Enable causal stacktrace in kernel

pkg/kernel/lib/transformations/continuation.dart

Index: pkg/kernel/lib/transformations/continuation.dart
diff --git a/pkg/kernel/lib/transformations/continuation.dart b/pkg/kernel/lib/transformations/continuation.dart
index 112ea43b8274b3f3e182cc2e99039834e589fcb6..da9430c168d37461a7e13dbd801cb5a534ff5d18 100644
--- a/pkg/kernel/lib/transformations/continuation.dart
+++ b/pkg/kernel/lib/transformations/continuation.dart
@@ -146,6 +146,7 @@ class SyncStarFunctionRewriter extends ContinuationRewriterBase {
       ..addAll(variableDeclarations())
       ..addAll([closureFunction, returnStatement]));
     enclosingFunction.body.parent = enclosingFunction;
+    enclosingFunction.originalAsyncMarker = enclosingFunction.asyncMarker;
     enclosingFunction.asyncMarker = AsyncMarker.Sync;
     return enclosingFunction;
   }
@@ -198,6 +199,8 @@ abstract class AsyncRewriterBase extends ContinuationRewriterBase {
       new VariableDeclaration(":async_op_then");
   final VariableDeclaration catchErrorContinuationVariable =
       new VariableDeclaration(":async_op_error");
+  final VariableDeclaration asyncStackTrace =
+      new VariableDeclaration(":async_stack_trace");
 
   LabeledStatement labeledBody;
 
@@ -215,6 +218,9 @@ abstract class AsyncRewriterBase extends ContinuationRewriterBase {
     // var :async_op_error;
     statements.add(catchErrorContinuationVariable);
 
+    // var :async_stack_trace;
+    statements.add(asyncStackTrace);
+
     // :async_op([:result, :exception, :stack_trace]) {
     //     modified <node.body>;
     // }
@@ -258,6 +264,13 @@ abstract class AsyncRewriterBase extends ContinuationRewriterBase {
         new VariableSet(
             catchErrorContinuationVariable, boundCatchErrorClosure));
     statements.add(catchErrorClosureVariableAssign);
+
+    // :async_stack_trace = _asyncStackTraceHelper();
+    final boundAsyncStackTrace = new StaticInvocation(
+        helper.asyncStackTraceHelper, new Arguments.empty());
+    final asyncStackTraceVariableAssign = new ExpressionStatement(
+        new VariableSet(asyncStackTrace, boundAsyncStackTrace));
+    statements.add(asyncStackTraceVariableAssign);

[kustermann, 2017/02/22 11:08:25]

We could actually just create the variable here and make this call in C++ (under
the FLAG_...).

Otherwise we might regress performance compared to the old VM pipeline if the
FLAG_... is not set.

[jensj, 2017/02/23 09:40:26]

Attempt made.

   }
 
   Statement buildWrappedBody() {
@@ -698,6 +711,7 @@ class AsyncStarFunctionRewriter extends AsyncRewriterBase {
 
     enclosingFunction.body = new Block(statements);
     enclosingFunction.body.parent = enclosingFunction;
+    enclosingFunction.originalAsyncMarker = enclosingFunction.asyncMarker;
     enclosingFunction.asyncMarker = AsyncMarker.Sync;
     return enclosingFunction;
   }
@@ -820,8 +834,8 @@ class AsyncFunctionRewriter extends AsyncRewriterBase {
 
     enclosingFunction.body = new Block(statements);
     enclosingFunction.body.parent = enclosingFunction;
+    enclosingFunction.originalAsyncMarker = enclosingFunction.asyncMarker;
     enclosingFunction.asyncMarker = AsyncMarker.Sync;
-    enclosingFunction.debuggable = false;
     return enclosingFunction;
   }
 
@@ -874,6 +888,7 @@ class HelperNodes {
   final Constructor streamIteratorConstructor;
   final Procedure asyncThenWrapper;
   final Procedure asyncErrorWrapper;
+  final Procedure asyncStackTraceHelper;
   final Procedure awaitHelper;
   final CoreTypes coreTypes;
 
@@ -891,6 +906,7 @@ class HelperNodes {
       this.streamControllerConstructor,
       this.asyncThenWrapper,
       this.asyncErrorWrapper,
+      this.asyncStackTraceHelper,
       this.awaitHelper,
       this.coreTypes);
 
@@ -973,6 +989,7 @@ class HelperNodes {
         findConstructor(streamControllerClass, ''),
         findProcedure(asyncLibrary, '_asyncThenWrapperHelper'),
         findProcedure(asyncLibrary, '_asyncErrorWrapperHelper'),
+        findProcedure(asyncLibrary, '_asyncStackTraceHelper'),
         findProcedure(asyncLibrary, '_awaitHelper'),
         new CoreTypes(program));
   }