[Atomics] Make Atomics.exchange a builtin using TF

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 160 matching lines @@
     case kX64Movss:
       return instr->HasOutput() ? kIsLoadOperation : kHasSideEffect;
 
     case kX64StackCheck:
       return kIsLoadOperation;
 
     case kX64Push:
     case kX64Poke:
       return kHasSideEffect;
 
-    case kX64Xchgb:
-    case kX64Xchgw:
-    case kX64Xchgl:
-      return kIsLoadOperation | kHasSideEffect;

[binji, 2017/01/17 21:45:50]

Where did this move to?

[aseemgarg, 2017/01/21 08:40:37]

These are removed. Instead we are now relying on the the common exchange
instructions (see instruction-scheduler.h)

-
 #define CASE(Name) case k##Name:
     COMMON_ARCH_OPCODE_LIST(CASE)
 #undef CASE
       // Already covered in architecture independent code.
       UNREACHABLE();
   }
 
   UNREACHABLE();
   return kNoOpcodeFlags;
 }
@@ skipping 69 matching lines @@
     case kArchTruncateDoubleToI:
       return 6;
     default:
       return 1;
   }
 }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8