[ObjC] Support objc_claimAutoreleasedReturnValue.

This adds basic support for objc_claimAutoreleasedReturnValue,
which is mostly equivalent to objc_retainAutoreleasedReturnValue,
with the difference that it doesn't require the marker nop to be
emitted between it and the call it was attached to.

To achieve that, this also teaches the AArch64 attachedcall bundle
lowering to pick whether the marker should be emitted or not
based on whether the attachedcall target is claimARV or retainARV.

Co-authored-by: Ahmed Bougacha <[email protected]>

Author: citymarina

llvm/include/llvm/Analysis/ObjCARCUtil.h

@@ -48,6 +48,21 @@ inline std::optional<Function *> getAttachedARCFunction(const CallBase *CB) {
   return cast<Function>(B->Inputs[0]);
 }
 
+/// This function determines whether the clang_arc_attachedcall should be
+/// emitted with or without the marker.
+/// Concretely, this is the difference between:
+///   objc_retainAutoreleasedReturnValue
+/// and
+///  objc_claimAutoreleasedReturnValue
+/// retainRV (and unsafeClaimRV) requires a marker, but claimRV does not.
+inline bool attachedCallOpBundleNeedsMarker(const CallBase *CB) {
+  // FIXME: do this on ARCRuntimeEntryPoints, and do the todo above ARCInstKind
+  if (std::optional<Function *> Fn = getAttachedARCFunction(CB))
+    if ((*Fn)->getName() == "objc_claimAutoreleasedReturnValue")
+      return false;
+  return true;
+}
+
 /// Check whether the function is retainRV/unsafeClaimRV.
 inline bool isRetainOrClaimRV(ARCInstKind Kind) {
   return Kind == ARCInstKind::RetainRV || Kind == ARCInstKind::UnsafeClaimRV;

llvm/include/llvm/IR/Intrinsics.td

@@ -777,10 +777,12 @@ def int_objc_loadWeakRetained               : Intrinsic<[llvm_ptr_ty],
 def int_objc_moveWeak                       : Intrinsic<[],
                                                         [llvm_ptr_ty,
                                                          llvm_ptr_ty]>;
+
 def int_objc_release                        : Intrinsic<[], [llvm_ptr_ty]>;
 def int_objc_retain                         : Intrinsic<[llvm_ptr_ty],
                                                         [llvm_ptr_ty],
                                                         [Returned<ArgIndex<0>>]>;
+
 def int_objc_retainAutorelease              : Intrinsic<[llvm_ptr_ty],
                                                         [llvm_ptr_ty],
                                                         [Returned<ArgIndex<0>>]>;
@@ -789,6 +791,11 @@ def int_objc_retainAutoreleaseReturnValue   : Intrinsic<[llvm_ptr_ty],
                                                         [Returned<ArgIndex<0>>]>;
 def int_objc_retainAutoreleasedReturnValue  : Intrinsic<[llvm_ptr_ty],
                                                         [llvm_ptr_ty]>;
+def int_objc_unsafeClaimAutoreleasedReturnValue : Intrinsic<[llvm_ptr_ty],
+                                                            [llvm_ptr_ty]>;
+def int_objc_claimAutoreleasedReturnValue   : Intrinsic<[llvm_ptr_ty],
+                                                        [llvm_ptr_ty]>;
+
 def int_objc_retainBlock                    : Intrinsic<[llvm_ptr_ty],
                                                         [llvm_ptr_ty]>;
 def int_objc_storeStrong                    : Intrinsic<[],
@@ -802,8 +809,6 @@ def int_objc_clang_arc_use                  : Intrinsic<[],
 def int_objc_clang_arc_noop_use : DefaultAttrsIntrinsic<[],
                                                         [llvm_vararg_ty],
                                                         [IntrInaccessibleMemOnly]>;
-def int_objc_unsafeClaimAutoreleasedReturnValue : Intrinsic<[llvm_ptr_ty],
-                                                            [llvm_ptr_ty]>;
 def int_objc_retainedObject                 : Intrinsic<[llvm_ptr_ty],
                                                         [llvm_ptr_ty]>;
 def int_objc_unretainedObject               : Intrinsic<[llvm_ptr_ty],

llvm/lib/CodeGen/PreISelIntrinsicLowering.cpp

@@ -160,10 +160,7 @@ static bool lowerObjCCall(Function &F, const char *NewFn,
     auto *CB = cast<CallBase>(U.getUser());
 
     if (CB->getCalledFunction() != &F) {
-      objcarc::ARCInstKind Kind = objcarc::getAttachedARCFunctionKind(CB);
-      (void)Kind;
-      assert((Kind == objcarc::ARCInstKind::RetainRV ||
-              Kind == objcarc::ARCInstKind::UnsafeClaimRV) &&
+      assert((*objcarc::getAttachedARCFunction(CB) == &F) &&
              "use expected to be the argument of operand bundle "
              "\"clang.arc.attachedcall\"");
       U.set(FCache.getCallee());
@@ -529,6 +526,9 @@ bool PreISelIntrinsicLowering::lowerIntrinsics(Module &M) const {
     case Intrinsic::objc_retainAutoreleasedReturnValue:
       Changed |= lowerObjCCall(F, "objc_retainAutoreleasedReturnValue");
       break;
+    case Intrinsic::objc_claimAutoreleasedReturnValue:
+      Changed |= lowerObjCCall(F, "objc_claimAutoreleasedReturnValue");
+      break;
     case Intrinsic::objc_retainBlock:
       Changed |= lowerObjCCall(F, "objc_retainBlock");
       break;

llvm/lib/IR/Verifier.cpp

@@ -7282,11 +7282,13 @@ void Verifier::verifyAttachedCallBundle(const CallBase &Call,
 
   if (IID) {
     Check((IID == Intrinsic::objc_retainAutoreleasedReturnValue ||
+           IID == Intrinsic::objc_claimAutoreleasedReturnValue ||
            IID == Intrinsic::objc_unsafeClaimAutoreleasedReturnValue),
           "invalid function argument", Call);
   } else {
     StringRef FnName = Fn->getName();
     Check((FnName == "objc_retainAutoreleasedReturnValue" ||
+           FnName == "objc_claimAutoreleasedReturnValue" ||
            FnName == "objc_unsafeClaimAutoreleasedReturnValue"),
           "invalid function argument", Call);
   }

llvm/lib/Target/AArch64/AArch64ISelLowering.cpp

@@ -9545,7 +9545,9 @@ AArch64TargetLowering::LowerCall(CallLoweringInfo &CLI,
     // Do what the frontend tells us: if the rvmarker module flag is present,
     // emit the marker.  Always emit the call regardless.
     // Tell the pseudo expansion using an additional boolean op.
-    SDValue DoEmitMarker = DAG.getTargetConstant(true, DL, MVT::i32);
+    bool ShouldEmitMarker = objcarc::attachedCallOpBundleNeedsMarker(CLI.CB);
+    SDValue DoEmitMarker =
+        DAG.getTargetConstant(ShouldEmitMarker, DL, MVT::i32);
     Ops.insert(Ops.begin() + 2, DoEmitMarker);
   } else if (CallConv == CallingConv::ARM64EC_Thunk_X64) {
     Opc = AArch64ISD::CALL_ARM64EC_TO_X64;

llvm/lib/Target/AArch64/GISel/AArch64CallLowering.cpp

@@ -1369,7 +1369,7 @@ bool AArch64CallLowering::lowerCall(MachineIRBuilder &MIRBuilder,
     // Do what the frontend tells us: if the rvmarker module flag is present,
     // emit the marker.  Always emit the call regardless.
     // Tell the pseudo expansion using an additional boolean op.
-    MIB.addImm(true);
+    MIB.addImm(objcarc::attachedCallOpBundleNeedsMarker(Info.CB));
     ++CalleeOpNo;
   } else if (Info.CFIType) {
     MIB->setCFIType(MF, Info.CFIType->getZExtValue());