Fix issue 1845: Mint BIT_AND Smi was incorrect for negative Smi-s. Jump to slow case on negative Sm…

runtime/vm/opt_code_generator_ia32.cc

 // Copyright (c) 2011, 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/globals.h"  // Needed here to get TARGET_ARCH_IA32.
 #if defined(TARGET_ARCH_IA32)
 
 #include "vm/opt_code_generator.h"
 
 #include "vm/assembler_macros.h"
@@ skipping 997 matching lines @@
     CodeGenerator::GenerateBinaryOperatorCall(node->id(),
                                               node->token_index(),
                                               node->Name());
   }
   __ Bind(&done);
   HandleResult(node, EAX);
 }
 
 
 // Supports some mixed Smi/Mint operations.
-// For BIT_AND operation with one operand being Smi, we can throw away
-// any Mint bits above the Smi range.
+// For BIT_AND operation with right operand being Smi, we can throw away
+// any Mint bits above the Smi range as long as the right operand is positive.
 // 'allow_smi' is true if Smi and Mint classes have been encountered.
 void OptimizingCodeGenerator::GenerateMintBinaryOp(BinaryOpNode* node,
                                                    bool allow_smi) {
   const char* kOptMessage = "Inline Mint binop.";
   ObjectStore* object_store = Isolate::Current()->object_store();
   const Token::Kind kind = node->kind();
   if (kind == Token::kBIT_AND) {
     TraceOpt(node, kOptMessage);
     Label is_smi, slow_case, done;
     DeoptimizationBlob* deopt_blob =
         AddDeoptimizationBlob(node, EAX, EDX, kDeoptMintBinaryOp);
     VisitLoadTwo(node->left(), node->right(), EAX, EDX);
     __ testl(EDX, Immediate(kSmiTagMask));
     __ j(NOT_ZERO, &slow_case);  // Call operator if right is not Smi.
+    __ cmpl(EDX, Immediate(0));
+    __ j(LESS, &slow_case);  // Result will not be Smi.
 
     // Test left.
     __ testl(EAX, Immediate(kSmiTagMask));
     __ j(ZERO, &is_smi);
 
     __ movl(EBX, FieldAddress(EAX, Object::class_offset()));
     __ CompareObject(EBX, Class::ZoneHandle(object_store->mint_class()));
     __ j(NOT_EQUAL, deopt_blob->label());
 
     // Load lower Mint word, convert to Smi. It is OK to loose bits.
@@ skipping 2104 matching lines @@
     }
   }
   // TODO(srdjan): Implement unary kSUB (negate) Mint.
   CodeGenerator::VisitUnaryOpNode(node);
 }
 
 
 }  // namespace dart
 
 #endif  // defined TARGET_ARCH_IA32