Detect leaf optimized methods and skip stack check overflow test in those, unless it is in a loop (…

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/code_descriptors.h"
 #include "vm/dart_entry.h"
@@ skipping 3365 matching lines @@
     // Print the function ast before IL generation.
     AstPrinter::PrintFunctionNodes(parsed_function());
   }
   // Compilation can be nested, preserve the computation-id.
   const Function& function = parsed_function().function();
   TargetEntryInstr* normal_entry =
       new TargetEntryInstr(AllocateBlockId(),
                            CatchClauseNode::kInvalidTryIndex);
   graph_entry_ = new GraphEntryInstr(parsed_function(), normal_entry);
   EffectGraphVisitor for_effect(this, 0);
-  // TODO(kmillikin): We can eliminate stack checks in some cases (e.g., the
-  // stack check on entry for leaf routines).
-  Instruction* check = new CheckStackOverflowInstr(function.token_pos());
+  // This check may be deleted if the generated code is leaf.
+  CheckStackOverflowInstr* check =
+      new CheckStackOverflowInstr(function.token_pos());
   // If we are inlining don't actually attach the stack check. We must still
   // create the stack check in order to allocate a deopt id.
   if (!IsInlining()) for_effect.AddInstruction(check);
   parsed_function().node_sequence()->Visit(&for_effect);
   AppendFragment(normal_entry, for_effect);
   // Check that the graph is properly terminated.
   ASSERT(!for_effect.is_open());
   FlowGraph* graph = new FlowGraph(*this, graph_entry_, last_used_block_id_);
   return graph;
 }
 
 
 void FlowGraphBuilder::Bailout(const char* reason) {
   const char* kFormat = "FlowGraphBuilder Bailout: %s %s";
   const char* function_name = parsed_function_.function().ToCString();
   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