Fix truncate divide bug (reported by sra) when dividing MIN_SMI by -1.

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 842 matching lines @@
         // No overflow check.
         __ orl(EAX, EDX);
         break;
       }
       case Token::kBIT_XOR: {
         // No overflow check.
         __ xorl(EAX, EDX);
         break;
       }
       case Token::kTRUNCDIV: {
-        // Handle Divide by zero in runtime.
+        // Handle divide by zero in runtime.
         __ cmpl(EDX, Immediate(0));
         __ j(EQUAL, overflow_label);
+        // Preserve left & right in case of 'overflow'.
+        __ pushl(EDX);
+        __ pushl(ECX);
         // Move right to ECX, left is in EAX.
         __ movl(ECX, EDX);
         __ SmiUntag(ECX);
         __ SmiUntag(EAX);
         // Sign extend EAX -> EDX:EAX.
         __ cdq();
-        __ idivl(ECX);
+        __ idivl(ECX);  // Result in EAX.
+        __ popl(ECX);
+        __ popl(EDX);
+        // Check the corner case of dividing the 'MIN_SMI' with -1, in which
+        // case we cannot tag the result.
+        __ cmpl(EAX, Immediate(0x40000000));
+        __ j(EQUAL, overflow_label);
         __ SmiTag(EAX);
         break;
       }
       default:
         UNREACHABLE();
     }
   } else if (kind == Token::kSHL) {
     GenerateSmiShiftBinaryOp(node);
   } else {
     TraceNotOpt(node, kOptMessage);
@@ skipping 1851 matching lines @@
 void OptimizingCodeGenerator::VisitTryCatchNode(TryCatchNode* node) {
   // TODO(srdjan): Set classes for locals.
   classes_for_locals_->Clear();
   CodeGenerator::VisitTryCatchNode(node);
 }
 
 
 }  // namespace dart
 
 #endif  // defined TARGET_ARCH_IA32