Improve perfromance of integer parsing for Smi-s.

runtime/lib/integers.cc

 // Copyright (c) 2012, 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/bootstrap_natives.h"
 
 #include "vm/bigint_operations.h"
 #include "vm/dart_entry.h"
 #include "vm/exceptions.h"
 #include "vm/native_entry.h"
@@ skipping 165 matching lines @@
   if (FLAG_trace_intrinsified_natives) {
     OS::Print("Integer_equalToInteger %s == %s\n",
         left.ToCString(), right.ToCString());
   }
   return Bool::Get(left.CompareWith(right) == 0);
 }
 
 
 DEFINE_NATIVE_ENTRY(Integer_parse, 1) {
   GET_NON_NULL_NATIVE_ARGUMENT(String, value, arguments->NativeArgAt(0));
+  if (value.IsOneByteString()) {
+    // Quick conversion for unpadded integers in strings.
+    const intptr_t len = value.Length();
+    if (len > 0) {
+      const char* cstr = value.ToCString();
+      ASSERT(cstr != NULL);
+      // Dart differences from strtol:
+      // a) '+5' is not a valid integer (leading plus).
+      if (cstr[0] != '+') {
+        char* p_end = NULL;
+        const int64_t int_value = strtol(cstr, &p_end, 10);
+        if (p_end == (cstr + len)) {
+          if ((Smi::kMinValue <= int_value) && (int_value <= Smi::kMaxValue)) {
+            return Smi::New(int_value);
+          }
+        }
+      }
+    }
+  }
+
   Scanner scanner(value, Symbols::Empty());
   const Scanner::GrowableTokenStream& tokens = scanner.GetStream();
   String* int_string;
   bool is_positive;
   if (Scanner::IsValidLiteral(tokens,
                              Token::kINTEGER,
                              &is_positive,
                              &int_string)) {
     if (is_positive) {
       return Integer::New(*int_string);
@@ skipping 108 matching lines @@
 
 DEFINE_NATIVE_ENTRY(Bigint_bitNegate, 1) {
   const Bigint& value = Bigint::CheckedHandle(arguments->NativeArgAt(0));
   const Bigint& result = Bigint::Handle(BigintOperations::BitNot(value));
   ASSERT(CheckInteger(value));
   ASSERT(CheckInteger(result));
   return result.AsValidInteger();
 }
 
 }  // namespace dart