#include "llvm/ADT/StringSwitch.h"
#include "llvm/ADT/Optional.h"
#include "llvm/Analysis/AliasAnalysis.h"
+#include "llvm/Analysis/ObjCARCAnalysisUtils.h"
+#include "llvm/Analysis/ObjCARCInstKind.h"
#include "llvm/Analysis/Passes.h"
#include "llvm/Analysis/ValueTracking.h"
#include "llvm/IR/CallSite.h"
#include "llvm/Pass.h"
#include "llvm/Transforms/ObjCARC.h"
#include "llvm/Transforms/Utils/Local.h"
-#include "ARCInstKind.h"
namespace llvm {
class raw_ostream;
namespace llvm {
namespace objcarc {
-/// \brief A handy option to enable/disable all ARC Optimizations.
-extern bool EnableARCOpts;
-
-/// \brief Test if the given module looks interesting to run ARC optimization
-/// on.
-static inline bool ModuleHasARC(const Module &M) {
- return
- M.getNamedValue("objc_retain") ||
- M.getNamedValue("objc_release") ||
- M.getNamedValue("objc_autorelease") ||
- M.getNamedValue("objc_retainAutoreleasedReturnValue") ||
- M.getNamedValue("objc_retainBlock") ||
- M.getNamedValue("objc_autoreleaseReturnValue") ||
- M.getNamedValue("objc_autoreleasePoolPush") ||
- M.getNamedValue("objc_loadWeakRetained") ||
- M.getNamedValue("objc_loadWeak") ||
- M.getNamedValue("objc_destroyWeak") ||
- M.getNamedValue("objc_storeWeak") ||
- M.getNamedValue("objc_initWeak") ||
- M.getNamedValue("objc_moveWeak") ||
- M.getNamedValue("objc_copyWeak") ||
- M.getNamedValue("objc_retainedObject") ||
- M.getNamedValue("objc_unretainedObject") ||
- M.getNamedValue("objc_unretainedPointer") ||
- M.getNamedValue("clang.arc.use");
-}
-
-/// \brief This is a wrapper around getUnderlyingObject which also knows how to
-/// look through objc_retain and objc_autorelease calls, which we know to return
-/// their argument verbatim.
-static inline const Value *GetUnderlyingObjCPtr(const Value *V,
- const DataLayout &DL) {
- for (;;) {
- V = GetUnderlyingObject(V, DL);
- if (!IsForwarding(GetBasicARCInstKind(V)))
- break;
- V = cast<CallInst>(V)->getArgOperand(0);
- }
-
- return V;
-}
-
-/// The RCIdentity root of a value \p V is a dominating value U for which
-/// retaining or releasing U is equivalent to retaining or releasing V. In other
-/// words, ARC operations on \p V are equivalent to ARC operations on \p U.
-///
-/// We use this in the ARC optimizer to make it easier to match up ARC
-/// operations by always mapping ARC operations to RCIdentityRoots instead of
-/// pointers themselves.
-///
-/// The two ways that we see RCIdentical values in ObjC are via:
-///
-/// 1. PointerCasts
-/// 2. Forwarding Calls that return their argument verbatim.
-///
-/// Thus this function strips off pointer casts and forwarding calls. *NOTE*
-/// This implies that two RCIdentical values must alias.
-static inline const Value *GetRCIdentityRoot(const Value *V) {
- for (;;) {
- V = V->stripPointerCasts();
- if (!IsForwarding(GetBasicARCInstKind(V)))
- break;
- V = cast<CallInst>(V)->getArgOperand(0);
- }
- return V;
-}
-
-/// Helper which calls const Value *GetRCIdentityRoot(const Value *V) and just
-/// casts away the const of the result. For documentation about what an
-/// RCIdentityRoot (and by extension GetRCIdentityRoot is) look at that
-/// function.
-static inline Value *GetRCIdentityRoot(Value *V) {
- return const_cast<Value *>(GetRCIdentityRoot((const Value *)V));
-}
-
-/// \brief Assuming the given instruction is one of the special calls such as
-/// objc_retain or objc_release, return the RCIdentity root of the argument of
-/// the call.
-static inline Value *GetArgRCIdentityRoot(Value *Inst) {
- return GetRCIdentityRoot(cast<CallInst>(Inst)->getArgOperand(0));
-}
-
-static inline bool IsNullOrUndef(const Value *V) {
- return isa<ConstantPointerNull>(V) || isa<UndefValue>(V);
-}
-
-static inline bool IsNoopInstruction(const Instruction *I) {
- return isa<BitCastInst>(I) ||
- (isa<GetElementPtrInst>(I) &&
- cast<GetElementPtrInst>(I)->hasAllZeroIndices());
-}
-
-
/// \brief Erase the given instruction.
///
/// Many ObjC calls return their argument verbatim,
RecursivelyDeleteTriviallyDeadInstructions(OldArg);
}
-/// \brief Test whether the given value is possible a retainable object pointer.
-static inline bool IsPotentialRetainableObjPtr(const Value *Op) {
- // Pointers to static or stack storage are not valid retainable object
- // pointers.
- if (isa<Constant>(Op) || isa<AllocaInst>(Op))
- return false;
- // Special arguments can not be a valid retainable object pointer.
- if (const Argument *Arg = dyn_cast<Argument>(Op))
- if (Arg->hasByValAttr() ||
- Arg->hasInAllocaAttr() ||
- Arg->hasNestAttr() ||
- Arg->hasStructRetAttr())
- return false;
- // Only consider values with pointer types.
- //
- // It seemes intuitive to exclude function pointer types as well, since
- // functions are never retainable object pointers, however clang occasionally
- // bitcasts retainable object pointers to function-pointer type temporarily.
- PointerType *Ty = dyn_cast<PointerType>(Op->getType());
- if (!Ty)
- return false;
- // Conservatively assume anything else is a potential retainable object
- // pointer.
- return true;
-}
-
-static inline bool IsPotentialRetainableObjPtr(const Value *Op,
- AliasAnalysis &AA) {
- // First make the rudimentary check.
- if (!IsPotentialRetainableObjPtr(Op))
- return false;
-
- // Objects in constant memory are not reference-counted.
- if (AA.pointsToConstantMemory(Op))
- return false;
-
- // Pointers in constant memory are not pointing to reference-counted objects.
- if (const LoadInst *LI = dyn_cast<LoadInst>(Op))
- if (AA.pointsToConstantMemory(LI->getPointerOperand()))
- return false;
-
- // Otherwise assume the worst.
- return true;
-}
-
-/// \brief Helper for GetARCInstKind. Determines what kind of construct CS
-/// is.
-static inline ARCInstKind GetCallSiteClass(ImmutableCallSite CS) {
- for (ImmutableCallSite::arg_iterator I = CS.arg_begin(), E = CS.arg_end();
- I != E; ++I)
- if (IsPotentialRetainableObjPtr(*I))
- return CS.onlyReadsMemory() ? ARCInstKind::User : ARCInstKind::CallOrUser;
-
- return CS.onlyReadsMemory() ? ARCInstKind::None : ARCInstKind::Call;
-}
-
-/// \brief Return true if this value refers to a distinct and identifiable
-/// object.
-///
-/// This is similar to AliasAnalysis's isIdentifiedObject, except that it uses
-/// special knowledge of ObjC conventions.
-static inline bool IsObjCIdentifiedObject(const Value *V) {
- // Assume that call results and arguments have their own "provenance".
- // Constants (including GlobalVariables) and Allocas are never
- // reference-counted.
- if (isa<CallInst>(V) || isa<InvokeInst>(V) ||
- isa<Argument>(V) || isa<Constant>(V) ||
- isa<AllocaInst>(V))
- return true;
-
- if (const LoadInst *LI = dyn_cast<LoadInst>(V)) {
- const Value *Pointer =
- GetRCIdentityRoot(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.
- if (Name.startswith("\01l_objc_msgSend_fixup_"))
- return true;
-
- StringRef Section = GV->getSection();
- if (Section.find("__message_refs") != StringRef::npos ||
- Section.find("__objc_classrefs") != StringRef::npos ||
- Section.find("__objc_superrefs") != StringRef::npos ||
- Section.find("__objc_methname") != StringRef::npos ||
- Section.find("__cstring") != StringRef::npos)
- return true;
- }
- }
-
- return false;
-}
-
-enum class ARCMDKindID {
- ImpreciseRelease,
- CopyOnEscape,
- NoObjCARCExceptions,
-};
-
-/// A cache of MDKinds used by various ARC optimizations.
-class ARCMDKindCache {
- Module *M;
-
- /// The Metadata Kind for clang.imprecise_release metadata.
- llvm::Optional<unsigned> ImpreciseReleaseMDKind;
-
- /// The Metadata Kind for clang.arc.copy_on_escape metadata.
- llvm::Optional<unsigned> CopyOnEscapeMDKind;
-
- /// The Metadata Kind for clang.arc.no_objc_arc_exceptions metadata.
- llvm::Optional<unsigned> NoObjCARCExceptionsMDKind;
-
-public:
- void init(Module *Mod) {
- M = Mod;
- ImpreciseReleaseMDKind = NoneType::None;
- CopyOnEscapeMDKind = NoneType::None;
- NoObjCARCExceptionsMDKind = NoneType::None;
- }
-
- unsigned get(ARCMDKindID ID) {
- switch (ID) {
- case ARCMDKindID::ImpreciseRelease:
- if (!ImpreciseReleaseMDKind)
- ImpreciseReleaseMDKind =
- M->getContext().getMDKindID("clang.imprecise_release");
- return *ImpreciseReleaseMDKind;
- case ARCMDKindID::CopyOnEscape:
- if (!CopyOnEscapeMDKind)
- CopyOnEscapeMDKind =
- M->getContext().getMDKindID("clang.arc.copy_on_escape");
- return *CopyOnEscapeMDKind;
- case ARCMDKindID::NoObjCARCExceptions:
- if (!NoObjCARCExceptionsMDKind)
- NoObjCARCExceptionsMDKind =
- M->getContext().getMDKindID("clang.arc.no_objc_arc_exceptions");
- return *NoObjCARCExceptionsMDKind;
- }
- llvm_unreachable("Covered switch isn't covered?!");
- }
-};
-
} // end namespace objcarc
} // end namespace llvm
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