MIPS64: Fix 32bit right shift operators

src/compiler/mips64/code-generator-mips64.cc

 // Copyright 2014 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.
 
 #include "src/ast/scopes.h"
 #include "src/compiler/code-generator.h"
 #include "src/compiler/code-generator-impl.h"
 #include "src/compiler/gap-resolver.h"
 #include "src/compiler/node-matchers.h"
 #include "src/compiler/osr.h"
@@ skipping 1113 matching lines @@
       if (instr->InputAt(1)->IsRegister()) {
         __ sllv(i.OutputRegister(), i.InputRegister(0), i.InputRegister(1));
       } else {
         int64_t imm = i.InputOperand(1).immediate();
         __ sll(i.OutputRegister(), i.InputRegister(0),
                static_cast<uint16_t>(imm));
       }
       break;
     case kMips64Shr:
       if (instr->InputAt(1)->IsRegister()) {
+        __ sll(i.InputRegister(0), i.InputRegister(0), 0x0);
         __ srlv(i.OutputRegister(), i.InputRegister(0), i.InputRegister(1));
       } else {
         int64_t imm = i.InputOperand(1).immediate();
+        __ sll(i.InputRegister(0), i.InputRegister(0), 0x0);
         __ srl(i.OutputRegister(), i.InputRegister(0),
                static_cast<uint16_t>(imm));
       }
       break;
     case kMips64Sar:
       if (instr->InputAt(1)->IsRegister()) {
+        __ sll(i.InputRegister(0), i.InputRegister(0), 0x0);
         __ srav(i.OutputRegister(), i.InputRegister(0), i.InputRegister(1));
       } else {
         int64_t imm = i.InputOperand(1).immediate();
+        __ sll(i.InputRegister(0), i.InputRegister(0), 0x0);
         __ sra(i.OutputRegister(), i.InputRegister(0),
                static_cast<uint16_t>(imm));
       }
       break;
     case kMips64Ext:
       __ Ext(i.OutputRegister(), i.InputRegister(0), i.InputInt8(1),
              i.InputInt8(2));
       break;
     case kMips64Ins:
       if (instr->InputAt(1)->IsImmediate() && i.InputInt8(1) == 0) {
@@ skipping 1288 matching lines @@
       padding_size -= v8::internal::Assembler::kInstrSize;
     }
   }
 }
 
 #undef __
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8