label in block.loopInformation.labels) {
-      addLabel(label);
+      addBreakLabel(label);

[ngeoffray, 2012/03/19 11:42:06]

What about continue labels here?

[Lasse Reichstein Nielsen, 2012/03/19 12:13:58]

Continue labels are put as labels on a block surrounding the body, so that we
can break the body to reach the update block.

       buffer.add(":");
     }
     buffer.add('while (true) {\n');
@@ -1343,12 +1378,6 @@ class SsaUnoptimizedCodeGenerator extends SsaCodeGenerator {
     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(LabelElement label) {
-    buffer.add("\$${label.labelName}");
-  }
 
   void beginLoop(HBasicBlock block) {
     // TODO(ngeoffray): Don't put labels on loops that don't bailout.
@@ -1358,8 +1387,8 @@ class SsaUnoptimizedCodeGenerator extends SsaCodeGenerator {
     }
 
     addIndentation();
-    for (LabelElement label in block.loopInformation.labels) {
-      addLabel(label);
+    for (SourceString label in block.loopInformation.labels) {
+      addBreakLabel(label);
       buffer.add(":");
     }
     buffer.add('$newLabel: while (true) {\n');