diff options
Diffstat (limited to 'llvm/lib/Transforms')
| -rw-r--r-- | llvm/lib/Transforms/Scalar/ObjCARC.cpp | 27 |
1 files changed, 25 insertions, 2 deletions
diff --git a/llvm/lib/Transforms/Scalar/ObjCARC.cpp b/llvm/lib/Transforms/Scalar/ObjCARC.cpp index 34700ebb02c..1607e8e80a5 100644 --- a/llvm/lib/Transforms/Scalar/ObjCARC.cpp +++ b/llvm/lib/Transforms/Scalar/ObjCARC.cpp @@ -426,10 +426,20 @@ static bool IsAlwaysTail(InstructionClass Class) { // IC_RetainBlock may be given a stack argument. return Class == IC_Retain || Class == IC_RetainRV || - Class == IC_Autorelease || Class == IC_AutoreleaseRV; } +/// \brief Test if the given class represents instructions which are never safe +/// to mark with the "tail" keyword. +static bool IsNeverTail(InstructionClass Class) { + /// It is never safe to tail call objc_autorelease since by tail calling + /// objc_autorelease, we also tail call -[NSObject autorelease] which supports + /// fast autoreleasing causing our object to be potentially reclaimed from the + /// autorelease pool which violates the semantics of __autoreleasing types in + /// ARC. + return Class == IC_Autorelease; +} + /// IsNoThrow - Test if the given class represents instructions which are always /// safe to mark with the nounwind attribute.. static bool IsNoThrow(InstructionClass Class) { @@ -2306,8 +2316,10 @@ ObjCARCOpt::OptimizeAutoreleaseRVCall(Function &F, Instruction *AutoreleaseRV) { " Old: " << *AutoreleaseRV << "\n"); - cast<CallInst>(AutoreleaseRV)-> + CallInst *AutoreleaseRVCI = cast<CallInst>(AutoreleaseRV); + AutoreleaseRVCI-> setCalledFunction(getAutoreleaseCallee(F.getParent())); + AutoreleaseRVCI->setTailCall(false); // Never tail call objc_autorelease. DEBUG(dbgs() << " New: " << *AutoreleaseRV << "\n"); @@ -2449,6 +2461,16 @@ void ObjCARCOpt::OptimizeIndividualCalls(Function &F) { cast<CallInst>(Inst)->setTailCall(); } + // Ensure that functions that can never have a "tail" keyword due to the + // semantics of ARC truly do not do so. + if (IsNeverTail(Class)) { + Changed = true; + DEBUG(dbgs() << "ObjCARCOpt::OptimizeIndividualCalls: Removing tail keyword" + " from function: " << *Inst << + "\n"); + cast<CallInst>(Inst)->setTailCall(false); + } + // Set nounwind as needed. if (IsNoThrow(Class)) { Changed = true; @@ -3756,6 +3778,7 @@ void ObjCARCOpt::OptimizeReturns(Function &F) { Autorelease->setCalledFunction(getAutoreleaseRVCallee(F.getParent())); DEBUG(dbgs() << " Out: " << *Autorelease << "\n"); + Autorelease->setTailCall(); // Always tail call autoreleaseRV. AutoreleaseClass = IC_AutoreleaseRV; } |
