Subzero: Fix g++ warnings.

src/IceTargetLoweringX8664Traits.h

 //===- subzero/src/IceTargetLoweringX8664Traits.h - x86-64 traits -*- C++ -*-=//
 //
 //                        The Subzero Code Generator
 //
 // This file is distributed under the University of Illinois Open Source
 // License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
 ///
 /// \file
@@ skipping 114 matching lines @@
                                       (encoding_at(1) & 7));
     }
 
     int8_t disp8() const {
       assert(length_ >= 2);
       return static_cast<int8_t>(encoding_[length_ - 1]);
     }
 
     int32_t disp32() const {
       assert(length_ >= 5);
-      return bit_copy<int32_t>(encoding_[length_ - 4]);
+      // TODO(stichnot): This method is not currently used.  Delete it along
+      // with other unused methods, or use a safe version of bitCopy().
+      llvm::report_fatal_error("Unexpected call to disp32()");
+      // return Utils::bitCopy<int32_t>(encoding_[length_ - 4]);
     }
 
     AssemblerFixup *fixup() const { return fixup_; }
 
   protected:
     Operand() : fixup_(nullptr), length_(0) {} // Needed by subclass Address.
 
     void SetModRM(int mod, GPRRegister rm) {
       assert((mod & ~3) == 0);
       encoding_[0] = (mod << 6) | (rm & 0x07);
@@ skipping 833 matching lines @@
     const char *FldString;   // s, l, or <blank>
   } TypeAttributes[];
 };
 
 using Traits = ::Ice::X8664::TargetX8664Traits;
 } // end of namespace X8664
 
 } // end of namespace Ice
 
 #endif // SUBZERO_SRC_ICETARGETLOWERINGX8664TRAITS_H