Revert of [x64] Zero/sign-extend loads to 64-bit registers.

src/compiler/x64/code-generator-x64.cc

 // Copyright 2013 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/compiler/code-generator.h"
 
 #include "src/ast/scopes.h"
 #include "src/compiler/code-generator-impl.h"
 #include "src/compiler/gap-resolver.h"
 #include "src/compiler/node-matchers.h"
@@ skipping 1719 matching lines @@
       __ Subsd(i.InputDoubleRegister(0), kScratchDoubleReg);
       break;
     case kX64Movsxbl:
       ASSEMBLE_MOVX(movsxbl);
       __ AssertZeroExtended(i.OutputRegister());
       break;
     case kX64Movzxbl:
       ASSEMBLE_MOVX(movzxbl);
       __ AssertZeroExtended(i.OutputRegister());
       break;
-    case kX64Movsxbq:
-      ASSEMBLE_MOVX(movsxbq);
-      __ AssertZeroExtended(i.OutputRegister());
-      break;
-    case kX64Movzxbq:
-      ASSEMBLE_MOVX(movzxbq);
-      __ AssertZeroExtended(i.OutputRegister());
-      break;
     case kX64Movb: {
       size_t index = 0;
       Operand operand = i.MemoryOperand(&index);
       if (HasImmediateInput(instr, index)) {
         __ movb(operand, Immediate(i.InputInt8(index)));
       } else {
         __ movb(operand, i.InputRegister(index));
       }
       break;
     }
     case kX64Movsxwl:
       ASSEMBLE_MOVX(movsxwl);
       __ AssertZeroExtended(i.OutputRegister());
       break;
     case kX64Movzxwl:
       ASSEMBLE_MOVX(movzxwl);
       __ AssertZeroExtended(i.OutputRegister());
       break;
-    case kX64Movsxwq:
-      ASSEMBLE_MOVX(movsxwq);
-      __ AssertZeroExtended(i.OutputRegister());
-      break;
-    case kX64Movzxwq:
-      ASSEMBLE_MOVX(movzxwq);
-      __ AssertZeroExtended(i.OutputRegister());
-      break;
     case kX64Movw: {
       size_t index = 0;
       Operand operand = i.MemoryOperand(&index);
       if (HasImmediateInput(instr, index)) {
         __ movw(operand, Immediate(i.InputInt16(index)));
       } else {
         __ movw(operand, i.InputRegister(index));
       }
       break;
     }
@@ skipping 807 matching lines @@
     int padding_size = last_lazy_deopt_pc_ + space_needed - current_pc;
     __ Nop(padding_size);
   }
 }
 
 #undef __
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8