-//===- ObjCARC.h - ObjC ARC Optimization --------------*- mode: c++ -*-----===//
+//===- ObjCARC.h - ObjC ARC Optimization --------------*- C++ -*-----------===//
//
// The LLVM Compiler Infrastructure
//
///
//===----------------------------------------------------------------------===//
-#ifndef LLVM_TRANSFORMS_SCALAR_OBJCARC_H
-#define LLVM_TRANSFORMS_SCALAR_OBJCARC_H
+#ifndef LLVM_LIB_TRANSFORMS_OBJCARC_OBJCARC_H
+#define LLVM_LIB_TRANSFORMS_OBJCARC_OBJCARC_H
#include "llvm/ADT/StringSwitch.h"
#include "llvm/Analysis/AliasAnalysis.h"
#include "llvm/Analysis/Passes.h"
#include "llvm/Analysis/ValueTracking.h"
+#include "llvm/IR/CallSite.h"
+#include "llvm/IR/InstIterator.h"
#include "llvm/IR/Module.h"
#include "llvm/Pass.h"
-#include "llvm/Support/Debug.h"
-#include "llvm/Support/InstIterator.h"
-#include "llvm/Support/raw_ostream.h"
#include "llvm/Transforms/ObjCARC.h"
+#include "llvm/Transforms/Utils/Local.h"
+
+namespace llvm {
+class raw_ostream;
+}
namespace llvm {
namespace objcarc {
M.getNamedValue("objc_copyWeak") ||
M.getNamedValue("objc_retainedObject") ||
M.getNamedValue("objc_unretainedObject") ||
- M.getNamedValue("objc_unretainedPointer");
+ M.getNamedValue("objc_unretainedPointer") ||
+ M.getNamedValue("clang.arc.use");
}
/// \enum InstructionClass
IC_CopyWeak, ///< objc_copyWeak (derived)
IC_DestroyWeak, ///< objc_destroyWeak (derived)
IC_StoreStrong, ///< objc_storeStrong (derived)
+ IC_IntrinsicUser, ///< clang.arc.use
IC_CallOrUser, ///< could call objc_release and/or "use" pointers
IC_Call, ///< could call objc_release
IC_User, ///< could "use" a pointer
IC_None ///< anything else
};
-static raw_ostream &operator<<(raw_ostream &OS, const InstructionClass Class)
- LLVM_ATTRIBUTE_USED;
+raw_ostream &operator<<(raw_ostream &OS, const InstructionClass Class);
-static raw_ostream &operator<<(raw_ostream &OS, const InstructionClass Class) {
- switch (Class) {
- case IC_Retain:
- return OS << "IC_Retain";
- case IC_RetainRV:
- return OS << "IC_RetainRV";
- case IC_RetainBlock:
- return OS << "IC_RetainBlock";
- case IC_Release:
- return OS << "IC_Release";
- case IC_Autorelease:
- return OS << "IC_Autorelease";
- case IC_AutoreleaseRV:
- return OS << "IC_AutoreleaseRV";
- case IC_AutoreleasepoolPush:
- return OS << "IC_AutoreleasepoolPush";
- case IC_AutoreleasepoolPop:
- return OS << "IC_AutoreleasepoolPop";
- case IC_NoopCast:
- return OS << "IC_NoopCast";
- case IC_FusedRetainAutorelease:
- return OS << "IC_FusedRetainAutorelease";
- case IC_FusedRetainAutoreleaseRV:
- return OS << "IC_FusedRetainAutoreleaseRV";
- case IC_LoadWeakRetained:
- return OS << "IC_LoadWeakRetained";
- case IC_StoreWeak:
- return OS << "IC_StoreWeak";
- case IC_InitWeak:
- return OS << "IC_InitWeak";
- case IC_LoadWeak:
- return OS << "IC_LoadWeak";
- case IC_MoveWeak:
- return OS << "IC_MoveWeak";
- case IC_CopyWeak:
- return OS << "IC_CopyWeak";
- case IC_DestroyWeak:
- return OS << "IC_DestroyWeak";
- case IC_StoreStrong:
- return OS << "IC_StoreStrong";
- case IC_CallOrUser:
- return OS << "IC_CallOrUser";
- case IC_Call:
- return OS << "IC_Call";
- case IC_User:
- return OS << "IC_User";
- case IC_None:
- return OS << "IC_None";
- }
- llvm_unreachable("Unknown instruction class!");
+/// \brief Test if the given class is a kind of user.
+inline static bool IsUser(InstructionClass Class) {
+ return Class == IC_User ||
+ Class == IC_CallOrUser ||
+ Class == IC_IntrinsicUser;
}
/// \brief Test if the given class is objc_retain or equivalent.
/// \brief Test if the given class represents instructions which return their
/// argument verbatim.
static inline bool IsForwarding(InstructionClass Class) {
- // objc_retainBlock technically doesn't always return its argument
- // verbatim, but it doesn't matter for our purposes here.
return Class == IC_Retain ||
Class == IC_RetainRV ||
Class == IC_Autorelease ||
Class == IC_AutoreleaseRV ||
- Class == IC_RetainBlock ||
Class == IC_NoopCast;
}
Class == IC_AutoreleasepoolPop;
}
+/// Test whether the given instruction can autorelease any pointer or cause an
+/// autoreleasepool pop.
+static inline bool
+CanInterruptRV(InstructionClass Class) {
+ switch (Class) {
+ case IC_AutoreleasepoolPop:
+ case IC_CallOrUser:
+ case IC_Call:
+ case IC_Autorelease:
+ case IC_AutoreleaseRV:
+ case IC_FusedRetainAutorelease:
+ case IC_FusedRetainAutoreleaseRV:
+ return true;
+ default:
+ return false;
+ }
+}
+
/// \brief Determine if F is one of the special known Functions. If it isn't,
/// return IC_CallOrUser.
-static InstructionClass GetFunctionClass(const Function *F)
- LLVM_ATTRIBUTE_USED;
-static InstructionClass GetFunctionClass(const Function *F) {
- Function::const_arg_iterator AI = F->arg_begin(), AE = F->arg_end();
-
- // No arguments.
- if (AI == AE)
- return StringSwitch<InstructionClass>(F->getName())
- .Case("objc_autoreleasePoolPush", IC_AutoreleasepoolPush)
- .Default(IC_CallOrUser);
-
- // One argument.
- const Argument *A0 = AI++;
- if (AI == AE)
- // Argument is a pointer.
- if (PointerType *PTy = dyn_cast<PointerType>(A0->getType())) {
- Type *ETy = PTy->getElementType();
- // Argument is i8*.
- if (ETy->isIntegerTy(8))
- return StringSwitch<InstructionClass>(F->getName())
- .Case("objc_retain", IC_Retain)
- .Case("objc_retainAutoreleasedReturnValue", IC_RetainRV)
- .Case("objc_retainBlock", IC_RetainBlock)
- .Case("objc_release", IC_Release)
- .Case("objc_autorelease", IC_Autorelease)
- .Case("objc_autoreleaseReturnValue", IC_AutoreleaseRV)
- .Case("objc_autoreleasePoolPop", IC_AutoreleasepoolPop)
- .Case("objc_retainedObject", IC_NoopCast)
- .Case("objc_unretainedObject", IC_NoopCast)
- .Case("objc_unretainedPointer", IC_NoopCast)
- .Case("objc_retain_autorelease", IC_FusedRetainAutorelease)
- .Case("objc_retainAutorelease", IC_FusedRetainAutorelease)
- .Case("objc_retainAutoreleaseReturnValue",IC_FusedRetainAutoreleaseRV)
- .Default(IC_CallOrUser);
-
- // Argument is i8**
- if (PointerType *Pte = dyn_cast<PointerType>(ETy))
- if (Pte->getElementType()->isIntegerTy(8))
- return StringSwitch<InstructionClass>(F->getName())
- .Case("objc_loadWeakRetained", IC_LoadWeakRetained)
- .Case("objc_loadWeak", IC_LoadWeak)
- .Case("objc_destroyWeak", IC_DestroyWeak)
- .Default(IC_CallOrUser);
- }
-
- // Two arguments, first is i8**.
- const Argument *A1 = AI++;
- if (AI == AE)
- if (PointerType *PTy = dyn_cast<PointerType>(A0->getType()))
- if (PointerType *Pte = dyn_cast<PointerType>(PTy->getElementType()))
- if (Pte->getElementType()->isIntegerTy(8))
- if (PointerType *PTy1 = dyn_cast<PointerType>(A1->getType())) {
- Type *ETy1 = PTy1->getElementType();
- // Second argument is i8*
- if (ETy1->isIntegerTy(8))
- return StringSwitch<InstructionClass>(F->getName())
- .Case("objc_storeWeak", IC_StoreWeak)
- .Case("objc_initWeak", IC_InitWeak)
- .Case("objc_storeStrong", IC_StoreStrong)
- .Default(IC_CallOrUser);
- // Second argument is i8**.
- if (PointerType *Pte1 = dyn_cast<PointerType>(ETy1))
- if (Pte1->getElementType()->isIntegerTy(8))
- return StringSwitch<InstructionClass>(F->getName())
- .Case("objc_moveWeak", IC_MoveWeak)
- .Case("objc_copyWeak", IC_CopyWeak)
- .Default(IC_CallOrUser);
- }
-
- // Anything else.
- return IC_CallOrUser;
-}
+InstructionClass GetFunctionClass(const Function *F);
/// \brief Determine which objc runtime call instruction class V belongs to.
///
return isa<InvokeInst>(V) ? IC_CallOrUser : IC_User;
}
+/// \brief Determine what kind of construct V is.
+InstructionClass GetInstructionClass(const Value *V);
/// \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
return V;
}
+/// \brief Assuming the given instruction is one of the special calls such as
+/// objc_retain or objc_release, return the argument value, stripped of no-op
+/// casts and forwarding calls.
+static inline Value *GetObjCArg(Value *Inst) {
+ return StripPointerCastsAndObjCCalls(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,
+/// so if it's such a call and the return value has users, replace them with the
+/// argument value.
+///
+static inline void EraseInstruction(Instruction *CI) {
+ Value *OldArg = cast<CallInst>(CI)->getArgOperand(0);
+
+ bool Unused = CI->use_empty();
+
+ if (!Unused) {
+ // Replace the return value with the argument.
+ assert((IsForwarding(GetBasicInstructionClass(CI)) ||
+ (IsNoopOnNull(GetBasicInstructionClass(CI)) &&
+ isa<ConstantPointerNull>(OldArg))) &&
+ "Can't delete non-forwarding instruction with users!");
+ CI->replaceAllUsesWith(OldArg);
+ }
+
+ CI->eraseFromParent();
+
+ if (Unused)
+ 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 GetInstructionClass. Determines what kind of construct CS
+/// is.
+static inline InstructionClass GetCallSiteClass(ImmutableCallSite CS) {
+ for (ImmutableCallSite::arg_iterator I = CS.arg_begin(), E = CS.arg_end();
+ I != E; ++I)
+ if (IsPotentialRetainableObjPtr(*I))
+ return CS.onlyReadsMemory() ? IC_User : IC_CallOrUser;
+
+ return CS.onlyReadsMemory() ? IC_None : IC_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 =
+ 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.
+ 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;
+}
} // end namespace objcarc
} // end namespace llvm
-#endif // LLVM_TRANSFORMS_SCALAR_OBJCARC_H
+#endif
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