Enable causal stacktrace in kernel

runtime/vm/kernel_to_il.cc

Index: runtime/vm/kernel_to_il.cc
diff --git a/runtime/vm/kernel_to_il.cc b/runtime/vm/kernel_to_il.cc
index 942a70f5e26ad0f46503d782cda6fcf3f37cdfd8..0b27355e6682c4cecce65cbf15b57540084fce94 100644
--- a/runtime/vm/kernel_to_il.cc
+++ b/runtime/vm/kernel_to_il.cc
@@ -720,6 +720,13 @@ void ScopeBuilder::VisitFunctionNode(FunctionNode* node) {
         scope_->CaptureVariable(temp);
       }
     }
+    if (FLAG_causal_async_stacks) {
+      LocalVariable* temp =
+          scope_->LookupVariable(Symbols::AsyncStackTraceVar(), true);
+      if (temp != NULL) {
+        scope_->CaptureVariable(temp);
+      }
+    }
   }
 }
 
@@ -2556,6 +2563,17 @@ Fragment FlowGraphBuilder::Return(TokenPosition position) {
         new (Z) DebugStepCheckInstr(position, RawPcDescriptors::kRuntimeCall);
   }
 
+  if (FLAG_causal_async_stacks &&
+      (function.IsAsyncClosure() || function.IsAsyncGenClosure())) {
+    // We are returning from an asynchronous closure. Before we do that, be
+    // sure to clear the thread's asynchronous stack trace.
+    const Function& target = Function::ZoneHandle(
+        Z, I->object_store()->async_clear_thread_stack_trace());
+    ASSERT(!target.IsNull());
+    instructions += StaticCall(TokenPosition::kNoSource, target, 0);
+    instructions += Drop();
+  }
+
   ReturnInstr* return_instr = new (Z) ReturnInstr(position, value);
   if (exit_collector_ != NULL) exit_collector_->AddExit(return_instr);
 
@@ -3172,7 +3190,7 @@ FlowGraph* FlowGraphBuilder::BuildGraphOfFunction(FunctionNode* function,
     // The code we are building will be executed right after we enter
     // the function and before any nested contexts are allocated.
     // Reset current context_depth_ to match this.
-    intptr_t current_context_depth = context_depth_;
+    const intptr_t current_context_depth = context_depth_;
     context_depth_ = scopes_->yield_jump_variable->owner()->context_level();
 
     // Prepend an entry corresponding to normal entry to the function.
@@ -3238,6 +3256,37 @@ FlowGraph* FlowGraphBuilder::BuildGraphOfFunction(FunctionNode* function,
     context_depth_ = current_context_depth;
   }
 
+  if (FLAG_causal_async_stacks &&
+      (dart_function.IsAsyncClosure() || dart_function.IsAsyncGenClosure())) {
+    // The code we are building will be executed right after we enter
+    // the function and before any nested contexts are allocated.
+    // Reset current context_depth_ to match this.
+    const intptr_t current_context_depth = context_depth_;
+    context_depth_ = scopes_->yield_jump_variable->owner()->context_level();
+
+    Fragment instructions;
+    LocalScope* scope = parsed_function_->node_sequence()->scope();
+
+    const Function& target = Function::ZoneHandle(
+        Z, I->object_store()->async_set_thread_stack_trace());
+    ASSERT(!target.IsNull());
+
+    // Fetch and load :async_stack_trace
+    LocalVariable* async_stack_trace_var =
+        scope->LookupVariable(Symbols::AsyncStackTraceVar(), false);
+    ASSERT((async_stack_trace_var != NULL) &&
+           async_stack_trace_var->is_captured());
+    instructions += LoadLocal(async_stack_trace_var);
+    instructions += PushArgument();
+
+    // Call _asyncSetThreadStackTrace
+    instructions += StaticCall(TokenPosition::kNoSource, target, 1);
+    instructions += Drop();
+
+    body = instructions + body;
+    context_depth_ = current_context_depth;
+  }
+
   if (FLAG_support_debugger && function->position().IsDebugPause() &&
       !dart_function.is_native() && dart_function.is_debuggable()) {
     // If a switch was added above: Start the switch by injecting a debugable
@@ -6103,6 +6152,7 @@ Fragment FlowGraphBuilder::TranslateFunctionNode(FunctionNode* node,
   // The VM has a per-isolate table of functions indexed by the enclosing
   // function and token position.
   Function& function = Function::ZoneHandle(Z);
+  LocalScope* scope = NULL;
   for (intptr_t i = 0; i < scopes_->function_scopes.length(); ++i) {
     if (scopes_->function_scopes[i].function != node) continue;
 
@@ -6119,6 +6169,7 @@ Fragment FlowGraphBuilder::TranslateFunctionNode(FunctionNode* node,
 
     // NOTE: This is not TokenPosition in the general sense!
     function = I->LookupClosureFunction(parsed_function_->function(), position);
+    scope = scopes_->function_scopes[i].scope;
     if (function.IsNull()) {
       const dart::String* name;
       if (parent->IsFunctionExpression()) {
@@ -6152,7 +6203,6 @@ Fragment FlowGraphBuilder::TranslateFunctionNode(FunctionNode* node,
                                      FunctionNode::kSyncYielding);
 
       function.set_end_token_pos(node->end_position());
-      LocalScope* scope = scopes_->function_scopes[i].scope;
       const ContextScope& context_scope =
           ContextScope::Handle(Z, scope->PreserveOuterScope(context_depth_));
       function.set_context_scope(context_scope);
@@ -6172,10 +6222,29 @@ Fragment FlowGraphBuilder::TranslateFunctionNode(FunctionNode* node,
     break;
   }
 
+  Fragment instructions;
+
+  if (FLAG_causal_async_stacks &&

[kustermann, 2017/02/23 10:30:37]

You can move this code to FlowGraphBuilder::BuildGraphOfFunction

if (dart_function.hasOriginalAysncMarker()) {
  // call async helper
  // store in :async_stack var.
}

+      (function.IsAsyncClosure() || function.IsAsyncGenClosure())) {
+    // :async_stack_trace = _asyncStackTraceHelper();
+    const dart::Library& async_lib =
+        dart::Library::Handle(dart::Library::AsyncLibrary());
+    const Function& target = Function::ZoneHandle(
+        Z,
+        async_lib.LookupFunctionAllowPrivate(Symbols::AsyncStackTraceHelper()));
+    ASSERT(!target.IsNull());
+    instructions += StaticCall(TokenPosition::kNoSource, target, 0);
+    LocalVariable* async_stack_trace_var =
+        scope->LookupVariable(Symbols::AsyncStackTraceVar(), false);
+    ASSERT(async_stack_trace_var != NULL);
+    instructions += StoreLocal(TokenPosition::kNoSource, async_stack_trace_var);
+    instructions += Drop();
+  }
+
   const dart::Class& closure_class =
       dart::Class::ZoneHandle(Z, I->object_store()->closure_class());
   ASSERT(!closure_class.IsNull());
-  Fragment instructions = AllocateObject(closure_class, function);
+  instructions += AllocateObject(closure_class, function);
   LocalVariable* closure = MakeTemporary();
 
   // TODO(27590): Generic closures need type arguments.