VM: Separate precompilation-specific code, make flags const.

runtime/vm/flow_graph_compiler.cc

Index: runtime/vm/flow_graph_compiler.cc
diff --git a/runtime/vm/flow_graph_compiler.cc b/runtime/vm/flow_graph_compiler.cc
index ef109ac8a8f4243658a862594c9ef8d017f26950..60e144b31ba0763997796b0f91f93c077ee54586 100644
--- a/runtime/vm/flow_graph_compiler.cc
+++ b/runtime/vm/flow_graph_compiler.cc
@@ -13,6 +13,7 @@
 #include "vm/debugger.h"
 #include "vm/deopt_instructions.h"
 #include "vm/exceptions.h"
+#include "vm/flags.h"
 #include "vm/flow_graph_allocator.h"
 #include "vm/il_printer.h"
 #include "vm/intrinsifier.h"
@@ -68,7 +69,6 @@ DECLARE_FLAG(bool, use_field_guards);
 DECLARE_FLAG(bool, use_cha_deopt);
 DECLARE_FLAG(bool, use_osr);
 DECLARE_FLAG(bool, print_stop_message);
-DECLARE_FLAG(bool, lazy_dispatchers);
 DECLARE_FLAG(bool, interpret_irregexp);
 DECLARE_FLAG(bool, enable_mirrors);
 DECLARE_FLAG(bool, link_natives_lazily);
@@ -111,7 +111,6 @@ static void PrecompilationModeHandler(bool value) {
     // 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_link_natives_lazily = true;
@@ -136,6 +135,11 @@ static void PrecompilationModeHandler(bool value) {
     // while precompilation has only one.
     FLAG_background_compilation = false;
     FLAG_collect_dynamic_function_names = true;
+#if !defined(DART_PRECOMPILED_RUNTIME)
+    FLAG_lazy_dispatchers = false;
+#else
+    ASSERT(!FLAG_lazy_dispatchers);

[rmacnak, 2016/02/19 00:54:31]

COMPILE_ASSERT ?

[Florian Schneider, 2016/02/19 17:42:29]

Done.

+#endif
   }
 }