[Atomics] Handle conversion to SMI in builtin, not code stub.

src/arm64/code-stubs-arm64.cc

Index: src/arm64/code-stubs-arm64.cc
diff --git a/src/arm64/code-stubs-arm64.cc b/src/arm64/code-stubs-arm64.cc
index 13438cfadeb37aa37ff9ecb7d987726a2cdd92fc..141d16e13ed6bec1d40c5ae7bc9dcc637249b106 100644
--- a/src/arm64/code-stubs-arm64.cc
+++ b/src/arm64/code-stubs-arm64.cc
@@ -6007,28 +6007,6 @@ void TypedArrayJumpTable(MacroAssembler* masm, Register object,
   __ Abort(kNoReason);
 }
 
-void ReturnUnsignedInteger32(MacroAssembler* masm, FPRegister dst,
-                             Register value, Register scratch,
-                             Register scratch2) {
-  Label not_smi, call_runtime;
-  __ Tbnz(value, 31, &not_smi);
-  __ SmiTag(x0, value);
-  __ Ret();
-
-  __ Bind(&not_smi);
-  __ Ucvtf(dst, value);
-  __ AllocateHeapNumber(x0, &call_runtime, scratch, scratch2, dst);
-  __ Ret();
-
-  __ Bind(&call_runtime);
-  {
-    FrameScope scope(masm, StackFrame::INTERNAL);
-    __ CallRuntimeSaveDoubles(Runtime::kAllocateHeapNumber);
-    __ Str(value, FieldMemOperand(x0, HeapNumber::kValueOffset));
-  }
-  __ Ret();
-}
-
 }  // anonymous namespace
 
 void AtomicsLoadStub::Generate(MacroAssembler* masm) {
@@ -6044,38 +6022,32 @@ void AtomicsLoadStub::Generate(MacroAssembler* masm) {
   __ Bind(&i8);
   __ Ldrsb(x0, MemOperand(backing_store, index));
   __ Dmb(InnerShareable, BarrierAll);
-  __ SmiTag(x0);
   __ Ret();
 
   __ Bind(&u8);
   __ Ldrb(x0, MemOperand(backing_store, index));
   __ Dmb(InnerShareable, BarrierAll);
-  __ SmiTag(x0);
   __ Ret();
 
   __ Bind(&i16);
   __ Ldrsh(x0, MemOperand(backing_store, index, UXTW, 1));
   __ Dmb(InnerShareable, BarrierAll);
-  __ SmiTag(x0);
   __ Ret();
 
   __ Bind(&u16);
   __ Ldrh(x0, MemOperand(backing_store, index, UXTW, 1));
   __ Dmb(InnerShareable, BarrierAll);
-  __ SmiTag(x0);
   __ Ret();
 
   __ Bind(&i32);
   __ Ldrsw(x0, MemOperand(backing_store, index, UXTW, 2));
   __ Dmb(InnerShareable, BarrierAll);
-  DCHECK(SmiValuesAre32Bits());
-  __ SmiTag(x0);
   __ Ret();
 
   __ Bind(&u32);
   __ Ldr(w0, MemOperand(backing_store, index, UXTW, 2));
   __ Dmb(InnerShareable, BarrierAll);
-  ReturnUnsignedInteger32(masm, d0, x0, x1, x2);
+  __ Ret();
 }
 
 #undef __