[Atomics] Make Atomics.compareExchange 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 b651dbd30244a4fec43cfc93624b48b0ea684cc1..4f7abd0d94c95d1e43d348157848e3633834b8e6 100644
--- a/src/builtins/builtins-sharedarraybuffer.cc
+++ b/src/builtins/builtins-sharedarraybuffer.cc
@@ -293,7 +293,6 @@ void Builtins::Generate_AtomicsExchange(compiler::CodeAssemblerState* state) {
 
 #if V8_TARGET_ARCH_MIPS || V8_TARGET_ARCH_MIPS64 || V8_TARGET_ARCH_PPC64 || \
     V8_TARGET_ARCH_PPC || V8_TARGET_ARCH_S390 || V8_TARGET_ARCH_S390X
-  // Node* index_integer = a.ToInteger(context, index);
   a.Return(a.CallRuntime(Runtime::kAtomicsExchange, context, array,
                          index_integer, value_integer));
 #else
@@ -348,5 +347,90 @@ void Builtins::Generate_AtomicsExchange(compiler::CodeAssemblerState* state) {
         // || V8_TARGET_ARCH_PPC || V8_TARGET_ARCH_S390 || V8_TARGET_ARCH_S390X
 }
 
+void Builtins::Generate_AtomicsCompareExchange(

[Jakob Kummerow, 2017/03/09 13:43:42]

please use the TF_BUILTIN macro to drop a bunch of visual clutter, see
https://codereview.chromium.org/2734323004

[aseemgarg, 2017/03/10 19:55:22]

Done.

+    compiler::CodeAssemblerState* state) {
+  using compiler::Node;
+  CodeStubAssembler a(state);
+  Node* array = a.Parameter(1);
+  Node* index = a.Parameter(2);
+  Node* old_value = a.Parameter(3);
+  Node* new_value = a.Parameter(4);
+  Node* context = a.Parameter(5 + 2);
+
+  Node* instance_type;
+  Node* backing_store;
+  ValidateSharedTypedArray(&a, array, context, &instance_type, &backing_store);
+
+  Node* index_integer;
+  Node* index_word32 =
+      ConvertTaggedAtomicIndexToWord32(&a, index, context, &index_integer);
+  Node* array_length_word32 = a.TruncateTaggedToWord32(
+      context, a.LoadObjectField(array, JSTypedArray::kLengthOffset));
+  ValidateAtomicIndex(&a, index_word32, array_length_word32, context);
+
+  Node* old_value_integer = a.ToInteger(context, old_value);
+
+  Node* new_value_integer = a.ToInteger(context, new_value);
+
+#if V8_TARGET_ARCH_MIPS || V8_TARGET_ARCH_MIPS64 || V8_TARGET_ARCH_PPC64 || \
+    V8_TARGET_ARCH_PPC || V8_TARGET_ARCH_S390 || V8_TARGET_ARCH_S390X
+  a.Return(a.CallRuntime(Runtime::kAtomicsCompareExchange, context, array,
+                         index_integer, old_value_integer, new_value_integer));
+#else
+  Node* index_word = a.ChangeUint32ToWord(index_word32);
+
+  Node* old_value_word32 = a.TruncateTaggedToWord32(context, old_value_integer);
+
+  Node* new_value_word32 = a.TruncateTaggedToWord32(context, new_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.AtomicCompareExchange(MachineType::Int8(), backing_store, index_word,
+                              old_value_word32, new_value_word32)));
+
+  a.Bind(&u8);
+  a.Return(a.SmiFromWord32(
+      a.AtomicCompareExchange(MachineType::Uint8(), backing_store, index_word,
+                              old_value_word32, new_value_word32)));
+
+  a.Bind(&i16);
+  a.Return(a.SmiFromWord32(a.AtomicCompareExchange(
+      MachineType::Int16(), backing_store, a.WordShl(index_word, 1),
+      old_value_word32, new_value_word32)));
+
+  a.Bind(&u16);
+  a.Return(a.SmiFromWord32(a.AtomicCompareExchange(
+      MachineType::Uint16(), backing_store, a.WordShl(index_word, 1),
+      old_value_word32, new_value_word32)));
+
+  a.Bind(&i32);
+  a.Return(a.ChangeInt32ToTagged(a.AtomicCompareExchange(
+      MachineType::Int32(), backing_store, a.WordShl(index_word, 2),
+      old_value_word32, new_value_word32)));
+
+  a.Bind(&u32);
+  a.Return(a.ChangeUint32ToTagged(a.AtomicCompareExchange(
+      MachineType::Uint32(), backing_store, a.WordShl(index_word, 2),
+      old_value_word32, new_value_word32)));
+
+  // This shouldn't happen, we've already validated the type.
+  a.Bind(&other);
+  a.Return(a.SmiConstant(0));

[Jakob Kummerow, 2017/03/09 13:43:42]

how about "Unreachable();" instead?

[aseemgarg, 2017/03/10 19:55:22]

Done.

+#endif  // V8_TARGET_ARCH_MIPS || V8_TARGET_ARCH_MIPS64 || V8_TARGET_ARCH_PPC64
+        // || V8_TARGET_ARCH_PPC || V8_TARGET_ARCH_S390 || V8_TARGET_ARCH_S390X
+}
+
 }  // namespace internal
 }  // namespace v8