[ObjC][ARC] Upgrade calls to ARC runtime functions to intrinsic calls if the bitcode has the arm64 retainAutoreleasedReturnValue marker

[ahatanak]

Summary

The ARC middle-end passes stopped optimizing or transforming bitcode that has been compiled with old compilers after we started emitting calls to ARC runtime functions as intrinsic calls instead of normal function calls in the front-end and made changes to teach the ARC middle-end passes about those intrinsics (see r349534). This patch converts calls to ARC runtime functions that are not intrinsic functions to intrinsic function calls if the bitcode has the arm64 retainAutoreleasedReturnValue marker. Checking for the presence of the marker is necessary to make sure we aren't changing ARC function calls that were originally MRR message sends (see r349952).

rdar://problem/53280660

[pete]

Looks like the tests are extremely comprehensive. LGTM.

[steven_wu]

From my previous change, we dropped clang.arc.used from the old bitcode. Should we upgrade clang.arc.used instead of dropping them?

[ahatanak]

Since ARC optimizer needs clang.arc.use to correctly move or remove retain/release pairs (see the comment in TopDownPtrState::HandlePotentialAlterRefCount), I think we should unconditionally upgrade the intrinsic calls instead of removing them even when the bitcode doesn't have the arm64 marker. I'll update the patch to convert clang.arc.use to llvm.objc.clang.arc.use.

[ahatanak]

Upgrade clang.arc.use to llvm.objc.clang.arc.use.

[ahatanak]

Initialize variable Changed with the return value of the call to UpgradeToIntrinsic.

[steven_wu]

LGTM

llvm/include/llvm/IR/AutoUpgrade.h

namespace llvm {
   /// This checks for module flags which should be upgraded. It returns true if
   /// module is modified.
   bool UpgradeModuleFlags(Module &M);
 
   /// This checks for objc retain release marker which should be upgraded. It
   /// returns true if module is modified.
   bool UpgradeRetainReleaseMarker(Module &M);
 
+  /// Convert calls to ARC runtime functions to intrinsic calls if the bitcode
+  /// has the arm64 retainAutoreleasedReturnValue marker.
+  bool UpgradeARCRuntimeCalls(Module &M);
+
   void UpgradeSectionAttributes(Module &M);
 
   /// If the given TBAA tag uses the scalar TBAA format, create a new node
   /// corresponding to the upgrade to the struct-path aware TBAA format.
   /// Otherwise return the \p TBAANode itself.
   MDNode *UpgradeTBAANode(MDNode &TBAANode);
 
   /// This is an auto-upgrade for bitcast between pointers with different

llvm/lib/Bitcode/Reader/BitcodeReader.cpp

Error BitcodeReader::materializeModule() {
   }
   RemangledIntrinsics.clear();
 
   UpgradeDebugInfo(*TheModule);
 
   UpgradeModuleFlags(*TheModule);
 
   UpgradeRetainReleaseMarker(*TheModule);
+  UpgradeARCRuntimeCalls(*TheModule);
 
   return Error::success();
 }
 
 std::vector<StructType *> BitcodeReader::getIdentifiedStructTypes() const {
   return IdentifiedStructTypes;
 }
 

llvm/lib/IR/AutoUpgrade.cpp

if (Op) {
         M.eraseNamedMetadata(ModRetainReleaseMarker);
         Changed = true;
       }
     }
   }
   return Changed;
 }
 
+bool llvm::UpgradeARCRuntimeCalls(Module &M) {
+  // Return if the bitcode doesn't have the arm64 retainAutoreleasedReturnValue
+  // marker. We don't know for sure that it was compiled with ARC in that case.
+  if (!M.getModuleFlag("clang.arc.retainAutoreleasedReturnValueMarker"))
+    return false;
+
+  bool Changed = false;
+  std::pair<const char *, llvm::Intrinsic::ID> RuntimeFuncs[] = {
+      {"objc_autorelease", llvm::Intrinsic::objc_autorelease},
+      {"objc_autoreleasePoolPop", llvm::Intrinsic::objc_autoreleasePoolPop},
+      {"objc_autoreleasePoolPush", llvm::Intrinsic::objc_autoreleasePoolPush},
+      {"objc_autoreleaseReturnValue",
+       llvm::Intrinsic::objc_autoreleaseReturnValue},
+      {"objc_copyWeak", llvm::Intrinsic::objc_copyWeak},
+      {"objc_destroyWeak", llvm::Intrinsic::objc_destroyWeak},
+      {"objc_initWeak", llvm::Intrinsic::objc_initWeak},
+      {"objc_loadWeak", llvm::Intrinsic::objc_loadWeak},
+      {"objc_loadWeakRetained", llvm::Intrinsic::objc_loadWeakRetained},
+      {"objc_moveWeak", llvm::Intrinsic::objc_moveWeak},
+      {"objc_release", llvm::Intrinsic::objc_release},
+      {"objc_retain", llvm::Intrinsic::objc_retain},
+      {"objc_retainAutorelease", llvm::Intrinsic::objc_retainAutorelease},
+      {"objc_retainAutoreleaseReturnValue",
+       llvm::Intrinsic::objc_retainAutoreleaseReturnValue},
+      {"objc_retainAutoreleasedReturnValue",
+       llvm::Intrinsic::objc_retainAutoreleasedReturnValue},
+      {"objc_retainBlock", llvm::Intrinsic::objc_retainBlock},
+      {"objc_storeStrong", llvm::Intrinsic::objc_storeStrong},
+      {"objc_storeWeak", llvm::Intrinsic::objc_storeWeak},
+      {"objc_clang_arc_use", llvm::Intrinsic::objc_clang_arc_use},
+      {"objc_unsafeClaimAutoreleasedReturnValue",
+       llvm::Intrinsic::objc_unsafeClaimAutoreleasedReturnValue},
+      {"objc_retainedObject", llvm::Intrinsic::objc_retainedObject},
+      {"objc_unretainedObject", llvm::Intrinsic::objc_unretainedObject},
+      {"objc_unretainedPointer", llvm::Intrinsic::objc_unretainedPointer},
+      {"objc_retain_autorelease", llvm::Intrinsic::objc_retain_autorelease},
+      {"objc_sync_enter", llvm::Intrinsic::objc_sync_enter},
+      {"objc_sync_exit", llvm::Intrinsic::objc_sync_exit},
+      {"objc_arc_annotation_topdown_bbstart",
+       llvm::Intrinsic::objc_arc_annotation_topdown_bbstart},
+      {"objc_arc_annotation_topdown_bbend",
+       llvm::Intrinsic::objc_arc_annotation_topdown_bbend},
+      {"objc_arc_annotation_bottomup_bbstart",
+       llvm::Intrinsic::objc_arc_annotation_bottomup_bbstart},
+      {"objc_arc_annotation_bottomup_bbend",
+       llvm::Intrinsic::objc_arc_annotation_bottomup_bbend}};
+
+  for (auto &I : RuntimeFuncs) {
+    Function *Fn = M.getFunction(I.first);
+
+    if (!Fn)
+      continue;
+
+    Function *NewFn = llvm::Intrinsic::getDeclaration(&M, I.second);
+    Fn->replaceAllUsesWith(NewFn);
+    Fn->eraseFromParent();
+    Changed = true;
+  }
+
+  return Changed;
+}
+
 bool llvm::UpgradeModuleFlags(Module &M) {
   NamedMDNode *ModFlags = M.getModuleFlagsMetadata();
   if (!ModFlags)
     return false;
 
   bool HasObjCFlag = false, HasClassProperties = false, Changed = false;
   for (unsigned I = 0, E = ModFlags->getNumOperands(); I != E; ++I) {
     MDNode *Op = ModFlags->getOperand(I);

llvm/test/Bitcode/upgrade-arc-runtime-calls.ll

+; Test that calls to ARC runtime functions are converted to intrinsic calls if
+; the bitcode has the arm64 retainAutoreleasedReturnValueMarker metadata.
+
+; upgrade-arc-runtime-calls.bc and upgrade-mrr-runtime-calls.bc are identical
+; except that the former has the arm64 retainAutoreleasedReturnValueMarker
+; metadata.
+
+; RUN: llvm-dis < %S/upgrade-arc-runtime-calls.bc | FileCheck -check-prefixes=ARC %s
+; RUN: llvm-dis < %S/upgrade-mrr-runtime-calls.bc | FileCheck -check-prefixes=MRR %s
+
+// ARC: define void @testRuntimeCalls(i8* %[[A:.*]], i8** %[[B:.*]], i8** %[[C:.*]]) {
+// ARC: %[[V0:.*]] = tail call i8* @llvm.objc.autorelease(i8* %[[A]])
+// ARC-NEXT: tail call void @llvm.objc.autoreleasePoolPop(i8* %[[A]])
+// ARC-NEXT: %[[V1:.*]] = tail call i8* @llvm.objc.autoreleasePoolPush()
+// ARC-NEXT: %[[V2:.*]] = tail call i8* @llvm.objc.autoreleaseReturnValue(i8* %[[A]])
+// ARC-NEXT: tail call void @llvm.objc.copyWeak(i8** %[[B]], i8** %[[C]])
+// ARC-NEXT: tail call void @llvm.objc.destroyWeak(i8** %[[B]])
+// ARC-NEXT: %[[V3:.*]] = tail call i8* @llvm.objc.initWeak(i8** %[[B]], i8* %[[A]])
+// ARC-NEXT: %[[V4:.*]] = tail call i8* @llvm.objc.loadWeak(i8** %[[B]])
+// ARC-NEXT: %[[V5:.*]] = tail call i8* @llvm.objc.loadWeakRetained(i8** %[[B]])
+// ARC-NEXT: tail call void @llvm.objc.moveWeak(i8** %[[B]], i8** %[[C]])
+// ARC-NEXT: tail call void @llvm.objc.release(i8* %[[A]])
+// ARC-NEXT: %[[V6:.*]] = tail call i8* @llvm.objc.retain(i8* %[[A]])
+// ARC-NEXT: %[[V7:.*]] = tail call i8* @llvm.objc.retainAutorelease(i8* %[[A]])
+// ARC-NEXT: %[[V8:.*]] = tail call i8* @llvm.objc.retainAutoreleaseReturnValue(i8* %[[A]])
+// ARC-NEXT: %[[V9:.*]] = tail call i8* @llvm.objc.retainAutoreleasedReturnValue(i8* %[[A]])
+// ARC-NEXT: %[[V10:.*]] = tail call i8* @llvm.objc.retainBlock(i8* %[[A]])
+// ARC-NEXT: tail call void @llvm.objc.storeStrong(i8** %[[B]], i8* %[[A]])
+// ARC-NEXT: %[[V11:.*]] = tail call i8* @llvm.objc.storeWeak(i8** %[[B]], i8* %[[A]])
+// ARC-NEXT: tail call void (...) @objc_arc_use(i8* %[[A]])
+// ARC-NEXT: %[[V12:.*]] = tail call i8* @llvm.objc.unsafeClaimAutoreleasedReturnValue(i8* %[[A]])
+// ARC-NEXT: %[[V13:.*]] = tail call i8* @llvm.objc.retainedObject(i8* %[[A]])
+// ARC-NEXT: %[[V14:.*]] = tail call i8* @llvm.objc.unretainedObject(i8* %[[A]])
+// ARC-NEXT: %[[V15:.*]] = tail call i8* @llvm.objc.unretainedPointer(i8* %[[A]])
+// ARC-NEXT: %[[V16:.*]] = tail call i8* @objc_retain.autorelease(i8* %[[A]])
+// ARC-NEXT: %[[V17:.*]] = tail call i32 @objc_sync.enter(i8* %[[A]])
+// ARC-NEXT: %[[V18:.*]] = tail call i32 @objc_sync.exit(i8* %[[A]])
+// ARC-NEXT: tail call void @llvm.objc.arc.annotation.topdown.bbstart(i8** %[[B]], i8** %[[C]])
+// ARC-NEXT: tail call void @llvm.objc.arc.annotation.topdown.bbend(i8** %[[B]], i8** %[[C]])
+// ARC-NEXT: tail call void @llvm.objc.arc.annotation.bottomup.bbstart(i8** %[[B]], i8** %[[C]])
+// ARC-NEXT: tail call void @llvm.objc.arc.annotation.bottomup.bbend(i8** %[[B]], i8** %[[C]])
+// ARC-NEXT: ret void
+
+// MRR: define void @testRuntimeCalls(i8* %[[A:.*]], i8** %[[B:.*]], i8** %[[C:.*]]) {
+// MRR: %[[V0:.*]] = tail call i8* @objc_autorelease(i8* %[[A]])
+// MRR-NEXT: tail call void @objc_autoreleasePoolPop(i8* %[[A]])
+// MRR-NEXT: %[[V1:.*]] = tail call i8* @objc_autoreleasePoolPush()
+// MRR-NEXT: %[[V2:.*]] = tail call i8* @objc_autoreleaseReturnValue(i8* %[[A]])
+// MRR-NEXT: tail call void @objc_copyWeak(i8** %[[B]], i8** %[[C]])
+// MRR-NEXT: tail call void @objc_destroyWeak(i8** %[[B]])
+// MRR-NEXT: %[[V3:.*]] = tail call i8* @objc_initWeak(i8** %[[B]], i8* %[[A]])
+// MRR-NEXT: %[[V4:.*]] = tail call i8* @objc_loadWeak(i8** %[[B]])
+// MRR-NEXT: %[[V5:.*]] = tail call i8* @objc_loadWeakRetained(i8** %[[B]])
+// MRR-NEXT: tail call void @objc_moveWeak(i8** %[[B]], i8** %[[C]])
+// MRR-NEXT: tail call void @objc_release(i8* %[[A]])
+// MRR-NEXT: %[[V6:.*]] = tail call i8* @objc_retain(i8* %[[A]])
+// MRR-NEXT: %[[V7:.*]] = tail call i8* @objc_retainAutorelease(i8* %[[A]])
+// MRR-NEXT: %[[V8:.*]] = tail call i8* @objc_retainAutoreleaseReturnValue(i8* %[[A]])
+// MRR-NEXT: %[[V9:.*]] = tail call i8* @objc_retainAutoreleasedReturnValue(i8* %[[A]])
+// MRR-NEXT: %[[V10:.*]] = tail call i8* @objc_retainBlock(i8* %[[A]])
+// MRR-NEXT: tail call void @objc_storeStrong(i8** %[[B]], i8* %[[A]])
+// MRR-NEXT: %[[V11:.*]] = tail call i8* @objc_storeWeak(i8** %[[B]], i8* %[[A]])
+// MRR-NEXT: tail call void (...) @objc_arc_use(i8* %[[A]])
+// MRR-NEXT: %[[V12:.*]] = tail call i8* @objc_unsafeClaimAutoreleasedReturnValue(i8* %[[A]])
+// MRR-NEXT: %[[V13:.*]] = tail call i8* @objc_retainedObject(i8* %[[A]])
+// MRR-NEXT: %[[V14:.*]] = tail call i8* @objc_unretainedObject(i8* %[[A]])
+// MRR-NEXT: %[[V15:.*]] = tail call i8* @objc_unretainedPointer(i8* %[[A]])
+// MRR-NEXT: %[[V16:.*]] = tail call i8* @objc_retain.autorelease(i8* %[[A]])
+// MRR-NEXT: %[[V17:.*]] = tail call i32 @objc_sync.enter(i8* %[[A]])
+// MRR-NEXT: %[[V18:.*]] = tail call i32 @objc_sync.exit(i8* %[[A]])
+// MRR-NEXT: tail call void @objc_arc_annotation_topdown_bbstart(i8** %[[B]], i8** %[[C]])
+// MRR-NEXT: tail call void @objc_arc_annotation_topdown_bbend(i8** %[[B]], i8** %[[C]])
+// MRR-NEXT: tail call void @objc_arc_annotation_bottomup_bbstart(i8** %[[B]], i8** %[[C]])
+// MRR-NEXT: tail call void @objc_arc_annotation_bottomup_bbend(i8** %[[B]], i8** %[[C]])
+// MRR-NEXT: ret void