[Atomics] code stubs for atomic operations

src/x64/code-stubs-x64.cc

Index: src/x64/code-stubs-x64.cc
diff --git a/src/x64/code-stubs-x64.cc b/src/x64/code-stubs-x64.cc
index 7f976940b5a2213e505c3af0005405d9efb1dc8b..8fdbf837a2c62c3b58ba1b8563fe32298c053147 100644
--- a/src/x64/code-stubs-x64.cc
+++ b/src/x64/code-stubs-x64.cc
@@ -5424,6 +5424,79 @@ void CallApiGetterStub::Generate(MacroAssembler* masm) {
 }
 
 
+void AtomicsLoadStub::Generate(MacroAssembler* masm) {
+  Register object = rdx;
+  Register index = rax;
+  Label table, i8, u8, i16, u16, i32, u32, f32, f64, u8c;
+
+  __ int3();
+  __ movp(rax, FieldOperand(object, JSTypedArray::kBufferOffset));
+  __ movp(rax, FieldOperand(object, JSArrayBuffer::kBackingStoreOffset));
+
+  __ movp(rcx, FieldOperand(object, JSObject::kElementsOffset));
+  __ movp(rcx, FieldOperand(rcx, HeapObject::kMapOffset));
+  __ movzxbl(rcx, FieldOperand(rcx, Map::kInstanceTypeOffset));
+  __ subb(rcx, Immediate(static_cast<int8_t>(FIXED_INT8_ARRAY_TYPE)));
+  __ Assert(below, kOffsetOutOfRange);
+  __ leaq(kScratchRegister, Operand(&table));
+  __ jmp(Operand(kScratchRegister, rcx, times_8, 0));
+
+  __ bind(&i8);
+  __ movl(rax, Immediate(1));
+  __ Integer32ToSmi(rax, rax);
+  __ Ret();
+
+  __ bind(&u8);
+  __ movl(rax, Immediate(2));
+  __ Integer32ToSmi(rax, rax);
+  __ Ret();
+
+  __ bind(&i16);
+  __ movl(rax, Immediate(3));
+  __ Integer32ToSmi(rax, rax);
+  __ Ret();
+
+  __ bind(&u16);
+  __ movl(rax, Immediate(4));
+  __ Integer32ToSmi(rax, rax);
+  __ Ret();
+
+  __ bind(&i32);
+  __ movl(rax, Immediate(5));
+  __ Integer32ToSmi(rax, rax);
+  __ Ret();
+
+  __ bind(&u32);
+  __ movl(rax, Immediate(6));
+  __ Integer32ToSmi(rax, rax);
+  __ Ret();
+
+  __ bind(&f32);
+  __ Abort(kNoReason);
+
+  __ bind(&f64);
+  __ Abort(kNoReason);
+
+  __ bind(&u8c);
+  __ movl(rax, Immediate(7));
+  __ Integer32ToSmi(rax, rax);
+  __ Ret();
+
+  __ bind(&table);
+  __ dq(&i8);
+  __ dq(&u8);
+  __ dq(&i16);
+  __ dq(&u16);
+  __ dq(&i32);
+  __ dq(&u32);
+  __ dq(&f32);
+  __ dq(&f64);
+  __ dq(&u8c);
+
+  __ Ret();
+}
+
+
 #undef __
 
 }  // namespace internal