Fast string construct stub (ia32 only for now).

src/ia32/macro-assembler-ia32.cc

Index: src/ia32/macro-assembler-ia32.cc
diff --git a/src/ia32/macro-assembler-ia32.cc b/src/ia32/macro-assembler-ia32.cc
index 79b40641b29783a33519765555f59cbd2f5acf3c..ff48d54f15096b3bc488c69850493f0977fc815d 100644
--- a/src/ia32/macro-assembler-ia32.cc
+++ b/src/ia32/macro-assembler-ia32.cc
@@ -1369,6 +1369,30 @@ void MacroAssembler::LoadContext(Register dst, int context_chain_length) {
 }
 
 
+void MacroAssembler::LoadGlobalFunction(int index, Register function) {
+  // Load the global or builtins object from the current context.
+  mov(function, Operand(esi, Context::SlotOffset(Context::GLOBAL_INDEX)));
+  // Load the global context from the global or builtins object.
+  mov(function, FieldOperand(function, GlobalObject::kGlobalContextOffset));
+  // Load the function from the global context.
+  mov(function, Operand(function, Context::SlotOffset(index)));
+}
+
+
+void MacroAssembler::LoadGlobalFunctionInitialMap(Register function,
+                                                  Register map) {
+  // Load the initial map.  The global functions all have initial maps.
+  mov(map, FieldOperand(function, JSFunction::kPrototypeOrInitialMapOffset));
+  if (FLAG_debug_code) {
+    Label ok, fail;
+    CheckMap(map, Factory::meta_map(), &fail, false);
+    jmp(&ok);
+    bind(&fail);
+    Abort("Global functions must have initial map");
+    bind(&ok);
+  }
+}
+
 
 void MacroAssembler::Ret() {
   ret(0);