[Atomics] use TFJ builtins for atomic add, sub, and, or, and xor

src/compiler/ppc/code-generator-ppc.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/compiler/code-generator.h"
 
 #include "src/compilation-info.h"
 #include "src/compiler/code-generator-impl.h"
 #include "src/compiler/gap-resolver.h"
 #include "src/compiler/node-matchers.h"
@@ skipping 1987 matching lines @@
     case kAtomicExchangeInt16:
       ASSEMBLE_ATOMIC_EXCHANGE_INTEGER(lharx, sthcx);
       __ extsh(i.OutputRegister(0), i.OutputRegister(0));
       break;
     case kAtomicExchangeUint16:
       ASSEMBLE_ATOMIC_EXCHANGE_INTEGER(lharx, sthcx);
       break;
     case kAtomicExchangeWord32:
       ASSEMBLE_ATOMIC_EXCHANGE_INTEGER(lwarx, stwcx);
       break;
-    case kAtomicCompareExchangeInt8:
-    case kAtomicCompareExchangeUint8:
-    case kAtomicCompareExchangeInt16:
-    case kAtomicCompareExchangeUint16:
-    case kAtomicCompareExchangeWord32:
-      UNREACHABLE();
-      break;
     default:
       UNREACHABLE();
       break;
   }
   return kSuccess;
 }  // NOLINT(readability/fn_size)
 
 
 // Assembles branches after an instruction.
 void CodeGenerator::AssembleArchBranch(Instruction* instr, BranchInfo* branch) {
@@ skipping 593 matching lines @@
       padding_size -= v8::internal::Assembler::kInstrSize;
     }
   }
 }
 
 #undef __
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8