[vm] Change TypedData_getUint64 native method to silently cast values

runtime/vm/object.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/object.h"
 
 #include "include/dart_api.h"
 #include "platform/assert.h"
 #include "vm/assembler.h"
 #include "vm/become.h"
@@ skipping 18137 matching lines @@
 
 RawInteger* Integer::New(int64_t value, Heap::Space space) {
   const bool is_smi = Smi::IsValid(value);
   if (is_smi) {
     return Smi::New(static_cast<intptr_t>(value));
   }
   return Mint::New(value, space);
 }
 
 RawInteger* Integer::NewFromUint64(uint64_t value, Heap::Space space) {
-  if (value > static_cast<uint64_t>(Mint::kMaxValue)) {
-    if (FLAG_limit_ints_to_64_bits) {
-      // Out of range.
-      return Integer::null();
-    } else {
-      return Bigint::NewFromUint64(value, space);
-    }
+  if (!FLAG_limit_ints_to_64_bits &&
+      (value > static_cast<uint64_t>(Mint::kMaxValue))) {
+    return Bigint::NewFromUint64(value, space);
   } else {

[zra, 2017/07/28 21:47:46]

The else is unnecessary.

[alexmarkov, 2017/07/28 23:09:29]

Done.

-    return Integer::New(value, space);
+    return Integer::New(static_cast<int64_t>(value), space);
   }
 }
 
+bool Integer::IsValidUint64(uint64_t value) {
+  if (FLAG_limit_ints_to_64_bits) {
+    return (value <= static_cast<uint64_t>(Mint::kMaxValue));
+  } else {

[zra, 2017/07/28 21:47:46]

ditto

[alexmarkov, 2017/07/28 23:09:29]

In this particular case I think 'else' adds readability: there are 2 distinct
implementations, and the active implementation is selected by a flag. There is
no preference between implementations, no fall-through or connection between
them. So I would prefer to treat them evenly, without placing one of them into
'if' and another after 'if'.

+    return true;
+  }
+}
+
 bool Integer::Equals(const Instance& other) const {
   // Integer is an abstract class.
   UNREACHABLE();
   return false;
 }
 
 bool Integer::IsZero() const {
   // Integer is an abstract class.
   UNREACHABLE();
   return false;
@@ skipping 4353 matching lines @@
   }
   return UserTag::null();
 }
 
 const char* UserTag::ToCString() const {
   const String& tag_label = String::Handle(label());
   return tag_label.ToCString();
 }
 
 }  // namespace dart