Skip to content

[ObjC] Support objc_claimAutoreleasedReturnValue #139720

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
merged 2 commits into from
May 13, 2025

Conversation

citymarina
Copy link
Contributor

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.

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]>
@llvmbot
Copy link
Member

llvmbot commented May 13, 2025

@llvm/pr-subscribers-backend-aarch64

@llvm/pr-subscribers-llvm-ir

Author: Marina Taylor (citymarina)

Changes

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.


Full diff: https://github.com/llvm/llvm-project/pull/139720.diff

7 Files Affected:

  • (modified) llvm/include/llvm/Analysis/ObjCARCUtil.h (+15)
  • (modified) llvm/include/llvm/IR/Intrinsics.td (+7-2)
  • (modified) llvm/lib/CodeGen/PreISelIntrinsicLowering.cpp (+4-4)
  • (modified) llvm/lib/IR/Verifier.cpp (+2)
  • (modified) llvm/lib/Target/AArch64/AArch64ISelLowering.cpp (+3-3)
  • (modified) llvm/lib/Target/AArch64/GISel/AArch64CallLowering.cpp (+1-3)
  • (modified) llvm/test/CodeGen/AArch64/call-rv-marker.ll (+28)
diff --git a/llvm/include/llvm/Analysis/ObjCARCUtil.h b/llvm/include/llvm/Analysis/ObjCARCUtil.h
index 62e13eb2a5722..7dc0c50809f06 100644
--- a/llvm/include/llvm/Analysis/ObjCARCUtil.h
+++ b/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;
diff --git a/llvm/include/llvm/IR/Intrinsics.td b/llvm/include/llvm/IR/Intrinsics.td
index 8d26961eebbf3..28450f03b7619 100644
--- a/llvm/include/llvm/IR/Intrinsics.td
+++ b/llvm/include/llvm/IR/Intrinsics.td
@@ -785,10 +785,12 @@ 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>>]>;
@@ -797,6 +799,11 @@ 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<[],
@@ -810,8 +817,6 @@ 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],
diff --git a/llvm/lib/CodeGen/PreISelIntrinsicLowering.cpp b/llvm/lib/CodeGen/PreISelIntrinsicLowering.cpp
index 1c2912358dcb3..6f52b7cac1d46 100644
--- a/llvm/lib/CodeGen/PreISelIntrinsicLowering.cpp
+++ b/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;
diff --git a/llvm/lib/IR/Verifier.cpp b/llvm/lib/IR/Verifier.cpp
index 2cfd3822ea05d..043249cd5b017 100644
--- a/llvm/lib/IR/Verifier.cpp
+++ b/llvm/lib/IR/Verifier.cpp
@@ -7283,11 +7283,13 @@ 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);
   }
diff --git a/llvm/lib/Target/AArch64/AArch64ISelLowering.cpp b/llvm/lib/Target/AArch64/AArch64ISelLowering.cpp
index ad48be4531d3b..13fb6a32233fe 100644
--- a/llvm/lib/Target/AArch64/AArch64ISelLowering.cpp
+++ b/llvm/lib/Target/AArch64/AArch64ISelLowering.cpp
@@ -9545,10 +9545,10 @@ AArch64TargetLowering::LowerCall(CallLoweringInfo &CLI,
     Ops.insert(Ops.begin() + 1, GA);
 
     // We may or may not need to emit both the marker and the retain/claim call.
-    // 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;
diff --git a/llvm/lib/Target/AArch64/GISel/AArch64CallLowering.cpp b/llvm/lib/Target/AArch64/GISel/AArch64CallLowering.cpp
index 91e453657f2f6..9bef102e8abf1 100644
--- a/llvm/lib/Target/AArch64/GISel/AArch64CallLowering.cpp
+++ b/llvm/lib/Target/AArch64/GISel/AArch64CallLowering.cpp
@@ -1366,10 +1366,8 @@ bool AArch64CallLowering::lowerCall(MachineIRBuilder &MIRBuilder,
     ++CalleeOpNo;
 
     // We may or may not need to emit both the marker and the retain/claim call.
-    // 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());
diff --git a/llvm/test/CodeGen/AArch64/call-rv-marker.ll b/llvm/test/CodeGen/AArch64/call-rv-marker.ll
index ee8cbe45da083..b22370a295749 100644
--- a/llvm/test/CodeGen/AArch64/call-rv-marker.ll
+++ b/llvm/test/CodeGen/AArch64/call-rv-marker.ll
@@ -544,7 +544,35 @@ define dso_local void @rv_marker_multiarg(i64 %a, i64 %b, i64 %c) {
   ret void
 }
 
+define dso_local ptr @rv_marker_claim() {
+; SELDAG-LABEL: rv_marker_claim:
+; SELDAG:       ; %bb.0: ; %entry
+; SELDAG-NEXT:    stp x29, x30, [sp, #-16]! ; 16-byte Folded Spill
+; SELDAG-NEXT:    .cfi_def_cfa_offset 16
+; SELDAG-NEXT:    .cfi_offset w30, -8
+; SELDAG-NEXT:    .cfi_offset w29, -16
+; SELDAG-NEXT:    bl _foo1
+; SELDAG-NEXT:    bl _objc_claimAutoreleasedReturnValue
+; SELDAG-NEXT:    ldp x29, x30, [sp], #16 ; 16-byte Folded Reload
+; SELDAG-NEXT:    ret
+;
+; GISEL-LABEL: rv_marker_claim:
+; GISEL:       ; %bb.0: ; %entry
+; GISEL-NEXT:    stp x29, x30, [sp, #-16]! ; 16-byte Folded Spill
+; GISEL-NEXT:    .cfi_def_cfa_offset 16
+; GISEL-NEXT:    .cfi_offset w30, -8
+; GISEL-NEXT:    .cfi_offset w29, -16
+; GISEL-NEXT:    bl _foo1
+; GISEL-NEXT:    bl _objc_claimAutoreleasedReturnValue
+; GISEL-NEXT:    ldp x29, x30, [sp], #16 ; 16-byte Folded Reload
+; GISEL-NEXT:    ret
+entry:
+  %call = call ptr @foo1() [ "clang.arc.attachedcall"(ptr @objc_claimAutoreleasedReturnValue) ]
+  ret ptr %call
+}
+
 declare ptr @objc_retainAutoreleasedReturnValue(ptr)
+declare ptr @objc_claimAutoreleasedReturnValue(ptr)
 declare ptr @objc_unsafeClaimAutoreleasedReturnValue(ptr)
 declare i32 @__gxx_personality_v0(...)
 ;; NOTE: These prefixes are unused and the list is autogenerated. Do not add tests below this line:

@citymarina
Copy link
Contributor Author

This was reviewed in #138696 but I accidentally merged it into my user branch rather than main. Sorry for the noise.

@citymarina citymarina merged commit 4b794c8 into llvm:main May 13, 2025
8 of 10 checks passed
@citymarina citymarina deleted the users/citymarina/objc-claim-oops2 branch May 13, 2025 18:25
Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment
Projects
None yet
Development

Successfully merging this pull request may close these issues.

2 participants