Save exception and stack trace variables in async catch clauses and use them

runtime/vm/flow_graph_builder.cc

 // 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.
 
 #include "vm/flow_graph_builder.h"
 
 #include "lib/invocation_mirror.h"
 #include "vm/ast_printer.h"
 #include "vm/bit_vector.h"
 #include "vm/class_finalizer.h"
@@ skipping 3982 matching lines @@
   // taken care of unchaining the context.
   if (nested_block.break_target() != NULL) {
     if (is_open()) Goto(nested_block.break_target());
     exit_ = nested_block.break_target();
   }
 }
 
 
 void EffectGraphVisitor::VisitCatchClauseNode(CatchClauseNode* node) {
   InlineBailout("EffectGraphVisitor::VisitCatchClauseNode (exception)");
-  // Restores current context from local variable ':saved_context'.
+  // Restores current context from local variable ':saved_try_context_var'.
   BuildRestoreContext(node->context_var());
 
   EffectGraphVisitor for_catch(owner());
   node->VisitChildren(&for_catch);
   Append(for_catch);
 }
 
 
 void EffectGraphVisitor::VisitTryCatchNode(TryCatchNode* node) {
   InlineBailout("EffectGraphVisitor::VisitTryCatchNode (exception)");
   intptr_t original_handler_index = owner()->try_index();
   const intptr_t try_handler_index = node->try_index();
   ASSERT(try_handler_index != original_handler_index);
   owner()->set_try_index(try_handler_index);
 
-  // Preserve current context into local variable '%saved_context'.
+  // Preserve current context into local variable ':saved_try_context_var'.
   BuildSaveContext(node->context_var());
 
   EffectGraphVisitor for_try(owner());
   node->try_block()->Visit(&for_try);
 
   if (for_try.is_open()) {
     JoinEntryInstr* after_try =
         new(I) JoinEntryInstr(owner()->AllocateBlockId(),
                               original_handler_index);
     for_try.Goto(after_try);
@@ skipping 20 matching lines @@
       : catch_block->catch_handler_index();
 
   const intptr_t prev_catch_try_index = owner()->catch_try_index();
 
   owner()->set_try_index(catch_handler_index);
   owner()->set_catch_try_index(try_handler_index);
   EffectGraphVisitor for_catch(owner());
   catch_block->Visit(&for_catch);
   owner()->set_catch_try_index(prev_catch_try_index);
 
-  // NOTE: The implicit variables ':saved_context', ':exception_var'
-  // and ':stacktrace_var' can never be captured variables.
+  // NOTE: The implicit variables ':saved_try_context_var', ':exception_var'
+  // and ':stack_trace_var' can never be captured variables.
   ASSERT(!catch_block->exception_var().is_captured());
   ASSERT(!catch_block->stacktrace_var().is_captured());

[Ivan Posva, 2015/02/24 20:52:39]

Why is the fact that ':saved_try_context_var' cannot be captures not asserted
here as well?

[regis, 2015/02/24 22:05:12]

No idea.
Assert added.

 
   CatchBlockEntryInstr* catch_entry =
       new(I) CatchBlockEntryInstr(owner()->AllocateBlockId(),
-                               catch_handler_index,
-                               catch_block->handler_types(),
-                               try_handler_index,
-                               catch_block->exception_var(),
-                               catch_block->stacktrace_var(),
-                               catch_block->needs_stacktrace());
+                                  catch_handler_index,
+                                  catch_block->handler_types(),
+                                  try_handler_index,
+                                  catch_block->exception_var(),
+                                  catch_block->stacktrace_var(),
+                                  catch_block->needs_stacktrace());
   owner()->AddCatchEntry(catch_entry);
   AppendFragment(catch_entry, for_catch);
 
   if (for_catch.is_open()) {
     JoinEntryInstr* join = new(I) JoinEntryInstr(owner()->AllocateBlockId(),
-                                              original_handler_index);
+                                                 original_handler_index);
     for_catch.Goto(join);
     if (is_open()) Goto(join);
     exit_ = join;
   }
 
   if (finally_block != NULL) {
     // Create a handler for the code in the catch block, containing the
     // code in the finally block.
     owner()->set_try_index(original_handler_index);
     EffectGraphVisitor for_finally(owner());
@@ skipping 11 matching lines @@
       for_finally.AddInstruction(
           new(I) ReThrowInstr(catch_block->token_pos(), catch_handler_index));
       for_finally.CloseFragment();
     }
     ASSERT(!for_finally.is_open());
 
     const Array& types = Array::ZoneHandle(I, Array::New(1, Heap::kOld));
     types.SetAt(0, Type::Handle(I, Type::DynamicType()));
     CatchBlockEntryInstr* finally_entry =
         new(I) CatchBlockEntryInstr(owner()->AllocateBlockId(),
-                                 original_handler_index,
-                                 types,
-                                 catch_handler_index,
-                                 catch_block->exception_var(),
-                                 catch_block->stacktrace_var(),
-                                 catch_block->needs_stacktrace());
+                                    original_handler_index,
+                                    types,
+                                    catch_handler_index,
+                                    catch_block->exception_var(),
+                                    catch_block->stacktrace_var(),
+                                    catch_block->needs_stacktrace());
     owner()->AddCatchEntry(finally_entry);
     AppendFragment(finally_entry, for_finally);
   }
 
   // Generate code for the finally block if one exists.
   if ((finally_block != NULL) && is_open()) {
     EffectGraphVisitor for_finally_block(owner());
     finally_block->Visit(&for_finally_block);
     Append(for_finally_block);
   }
@@ skipping 230 matching lines @@
   Report::MessageF(Report::kBailout,
                    Script::Handle(function.script()),
                    function.token_pos(),
                    "FlowGraphBuilder Bailout: %s %s",
                    String::Handle(function.name()).ToCString(),
                    reason);
   UNREACHABLE();
 }
 
 }  // namespace dart