Adds a flag to the standalone vm to throw an exception on 53-bit integer overflow.

runtime/vm/object.cc

Index: runtime/vm/object.cc
===================================================================
--- runtime/vm/object.cc	(revision 23187)
+++ runtime/vm/object.cc	(working copy)
@@ -50,6 +50,8 @@
     "Huge method cutoff in tokens: Disables optimizations for huge methods.");
 DEFINE_FLAG(int, huge_method_cutoff_in_code_size, 200000,
     "Huge method cutoff in unoptimized code size (in bytes).");
+DEFINE_FLAG(bool, throw_on_javascript_int_overflow, false,
+    "Throw an exception when integer arithmetic exceeds 53 bits.");
 DECLARE_FLAG(bool, trace_compiler);
 DECLARE_FLAG(bool, eliminate_type_checks);
 DECLARE_FLAG(bool, enable_type_checks);
@@ -10438,16 +10440,30 @@
 }
 
 
+// Throw FiftyThreeBitOverflow exception.
+static void ThrowFiftyThreeBitOverflow() {
+  const Array& exc_args = Array::Handle(Array::New(0));
+  Exceptions::ThrowByType(Exceptions::kFiftyThreeBitOverflowError, exc_args);
+  return;

[srdjan, 2013/05/28 10:57:14]

remove return.

[zra, 2013/05/28 17:06:39]

Done.

+}
+
+
 RawInteger* Integer::New(int64_t value, Heap::Space space) {
   if ((value <= Smi::kMaxValue) && (value >= Smi::kMinValue)) {
     return Smi::New(value);
   }
+  if (FLAG_throw_on_javascript_int_overflow && !Utils::IsInt(53, value)) {
+    ThrowFiftyThreeBitOverflow();
+  }
   return Mint::New(value, space);
 }
 
 
 RawInteger* Integer::NewFromUint64(uint64_t value, Heap::Space space) {
   if (value > static_cast<uint64_t>(Mint::kMaxValue)) {
+    if (FLAG_throw_on_javascript_int_overflow) {
+      ThrowFiftyThreeBitOverflow();
+    }
     return BigintOperations::NewFromUint64(value);
   } else {
     return Integer::New(value);
@@ -10473,7 +10489,33 @@
 }
 
 
+static void CheckFiftyThreeBitOverflow(const Integer &i) {

[srdjan, 2013/05/28 10:57:14]

Optional: The code would be simpler if you have ThrowFifty... only once and use
if (Util::IsInt (...)) return;

[zra, 2013/05/28 17:06:39]

I gave this a shot. Please let me know if it looks like it could be simplified
further.

+  if (i.IsSmi()) return;
+  if (i.IsMint()) {
+    Mint& mint = Mint::Handle();
+    mint ^= i.raw();
+    if (!Utils::IsInt(53, mint.value())) {
+      ThrowFiftyThreeBitOverflow();
+    }
+    return;
+  }
+  ASSERT(i.IsBigint());
+  Bigint& big_value = Bigint::Handle();
+  big_value ^= i.raw();
+  if (BigintOperations::FitsIntoInt64(big_value)) {
+    if (!Utils::IsInt(53, BigintOperations::ToInt64(big_value))) {
+      ThrowFiftyThreeBitOverflow();
+    }
+  } else {
+    ThrowFiftyThreeBitOverflow();
+  }
+}
+
+
 RawInteger* Integer::AsValidInteger() const {
+  if (FLAG_throw_on_javascript_int_overflow) {
+    CheckFiftyThreeBitOverflow(*this);
+  }
   if (IsSmi()) return raw();
   if (IsMint()) {
     Mint& mint = Mint::Handle();