MIPS64: Enable shorten-64-to-32 warning.

src/mips64/disasm-mips64.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // A Disassembler object is used to disassemble a block of code instruction by
 // instruction. The default implementation of the NameConverter object can be
 // overriden to modify register names or to do symbol lookup on addresses.
 //
 // The example below will disassemble a block of code and print it to stdout.
 //
@@ skipping 254 matching lines @@
 
 // Print 21-bit immediate value.
 void Decoder::PrintXImm21(Instruction* instr) {
   uint32_t imm = instr->Imm21Value();
   out_buffer_pos_ += SNPrintF(out_buffer_ + out_buffer_pos_, "0x%x", imm);
 }
 
 
 // Print 26-bit immediate value.
 void Decoder::PrintXImm26(Instruction* instr) {
-  uint32_t imm = instr->Imm26Value() << kImmFieldShift;
+  uint32_t imm = static_cast<uint32_t>(instr->Imm26Value()) << kImmFieldShift;
   out_buffer_pos_ += SNPrintF(out_buffer_ + out_buffer_pos_, "0x%x", imm);
 }
 
 
 // Print 26-bit immediate value.
 void Decoder::PrintCode(Instruction* instr) {
   if (instr->OpcodeFieldRaw() != SPECIAL)
     return;  // Not a break or trap instruction.
   switch (instr->FunctionFieldRaw()) {
     case BREAK: {
@@ skipping 1297 matching lines @@
         prev_pc, *reinterpret_cast<int32_t*>(prev_pc), buffer.start());
   }
 }
 
 
 #undef UNSUPPORTED
 
 }  // namespace disasm
 
 #endif  // V8_TARGET_ARCH_MIPS64