Initial design for background compilation

runtime/vm/flow_graph_compiler.cc

 // Copyright (c) 2013, 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/globals.h"  // Needed here to get TARGET_ARCH_XXX.
 
 #include "vm/flow_graph_compiler.h"
 
 #include "vm/bit_vector.h"
 #include "vm/cha.h"
@@ skipping 28 matching lines @@
 DEFINE_FLAG(int, optimization_counter_scale, 2000,
     "The scale of invocation count, by size of the function.");
 DEFINE_FLAG(bool, polymorphic_with_deopt, true,
     "Polymorphic calls can be generated so that failure either causes "
     "deoptimization or falls through to a megamorphic call");
 DEFINE_FLAG(bool, source_lines, false, "Emit source line as assembly comment.");
 DEFINE_FLAG(bool, trace_inlining_intervals, false,
     "Inlining interval diagnostics");
 DEFINE_FLAG(bool, use_megamorphic_stub, true, "Out of line megamorphic lookup");
 
+DECLARE_FLAG(bool, background_compilation);
 DECLARE_FLAG(bool, code_comments);
 DECLARE_FLAG(bool, deoptimize_alot);
 DECLARE_FLAG(int, deoptimize_every);
 DECLARE_FLAG(charp, deoptimize_filter);
 DECLARE_FLAG(bool, disassemble);
 DECLARE_FLAG(bool, disassemble_optimized);
 DECLARE_FLAG(bool, emit_edge_counters);
 DECLARE_FLAG(bool, fields_may_be_reset);
 DECLARE_FLAG(bool, guess_other_cid);
 DECLARE_FLAG(bool, ic_range_profiling);
@@ skipping 48 matching lines @@
     // since it is done at places where no pool pointer is loaded.
     FLAG_print_stop_message = false;
 
     FLAG_lazy_dispatchers = false;
     FLAG_interpret_irregexp = true;
     FLAG_enable_mirrors = false;
     FLAG_precompile_collect_closures = true;
     FLAG_link_natives_lazily = true;
     FLAG_fields_may_be_reset = true;
     FLAG_allow_absolute_addresses = false;
+
+    // Background compilation relies on two-stage compilation pipeline,
+    // while precompilation has only one.
+    FLAG_background_compilation = false;
   }
 }
 
 
 DEFINE_FLAG_HANDLER(PrecompilationModeHandler,
                     precompilation,
                     "Precompilation mode");
 
 
 // Assign locations to incoming arguments, i.e., values pushed above spill slots
@@ skipping 1708 matching lines @@
 
 
 void FlowGraphCompiler::FrameStateClear() {
   ASSERT(!is_optimizing());
   frame_state_.TruncateTo(0);
 }
 #endif
 
 
 }  // namespace dart