[Atomics] Remove Atomics code stubs; use TF ops

src/compiler/arm64/code-generator-arm64.cc

Index: src/compiler/arm64/code-generator-arm64.cc
diff --git a/src/compiler/arm64/code-generator-arm64.cc b/src/compiler/arm64/code-generator-arm64.cc
index 57e1e4661269218eb32f12356b93268e98e1359a..6a96d7eb5b31264353c9eef1a3c668cbb8be33ce 100644
--- a/src/compiler/arm64/code-generator-arm64.cc
+++ b/src/compiler/arm64/code-generator-arm64.cc
@@ -472,6 +472,13 @@ Condition FlagsConditionToCondition(FlagsCondition condition) {
     }                                                                       \
   } while (0)
 
+#define ASSEMBLE_ATOMIC_LOAD_INTEGER(asm_instr)                       \
+  do {                                                                \
+    __ asm_instr(i.OutputRegister(),                                  \
+                 MemOperand(i.InputRegister(0), i.InputRegister(1))); \
+    __ Dmb(InnerShareable, BarrierAll);                               \
+  } while (0)
+
 void CodeGenerator::AssembleDeconstructFrame() {
   const CallDescriptor* descriptor = linkage()->GetIncomingDescriptor();
   if (descriptor->IsCFunctionCall() || descriptor->UseNativeStack()) {
@@ -1404,6 +1411,23 @@ void CodeGenerator::AssembleArchInstruction(Instruction* instr) {
     case kCheckedStoreFloat64:
       ASSEMBLE_CHECKED_STORE_FLOAT(64);
       break;
+    case kAtomicLoadInt8:
+      ASSEMBLE_ATOMIC_LOAD_INTEGER(Ldrsb);
+      break;
+    case kAtomicLoadUint8:
+      ASSEMBLE_ATOMIC_LOAD_INTEGER(Ldrb);
+      break;
+    case kAtomicLoadInt16:
+      ASSEMBLE_ATOMIC_LOAD_INTEGER(Ldrsh);
+      break;
+    case kAtomicLoadUint16:
+      ASSEMBLE_ATOMIC_LOAD_INTEGER(Ldrh);
+      break;
+    case kAtomicLoadWord32:
+      __ Ldr(i.OutputRegister32(),
+             MemOperand(i.InputRegister(0), i.InputRegister(1)));
+      __ Dmb(InnerShareable, BarrierAll);
+      break;
   }
 }  // NOLINT(readability/fn_size)