Fix for running with --throw_on_javascript_int_overflow: recognize pattern (a << b) & mask and test…

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 205 matching lines @@
     return Integer::New(temp);
   }
 
   const Array& args = Array::Handle(Array::New(1));
   args.SetAt(0, value);
   Exceptions::ThrowByType(Exceptions::kFormat, args);
   return Object::null();
 }
 
 
+// Passing true for 'silent' prevents throwing JavascriptIntegerOverflow.
 static RawInteger* ShiftOperationHelper(Token::Kind kind,
                                         const Integer& value,
-                                        const Smi& amount) {
+                                        const Smi& amount,
+                                        const bool silent = false) {
   if (amount.Value() < 0) {
     const Array& args = Array::Handle(Array::New(1));
     args.SetAt(0, amount);
     Exceptions::ThrowByType(Exceptions::kArgument, args);
   }
   if (value.IsSmi()) {
     const Smi& smi_value = Smi::Cast(value);
-    return smi_value.ShiftOp(kind, amount);
+    return smi_value.ShiftOp(kind, amount, silent);
   }
   Bigint& big_value = Bigint::Handle();
   if (value.IsMint()) {
     const int64_t mint_value = value.AsInt64Value();
     const int count = Utils::HighestBit(mint_value);
     if ((count + amount.Value()) < Mint::kBits) {
       switch (kind) {
         case Token::kSHL:
-          return Integer::New(mint_value << amount.Value());
+          return Integer::New(mint_value << amount.Value(), Heap::kNew, silent);
         case Token::kSHR:
-          return Integer::New(mint_value >> amount.Value());
+          return Integer::New(mint_value >> amount.Value(), Heap::kNew, silent);
         default:
           UNIMPLEMENTED();
       }
     } else {
       // Overflow in shift, use Bigints
       big_value = BigintOperations::NewFromInt64(mint_value);
     }
   } else {
     ASSERT(value.IsBigint());
     big_value = Bigint::Cast(value).raw();
   }
   switch (kind) {
     case Token::kSHL:
       return BigintOperations::ShiftLeft(big_value, amount.Value());
     case Token::kSHR:
       return BigintOperations::ShiftRight(big_value, amount.Value());
     default:
       UNIMPLEMENTED();
   }
   return Integer::null();
 }
 
 
+DEFINE_NATIVE_ENTRY(Integer_leftShiftWithMask32, 3) {
+  const Integer& value = Integer::CheckedHandle(arguments->NativeArgAt(0));
+  GET_NON_NULL_NATIVE_ARGUMENT(Integer, shift_count, arguments->NativeArgAt(1));
+  GET_NON_NULL_NATIVE_ARGUMENT(Integer, mask, arguments->NativeArgAt(2));
+  ASSERT(CheckInteger(value));
+  ASSERT(CheckInteger(shift_count));
+  ASSERT(CheckInteger(mask));
+  if (!shift_count.IsSmi()) {
+    // Shift count is too large..
+    const Instance& exception =
+        Instance::Handle(isolate->object_store()->out_of_memory());
+    Exceptions::Throw(exception);
+  }
+  const Smi& smi_shift_count = Smi::Cast(shift_count);
+  const Integer& shift_result = Integer::Handle(
+      ShiftOperationHelper(Token::kSHL, value, smi_shift_count, true));
+  const Integer& result =
+      Integer::Handle(shift_result.BitOp(Token::kBIT_AND, mask));
+  return result.AsValidInteger();
+}
+
+
 DEFINE_NATIVE_ENTRY(Smi_shrFromInt, 2) {
   const Smi& amount = Smi::CheckedHandle(arguments->NativeArgAt(0));
   GET_NON_NULL_NATIVE_ARGUMENT(Integer, value, arguments->NativeArgAt(1));
   ASSERT(CheckInteger(amount));
   ASSERT(CheckInteger(value));
   const Integer& result = Integer::Handle(
       ShiftOperationHelper(Token::kSHR, value, amount));
   return result.AsValidInteger();
 }
 
@@ skipping 64 matching lines @@
   // Use the preallocated out of memory exception to avoid calling
   // into dart code or allocating any code.
   const Instance& exception =
       Instance::Handle(isolate->object_store()->out_of_memory());
   Exceptions::Throw(exception);
   UNREACHABLE();
   return 0;
 }
 
 }  // namespace dart