Option to truncate integers to 64 bits, part 2

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 "include/dart_api.h"
 #include "vm/dart_api_impl.h"
 #include "vm/dart_entry.h"
 #include "vm/exceptions.h"
 #include "vm/isolate.h"
 #include "vm/native_entry.h"
 #include "vm/object.h"
 #include "vm/object_store.h"
 #include "vm/symbols.h"
 
 namespace dart {
 
 DEFINE_FLAG(bool,
             trace_intrinsified_natives,
             false,
             "Report if any of the intrinsified natives are called");
 
 // Smi natives.
 
 // Returns false if integer is in wrong representation, e.g., as is a Bigint
 // when it could have been a Smi.
 static bool CheckInteger(const Integer& i) {
   if (i.IsBigint()) {
-    ASSERT(!FLAG_limit_ints_to_64_bits);
+    ASSERT(!Bigint::IsDisabled());
     const Bigint& bigint = Bigint::Cast(i);
     return !bigint.FitsIntoSmi() && !bigint.FitsIntoInt64();
   }

[siva, 2017/07/14 20:53:29]

When --limit-ints-to-64-bits mode is specified i.IsBigint() should always be
false right.

I am wondering if we will be eliminating some code from the VM if we used
if (!FLAG_limit_ints_to_64_bits) {
} else {
  ....
}
when the flag becomes a const with a value of true.

In other words I am asking if there is a plan in future CLs to completely remove
the BigInt stuff from the executable when the flag FLAG_limit_ints_to_64_bits is
specified.

   if (i.IsMint()) {
     const Mint& mint = Mint::Cast(i);
     return !Smi::IsValid(mint.value());
   }
   return true;
 }
 
 DEFINE_NATIVE_ENTRY(Integer_bitAndFromInteger, 2) {
   const Integer& right = Integer::CheckedHandle(arguments->NativeArgAt(0));
   GET_NON_NULL_NATIVE_ARGUMENT(Integer, left, arguments->NativeArgAt(1));
@@ skipping 221 matching lines @@
         }
       case Token::kSHR:
         shift_count = Utils::Minimum(shift_count, Mint::kBits);
         return Integer::New(mint_value >> shift_count, Heap::kNew);
       default:
         UNIMPLEMENTED();
     }
   } else {
     ASSERT(value.IsBigint());
   }
-  ASSERT(!FLAG_limit_ints_to_64_bits);
+  ASSERT(!Bigint::IsDisabled());
   return Integer::null();
 }
 
 DEFINE_NATIVE_ENTRY(Smi_bitAndFromSmi, 2) {
   const Smi& left = Smi::CheckedHandle(arguments->NativeArgAt(0));
   GET_NON_NULL_NATIVE_ARGUMENT(Smi, right, arguments->NativeArgAt(1));
   if (FLAG_trace_intrinsified_natives) {
     OS::Print("Smi_bitAndFromSmi %s & %s\n", left.ToCString(),
               right.ToCString());
   }
@@ skipping 94 matching lines @@
   const Bigint& bigint = Bigint::CheckedHandle(arguments->NativeArgAt(0));
   return bigint.used();
 }
 
 DEFINE_NATIVE_ENTRY(Bigint_getDigits, 1) {
   const Bigint& bigint = Bigint::CheckedHandle(arguments->NativeArgAt(0));
   return bigint.digits();
 }
 
 DEFINE_NATIVE_ENTRY(Bigint_allocate, 4) {
-  // TODO(alexmarkov): Revise this assertion if this native method can be used
-  // to explicitly allocate Bigint objects in --limit-ints-to-64-bits mode.
-  ASSERT(!FLAG_limit_ints_to_64_bits);
+  ASSERT(!Bigint::IsDisabled());
   // First arg is null type arguments, since class Bigint is not parameterized.
   const Bool& neg = Bool::CheckedHandle(arguments->NativeArgAt(1));
   const Smi& used = Smi::CheckedHandle(arguments->NativeArgAt(2));
   const TypedData& digits = TypedData::CheckedHandle(arguments->NativeArgAt(3));
   ASSERT(!digits.IsNull());
   return Bigint::New(neg.value(), used.Value(), digits);
 }
 
 }  // namespace dart