[Atomics] Make Atomics.exchange a builtin using TF

src/builtins/builtins-sharedarraybuffer.cc

Index: src/builtins/builtins-sharedarraybuffer.cc
diff --git a/src/builtins/builtins-sharedarraybuffer.cc b/src/builtins/builtins-sharedarraybuffer.cc
index 7ee144901e1a074818704e50886065439ee1234f..7011d69682066675e181d7848d067ed975197144 100644
--- a/src/builtins/builtins-sharedarraybuffer.cc
+++ b/src/builtins/builtins-sharedarraybuffer.cc
@@ -273,6 +273,72 @@ void Builtins::Generate_AtomicsStore(compiler::CodeAssemblerState* state) {
   a.Return(a.SmiConstant(0));
 }
 
+void Builtins::Generate_AtomicsExchange(compiler::CodeAssemblerState* state) {
+  using compiler::Node;
+  CodeStubAssembler a(state);
+  Node* array = a.Parameter(1);
+  Node* index = a.Parameter(2);
+  Node* value = a.Parameter(3);
+  Node* context = a.Parameter(4 + 2);
+
+  Node* instance_type;
+  Node* backing_store;
+  ValidateSharedTypedArray(&a, array, context, &instance_type, &backing_store);
+
+  Node* index_word32 = ConvertTaggedAtomicIndexToWord32(&a, index, context);
+  Node* array_length_word32 = a.TruncateTaggedToWord32(
+      context, a.LoadObjectField(array, JSTypedArray::kLengthOffset));
+  ValidateAtomicIndex(&a, index_word32, array_length_word32, context);
+  Node* index_word = a.ChangeUint32ToWord(index_word32);
+
+  Node* value_integer = a.ToInteger(context, value);
+  Node* value_word32 = a.TruncateTaggedToWord32(context, value_integer);
+
+  CodeStubAssembler::Label i8(&a), u8(&a), i16(&a), u16(&a), i32(&a), u32(&a),
+      other(&a);
+  int32_t case_values[] = {
+      FIXED_INT8_ARRAY_TYPE,   FIXED_UINT8_ARRAY_TYPE, FIXED_INT16_ARRAY_TYPE,
+      FIXED_UINT16_ARRAY_TYPE, FIXED_INT32_ARRAY_TYPE, FIXED_UINT32_ARRAY_TYPE,
+  };
+  CodeStubAssembler::Label* case_labels[] = {
+      &i8, &u8, &i16, &u16, &i32, &u32,
+  };
+  a.Switch(instance_type, &other, case_values, case_labels,
+           arraysize(case_labels));
+
+  a.Bind(&i8);
+  a.Return(a.SmiFromWord32(a.AtomicExchange(MachineType::Int8(), backing_store,
+                                            index_word, value_word32)));
+
+  a.Bind(&u8);
+  a.Return(a.SmiFromWord32(a.AtomicExchange(MachineType::Uint8(), backing_store,
+                                            index_word, value_word32)));
+
+  a.Bind(&i16);
+  a.Return(a.SmiFromWord32(a.AtomicExchange(MachineType::Int16(), backing_store,
+                                            a.WordShl(index_word, 1),
+                                            value_word32)));
+
+  a.Bind(&u16);
+  a.Return(a.SmiFromWord32(
+      a.AtomicExchange(MachineType::Uint16(), backing_store,
+                       a.WordShl(index_word, 1), value_word32)));
+
+  a.Bind(&i32);
+  a.Return(a.ChangeInt32ToTagged(
+      a.AtomicExchange(MachineType::Int32(), backing_store,
+                       a.WordShl(index_word, 2), value_word32)));
+
+  a.Bind(&u32);
+  a.Return(a.ChangeUint32ToTagged(
+      a.AtomicExchange(MachineType::Uint32(), backing_store,
+                       a.WordShl(index_word, 2), value_word32)));
+
+  // This shouldn't happen, we've already validated the type.
+  a.Bind(&other);
+  a.Return(a.SmiConstant(0));
+}
+
 inline bool AtomicIsLockFree(uint32_t size) {
   return size == 1 || size == 2 || size == 4;
 }
@@ -454,15 +520,10 @@ inline T XorSeqCst(T* p, T value) {
   return __atomic_fetch_xor(p, value, __ATOMIC_SEQ_CST);
 }
 
-template <typename T>
-inline T ExchangeSeqCst(T* p, T value) {
-  return __atomic_exchange_n(p, value, __ATOMIC_SEQ_CST);
-}
 
 #elif V8_CC_MSVC
 
 #define InterlockedCompareExchange32 _InterlockedCompareExchange
-#define InterlockedExchange32 _InterlockedExchange
 #define InterlockedExchangeAdd32 _InterlockedExchangeAdd
 #define InterlockedAnd32 _InterlockedAnd
 #define InterlockedOr32 _InterlockedOr
@@ -492,10 +553,6 @@ inline T ExchangeSeqCst(T* p, T value) {
     return InterlockedXor##suffix(reinterpret_cast<vctype*>(p),             \
                                   bit_cast<vctype>(value));                 \
   }                                                                         \
-  inline type ExchangeSeqCst(type* p, type value) {                         \
-    return InterlockedExchange##suffix(reinterpret_cast<vctype*>(p),        \
-                                       bit_cast<vctype>(value));            \
-  }                                                                         \
                                                                             \
   inline type CompareExchangeSeqCst(type* p, type oldval, type newval) {    \
     return InterlockedCompareExchange##suffix(reinterpret_cast<vctype*>(p), \
@@ -514,7 +571,6 @@ ATOMIC_OPS(uint32_t, 32, long)  /* NOLINT(runtime/int) */
 #undef ATOMIC_OPS
 
 #undef InterlockedCompareExchange32
-#undef InterlockedExchange32
 #undef InterlockedExchangeAdd32
 #undef InterlockedAnd32
 #undef InterlockedOr32
@@ -630,14 +686,6 @@ inline Object* DoXor(Isolate* isolate, void* buffer, size_t index,
   return ToObject(isolate, result);
 }
 
-template <typename T>
-inline Object* DoExchange(Isolate* isolate, void* buffer, size_t index,
-                          Handle<Object> obj) {
-  T value = FromObject<T>(obj);
-  T result = ExchangeSeqCst(static_cast<T*>(buffer) + index, value);
-  return ToObject(isolate, result);
-}
-
 // Uint8Clamped functions
 
 uint8_t ClampToUint8(int32_t value) {
@@ -681,17 +729,6 @@ DO_UINT8_CLAMPED_OP(Xor, ^)
 
 #undef DO_UINT8_CLAMPED_OP
 
-inline Object* DoExchangeUint8Clamped(Isolate* isolate, void* buffer,
-                                      size_t index, Handle<Object> obj) {
-  typedef int32_t convert_type;
-  uint8_t* p = static_cast<uint8_t*>(buffer) + index;
-  uint8_t result = ClampToUint8(FromObject<convert_type>(obj));
-  uint8_t expected;
-  do {
-    expected = *p;
-  } while (CompareExchangeSeqCst(p, expected, result) != expected);
-  return ToObject(isolate, expected);
-}
 
 }  // anonymous namespace
 
@@ -957,46 +994,6 @@ BUILTIN(AtomicsXor) {
   return isolate->heap()->undefined_value();
 }
 
-// ES #sec-atomics.exchange
-// Atomics.exchange( typedArray, index, value )
-BUILTIN(AtomicsExchange) {
-  HandleScope scope(isolate);
-  Handle<Object> array = args.atOrUndefined(isolate, 1);
-  Handle<Object> index = args.atOrUndefined(isolate, 2);
-  Handle<Object> value = args.atOrUndefined(isolate, 3);
-
-  Handle<JSTypedArray> sta;
-  ASSIGN_RETURN_FAILURE_ON_EXCEPTION(
-      isolate, sta, ValidateSharedIntegerTypedArray(isolate, array));
-
-  Maybe<size_t> maybeIndex = ValidateAtomicAccess(isolate, sta, index);
-  if (maybeIndex.IsNothing()) return isolate->heap()->exception();
-  size_t i = maybeIndex.FromJust();
-
-  ASSIGN_RETURN_FAILURE_ON_EXCEPTION(isolate, value,
-                                     Object::ToInteger(isolate, value));
-
-  uint8_t* source = static_cast<uint8_t*>(sta->GetBuffer()->backing_store()) +
-                    NumberToSize(sta->byte_offset());
-
-  switch (sta->type()) {
-#define TYPED_ARRAY_CASE(Type, typeName, TYPE, ctype, size) \
-  case kExternal##Type##Array:                              \
-    return DoExchange<ctype>(isolate, source, i, value);
-
-    INTEGER_TYPED_ARRAYS(TYPED_ARRAY_CASE)
-#undef TYPED_ARRAY_CASE
-
-    case kExternalUint8ClampedArray:
-      return DoExchangeUint8Clamped(isolate, source, i, value);
-
-    default:
-      break;
-  }
-
-  UNREACHABLE();
-  return isolate->heap()->undefined_value();
-}
 
 }  // namespace internal
 }  // namespace v8