Some optimizations for packer.js.

src/runtime.cc

Index: src/runtime.cc
===================================================================
--- src/runtime.cc	(revision 3335)
+++ src/runtime.cc	(working copy)
@@ -2356,16 +2356,28 @@
   ASSERT(args.length() == 3);
 
   CONVERT_CHECKED(String, value, args[0]);
-  CONVERT_DOUBLE_CHECKED(from_number, args[1]);
-  CONVERT_DOUBLE_CHECKED(to_number, args[2]);
+  Object* from = args[1];
+  Object* to = args[2];
+  if (from->IsSmi() && to->IsSmi()) {

[Søren Thygesen Gjesse, 2009/11/19 21:42:57]

Maybe add a comment to this fast case.

+    int start = Smi::cast(from)->value();
+    int end = Smi::cast(to)->value();
 

[Søren Thygesen Gjesse, 2009/11/19 21:42:57]

Please move the declaration of start and end before the if and the following
four lines after the else block to avoid commin code in if and else block.

-  int start = FastD2I(from_number);
-  int end = FastD2I(to_number);
+    RUNTIME_ASSERT(end >= start);
+    RUNTIME_ASSERT(start >= 0);
+    RUNTIME_ASSERT(end <= value->length());
+    return value->SubString(start, end);
+  } else {
+    CONVERT_DOUBLE_CHECKED(from_number, from);
+    CONVERT_DOUBLE_CHECKED(to_number, to);
 
-  RUNTIME_ASSERT(end >= start);
-  RUNTIME_ASSERT(start >= 0);
-  RUNTIME_ASSERT(end <= value->length());
-  return value->SubString(start, end);
+    int start = FastD2I(from_number);
+    int end = FastD2I(to_number);
+
+    RUNTIME_ASSERT(end >= start);
+    RUNTIME_ASSERT(start >= 0);
+    RUNTIME_ASSERT(end <= value->length());
+    return value->SubString(start, end);
+  }
 }