diff options
| -rw-r--r-- | llvm/lib/Transforms/Scalar/ObjCARC.cpp | 13 | ||||
| -rw-r--r-- | llvm/test/Transforms/ObjCARC/basic.ll | 33 |
2 files changed, 46 insertions, 0 deletions
diff --git a/llvm/lib/Transforms/Scalar/ObjCARC.cpp b/llvm/lib/Transforms/Scalar/ObjCARC.cpp index fea03b5f5b5..9654b1ecd30 100644 --- a/llvm/lib/Transforms/Scalar/ObjCARC.cpp +++ b/llvm/lib/Transforms/Scalar/ObjCARC.cpp @@ -515,6 +515,10 @@ static bool IsObjCIdentifiedObject(const Value *V) { const Value *Pointer = StripPointerCastsAndObjCCalls(LI->getPointerOperand()); if (const GlobalVariable *GV = dyn_cast<GlobalVariable>(Pointer)) { + // A constant pointer can't be pointing to an object on the heap. It may + // be reference-counted, but it won't be deleted. + if (GV->isConstant()) + return true; StringRef Name = GV->getName(); // These special variables are known to hold values which are not // reference-counted pointers. @@ -2744,6 +2748,15 @@ ObjCARCOpt::PerformCodePlacement(DenseMap<const BasicBlock *, BBState> // regardless of what possible decrements or uses lie between them. bool KnownSafe = isa<Constant>(Arg) || isa<AllocaInst>(Arg); + // A constant pointer can't be pointing to an object on the heap. It may + // be reference-counted, but it won't be deleted. + if (const LoadInst *LI = dyn_cast<LoadInst>(Arg)) + if (const GlobalVariable *GV = + dyn_cast<GlobalVariable>( + StripPointerCastsAndObjCCalls(LI->getPointerOperand()))) + if (GV->isConstant()) + KnownSafe = true; + // If a pair happens in a region where it is known that the reference count // is already incremented, we can similarly ignore possible decrements. bool KnownSafeTD = true, KnownSafeBU = true; diff --git a/llvm/test/Transforms/ObjCARC/basic.ll b/llvm/test/Transforms/ObjCARC/basic.ll index def703910c1..72f05ffaac9 100644 --- a/llvm/test/Transforms/ObjCARC/basic.ll +++ b/llvm/test/Transforms/ObjCARC/basic.ll @@ -1638,6 +1638,39 @@ entry: ret void } +; Constant pointers to objects don't need reference counting. + +@constptr = external constant i8* +@something = external global i8* + +; CHECK: define void @test60( +; CHECK-NOT: @objc_ +; CHECK: } +define void @test60() { + %t = load i8** @constptr + %s = load i8** @something + call i8* @objc_retain(i8* %s) + call void @callee() + call void @use_pointer(i8* %t) + call void @objc_release(i8* %s) + ret void +} + +; Constant pointers to objects don't need to be considered related to other +; pointers. + +; CHECK: define void @test61( +; CHECK-NOT: @objc_ +; CHECK: } +define void @test61() { + %t = load i8** @constptr + call i8* @objc_retain(i8* %t) + call void @callee() + call void @use_pointer(i8* %t) + call void @objc_release(i8* %t) + ret void +} + declare void @bar(i32 ()*) ; A few real-world testcases. |
