PPC: [Atomics] Make Atomics.exchange a builtin using TF

src/builtins/builtins-sharedarraybuffer-gen.cc

Index: src/builtins/builtins-sharedarraybuffer-gen.cc
diff --git a/src/builtins/builtins-sharedarraybuffer-gen.cc b/src/builtins/builtins-sharedarraybuffer-gen.cc
index 65a1733420ae7aa067ac0177ae11db5a3fceeda7..a3acbd55c893107b36ed699673ea39b7f05d6bc7 100644
--- a/src/builtins/builtins-sharedarraybuffer-gen.cc
+++ b/src/builtins/builtins-sharedarraybuffer-gen.cc
@@ -268,8 +268,7 @@ TF_BUILTIN(AtomicsExchange, SharedArrayBufferBuiltinsAssembler) {
 
   Node* value_integer = ToInteger(context, value);
 
-#if V8_TARGET_ARCH_MIPS || V8_TARGET_ARCH_MIPS64 || V8_TARGET_ARCH_PPC64 || \
-    V8_TARGET_ARCH_PPC
+#if V8_TARGET_ARCH_MIPS || V8_TARGET_ARCH_MIPS64
   Return(CallRuntime(Runtime::kAtomicsExchange, context, array, index_integer,
                      value_integer));
 #else
@@ -318,8 +317,7 @@ TF_BUILTIN(AtomicsExchange, SharedArrayBufferBuiltinsAssembler) {
   // This shouldn't happen, we've already validated the type.
   Bind(&other);
   Unreachable();
-#endif  // V8_TARGET_ARCH_MIPS || V8_TARGET_ARCH_MIPS64 || V8_TARGET_ARCH_PPC64
-        // || V8_TARGET_ARCH_PPC
+#endif  // V8_TARGET_ARCH_MIPS || V8_TARGET_ARCH_MIPS64
 }
 
 TF_BUILTIN(AtomicsCompareExchange, SharedArrayBufferBuiltinsAssembler) {