Fix issue 1950:

vm/flags.cc

Index: vm/flags.cc
===================================================================
--- vm/flags.cc	(revision 5257)
+++ vm/flags.cc	(working copy)
@@ -24,12 +24,16 @@
     kBoolean,
     kInteger,
     kString,
+    kFunc,
     kNumFlagTypes
   };
 
   Flag(const char* name, const char* comment, void* addr, FlagType type)
       : name_(name), comment_(comment), addr_(addr), type_(type) {
   }
+  Flag(const char* name, const char* comment, FlagHandler handler)
+      : name_(name), comment_(comment), handler_(handler), type_(kFunc) {
+  }
 
   void Print() {
     if (IsUnrecognized()) {
@@ -54,6 +58,10 @@
         }
         break;
       }
+      case kFunc: {
+        // No value to print here.

[regis, 2012/03/09 23:16:03]

You could maybe print the name of the flag.

[Ivan Posva, 2012/03/09 23:20:37]

Done.

+        break;
+      }
       default:
         UNREACHABLE();
         break;
@@ -72,6 +80,7 @@
     bool* bool_ptr_;
     int* int_ptr_;
     charp* charp_ptr_;
+    FlagHandler handler_;
   };
   FlagType type_;
 };
@@ -129,6 +138,17 @@
 }
 
 
+bool Flags::Register_func(FlagHandler handler,
+                          const char* name,
+                          const char* comment) {
+  ASSERT(Lookup(name) == NULL);
+  Flag* flag = new Flag(name, comment, handler);
+  flag->next_ = Flags::flags_;
+  Flags::flags_ = flag;
+  return false;
+}
+
+
 static void Normalize(char* s) {
   intptr_t len = strlen(s);
   for (intptr_t i = 0; i < len; i++) {
@@ -206,6 +226,16 @@
           }
           break;
         }
+        case Flag::kFunc: {
+          if (strcmp(argument, "true") == 0) {
+            (flag->handler_)(true);
+          } else if (strcmp(argument, "false") == 0) {
+            (flag->handler_)(false);
+          } else {
+            OS::Print("Ignoring flag: %s is a bool flag.\n", name);
+          }
+          break;
+        }
         default: {
           UNREACHABLE();
           break;