Subzero: Fix a mul lowering error.

src/IceTargetLoweringX86BaseImpl.h

 //===- subzero/src/IceTargetLoweringX86BaseImpl.h - x86 lowering -*- C++ -*-==//
 //
 //                        The Subzero Code Generator
 //
 // This file is distributed under the University of Illinois Open Source
 // License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
 ///
 /// \file
@@ skipping 1936 matching lines @@
       //   a.hi = t4.hi
       // The mul instruction cannot take an immediate operand.
       Src1Lo = legalize(Src1Lo, Legal_Reg | Legal_Mem);
       _mov(T_1, Src0Hi);
       _imul(T_1, Src1Lo);
       _mov(T_3, Src0Lo, Traits::RegisterSet::Reg_eax);
       _mul(T_4Lo, T_3, Src1Lo);
       // The mul instruction produces two dest variables, edx:eax. We create a
       // fake definition of edx to account for this.
       Context.insert<InstFakeDef>(T_4Hi, T_4Lo);
+      Context.insert<InstFakeUse>(T_4Hi);
       _mov(DestLo, T_4Lo);
       _add(T_4Hi, T_1);
       _mov(T_2, Src1Hi);
       _imul(T_2, Src0Lo);
       _add(T_4Hi, T_2);
       _mov(DestHi, T_4Hi);
     } break;
     case InstArithmetic::Shl:
     case InstArithmetic::Lshr:
     case InstArithmetic::Ashr:
@@ skipping 5490 matching lines @@
         emitGlobal(*Var, SectionSuffix);
       }
     }
   } break;
   }
 }
 } // end of namespace X86NAMESPACE
 } // end of namespace Ice
 
 #endif // SUBZERO_SRC_ICETARGETLOWERINGX86BASEIMPL_H