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

src/compiler/x64/instruction-scheduler-x64.cc

 // Copyright 2015 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/instruction-scheduler.h"
 
 namespace v8 {
 namespace internal {
 namespace compiler {
 
@@ skipping 113 matching lines @@
     case kX64Lea32:
     case kX64Lea:
     case kX64Dec32:
     case kX64Inc32:
       return (instr->addressing_mode() == kMode_None)
           ? kNoOpcodeFlags
           : kIsLoadOperation | kHasSideEffect;
 
     case kX64Movsxbl:
     case kX64Movzxbl:
-    case kX64Movsxbq:
-    case kX64Movzxbq:
     case kX64Movsxwl:
     case kX64Movzxwl:
-    case kX64Movsxwq:
-    case kX64Movzxwq:
     case kX64Movsxlq:
       DCHECK(instr->InputCount() >= 1);
       return instr->InputAt(0)->IsRegister() ? kNoOpcodeFlags
                                              : kIsLoadOperation;
 
     case kX64Movb:
     case kX64Movw:
       return kHasSideEffect;
 
     case kX64Movl:
@@ skipping 35 matching lines @@
 
 
 int InstructionScheduler::GetInstructionLatency(const Instruction* instr) {
   // TODO(all): Add instruction cost modeling.
   return 1;
 }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8