VM: Fix checked mode crash (issue 13831).

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/code_descriptors.h"
 #include "vm/dart_entry.h"
 #include "vm/flags.h"
 #include "vm/flow_graph_compiler.h"
 #include "vm/il_printer.h"
 #include "vm/intermediate_language.h"
 #include "vm/longjump.h"
 #include "vm/object_store.h"
 #include "vm/os.h"
 #include "vm/parser.h"
 #include "vm/resolver.h"
 #include "vm/stack_frame.h"
 #include "vm/stub_code.h"
 #include "vm/symbols.h"
 
 namespace dart {
 
 DEFINE_FLAG(bool, eliminate_type_checks, true,
             "Eliminate type checks when allowed by static type analysis.");
 DEFINE_FLAG(bool, print_ast, false, "Print abstract syntax tree.");
+DEFINE_FLAG(bool, print_scopes, false, "Print scopes of local variables.");
 DEFINE_FLAG(bool, print_flow_graph, false, "Print the IR flow graph.");
 DEFINE_FLAG(bool, print_flow_graph_optimized, false,
             "Print the IR flow graph when optimizing.");
 DEFINE_FLAG(bool, trace_type_check_elimination, false,
             "Trace type check elimination at compile time.");
 DECLARE_FLAG(bool, enable_type_checks);
 
 
 FlowGraphBuilder::FlowGraphBuilder(ParsedFunction* parsed_function,
                                    const Array& ic_data_array,
@@ skipping 3759 matching lines @@
   AppendFragment(finally_entry, for_finally_block);
   exit_ = for_finally_block.exit_;
 }
 
 
 FlowGraph* FlowGraphBuilder::BuildGraph() {
   if (FLAG_print_ast) {
     // Print the function ast before IL generation.
     AstPrinter::PrintFunctionNodes(*parsed_function());
   }
+  if (FLAG_print_scopes) {
+    AstPrinter::PrintFunctionScope(*parsed_function());
+  }
   const Function& function = parsed_function()->function();
   TargetEntryInstr* normal_entry =
       new TargetEntryInstr(AllocateBlockId(),
                            CatchClauseNode::kInvalidTryIndex);
   graph_entry_ = new GraphEntryInstr(parsed_function(), normal_entry, osr_id_);
   EffectGraphVisitor for_effect(this, 0);
   // This check may be deleted if the generated code is leaf.
   // Native functions don't need a stack check at entry.
   if (!function.is_native()) {
     CheckStackOverflowInstr* check =
@@ skipping 37 matching lines @@
   intptr_t len = OS::SNPrint(NULL, 0, kFormat, function_name, reason) + 1;
   char* chars = Isolate::Current()->current_zone()->Alloc<char>(len);
   OS::SNPrint(chars, len, kFormat, function_name, reason);
   const Error& error = Error::Handle(
       LanguageError::New(String::Handle(String::New(chars))));
   Isolate::Current()->long_jump_base()->Jump(1, error);
 }
 
 
 }  // namespace dart