[Atomics] Make Atomics.exchange a builtin using TF

src/compiler/instruction-scheduler.cc

Index: src/compiler/instruction-scheduler.cc
diff --git a/src/compiler/instruction-scheduler.cc b/src/compiler/instruction-scheduler.cc
index 8ba287b1bcf1123af5c74df40ef24d473fcd26ba..8693cb729f0629a29b4117bb10b5bfb751fb23a3 100644
--- a/src/compiler/instruction-scheduler.cc
+++ b/src/compiler/instruction-scheduler.cc
@@ -326,6 +326,13 @@ int InstructionScheduler::GetInstructionFlags(const Instruction* instr) const {
     case kAtomicStoreWord32:
       return kHasSideEffect;
 
+    case kAtomicExchangeInt8:
+    case kAtomicExchangeUint8:
+    case kAtomicExchangeInt16:
+    case kAtomicExchangeUint16:
+    case kAtomicExchangeWord32:
+      return kIsLoadOperation | kHasSideEffect;

[Jarin, 2017/03/01 07:45:37]

kIsLoadOperation is redundant here, kHasSideEffect already means that we can
reorder it with any load or side-effect.

[aseemgarg, 2017/03/02 03:26:56]

Done.

+
 #define CASE(Name) case k##Name:
     TARGET_ARCH_OPCODE_LIST(CASE)
 #undef CASE