///
/// The optimizations performed include elimination of redundant, partially
/// redundant, and inconsequential reference count operations, elimination of
-/// redundant weak pointer operations, pattern-matching and replacement of
-/// low-level operations into higher-level operations, and numerous minor
-/// simplifications.
-///
-/// This file also defines a simple ARC-aware AliasAnalysis.
+/// redundant weak pointer operations, and numerous minor simplifications.
///
/// WARNING: This file knows about certain library functions. It recognizes them
/// by name, and hardwires knowledge of their semantics.
#define DEBUG_TYPE "objc-arc-opts"
#include "ObjCARC.h"
-
+#include "ARCRuntimeEntryPoints.h"
+#include "DependencyAnalysis.h"
+#include "ObjCARCAliasAnalysis.h"
+#include "ProvenanceAnalysis.h"
#include "llvm/ADT/DenseMap.h"
-#include "llvm/ADT/SmallPtrSet.h"
+#include "llvm/ADT/DenseSet.h"
#include "llvm/ADT/STLExtras.h"
+#include "llvm/ADT/SmallPtrSet.h"
+#include "llvm/ADT/Statistic.h"
+#include "llvm/IR/IRBuilder.h"
+#include "llvm/IR/LLVMContext.h"
+#include "llvm/Support/CFG.h"
+#include "llvm/Support/Debug.h"
+#include "llvm/Support/raw_ostream.h"
using namespace llvm;
using namespace llvm::objcarc;
return std::make_pair(Vector.begin() + Pair.first->second, false);
}
+ iterator find(const KeyT &Key) {
+ typename MapTy::iterator It = Map.find(Key);
+ if (It == Map.end()) return Vector.end();
+ return Vector.begin() + It->second;
+ }
+
const_iterator find(const KeyT &Key) const {
typename MapTy::const_iterator It = Map.find(Key);
if (It == Map.end()) return Vector.end();
/// \defgroup ARCUtilities Utility declarations/definitions specific to ARC.
/// @{
-#include "llvm/Analysis/ValueTracking.h"
-#include "llvm/IR/Intrinsics.h"
-#include "llvm/Support/CallSite.h"
-#include "llvm/Transforms/Utils/Local.h"
-
-/// \brief Test whether the given value is possible a retainable object pointer.
-static 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->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;
-}
-
-/// \brief Helper for GetInstructionClass. Determines what kind of construct CS
-/// is.
-static 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 Determine what kind of construct V is.
-static InstructionClass GetInstructionClass(const Value *V) {
- if (const Instruction *I = dyn_cast<Instruction>(V)) {
- // Any instruction other than bitcast and gep with a pointer operand have a
- // use of an objc pointer. Bitcasts, GEPs, Selects, PHIs transfer a pointer
- // to a subsequent use, rather than using it themselves, in this sense.
- // As a short cut, several other opcodes are known to have no pointer
- // operands of interest. And ret is never followed by a release, so it's
- // not interesting to examine.
- switch (I->getOpcode()) {
- case Instruction::Call: {
- const CallInst *CI = cast<CallInst>(I);
- // Check for calls to special functions.
- if (const Function *F = CI->getCalledFunction()) {
- InstructionClass Class = GetFunctionClass(F);
- if (Class != IC_CallOrUser)
- return Class;
-
- // None of the intrinsic functions do objc_release. For intrinsics, the
- // only question is whether or not they may be users.
- switch (F->getIntrinsicID()) {
- case Intrinsic::returnaddress: case Intrinsic::frameaddress:
- case Intrinsic::stacksave: case Intrinsic::stackrestore:
- case Intrinsic::vastart: case Intrinsic::vacopy: case Intrinsic::vaend:
- case Intrinsic::objectsize: case Intrinsic::prefetch:
- case Intrinsic::stackprotector:
- case Intrinsic::eh_return_i32: case Intrinsic::eh_return_i64:
- case Intrinsic::eh_typeid_for: case Intrinsic::eh_dwarf_cfa:
- case Intrinsic::eh_sjlj_lsda: case Intrinsic::eh_sjlj_functioncontext:
- case Intrinsic::init_trampoline: case Intrinsic::adjust_trampoline:
- case Intrinsic::lifetime_start: case Intrinsic::lifetime_end:
- case Intrinsic::invariant_start: case Intrinsic::invariant_end:
- // Don't let dbg info affect our results.
- case Intrinsic::dbg_declare: case Intrinsic::dbg_value:
- // Short cut: Some intrinsics obviously don't use ObjC pointers.
- return IC_None;
- default:
- break;
- }
- }
- return GetCallSiteClass(CI);
- }
- case Instruction::Invoke:
- return GetCallSiteClass(cast<InvokeInst>(I));
- case Instruction::BitCast:
- case Instruction::GetElementPtr:
- case Instruction::Select: case Instruction::PHI:
- case Instruction::Ret: case Instruction::Br:
- case Instruction::Switch: case Instruction::IndirectBr:
- case Instruction::Alloca: case Instruction::VAArg:
- case Instruction::Add: case Instruction::FAdd:
- case Instruction::Sub: case Instruction::FSub:
- case Instruction::Mul: case Instruction::FMul:
- case Instruction::SDiv: case Instruction::UDiv: case Instruction::FDiv:
- case Instruction::SRem: case Instruction::URem: case Instruction::FRem:
- case Instruction::Shl: case Instruction::LShr: case Instruction::AShr:
- case Instruction::And: case Instruction::Or: case Instruction::Xor:
- case Instruction::SExt: case Instruction::ZExt: case Instruction::Trunc:
- case Instruction::IntToPtr: case Instruction::FCmp:
- case Instruction::FPTrunc: case Instruction::FPExt:
- case Instruction::FPToUI: case Instruction::FPToSI:
- case Instruction::UIToFP: case Instruction::SIToFP:
- case Instruction::InsertElement: case Instruction::ExtractElement:
- case Instruction::ShuffleVector:
- case Instruction::ExtractValue:
- break;
- case Instruction::ICmp:
- // Comparing a pointer with null, or any other constant, isn't an
- // interesting use, because we don't care what the pointer points to, or
- // about the values of any other dynamic reference-counted pointers.
- if (IsPotentialRetainableObjPtr(I->getOperand(1)))
- return IC_User;
- break;
- default:
- // For anything else, check all the operands.
- // Note that this includes both operands of a Store: while the first
- // operand isn't actually being dereferenced, it is being stored to
- // memory where we can no longer track who might read it and dereference
- // it, so we have to consider it potentially used.
- for (User::const_op_iterator OI = I->op_begin(), OE = I->op_end();
- OI != OE; ++OI)
- if (IsPotentialRetainableObjPtr(*OI))
- return IC_User;
- }
- }
-
- // Otherwise, it's totally inert for ARC purposes.
- return IC_None;
-}
-
-/// \brief Test if the given class is objc_retain or equivalent.
-static bool IsRetain(InstructionClass Class) {
- return Class == IC_Retain ||
- Class == IC_RetainRV;
-}
-
-/// \brief Test if the given class is objc_autorelease or equivalent.
-static bool IsAutorelease(InstructionClass Class) {
- return Class == IC_Autorelease ||
- Class == IC_AutoreleaseRV;
-}
-
-/// \brief Test if the given class represents instructions which return their
-/// argument verbatim.
-static 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;
-}
-
-/// \brief Test if the given class represents instructions which do nothing if
-/// passed a null pointer.
-static bool IsNoopOnNull(InstructionClass Class) {
- return Class == IC_Retain ||
- Class == IC_RetainRV ||
- Class == IC_Release ||
- Class == IC_Autorelease ||
- Class == IC_AutoreleaseRV ||
- Class == IC_RetainBlock;
-}
-
-/// \brief Test if the given class represents instructions which are always safe
-/// to mark with the "tail" keyword.
-static bool IsAlwaysTail(InstructionClass Class) {
- // IC_RetainBlock may be given a stack argument.
- return Class == IC_Retain ||
- Class == IC_RetainRV ||
- 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;
-}
-
-/// \brief Test if the given class represents instructions which are always safe
-/// to mark with the nounwind attribute.
-static bool IsNoThrow(InstructionClass Class) {
- // objc_retainBlock is not nounwind because it calls user copy constructors
- // which could theoretically throw.
- return Class == IC_Retain ||
- Class == IC_RetainRV ||
- Class == IC_Release ||
- Class == IC_Autorelease ||
- Class == IC_AutoreleaseRV ||
- Class == IC_AutoreleasepoolPush ||
- Class == IC_AutoreleasepoolPop;
-}
-
-/// \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 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)) &&
- "Can't delete non-forwarding instruction with users!");
- CI->replaceAllUsesWith(OldArg);
- }
-
- CI->eraseFromParent();
-
- if (Unused)
- RecursivelyDeleteTriviallyDeadInstructions(OldArg);
-}
-
-/// \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 const Value *GetUnderlyingObjCPtr(const Value *V) {
- for (;;) {
- V = GetUnderlyingObject(V);
- if (!IsForwarding(GetBasicInstructionClass(V)))
- break;
- V = cast<CallInst>(V)->getArgOperand(0);
- }
-
- return V;
-}
-
-/// \brief This is a wrapper around Value::stripPointerCasts which also knows
-/// how to look through objc_retain and objc_autorelease calls, which we know to
-/// return their argument verbatim.
-static const Value *StripPointerCastsAndObjCCalls(const Value *V) {
- for (;;) {
- V = V->stripPointerCasts();
- if (!IsForwarding(GetBasicInstructionClass(V)))
- break;
- V = cast<CallInst>(V)->getArgOperand(0);
- }
- return V;
-}
-
-/// \brief This is a wrapper around Value::stripPointerCasts which also knows
-/// how to look through objc_retain and objc_autorelease calls, which we know to
-/// return their argument verbatim.
-static Value *StripPointerCastsAndObjCCalls(Value *V) {
- for (;;) {
- V = V->stripPointerCasts();
- if (!IsForwarding(GetBasicInstructionClass(V)))
- break;
- V = cast<CallInst>(V)->getArgOperand(0);
- }
- 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 Value *GetObjCArg(Value *Inst) {
- return StripPointerCastsAndObjCCalls(cast<CallInst>(Inst)->getArgOperand(0));
-}
-
-/// \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 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_SELECTOR_REFERENCES_") ||
- Name.startswith("\01L_OBJC_CLASSLIST_REFERENCES_") ||
- Name.startswith("\01L_OBJC_CLASSLIST_SUP_REFS_$_") ||
- Name.startswith("\01L_OBJC_METH_VAR_NAME_") ||
- Name.startswith("\01l_objc_msgSend_fixup_"))
- return true;
- }
- }
-
- return false;
-}
-
/// \brief This is similar to StripPointerCastsAndObjCCalls but it stops as soon
/// as it finds a value with multiple uses.
static const Value *FindSingleUseIdentifiedObject(const Value *Arg) {
return 0;
}
-/// \brief Test whether the given pointer, which is an Objective C block
-/// pointer, does not "escape".
+/// \brief Test whether the given retainable object pointer escapes.
///
/// This differs from regular escape analysis in that a use as an
/// argument to a call is not considered an escape.
///
-static bool DoesObjCBlockEscape(const Value *BlockPtr) {
-
- DEBUG(dbgs() << "DoesObjCBlockEscape: Target: " << *BlockPtr << "\n");
+static bool DoesRetainableObjPtrEscape(const User *Ptr) {
+ DEBUG(dbgs() << "DoesRetainableObjPtrEscape: Target: " << *Ptr << "\n");
// Walk the def-use chains.
SmallVector<const Value *, 4> Worklist;
- Worklist.push_back(BlockPtr);
+ Worklist.push_back(Ptr);
+ // If Ptr has any operands add them as well.
+ for (User::const_op_iterator I = Ptr->op_begin(), E = Ptr->op_end(); I != E;
+ ++I) {
+ Worklist.push_back(*I);
+ }
// Ensure we do not visit any value twice.
- SmallPtrSet<const Value *, 4> VisitedSet;
+ SmallPtrSet<const Value *, 8> VisitedSet;
do {
const Value *V = Worklist.pop_back_val();
- DEBUG(dbgs() << "DoesObjCBlockEscape: Visiting: " << *V << "\n");
+ DEBUG(dbgs() << "Visiting: " << *V << "\n");
for (Value::const_use_iterator UI = V->use_begin(), UE = V->use_end();
UI != UE; ++UI) {
const User *UUser = *UI;
- DEBUG(dbgs() << "DoesObjCBlockEscape: User: " << *UUser << "\n");
+ DEBUG(dbgs() << "User: " << *UUser << "\n");
// Special - Use by a call (callee or argument) is not considered
// to be an escape.
case IC_StoreStrong:
case IC_Autorelease:
case IC_AutoreleaseRV: {
- DEBUG(dbgs() << "DoesObjCBlockEscape: User copies pointer arguments. "
- "Block Escapes!\n");
+ DEBUG(dbgs() << "User copies pointer arguments. Pointer Escapes!\n");
// These special functions make copies of their pointer arguments.
return true;
}
+ case IC_IntrinsicUser:
+ // Use by the use intrinsic is not an escape.
+ continue;
case IC_User:
case IC_None:
// Use by an instruction which copies the value is an escape if the
if (isa<BitCastInst>(UUser) || isa<GetElementPtrInst>(UUser) ||
isa<PHINode>(UUser) || isa<SelectInst>(UUser)) {
- if (!VisitedSet.insert(UUser)) {
- DEBUG(dbgs() << "DoesObjCBlockEscape: User copies value. Escapes "
- "if result escapes. Adding to list.\n");
+ if (VisitedSet.insert(UUser)) {
+ DEBUG(dbgs() << "User copies value. Ptr escapes if result escapes."
+ " Adding to list.\n");
Worklist.push_back(UUser);
} else {
- DEBUG(dbgs() << "DoesObjCBlockEscape: Already visited node.\n");
+ DEBUG(dbgs() << "Already visited node.\n");
}
continue;
}
continue;
}
// Otherwise, conservatively assume an escape.
- DEBUG(dbgs() << "DoesObjCBlockEscape: Assuming block escapes.\n");
+ DEBUG(dbgs() << "Assuming ptr escapes.\n");
return true;
}
} while (!Worklist.empty());
// No escapes found.
- DEBUG(dbgs() << "DoesObjCBlockEscape: Block does not escape.\n");
+ DEBUG(dbgs() << "Ptr does not escape.\n");
return false;
}
-/// @}
-///
-/// \defgroup ARCAA Extends alias analysis using ObjC specific knowledge.
-/// @{
+/// This is a wrapper around getUnderlyingObjCPtr along the lines of
+/// GetUnderlyingObjects except that it returns early when it sees the first
+/// alloca.
+static inline bool AreAnyUnderlyingObjectsAnAlloca(const Value *V) {
+ SmallPtrSet<const Value *, 4> Visited;
+ SmallVector<const Value *, 4> Worklist;
+ Worklist.push_back(V);
+ do {
+ const Value *P = Worklist.pop_back_val();
+ P = GetUnderlyingObjCPtr(P);
-namespace {
- /// \brief This is a simple alias analysis implementation that uses knowledge
- /// of ARC constructs to answer queries.
- ///
- /// TODO: This class could be generalized to know about other ObjC-specific
- /// tricks. Such as knowing that ivars in the non-fragile ABI are non-aliasing
- /// even though their offsets are dynamic.
- class ObjCARCAliasAnalysis : public ImmutablePass,
- public AliasAnalysis {
- public:
- static char ID; // Class identification, replacement for typeinfo
- ObjCARCAliasAnalysis() : ImmutablePass(ID) {
- initializeObjCARCAliasAnalysisPass(*PassRegistry::getPassRegistry());
- }
+ if (isa<AllocaInst>(P))
+ return true;
- private:
- virtual void initializePass() {
- InitializeAliasAnalysis(this);
- }
+ if (!Visited.insert(P))
+ continue;
- /// This method is used when a pass implements an analysis interface through
- /// multiple inheritance. If needed, it should override this to adjust the
- /// this pointer as needed for the specified pass info.
- virtual void *getAdjustedAnalysisPointer(const void *PI) {
- if (PI == &AliasAnalysis::ID)
- return static_cast<AliasAnalysis *>(this);
- return this;
+ if (const SelectInst *SI = dyn_cast<const SelectInst>(P)) {
+ Worklist.push_back(SI->getTrueValue());
+ Worklist.push_back(SI->getFalseValue());
+ continue;
}
- virtual void getAnalysisUsage(AnalysisUsage &AU) const;
- virtual AliasResult alias(const Location &LocA, const Location &LocB);
- virtual bool pointsToConstantMemory(const Location &Loc, bool OrLocal);
- virtual ModRefBehavior getModRefBehavior(ImmutableCallSite CS);
- virtual ModRefBehavior getModRefBehavior(const Function *F);
- virtual ModRefResult getModRefInfo(ImmutableCallSite CS,
- const Location &Loc);
- virtual ModRefResult getModRefInfo(ImmutableCallSite CS1,
- ImmutableCallSite CS2);
- };
-} // End of anonymous namespace
-
-// Register this pass...
-char ObjCARCAliasAnalysis::ID = 0;
-INITIALIZE_AG_PASS(ObjCARCAliasAnalysis, AliasAnalysis, "objc-arc-aa",
- "ObjC-ARC-Based Alias Analysis", false, true, false)
-
-ImmutablePass *llvm::createObjCARCAliasAnalysisPass() {
- return new ObjCARCAliasAnalysis();
-}
-
-void
-ObjCARCAliasAnalysis::getAnalysisUsage(AnalysisUsage &AU) const {
- AU.setPreservesAll();
- AliasAnalysis::getAnalysisUsage(AU);
-}
-
-AliasAnalysis::AliasResult
-ObjCARCAliasAnalysis::alias(const Location &LocA, const Location &LocB) {
- if (!EnableARCOpts)
- return AliasAnalysis::alias(LocA, LocB);
-
- // First, strip off no-ops, including ObjC-specific no-ops, and try making a
- // precise alias query.
- const Value *SA = StripPointerCastsAndObjCCalls(LocA.Ptr);
- const Value *SB = StripPointerCastsAndObjCCalls(LocB.Ptr);
- AliasResult Result =
- AliasAnalysis::alias(Location(SA, LocA.Size, LocA.TBAATag),
- Location(SB, LocB.Size, LocB.TBAATag));
- if (Result != MayAlias)
- return Result;
-
- // If that failed, climb to the underlying object, including climbing through
- // ObjC-specific no-ops, and try making an imprecise alias query.
- const Value *UA = GetUnderlyingObjCPtr(SA);
- const Value *UB = GetUnderlyingObjCPtr(SB);
- if (UA != SA || UB != SB) {
- Result = AliasAnalysis::alias(Location(UA), Location(UB));
- // We can't use MustAlias or PartialAlias results here because
- // GetUnderlyingObjCPtr may return an offsetted pointer value.
- if (Result == NoAlias)
- return NoAlias;
- }
-
- // If that failed, fail. We don't need to chain here, since that's covered
- // by the earlier precise query.
- return MayAlias;
-}
+ if (const PHINode *PN = dyn_cast<const PHINode>(P)) {
+ for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i)
+ Worklist.push_back(PN->getIncomingValue(i));
+ continue;
+ }
+ } while (!Worklist.empty());
-bool
-ObjCARCAliasAnalysis::pointsToConstantMemory(const Location &Loc,
- bool OrLocal) {
- if (!EnableARCOpts)
- return AliasAnalysis::pointsToConstantMemory(Loc, OrLocal);
-
- // First, strip off no-ops, including ObjC-specific no-ops, and try making
- // a precise alias query.
- const Value *S = StripPointerCastsAndObjCCalls(Loc.Ptr);
- if (AliasAnalysis::pointsToConstantMemory(Location(S, Loc.Size, Loc.TBAATag),
- OrLocal))
- return true;
-
- // If that failed, climb to the underlying object, including climbing through
- // ObjC-specific no-ops, and try making an imprecise alias query.
- const Value *U = GetUnderlyingObjCPtr(S);
- if (U != S)
- return AliasAnalysis::pointsToConstantMemory(Location(U), OrLocal);
-
- // If that failed, fail. We don't need to chain here, since that's covered
- // by the earlier precise query.
return false;
}
-AliasAnalysis::ModRefBehavior
-ObjCARCAliasAnalysis::getModRefBehavior(ImmutableCallSite CS) {
- // We have nothing to do. Just chain to the next AliasAnalysis.
- return AliasAnalysis::getModRefBehavior(CS);
-}
-
-AliasAnalysis::ModRefBehavior
-ObjCARCAliasAnalysis::getModRefBehavior(const Function *F) {
- if (!EnableARCOpts)
- return AliasAnalysis::getModRefBehavior(F);
-
- switch (GetFunctionClass(F)) {
- case IC_NoopCast:
- return DoesNotAccessMemory;
- default:
- break;
- }
-
- return AliasAnalysis::getModRefBehavior(F);
-}
-
-AliasAnalysis::ModRefResult
-ObjCARCAliasAnalysis::getModRefInfo(ImmutableCallSite CS, const Location &Loc) {
- if (!EnableARCOpts)
- return AliasAnalysis::getModRefInfo(CS, Loc);
-
- switch (GetBasicInstructionClass(CS.getInstruction())) {
- case IC_Retain:
- case IC_RetainRV:
- case IC_Autorelease:
- case IC_AutoreleaseRV:
- case IC_NoopCast:
- case IC_AutoreleasepoolPush:
- case IC_FusedRetainAutorelease:
- case IC_FusedRetainAutoreleaseRV:
- // These functions don't access any memory visible to the compiler.
- // Note that this doesn't include objc_retainBlock, because it updates
- // pointers when it copies block data.
- return NoModRef;
- default:
- break;
- }
-
- return AliasAnalysis::getModRefInfo(CS, Loc);
-}
-
-AliasAnalysis::ModRefResult
-ObjCARCAliasAnalysis::getModRefInfo(ImmutableCallSite CS1,
- ImmutableCallSite CS2) {
- // TODO: Theoretically we could check for dependencies between objc_* calls
- // and OnlyAccessesArgumentPointees calls or other well-behaved calls.
- return AliasAnalysis::getModRefInfo(CS1, CS2);
-}
/// @}
///
// TODO: Delete release+retain pairs (rare).
-#include "llvm/ADT/SmallPtrSet.h"
-#include "llvm/ADT/Statistic.h"
-#include "llvm/IR/LLVMContext.h"
-#include "llvm/Support/CFG.h"
-
STATISTIC(NumNoops, "Number of no-op objc calls eliminated");
STATISTIC(NumPartialNoops, "Number of partially no-op objc calls eliminated");
STATISTIC(NumAutoreleases,"Number of autoreleases converted to releases");
STATISTIC(NumRets, "Number of return value forwarding "
- "retain+autoreleaes eliminated");
+ "retain+autoreleases eliminated");
STATISTIC(NumRRs, "Number of retain+release paths eliminated");
STATISTIC(NumPeeps, "Number of calls peephole-optimized");
-
-namespace {
- /// \brief This is similar to BasicAliasAnalysis, and it uses many of the same
- /// techniques, except it uses special ObjC-specific reasoning about pointer
- /// relationships.
- ///
- /// In this context ``Provenance'' is defined as the history of an object's
- /// ownership. Thus ``Provenance Analysis'' is defined by using the notion of
- /// an ``independent provenance source'' of a pointer to determine whether or
- /// not two pointers have the same provenance source and thus could
- /// potentially be related.
- class ProvenanceAnalysis {
- AliasAnalysis *AA;
-
- typedef std::pair<const Value *, const Value *> ValuePairTy;
- typedef DenseMap<ValuePairTy, bool> CachedResultsTy;
- CachedResultsTy CachedResults;
-
- bool relatedCheck(const Value *A, const Value *B);
- bool relatedSelect(const SelectInst *A, const Value *B);
- bool relatedPHI(const PHINode *A, const Value *B);
-
- void operator=(const ProvenanceAnalysis &) LLVM_DELETED_FUNCTION;
- ProvenanceAnalysis(const ProvenanceAnalysis &) LLVM_DELETED_FUNCTION;
-
- public:
- ProvenanceAnalysis() {}
-
- void setAA(AliasAnalysis *aa) { AA = aa; }
-
- AliasAnalysis *getAA() const { return AA; }
-
- bool related(const Value *A, const Value *B);
-
- void clear() {
- CachedResults.clear();
- }
- };
-}
-
-bool ProvenanceAnalysis::relatedSelect(const SelectInst *A, const Value *B) {
- // If the values are Selects with the same condition, we can do a more precise
- // check: just check for relations between the values on corresponding arms.
- if (const SelectInst *SB = dyn_cast<SelectInst>(B))
- if (A->getCondition() == SB->getCondition())
- return related(A->getTrueValue(), SB->getTrueValue()) ||
- related(A->getFalseValue(), SB->getFalseValue());
-
- // Check both arms of the Select node individually.
- return related(A->getTrueValue(), B) ||
- related(A->getFalseValue(), B);
-}
-
-bool ProvenanceAnalysis::relatedPHI(const PHINode *A, const Value *B) {
- // If the values are PHIs in the same block, we can do a more precise as well
- // as efficient check: just check for relations between the values on
- // corresponding edges.
- if (const PHINode *PNB = dyn_cast<PHINode>(B))
- if (PNB->getParent() == A->getParent()) {
- for (unsigned i = 0, e = A->getNumIncomingValues(); i != e; ++i)
- if (related(A->getIncomingValue(i),
- PNB->getIncomingValueForBlock(A->getIncomingBlock(i))))
- return true;
- return false;
- }
-
- // Check each unique source of the PHI node against B.
- SmallPtrSet<const Value *, 4> UniqueSrc;
- for (unsigned i = 0, e = A->getNumIncomingValues(); i != e; ++i) {
- const Value *PV1 = A->getIncomingValue(i);
- if (UniqueSrc.insert(PV1) && related(PV1, B))
- return true;
- }
-
- // All of the arms checked out.
- return false;
-}
-
-/// Test if the value of P, or any value covered by its provenance, is ever
-/// stored within the function (not counting callees).
-static bool isStoredObjCPointer(const Value *P) {
- SmallPtrSet<const Value *, 8> Visited;
- SmallVector<const Value *, 8> Worklist;
- Worklist.push_back(P);
- Visited.insert(P);
- do {
- P = Worklist.pop_back_val();
- for (Value::const_use_iterator UI = P->use_begin(), UE = P->use_end();
- UI != UE; ++UI) {
- const User *Ur = *UI;
- if (isa<StoreInst>(Ur)) {
- if (UI.getOperandNo() == 0)
- // The pointer is stored.
- return true;
- // The pointed is stored through.
- continue;
- }
- if (isa<CallInst>(Ur))
- // The pointer is passed as an argument, ignore this.
- continue;
- if (isa<PtrToIntInst>(P))
- // Assume the worst.
- return true;
- if (Visited.insert(Ur))
- Worklist.push_back(Ur);
- }
- } while (!Worklist.empty());
-
- // Everything checked out.
- return false;
-}
-
-bool ProvenanceAnalysis::relatedCheck(const Value *A, const Value *B) {
- // Skip past provenance pass-throughs.
- A = GetUnderlyingObjCPtr(A);
- B = GetUnderlyingObjCPtr(B);
-
- // Quick check.
- if (A == B)
- return true;
-
- // Ask regular AliasAnalysis, for a first approximation.
- switch (AA->alias(A, B)) {
- case AliasAnalysis::NoAlias:
- return false;
- case AliasAnalysis::MustAlias:
- case AliasAnalysis::PartialAlias:
- return true;
- case AliasAnalysis::MayAlias:
- break;
- }
-
- bool AIsIdentified = IsObjCIdentifiedObject(A);
- bool BIsIdentified = IsObjCIdentifiedObject(B);
-
- // An ObjC-Identified object can't alias a load if it is never locally stored.
- if (AIsIdentified) {
- // Check for an obvious escape.
- if (isa<LoadInst>(B))
- return isStoredObjCPointer(A);
- if (BIsIdentified) {
- // Check for an obvious escape.
- if (isa<LoadInst>(A))
- return isStoredObjCPointer(B);
- // Both pointers are identified and escapes aren't an evident problem.
- return false;
- }
- } else if (BIsIdentified) {
- // Check for an obvious escape.
- if (isa<LoadInst>(A))
- return isStoredObjCPointer(B);
- }
-
- // Special handling for PHI and Select.
- if (const PHINode *PN = dyn_cast<PHINode>(A))
- return relatedPHI(PN, B);
- if (const PHINode *PN = dyn_cast<PHINode>(B))
- return relatedPHI(PN, A);
- if (const SelectInst *S = dyn_cast<SelectInst>(A))
- return relatedSelect(S, B);
- if (const SelectInst *S = dyn_cast<SelectInst>(B))
- return relatedSelect(S, A);
-
- // Conservative.
- return true;
-}
-
-bool ProvenanceAnalysis::related(const Value *A, const Value *B) {
- // Begin by inserting a conservative value into the map. If the insertion
- // fails, we have the answer already. If it succeeds, leave it there until we
- // compute the real answer to guard against recursive queries.
- if (A > B) std::swap(A, B);
- std::pair<CachedResultsTy::iterator, bool> Pair =
- CachedResults.insert(std::make_pair(ValuePairTy(A, B), true));
- if (!Pair.second)
- return Pair.first->second;
-
- bool Result = relatedCheck(A, B);
- CachedResults[ValuePairTy(A, B)] = Result;
- return Result;
-}
+#ifndef NDEBUG
+STATISTIC(NumRetainsBeforeOpt,
+ "Number of retains before optimization");
+STATISTIC(NumReleasesBeforeOpt,
+ "Number of releases before optimization");
+STATISTIC(NumRetainsAfterOpt,
+ "Number of retains after optimization");
+STATISTIC(NumReleasesAfterOpt,
+ "Number of releases after optimization");
+#endif
namespace {
/// \enum Sequence
/// objc_retain and objc_release are actually needed.
enum Sequence {
S_None,
- S_Retain, ///< objc_retain(x)
- S_CanRelease, ///< foo(x) -- x could possibly see a ref count decrement
- S_Use, ///< any use of x
- S_Stop, ///< like S_Release, but code motion is stopped
- S_Release, ///< objc_release(x)
- S_MovableRelease ///< objc_release(x), !clang.imprecise_release
+ S_Retain, ///< objc_retain(x).
+ S_CanRelease, ///< foo(x) -- x could possibly see a ref count decrement.
+ S_Use, ///< any use of x.
+ S_Stop, ///< like S_Release, but code motion is stopped.
+ S_Release, ///< objc_release(x).
+ S_MovableRelease ///< objc_release(x), !clang.imprecise_release.
};
+
+ raw_ostream &operator<<(raw_ostream &OS, const Sequence S)
+ LLVM_ATTRIBUTE_UNUSED;
+ raw_ostream &operator<<(raw_ostream &OS, const Sequence S) {
+ switch (S) {
+ case S_None:
+ return OS << "S_None";
+ case S_Retain:
+ return OS << "S_Retain";
+ case S_CanRelease:
+ return OS << "S_CanRelease";
+ case S_Use:
+ return OS << "S_Use";
+ case S_Release:
+ return OS << "S_Release";
+ case S_MovableRelease:
+ return OS << "S_MovableRelease";
+ case S_Stop:
+ return OS << "S_Stop";
+ }
+ llvm_unreachable("Unknown sequence type.");
+ }
}
static Sequence MergeSeqs(Sequence A, Sequence B, bool TopDown) {
namespace {
/// \brief Unidirectional information about either a
/// retain-decrement-use-release sequence or release-use-decrement-retain
- /// reverese sequence.
+ /// reverse sequence.
struct RRInfo {
/// After an objc_retain, the reference count of the referenced
/// object is known to be positive. Similarly, before an objc_release, the
/// KnownSafe is true when either of these conditions is satisfied.
bool KnownSafe;
- /// True if the Calls are objc_retainBlock calls (as opposed to objc_retain
- /// calls).
- bool IsRetainBlock;
-
/// True of the objc_release calls are all marked with the "tail" keyword.
bool IsTailCallRelease;
/// sequence.
SmallPtrSet<Instruction *, 2> ReverseInsertPts;
+ /// If this is true, we cannot perform code motion but can still remove
+ /// retain/release pairs.
+ bool CFGHazardAfflicted;
+
RRInfo() :
- KnownSafe(false), IsRetainBlock(false),
- IsTailCallRelease(false),
- ReleaseMetadata(0) {}
+ KnownSafe(false), IsTailCallRelease(false), ReleaseMetadata(0),
+ CFGHazardAfflicted(false) {}
void clear();
+
+ /// Conservatively merge the two RRInfo. Returns true if a partial merge has
+ /// occured, false otherwise.
+ bool Merge(const RRInfo &Other);
+
};
}
void RRInfo::clear() {
KnownSafe = false;
- IsRetainBlock = false;
IsTailCallRelease = false;
ReleaseMetadata = 0;
Calls.clear();
ReverseInsertPts.clear();
+ CFGHazardAfflicted = false;
+}
+
+bool RRInfo::Merge(const RRInfo &Other) {
+ // Conservatively merge the ReleaseMetadata information.
+ if (ReleaseMetadata != Other.ReleaseMetadata)
+ ReleaseMetadata = 0;
+
+ // Conservatively merge the boolean state.
+ KnownSafe &= Other.KnownSafe;
+ IsTailCallRelease &= Other.IsTailCallRelease;
+ CFGHazardAfflicted |= Other.CFGHazardAfflicted;
+
+ // Merge the call sets.
+ Calls.insert(Other.Calls.begin(), Other.Calls.end());
+
+ // Merge the insert point sets. If there are any differences,
+ // that makes this a partial merge.
+ bool Partial = ReverseInsertPts.size() != Other.ReverseInsertPts.size();
+ for (SmallPtrSet<Instruction *, 2>::const_iterator
+ I = Other.ReverseInsertPts.begin(),
+ E = Other.ReverseInsertPts.end(); I != E; ++I)
+ Partial |= ReverseInsertPts.insert(*I);
+ return Partial;
}
namespace {
/// True if the reference count is known to be incremented.
bool KnownPositiveRefCount;
- /// True of we've seen an opportunity for partial RR elimination, such as
+ /// True if we've seen an opportunity for partial RR elimination, such as
/// pushing calls into a CFG triangle or into one side of a CFG diamond.
bool Partial;
/// The current position in the sequence.
Sequence Seq : 8;
- public:
/// Unidirectional information about the current sequence.
- ///
- /// TODO: Encapsulate this better.
RRInfo RRI;
+ public:
PtrState() : KnownPositiveRefCount(false), Partial(false),
Seq(S_None) {}
+
+ bool IsKnownSafe() const {
+ return RRI.KnownSafe;
+ }
+
+ void SetKnownSafe(const bool NewValue) {
+ RRI.KnownSafe = NewValue;
+ }
+
+ bool IsTailCallRelease() const {
+ return RRI.IsTailCallRelease;
+ }
+
+ void SetTailCallRelease(const bool NewValue) {
+ RRI.IsTailCallRelease = NewValue;
+ }
+
+ bool IsTrackingImpreciseReleases() const {
+ return RRI.ReleaseMetadata != 0;
+ }
+
+ const MDNode *GetReleaseMetadata() const {
+ return RRI.ReleaseMetadata;
+ }
+
+ void SetReleaseMetadata(MDNode *NewValue) {
+ RRI.ReleaseMetadata = NewValue;
+ }
+
+ bool IsCFGHazardAfflicted() const {
+ return RRI.CFGHazardAfflicted;
+ }
+
+ void SetCFGHazardAfflicted(const bool NewValue) {
+ RRI.CFGHazardAfflicted = NewValue;
+ }
+
void SetKnownPositiveRefCount() {
+ DEBUG(dbgs() << "Setting Known Positive.\n");
KnownPositiveRefCount = true;
}
- void ClearRefCount() {
+ void ClearKnownPositiveRefCount() {
+ DEBUG(dbgs() << "Clearing Known Positive.\n");
KnownPositiveRefCount = false;
}
- bool IsKnownIncremented() const {
+ bool HasKnownPositiveRefCount() const {
return KnownPositiveRefCount;
}
void SetSeq(Sequence NewSeq) {
+ DEBUG(dbgs() << "Old: " << Seq << "; New: " << NewSeq << "\n");
Seq = NewSeq;
}
}
void ResetSequenceProgress(Sequence NewSeq) {
- Seq = NewSeq;
+ DEBUG(dbgs() << "Resetting sequence progress.\n");
+ SetSeq(NewSeq);
Partial = false;
RRI.clear();
}
void Merge(const PtrState &Other, bool TopDown);
+
+ void InsertCall(Instruction *I) {
+ RRI.Calls.insert(I);
+ }
+
+ void InsertReverseInsertPt(Instruction *I) {
+ RRI.ReverseInsertPts.insert(I);
+ }
+
+ void ClearReverseInsertPts() {
+ RRI.ReverseInsertPts.clear();
+ }
+
+ bool HasReverseInsertPts() const {
+ return !RRI.ReverseInsertPts.empty();
+ }
+
+ const RRInfo &GetRRInfo() const {
+ return RRI;
+ }
};
}
void
PtrState::Merge(const PtrState &Other, bool TopDown) {
Seq = MergeSeqs(Seq, Other.Seq, TopDown);
- KnownPositiveRefCount = KnownPositiveRefCount && Other.KnownPositiveRefCount;
-
- // We can't merge a plain objc_retain with an objc_retainBlock.
- if (RRI.IsRetainBlock != Other.RRI.IsRetainBlock)
- Seq = S_None;
+ KnownPositiveRefCount &= Other.KnownPositiveRefCount;
// If we're not in a sequence (anymore), drop all associated state.
if (Seq == S_None) {
// mixing them is unsafe.
ClearSequenceProgress();
} else {
- // Conservatively merge the ReleaseMetadata information.
- if (RRI.ReleaseMetadata != Other.RRI.ReleaseMetadata)
- RRI.ReleaseMetadata = 0;
-
- RRI.KnownSafe = RRI.KnownSafe && Other.RRI.KnownSafe;
- RRI.IsTailCallRelease = RRI.IsTailCallRelease &&
- Other.RRI.IsTailCallRelease;
- RRI.Calls.insert(Other.RRI.Calls.begin(), Other.RRI.Calls.end());
-
- // Merge the insert point sets. If there are any differences,
- // that makes this a partial merge.
- Partial = RRI.ReverseInsertPts.size() != Other.RRI.ReverseInsertPts.size();
- for (SmallPtrSet<Instruction *, 2>::const_iterator
- I = Other.RRI.ReverseInsertPts.begin(),
- E = Other.RRI.ReverseInsertPts.end(); I != E; ++I)
- Partial |= RRI.ReverseInsertPts.insert(*I);
+ // Otherwise merge the other PtrState's RRInfo into our RRInfo. At this
+ // point, we know that currently we are not partial. Stash whether or not
+ // the merge operation caused us to undergo a partial merging of reverse
+ // insertion points.
+ Partial = RRI.Merge(Other.RRI);
}
}
/// definition.
void SetAsExit() { BottomUpPathCount = 1; }
+ /// Attempt to find the PtrState object describing the top down state for
+ /// pointer Arg. Return a new initialized PtrState describing the top down
+ /// state for Arg if we do not find one.
PtrState &getPtrTopDownState(const Value *Arg) {
return PerPtrTopDown[Arg];
}
+ /// Attempt to find the PtrState object describing the bottom up state for
+ /// pointer Arg. Return a new initialized PtrState describing the bottom up
+ /// state for Arg if we do not find one.
PtrState &getPtrBottomUpState(const Value *Arg) {
return PerPtrBottomUp[Arg];
}
+ /// Attempt to find the PtrState object describing the bottom up state for
+ /// pointer Arg.
+ ptr_iterator findPtrBottomUpState(const Value *Arg) {
+ return PerPtrBottomUp.find(Arg);
+ }
+
void clearBottomUpPointers() {
PerPtrBottomUp.clear();
}
void MergePred(const BBState &Other);
void MergeSucc(const BBState &Other);
- /// Return the number of possible unique paths from an entry to an exit
+ /// Compute the number of possible unique paths from an entry to an exit
/// which pass through this block. This is only valid after both the
/// top-down and bottom-up traversals are complete.
- unsigned GetAllPathCount() const {
+ ///
+ /// Returns true if overflow occured. Returns false if overflow did not
+ /// occur.
+ bool GetAllPathCountWithOverflow(unsigned &PathCount) const {
assert(TopDownPathCount != 0);
assert(BottomUpPathCount != 0);
- return TopDownPathCount * BottomUpPathCount;
+ unsigned long long Product =
+ (unsigned long long)TopDownPathCount*BottomUpPathCount;
+ PathCount = Product;
+ // Overflow occured if any of the upper bits of Product are set.
+ return Product >> 32;
}
// Specialized CFG utilities.
typedef SmallVectorImpl<BasicBlock *>::const_iterator edge_iterator;
- edge_iterator pred_begin() { return Preds.begin(); }
- edge_iterator pred_end() { return Preds.end(); }
- edge_iterator succ_begin() { return Succs.begin(); }
- edge_iterator succ_end() { return Succs.end(); }
+ edge_iterator pred_begin() const { return Preds.begin(); }
+ edge_iterator pred_end() const { return Preds.end(); }
+ edge_iterator succ_begin() const { return Succs.begin(); }
+ edge_iterator succ_end() const { return Succs.end(); }
void addSucc(BasicBlock *Succ) { Succs.push_back(Succ); }
void addPred(BasicBlock *Pred) { Preds.push_back(Pred); }
/*TopDown=*/false);
}
- // For each entry in our set, if the other set doesn't have an entry
- // with the same key, force it to merge with an empty entry.
- for (ptr_iterator MI = bottom_up_ptr_begin(),
- ME = bottom_up_ptr_end(); MI != ME; ++MI)
- if (Other.PerPtrBottomUp.find(MI->first) == Other.PerPtrBottomUp.end())
- MI->second.Merge(PtrState(), /*TopDown=*/false);
-}
+ // For each entry in our set, if the other set doesn't have an entry
+ // with the same key, force it to merge with an empty entry.
+ for (ptr_iterator MI = bottom_up_ptr_begin(),
+ ME = bottom_up_ptr_end(); MI != ME; ++MI)
+ if (Other.PerPtrBottomUp.find(MI->first) == Other.PerPtrBottomUp.end())
+ MI->second.Merge(PtrState(), /*TopDown=*/false);
+}
+
+// Only enable ARC Annotations if we are building a debug version of
+// libObjCARCOpts.
+#ifndef NDEBUG
+#define ARC_ANNOTATIONS
+#endif
+
+// Define some macros along the lines of DEBUG and some helper functions to make
+// it cleaner to create annotations in the source code and to no-op when not
+// building in debug mode.
+#ifdef ARC_ANNOTATIONS
+
+#include "llvm/Support/CommandLine.h"
+
+/// Enable/disable ARC sequence annotations.
+static cl::opt<bool>
+EnableARCAnnotations("enable-objc-arc-annotations", cl::init(false),
+ cl::desc("Enable emission of arc data flow analysis "
+ "annotations"));
+static cl::opt<bool>
+DisableCheckForCFGHazards("disable-objc-arc-checkforcfghazards", cl::init(false),
+ cl::desc("Disable check for cfg hazards when "
+ "annotating"));
+static cl::opt<std::string>
+ARCAnnotationTargetIdentifier("objc-arc-annotation-target-identifier",
+ cl::init(""),
+ cl::desc("filter out all data flow annotations "
+ "but those that apply to the given "
+ "target llvm identifier."));
+
+/// This function appends a unique ARCAnnotationProvenanceSourceMDKind id to an
+/// instruction so that we can track backwards when post processing via the llvm
+/// arc annotation processor tool. If the function is an
+static MDString *AppendMDNodeToSourcePtr(unsigned NodeId,
+ Value *Ptr) {
+ MDString *Hash = 0;
+
+ // If pointer is a result of an instruction and it does not have a source
+ // MDNode it, attach a new MDNode onto it. If pointer is a result of
+ // an instruction and does have a source MDNode attached to it, return a
+ // reference to said Node. Otherwise just return 0.
+ if (Instruction *Inst = dyn_cast<Instruction>(Ptr)) {
+ MDNode *Node;
+ if (!(Node = Inst->getMetadata(NodeId))) {
+ // We do not have any node. Generate and attatch the hash MDString to the
+ // instruction.
+
+ // We just use an MDString to ensure that this metadata gets written out
+ // of line at the module level and to provide a very simple format
+ // encoding the information herein. Both of these makes it simpler to
+ // parse the annotations by a simple external program.
+ std::string Str;
+ raw_string_ostream os(Str);
+ os << "(" << Inst->getParent()->getParent()->getName() << ",%"
+ << Inst->getName() << ")";
+
+ Hash = MDString::get(Inst->getContext(), os.str());
+ Inst->setMetadata(NodeId, MDNode::get(Inst->getContext(),Hash));
+ } else {
+ // We have a node. Grab its hash and return it.
+ assert(Node->getNumOperands() == 1 &&
+ "An ARCAnnotationProvenanceSourceMDKind can only have 1 operand.");
+ Hash = cast<MDString>(Node->getOperand(0));
+ }
+ } else if (Argument *Arg = dyn_cast<Argument>(Ptr)) {
+ std::string str;
+ raw_string_ostream os(str);
+ os << "(" << Arg->getParent()->getName() << ",%" << Arg->getName()
+ << ")";
+ Hash = MDString::get(Arg->getContext(), os.str());
+ }
+
+ return Hash;
+}
+
+static std::string SequenceToString(Sequence A) {
+ std::string str;
+ raw_string_ostream os(str);
+ os << A;
+ return os.str();
+}
+
+/// Helper function to change a Sequence into a String object using our overload
+/// for raw_ostream so we only have printing code in one location.
+static MDString *SequenceToMDString(LLVMContext &Context,
+ Sequence A) {
+ return MDString::get(Context, SequenceToString(A));
+}
+
+/// A simple function to generate a MDNode which describes the change in state
+/// for Value *Ptr caused by Instruction *Inst.
+static void AppendMDNodeToInstForPtr(unsigned NodeId,
+ Instruction *Inst,
+ Value *Ptr,
+ MDString *PtrSourceMDNodeID,
+ Sequence OldSeq,
+ Sequence NewSeq) {
+ MDNode *Node = 0;
+ Value *tmp[3] = {PtrSourceMDNodeID,
+ SequenceToMDString(Inst->getContext(),
+ OldSeq),
+ SequenceToMDString(Inst->getContext(),
+ NewSeq)};
+ Node = MDNode::get(Inst->getContext(),
+ ArrayRef<Value*>(tmp, 3));
+
+ Inst->setMetadata(NodeId, Node);
+}
+
+/// Add to the beginning of the basic block llvm.ptr.annotations which show the
+/// state of a pointer at the entrance to a basic block.
+static void GenerateARCBBEntranceAnnotation(const char *Name, BasicBlock *BB,
+ Value *Ptr, Sequence Seq) {
+ // If we have a target identifier, make sure that we match it before
+ // continuing.
+ if(!ARCAnnotationTargetIdentifier.empty() &&
+ !Ptr->getName().equals(ARCAnnotationTargetIdentifier))
+ return;
+
+ Module *M = BB->getParent()->getParent();
+ LLVMContext &C = M->getContext();
+ Type *I8X = PointerType::getUnqual(Type::getInt8Ty(C));
+ Type *I8XX = PointerType::getUnqual(I8X);
+ Type *Params[] = {I8XX, I8XX};
+ FunctionType *FTy = FunctionType::get(Type::getVoidTy(C),
+ ArrayRef<Type*>(Params, 2),
+ /*isVarArg=*/false);
+ Constant *Callee = M->getOrInsertFunction(Name, FTy);
+
+ IRBuilder<> Builder(BB, BB->getFirstInsertionPt());
+
+ Value *PtrName;
+ StringRef Tmp = Ptr->getName();
+ if (0 == (PtrName = M->getGlobalVariable(Tmp, true))) {
+ Value *ActualPtrName = Builder.CreateGlobalStringPtr(Tmp,
+ Tmp + "_STR");
+ PtrName = new GlobalVariable(*M, I8X, true, GlobalVariable::InternalLinkage,
+ cast<Constant>(ActualPtrName), Tmp);
+ }
+
+ Value *S;
+ std::string SeqStr = SequenceToString(Seq);
+ if (0 == (S = M->getGlobalVariable(SeqStr, true))) {
+ Value *ActualPtrName = Builder.CreateGlobalStringPtr(SeqStr,
+ SeqStr + "_STR");
+ S = new GlobalVariable(*M, I8X, true, GlobalVariable::InternalLinkage,
+ cast<Constant>(ActualPtrName), SeqStr);
+ }
+
+ Builder.CreateCall2(Callee, PtrName, S);
+}
+
+/// Add to the end of the basic block llvm.ptr.annotations which show the state
+/// of the pointer at the bottom of the basic block.
+static void GenerateARCBBTerminatorAnnotation(const char *Name, BasicBlock *BB,
+ Value *Ptr, Sequence Seq) {
+ // If we have a target identifier, make sure that we match it before emitting
+ // an annotation.
+ if(!ARCAnnotationTargetIdentifier.empty() &&
+ !Ptr->getName().equals(ARCAnnotationTargetIdentifier))
+ return;
+
+ Module *M = BB->getParent()->getParent();
+ LLVMContext &C = M->getContext();
+ Type *I8X = PointerType::getUnqual(Type::getInt8Ty(C));
+ Type *I8XX = PointerType::getUnqual(I8X);
+ Type *Params[] = {I8XX, I8XX};
+ FunctionType *FTy = FunctionType::get(Type::getVoidTy(C),
+ ArrayRef<Type*>(Params, 2),
+ /*isVarArg=*/false);
+ Constant *Callee = M->getOrInsertFunction(Name, FTy);
+
+ IRBuilder<> Builder(BB, llvm::prior(BB->end()));
+
+ Value *PtrName;
+ StringRef Tmp = Ptr->getName();
+ if (0 == (PtrName = M->getGlobalVariable(Tmp, true))) {
+ Value *ActualPtrName = Builder.CreateGlobalStringPtr(Tmp,
+ Tmp + "_STR");
+ PtrName = new GlobalVariable(*M, I8X, true, GlobalVariable::InternalLinkage,
+ cast<Constant>(ActualPtrName), Tmp);
+ }
+
+ Value *S;
+ std::string SeqStr = SequenceToString(Seq);
+ if (0 == (S = M->getGlobalVariable(SeqStr, true))) {
+ Value *ActualPtrName = Builder.CreateGlobalStringPtr(SeqStr,
+ SeqStr + "_STR");
+ S = new GlobalVariable(*M, I8X, true, GlobalVariable::InternalLinkage,
+ cast<Constant>(ActualPtrName), SeqStr);
+ }
+ Builder.CreateCall2(Callee, PtrName, S);
+}
+
+/// Adds a source annotation to pointer and a state change annotation to Inst
+/// referencing the source annotation and the old/new state of pointer.
+static void GenerateARCAnnotation(unsigned InstMDId,
+ unsigned PtrMDId,
+ Instruction *Inst,
+ Value *Ptr,
+ Sequence OldSeq,
+ Sequence NewSeq) {
+ if (EnableARCAnnotations) {
+ // If we have a target identifier, make sure that we match it before
+ // emitting an annotation.
+ if(!ARCAnnotationTargetIdentifier.empty() &&
+ !Ptr->getName().equals(ARCAnnotationTargetIdentifier))
+ return;
+
+ // First generate the source annotation on our pointer. This will return an
+ // MDString* if Ptr actually comes from an instruction implying we can put
+ // in a source annotation. If AppendMDNodeToSourcePtr returns 0 (i.e. NULL),
+ // then we know that our pointer is from an Argument so we put a reference
+ // to the argument number.
+ //
+ // The point of this is to make it easy for the
+ // llvm-arc-annotation-processor tool to cross reference where the source
+ // pointer is in the LLVM IR since the LLVM IR parser does not submit such
+ // information via debug info for backends to use (since why would anyone
+ // need such a thing from LLVM IR besides in non standard cases
+ // [i.e. this]).
+ MDString *SourcePtrMDNode =
+ AppendMDNodeToSourcePtr(PtrMDId, Ptr);
+ AppendMDNodeToInstForPtr(InstMDId, Inst, Ptr, SourcePtrMDNode, OldSeq,
+ NewSeq);
+ }
+}
+
+// The actual interface for accessing the above functionality is defined via
+// some simple macros which are defined below. We do this so that the user does
+// not need to pass in what metadata id is needed resulting in cleaner code and
+// additionally since it provides an easy way to conditionally no-op all
+// annotation support in a non-debug build.
+
+/// Use this macro to annotate a sequence state change when processing
+/// instructions bottom up,
+#define ANNOTATE_BOTTOMUP(inst, ptr, old, new) \
+ GenerateARCAnnotation(ARCAnnotationBottomUpMDKind, \
+ ARCAnnotationProvenanceSourceMDKind, (inst), \
+ const_cast<Value*>(ptr), (old), (new))
+/// Use this macro to annotate a sequence state change when processing
+/// instructions top down.
+#define ANNOTATE_TOPDOWN(inst, ptr, old, new) \
+ GenerateARCAnnotation(ARCAnnotationTopDownMDKind, \
+ ARCAnnotationProvenanceSourceMDKind, (inst), \
+ const_cast<Value*>(ptr), (old), (new))
+
+#define ANNOTATE_BB(_states, _bb, _name, _type, _direction) \
+ do { \
+ if (EnableARCAnnotations) { \
+ for(BBState::ptr_const_iterator I = (_states)._direction##_ptr_begin(), \
+ E = (_states)._direction##_ptr_end(); I != E; ++I) { \
+ Value *Ptr = const_cast<Value*>(I->first); \
+ Sequence Seq = I->second.GetSeq(); \
+ GenerateARCBB ## _type ## Annotation(_name, (_bb), Ptr, Seq); \
+ } \
+ } \
+ } while (0)
+
+#define ANNOTATE_BOTTOMUP_BBSTART(_states, _basicblock) \
+ ANNOTATE_BB(_states, _basicblock, "llvm.arc.annotation.bottomup.bbstart", \
+ Entrance, bottom_up)
+#define ANNOTATE_BOTTOMUP_BBEND(_states, _basicblock) \
+ ANNOTATE_BB(_states, _basicblock, "llvm.arc.annotation.bottomup.bbend", \
+ Terminator, bottom_up)
+#define ANNOTATE_TOPDOWN_BBSTART(_states, _basicblock) \
+ ANNOTATE_BB(_states, _basicblock, "llvm.arc.annotation.topdown.bbstart", \
+ Entrance, top_down)
+#define ANNOTATE_TOPDOWN_BBEND(_states, _basicblock) \
+ ANNOTATE_BB(_states, _basicblock, "llvm.arc.annotation.topdown.bbend", \
+ Terminator, top_down)
+
+#else // !ARC_ANNOTATION
+// If annotations are off, noop.
+#define ANNOTATE_BOTTOMUP(inst, ptr, old, new)
+#define ANNOTATE_TOPDOWN(inst, ptr, old, new)
+#define ANNOTATE_BOTTOMUP_BBSTART(states, basicblock)
+#define ANNOTATE_BOTTOMUP_BBEND(states, basicblock)
+#define ANNOTATE_TOPDOWN_BBSTART(states, basicblock)
+#define ANNOTATE_TOPDOWN_BBEND(states, basicblock)
+#endif // !ARC_ANNOTATION
namespace {
/// \brief The main ARC optimization pass.
class ObjCARCOpt : public FunctionPass {
bool Changed;
ProvenanceAnalysis PA;
+ ARCRuntimeEntryPoints EP;
+
+ // This is used to track if a pointer is stored into an alloca.
+ DenseSet<const Value *> MultiOwnersSet;
/// A flag indicating whether this optimization pass should run.
bool Run;
- /// Declarations for ObjC runtime functions, for use in creating calls to
- /// them. These are initialized lazily to avoid cluttering up the Module
- /// with unused declarations.
-
- /// Declaration for ObjC runtime function
- /// objc_retainAutoreleasedReturnValue.
- Constant *RetainRVCallee;
- /// Declaration for ObjC runtime function objc_autoreleaseReturnValue.
- Constant *AutoreleaseRVCallee;
- /// Declaration for ObjC runtime function objc_release.
- Constant *ReleaseCallee;
- /// Declaration for ObjC runtime function objc_retain.
- Constant *RetainCallee;
- /// Declaration for ObjC runtime function objc_retainBlock.
- Constant *RetainBlockCallee;
- /// Declaration for ObjC runtime function objc_autorelease.
- Constant *AutoreleaseCallee;
-
/// Flags which determine whether each of the interesting runtine functions
/// is in fact used in the current function.
unsigned UsedInThisFunction;
/// The Metadata Kind for clang.arc.no_objc_arc_exceptions metadata.
unsigned NoObjCARCExceptionsMDKind;
- Constant *getRetainRVCallee(Module *M);
- Constant *getAutoreleaseRVCallee(Module *M);
- Constant *getReleaseCallee(Module *M);
- Constant *getRetainCallee(Module *M);
- Constant *getRetainBlockCallee(Module *M);
- Constant *getAutoreleaseCallee(Module *M);
+#ifdef ARC_ANNOTATIONS
+ /// The Metadata Kind for llvm.arc.annotation.bottomup metadata.
+ unsigned ARCAnnotationBottomUpMDKind;
+ /// The Metadata Kind for llvm.arc.annotation.topdown metadata.
+ unsigned ARCAnnotationTopDownMDKind;
+ /// The Metadata Kind for llvm.arc.annotation.provenancesource metadata.
+ unsigned ARCAnnotationProvenanceSourceMDKind;
+#endif // ARC_ANNOATIONS
bool IsRetainBlockOptimizable(const Instruction *Inst);
- void OptimizeRetainCall(Function &F, Instruction *Retain);
bool OptimizeRetainRVCall(Function &F, Instruction *RetainRV);
void OptimizeAutoreleaseRVCall(Function &F, Instruction *AutoreleaseRV,
InstructionClass &Class);
+ bool OptimizeRetainBlockCall(Function &F, Instruction *RetainBlock,
+ InstructionClass &Class);
void OptimizeIndividualCalls(Function &F);
void CheckForCFGHazards(const BasicBlock *BB,
MapVector<Value *, RRInfo> &Retains,
DenseMap<Value *, RRInfo> &Releases,
Module *M,
- SmallVector<Instruction *, 4> &NewRetains,
- SmallVector<Instruction *, 4> &NewReleases,
- SmallVector<Instruction *, 8> &DeadInsts,
+ SmallVectorImpl<Instruction *> &NewRetains,
+ SmallVectorImpl<Instruction *> &NewReleases,
+ SmallVectorImpl<Instruction *> &DeadInsts,
RRInfo &RetainsToMove,
RRInfo &ReleasesToMove,
Value *Arg,
void OptimizeReturns(Function &F);
+#ifndef NDEBUG
+ void GatherStatistics(Function &F, bool AfterOptimization = false);
+#endif
+
virtual void getAnalysisUsage(AnalysisUsage &AU) const;
virtual bool doInitialization(Module &M);
virtual bool runOnFunction(Function &F);
// If the pointer "escapes" (not including being used in a call),
// the copy may be needed.
- if (DoesObjCBlockEscape(Inst))
+ if (DoesRetainableObjPtrEscape(Inst))
return false;
// Otherwise, it's not needed.
return true;
}
-Constant *ObjCARCOpt::getRetainRVCallee(Module *M) {
- if (!RetainRVCallee) {
- LLVMContext &C = M->getContext();
- Type *I8X = PointerType::getUnqual(Type::getInt8Ty(C));
- Type *Params[] = { I8X };
- FunctionType *FTy = FunctionType::get(I8X, Params, /*isVarArg=*/false);
- AttributeSet Attribute =
- AttributeSet().addAttribute(M->getContext(), AttributeSet::FunctionIndex,
- Attribute::NoUnwind);
- RetainRVCallee =
- M->getOrInsertFunction("objc_retainAutoreleasedReturnValue", FTy,
- Attribute);
- }
- return RetainRVCallee;
-}
-
-Constant *ObjCARCOpt::getAutoreleaseRVCallee(Module *M) {
- if (!AutoreleaseRVCallee) {
- LLVMContext &C = M->getContext();
- Type *I8X = PointerType::getUnqual(Type::getInt8Ty(C));
- Type *Params[] = { I8X };
- FunctionType *FTy = FunctionType::get(I8X, Params, /*isVarArg=*/false);
- AttributeSet Attribute =
- AttributeSet().addAttribute(M->getContext(), AttributeSet::FunctionIndex,
- Attribute::NoUnwind);
- AutoreleaseRVCallee =
- M->getOrInsertFunction("objc_autoreleaseReturnValue", FTy,
- Attribute);
- }
- return AutoreleaseRVCallee;
-}
-
-Constant *ObjCARCOpt::getReleaseCallee(Module *M) {
- if (!ReleaseCallee) {
- LLVMContext &C = M->getContext();
- Type *Params[] = { PointerType::getUnqual(Type::getInt8Ty(C)) };
- AttributeSet Attribute =
- AttributeSet().addAttribute(M->getContext(), AttributeSet::FunctionIndex,
- Attribute::NoUnwind);
- ReleaseCallee =
- M->getOrInsertFunction(
- "objc_release",
- FunctionType::get(Type::getVoidTy(C), Params, /*isVarArg=*/false),
- Attribute);
- }
- return ReleaseCallee;
-}
-
-Constant *ObjCARCOpt::getRetainCallee(Module *M) {
- if (!RetainCallee) {
- LLVMContext &C = M->getContext();
- Type *Params[] = { PointerType::getUnqual(Type::getInt8Ty(C)) };
- AttributeSet Attribute =
- AttributeSet().addAttribute(M->getContext(), AttributeSet::FunctionIndex,
- Attribute::NoUnwind);
- RetainCallee =
- M->getOrInsertFunction(
- "objc_retain",
- FunctionType::get(Params[0], Params, /*isVarArg=*/false),
- Attribute);
- }
- return RetainCallee;
-}
-
-Constant *ObjCARCOpt::getRetainBlockCallee(Module *M) {
- if (!RetainBlockCallee) {
- LLVMContext &C = M->getContext();
- Type *Params[] = { PointerType::getUnqual(Type::getInt8Ty(C)) };
- // objc_retainBlock is not nounwind because it calls user copy constructors
- // which could theoretically throw.
- RetainBlockCallee =
- M->getOrInsertFunction(
- "objc_retainBlock",
- FunctionType::get(Params[0], Params, /*isVarArg=*/false),
- AttributeSet());
- }
- return RetainBlockCallee;
-}
-
-Constant *ObjCARCOpt::getAutoreleaseCallee(Module *M) {
- if (!AutoreleaseCallee) {
- LLVMContext &C = M->getContext();
- Type *Params[] = { PointerType::getUnqual(Type::getInt8Ty(C)) };
- AttributeSet Attribute =
- AttributeSet().addAttribute(M->getContext(), AttributeSet::FunctionIndex,
- Attribute::NoUnwind);
- AutoreleaseCallee =
- M->getOrInsertFunction(
- "objc_autorelease",
- FunctionType::get(Params[0], Params, /*isVarArg=*/false),
- Attribute);
- }
- return AutoreleaseCallee;
-}
-
-/// Test whether the given value is possible a reference-counted pointer,
-/// including tests which utilize AliasAnalysis.
-static 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;
-}
-
-/// Test whether the given instruction can result in a reference count
-/// modification (positive or negative) for the pointer's object.
-static bool
-CanAlterRefCount(const Instruction *Inst, const Value *Ptr,
- ProvenanceAnalysis &PA, InstructionClass Class) {
- switch (Class) {
- case IC_Autorelease:
- case IC_AutoreleaseRV:
- case IC_User:
- // These operations never directly modify a reference count.
- return false;
- default: break;
- }
-
- ImmutableCallSite CS = static_cast<const Value *>(Inst);
- assert(CS && "Only calls can alter reference counts!");
-
- // See if AliasAnalysis can help us with the call.
- AliasAnalysis::ModRefBehavior MRB = PA.getAA()->getModRefBehavior(CS);
- if (AliasAnalysis::onlyReadsMemory(MRB))
- return false;
- if (AliasAnalysis::onlyAccessesArgPointees(MRB)) {
- for (ImmutableCallSite::arg_iterator I = CS.arg_begin(), E = CS.arg_end();
- I != E; ++I) {
- const Value *Op = *I;
- if (IsPotentialRetainableObjPtr(Op, *PA.getAA()) && PA.related(Ptr, Op))
- return true;
- }
- return false;
- }
-
- // Assume the worst.
- return true;
-}
-
-/// Test whether the given instruction can "use" the given pointer's object in a
-/// way that requires the reference count to be positive.
-static bool
-CanUse(const Instruction *Inst, const Value *Ptr, ProvenanceAnalysis &PA,
- InstructionClass Class) {
- // IC_Call operations (as opposed to IC_CallOrUser) never "use" objc pointers.
- if (Class == IC_Call)
- return false;
-
- // Consider various instructions which may have pointer arguments which are
- // not "uses".
- if (const ICmpInst *ICI = dyn_cast<ICmpInst>(Inst)) {
- // Comparing a pointer with null, or any other constant, isn't really a use,
- // because we don't care what the pointer points to, or about the values
- // of any other dynamic reference-counted pointers.
- if (!IsPotentialRetainableObjPtr(ICI->getOperand(1), *PA.getAA()))
- return false;
- } else if (ImmutableCallSite CS = static_cast<const Value *>(Inst)) {
- // For calls, just check the arguments (and not the callee operand).
- for (ImmutableCallSite::arg_iterator OI = CS.arg_begin(),
- OE = CS.arg_end(); OI != OE; ++OI) {
- const Value *Op = *OI;
- if (IsPotentialRetainableObjPtr(Op, *PA.getAA()) && PA.related(Ptr, Op))
- return true;
- }
- return false;
- } else if (const StoreInst *SI = dyn_cast<StoreInst>(Inst)) {
- // Special-case stores, because we don't care about the stored value, just
- // the store address.
- const Value *Op = GetUnderlyingObjCPtr(SI->getPointerOperand());
- // If we can't tell what the underlying object was, assume there is a
- // dependence.
- return IsPotentialRetainableObjPtr(Op, *PA.getAA()) && PA.related(Op, Ptr);
- }
-
- // Check each operand for a match.
- for (User::const_op_iterator OI = Inst->op_begin(), OE = Inst->op_end();
- OI != OE; ++OI) {
- const Value *Op = *OI;
- if (IsPotentialRetainableObjPtr(Op, *PA.getAA()) && PA.related(Ptr, Op))
- return true;
- }
- return false;
-}
-
-/// Test whether the given instruction can autorelease any pointer or cause an
-/// autoreleasepool pop.
-static 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;
- }
-}
-
-namespace {
- /// \enum DependenceKind
- /// \brief Defines different dependence kinds among various ARC constructs.
- ///
- /// There are several kinds of dependence-like concepts in use here.
- ///
- enum DependenceKind {
- NeedsPositiveRetainCount,
- AutoreleasePoolBoundary,
- CanChangeRetainCount,
- RetainAutoreleaseDep, ///< Blocks objc_retainAutorelease.
- RetainAutoreleaseRVDep, ///< Blocks objc_retainAutoreleaseReturnValue.
- RetainRVDep ///< Blocks objc_retainAutoreleasedReturnValue.
- };
-}
-
-/// Test if there can be dependencies on Inst through Arg. This function only
-/// tests dependencies relevant for removing pairs of calls.
-static bool
-Depends(DependenceKind Flavor, Instruction *Inst, const Value *Arg,
- ProvenanceAnalysis &PA) {
- // If we've reached the definition of Arg, stop.
- if (Inst == Arg)
- return true;
-
- switch (Flavor) {
- case NeedsPositiveRetainCount: {
- InstructionClass Class = GetInstructionClass(Inst);
- switch (Class) {
- case IC_AutoreleasepoolPop:
- case IC_AutoreleasepoolPush:
- case IC_None:
- return false;
- default:
- return CanUse(Inst, Arg, PA, Class);
- }
- }
-
- case AutoreleasePoolBoundary: {
- InstructionClass Class = GetInstructionClass(Inst);
- switch (Class) {
- case IC_AutoreleasepoolPop:
- case IC_AutoreleasepoolPush:
- // These mark the end and begin of an autorelease pool scope.
- return true;
- default:
- // Nothing else does this.
- return false;
- }
- }
-
- case CanChangeRetainCount: {
- InstructionClass Class = GetInstructionClass(Inst);
- switch (Class) {
- case IC_AutoreleasepoolPop:
- // Conservatively assume this can decrement any count.
- return true;
- case IC_AutoreleasepoolPush:
- case IC_None:
- return false;
- default:
- return CanAlterRefCount(Inst, Arg, PA, Class);
- }
- }
-
- case RetainAutoreleaseDep:
- switch (GetBasicInstructionClass(Inst)) {
- case IC_AutoreleasepoolPop:
- case IC_AutoreleasepoolPush:
- // Don't merge an objc_autorelease with an objc_retain inside a different
- // autoreleasepool scope.
- return true;
- case IC_Retain:
- case IC_RetainRV:
- // Check for a retain of the same pointer for merging.
- return GetObjCArg(Inst) == Arg;
- default:
- // Nothing else matters for objc_retainAutorelease formation.
- return false;
- }
-
- case RetainAutoreleaseRVDep: {
- InstructionClass Class = GetBasicInstructionClass(Inst);
- switch (Class) {
- case IC_Retain:
- case IC_RetainRV:
- // Check for a retain of the same pointer for merging.
- return GetObjCArg(Inst) == Arg;
- default:
- // Anything that can autorelease interrupts
- // retainAutoreleaseReturnValue formation.
- return CanInterruptRV(Class);
- }
- }
-
- case RetainRVDep:
- return CanInterruptRV(GetBasicInstructionClass(Inst));
- }
-
- llvm_unreachable("Invalid dependence flavor");
-}
-
-/// Walk up the CFG from StartPos (which is in StartBB) and find local and
-/// non-local dependencies on Arg.
-///
-/// TODO: Cache results?
-static void
-FindDependencies(DependenceKind Flavor,
- const Value *Arg,
- BasicBlock *StartBB, Instruction *StartInst,
- SmallPtrSet<Instruction *, 4> &DependingInstructions,
- SmallPtrSet<const BasicBlock *, 4> &Visited,
- ProvenanceAnalysis &PA) {
- BasicBlock::iterator StartPos = StartInst;
-
- SmallVector<std::pair<BasicBlock *, BasicBlock::iterator>, 4> Worklist;
- Worklist.push_back(std::make_pair(StartBB, StartPos));
- do {
- std::pair<BasicBlock *, BasicBlock::iterator> Pair =
- Worklist.pop_back_val();
- BasicBlock *LocalStartBB = Pair.first;
- BasicBlock::iterator LocalStartPos = Pair.second;
- BasicBlock::iterator StartBBBegin = LocalStartBB->begin();
- for (;;) {
- if (LocalStartPos == StartBBBegin) {
- pred_iterator PI(LocalStartBB), PE(LocalStartBB, false);
- if (PI == PE)
- // If we've reached the function entry, produce a null dependence.
- DependingInstructions.insert(0);
- else
- // Add the predecessors to the worklist.
- do {
- BasicBlock *PredBB = *PI;
- if (Visited.insert(PredBB))
- Worklist.push_back(std::make_pair(PredBB, PredBB->end()));
- } while (++PI != PE);
- break;
- }
-
- Instruction *Inst = --LocalStartPos;
- if (Depends(Flavor, Inst, Arg, PA)) {
- DependingInstructions.insert(Inst);
- break;
- }
- }
- } while (!Worklist.empty());
-
- // Determine whether the original StartBB post-dominates all of the blocks we
- // visited. If not, insert a sentinal indicating that most optimizations are
- // not safe.
- for (SmallPtrSet<const BasicBlock *, 4>::const_iterator I = Visited.begin(),
- E = Visited.end(); I != E; ++I) {
- const BasicBlock *BB = *I;
- if (BB == StartBB)
- continue;
- const TerminatorInst *TI = cast<TerminatorInst>(&BB->back());
- for (succ_const_iterator SI(TI), SE(TI, false); SI != SE; ++SI) {
- const BasicBlock *Succ = *SI;
- if (Succ != StartBB && !Visited.count(Succ)) {
- DependingInstructions.insert(reinterpret_cast<Instruction *>(-1));
- return;
- }
- }
- }
-}
-
-static bool isNullOrUndef(const Value *V) {
- return isa<ConstantPointerNull>(V) || isa<UndefValue>(V);
-}
-
-static bool isNoopInstruction(const Instruction *I) {
- return isa<BitCastInst>(I) ||
- (isa<GetElementPtrInst>(I) &&
- cast<GetElementPtrInst>(I)->hasAllZeroIndices());
-}
-
-/// Turn objc_retain into objc_retainAutoreleasedReturnValue if the operand is a
-/// return value.
-void
-ObjCARCOpt::OptimizeRetainCall(Function &F, Instruction *Retain) {
- ImmutableCallSite CS(GetObjCArg(Retain));
- const Instruction *Call = CS.getInstruction();
- if (!Call) return;
- if (Call->getParent() != Retain->getParent()) return;
-
- // Check that the call is next to the retain.
- BasicBlock::const_iterator I = Call;
- ++I;
- while (isNoopInstruction(I)) ++I;
- if (&*I != Retain)
- return;
-
- // Turn it to an objc_retainAutoreleasedReturnValue..
- Changed = true;
- ++NumPeeps;
-
- DEBUG(dbgs() << "ObjCARCOpt::OptimizeRetainCall: Transforming "
- "objc_retain => objc_retainAutoreleasedReturnValue"
- " since the operand is a return value.\n"
- " Old: "
- << *Retain << "\n");
-
- cast<CallInst>(Retain)->setCalledFunction(getRetainRVCallee(F.getParent()));
-
- DEBUG(dbgs() << " New: "
- << *Retain << "\n");
-}
-
/// Turn objc_retainAutoreleasedReturnValue into objc_retain if the operand is
/// not a return value. Or, if it can be paired with an
/// objc_autoreleaseReturnValue, delete the pair and return true.
if (Call->getParent() == RetainRV->getParent()) {
BasicBlock::const_iterator I = Call;
++I;
- while (isNoopInstruction(I)) ++I;
+ while (IsNoopInstruction(I)) ++I;
if (&*I == RetainRV)
return false;
} else if (const InvokeInst *II = dyn_cast<InvokeInst>(Call)) {
BasicBlock *RetainRVParent = RetainRV->getParent();
if (II->getNormalDest() == RetainRVParent) {
BasicBlock::const_iterator I = RetainRVParent->begin();
- while (isNoopInstruction(I)) ++I;
+ while (IsNoopInstruction(I)) ++I;
if (&*I == RetainRV)
return false;
}
// pointer. In this case, we can delete the pair.
BasicBlock::iterator I = RetainRV, Begin = RetainRV->getParent()->begin();
if (I != Begin) {
- do --I; while (I != Begin && isNoopInstruction(I));
+ do --I; while (I != Begin && IsNoopInstruction(I));
if (GetBasicInstructionClass(I) == IC_AutoreleaseRV &&
GetObjCArg(I) == Arg) {
Changed = true;
++NumPeeps;
- DEBUG(dbgs() << "ObjCARCOpt::OptimizeRetainRVCall: Erasing " << *I << "\n"
- << " Erasing " << *RetainRV
- << "\n");
+ DEBUG(dbgs() << "Erasing autoreleaseRV,retainRV pair: " << *I << "\n"
+ << "Erasing " << *RetainRV << "\n");
EraseInstruction(I);
EraseInstruction(RetainRV);
Changed = true;
++NumPeeps;
- DEBUG(dbgs() << "ObjCARCOpt::OptimizeRetainRVCall: Transforming "
- "objc_retainAutoreleasedReturnValue => "
+ DEBUG(dbgs() << "Transforming objc_retainAutoreleasedReturnValue => "
"objc_retain since the operand is not a return value.\n"
- " Old: "
- << *RetainRV << "\n");
+ "Old = " << *RetainRV << "\n");
- cast<CallInst>(RetainRV)->setCalledFunction(getRetainCallee(F.getParent()));
+ Constant *NewDecl = EP.get(ARCRuntimeEntryPoints::EPT_Retain);
+ cast<CallInst>(RetainRV)->setCalledFunction(NewDecl);
- DEBUG(dbgs() << " New: "
- << *RetainRV << "\n");
+ DEBUG(dbgs() << "New = " << *RetainRV << "\n");
return false;
}
Changed = true;
++NumPeeps;
- DEBUG(dbgs() << "ObjCARCOpt::OptimizeAutoreleaseRVCall: Transforming "
- "objc_autoreleaseReturnValue => "
+ DEBUG(dbgs() << "Transforming objc_autoreleaseReturnValue => "
"objc_autorelease since its operand is not used as a return "
"value.\n"
- " Old: "
- << *AutoreleaseRV << "\n");
+ "Old = " << *AutoreleaseRV << "\n");
CallInst *AutoreleaseRVCI = cast<CallInst>(AutoreleaseRV);
- AutoreleaseRVCI->
- setCalledFunction(getAutoreleaseCallee(F.getParent()));
+ Constant *NewDecl = EP.get(ARCRuntimeEntryPoints::EPT_Autorelease);
+ AutoreleaseRVCI->setCalledFunction(NewDecl);
AutoreleaseRVCI->setTailCall(false); // Never tail call objc_autorelease.
Class = IC_Autorelease;
- DEBUG(dbgs() << " New: "
- << *AutoreleaseRV << "\n");
+ DEBUG(dbgs() << "New: " << *AutoreleaseRV << "\n");
+
+}
+
+// \brief Attempt to strength reduce objc_retainBlock calls to objc_retain
+// calls.
+//
+// Specifically: If an objc_retainBlock call has the copy_on_escape metadata and
+// does not escape (following the rules of block escaping), strength reduce the
+// objc_retainBlock to an objc_retain.
+//
+// TODO: If an objc_retainBlock call is dominated period by a previous
+// objc_retainBlock call, strength reduce the objc_retainBlock to an
+// objc_retain.
+bool
+ObjCARCOpt::OptimizeRetainBlockCall(Function &F, Instruction *Inst,
+ InstructionClass &Class) {
+ assert(GetBasicInstructionClass(Inst) == Class);
+ assert(IC_RetainBlock == Class);
+
+ // If we can not optimize Inst, return false.
+ if (!IsRetainBlockOptimizable(Inst))
+ return false;
+
+ Changed = true;
+ ++NumPeeps;
+ DEBUG(dbgs() << "Strength reduced retainBlock => retain.\n");
+ DEBUG(dbgs() << "Old: " << *Inst << "\n");
+ CallInst *RetainBlock = cast<CallInst>(Inst);
+ Constant *NewDecl = EP.get(ARCRuntimeEntryPoints::EPT_Retain);
+ RetainBlock->setCalledFunction(NewDecl);
+ // Remove copy_on_escape metadata.
+ RetainBlock->setMetadata(CopyOnEscapeMDKind, 0);
+ Class = IC_Retain;
+ DEBUG(dbgs() << "New: " << *Inst << "\n");
+ return true;
}
/// Visit each call, one at a time, and make simplifications without doing any
/// additional analysis.
void ObjCARCOpt::OptimizeIndividualCalls(Function &F) {
+ DEBUG(dbgs() << "\n== ObjCARCOpt::OptimizeIndividualCalls ==\n");
// Reset all the flags in preparation for recomputing them.
UsedInThisFunction = 0;
InstructionClass Class = GetBasicInstructionClass(Inst);
- DEBUG(dbgs() << "ObjCARCOpt::OptimizeIndividualCalls: Visiting: Class: "
- << Class << "; " << *Inst << "\n");
+ DEBUG(dbgs() << "Visiting: Class: " << Class << "; " << *Inst << "\n");
switch (Class) {
default: break;
case IC_NoopCast:
Changed = true;
++NumNoops;
- DEBUG(dbgs() << "ObjCARCOpt::OptimizeIndividualCalls: Erasing no-op cast:"
- " " << *Inst << "\n");
+ DEBUG(dbgs() << "Erasing no-op cast: " << *Inst << "\n");
EraseInstruction(Inst);
continue;
case IC_InitWeak:
case IC_DestroyWeak: {
CallInst *CI = cast<CallInst>(Inst);
- if (isNullOrUndef(CI->getArgOperand(0))) {
+ if (IsNullOrUndef(CI->getArgOperand(0))) {
Changed = true;
Type *Ty = CI->getArgOperand(0)->getType();
new StoreInst(UndefValue::get(cast<PointerType>(Ty)->getElementType()),
Constant::getNullValue(Ty),
CI);
llvm::Value *NewValue = UndefValue::get(CI->getType());
- DEBUG(dbgs() << "ObjCARCOpt::OptimizeIndividualCalls: A null "
- "pointer-to-weak-pointer is undefined behavior.\n"
- " Old = " << *CI <<
- "\n New = " <<
- *NewValue << "\n");
+ DEBUG(dbgs() << "A null pointer-to-weak-pointer is undefined behavior."
+ "\nOld = " << *CI << "\nNew = " << *NewValue << "\n");
CI->replaceAllUsesWith(NewValue);
CI->eraseFromParent();
continue;
case IC_CopyWeak:
case IC_MoveWeak: {
CallInst *CI = cast<CallInst>(Inst);
- if (isNullOrUndef(CI->getArgOperand(0)) ||
- isNullOrUndef(CI->getArgOperand(1))) {
+ if (IsNullOrUndef(CI->getArgOperand(0)) ||
+ IsNullOrUndef(CI->getArgOperand(1))) {
Changed = true;
Type *Ty = CI->getArgOperand(0)->getType();
new StoreInst(UndefValue::get(cast<PointerType>(Ty)->getElementType()),
CI);
llvm::Value *NewValue = UndefValue::get(CI->getType());
- DEBUG(dbgs() << "ObjCARCOpt::OptimizeIndividualCalls: A null "
- "pointer-to-weak-pointer is undefined behavior.\n"
- " Old = " << *CI <<
- "\n New = " <<
- *NewValue << "\n");
+ DEBUG(dbgs() << "A null pointer-to-weak-pointer is undefined behavior."
+ "\nOld = " << *CI << "\nNew = " << *NewValue << "\n");
CI->replaceAllUsesWith(NewValue);
CI->eraseFromParent();
}
break;
}
- case IC_Retain:
- OptimizeRetainCall(F, Inst);
+ case IC_RetainBlock:
+ // If we strength reduce an objc_retainBlock to an objc_retain, continue
+ // onto the objc_retain peephole optimizations. Otherwise break.
+ OptimizeRetainBlockCall(F, Inst, Class);
break;
case IC_RetainRV:
if (OptimizeRetainRVCall(F, Inst))
// Create the declaration lazily.
LLVMContext &C = Inst->getContext();
- CallInst *NewCall =
- CallInst::Create(getReleaseCallee(F.getParent()),
- Call->getArgOperand(0), "", Call);
- NewCall->setMetadata(ImpreciseReleaseMDKind,
- MDNode::get(C, ArrayRef<Value *>()));
-
- DEBUG(dbgs() << "ObjCARCOpt::OptimizeIndividualCalls: Replacing "
- "objc_autorelease(x) with objc_release(x) since x is "
- "otherwise unused.\n"
- " Old: " << *Call <<
- "\n New: " <<
- *NewCall << "\n");
+
+ Constant *Decl = EP.get(ARCRuntimeEntryPoints::EPT_Release);
+ CallInst *NewCall = CallInst::Create(Decl, Call->getArgOperand(0), "",
+ Call);
+ NewCall->setMetadata(ImpreciseReleaseMDKind, MDNode::get(C, None));
+
+ DEBUG(dbgs() << "Replacing autorelease{,RV}(x) with objc_release(x) "
+ "since x is otherwise unused.\nOld: " << *Call << "\nNew: "
+ << *NewCall << "\n");
EraseInstruction(Call);
Inst = NewCall;
// a tail keyword.
if (IsAlwaysTail(Class)) {
Changed = true;
- DEBUG(dbgs() << "ObjCARCOpt::OptimizeIndividualCalls: Adding tail keyword"
- " to function since it can never be passed stack args: " << *Inst <<
- "\n");
+ DEBUG(dbgs() << "Adding tail keyword to function since it can never be "
+ "passed stack args: " << *Inst << "\n");
cast<CallInst>(Inst)->setTailCall();
}
// semantics of ARC truly do not do so.
if (IsNeverTail(Class)) {
Changed = true;
- DEBUG(dbgs() << "ObjCARCOpt::OptimizeIndividualCalls: Removing tail "
- "keyword from function: " << *Inst <<
+ DEBUG(dbgs() << "Removing tail keyword from function: " << *Inst <<
"\n");
cast<CallInst>(Inst)->setTailCall(false);
}
// Set nounwind as needed.
if (IsNoThrow(Class)) {
Changed = true;
- DEBUG(dbgs() << "ObjCARCOpt::OptimizeIndividualCalls: Found no throw"
- " class. Setting nounwind on: " << *Inst << "\n");
+ DEBUG(dbgs() << "Found no throw class. Setting nounwind on: " << *Inst
+ << "\n");
cast<CallInst>(Inst)->setDoesNotThrow();
}
const Value *Arg = GetObjCArg(Inst);
// ARC calls with null are no-ops. Delete them.
- if (isNullOrUndef(Arg)) {
+ if (IsNullOrUndef(Arg)) {
Changed = true;
++NumNoops;
- DEBUG(dbgs() << "ObjCARCOpt::OptimizeIndividualCalls: ARC calls with "
- " null are no-ops. Erasing: " << *Inst << "\n");
+ DEBUG(dbgs() << "ARC calls with null are no-ops. Erasing: " << *Inst
+ << "\n");
EraseInstruction(Inst);
continue;
}
for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) {
Value *Incoming =
StripPointerCastsAndObjCCalls(PN->getIncomingValue(i));
- if (isNullOrUndef(Incoming))
+ if (IsNullOrUndef(Incoming))
HasNull = true;
else if (cast<TerminatorInst>(PN->getIncomingBlock(i)->back())
.getNumSuccessors() != 1) {
for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) {
Value *Incoming =
StripPointerCastsAndObjCCalls(PN->getIncomingValue(i));
- if (!isNullOrUndef(Incoming)) {
+ if (!IsNullOrUndef(Incoming)) {
CallInst *Clone = cast<CallInst>(CInst->clone());
Value *Op = PN->getIncomingValue(i);
Instruction *InsertPos = &PN->getIncomingBlock(i)->back();
Clone->setArgOperand(0, Op);
Clone->insertBefore(InsertPos);
- DEBUG(dbgs() << "ObjCARCOpt::OptimizeIndividualCalls: Cloning "
+ DEBUG(dbgs() << "Cloning "
<< *CInst << "\n"
- " And inserting "
- "clone at " << *InsertPos << "\n");
+ "And inserting clone at " << *InsertPos << "\n");
Worklist.push_back(std::make_pair(Clone, Incoming));
}
}
}
} while (!Worklist.empty());
}
- DEBUG(dbgs() << "ObjCARCOpt::OptimizeIndividualCalls: Finished List.\n");
+}
+
+/// If we have a top down pointer in the S_Use state, make sure that there are
+/// no CFG hazards by checking the states of various bottom up pointers.
+static void CheckForUseCFGHazard(const Sequence SuccSSeq,
+ const bool SuccSRRIKnownSafe,
+ PtrState &S,
+ bool &SomeSuccHasSame,
+ bool &AllSuccsHaveSame,
+ bool &NotAllSeqEqualButKnownSafe,
+ bool &ShouldContinue) {
+ switch (SuccSSeq) {
+ case S_CanRelease: {
+ if (!S.IsKnownSafe() && !SuccSRRIKnownSafe) {
+ S.ClearSequenceProgress();
+ break;
+ }
+ S.SetCFGHazardAfflicted(true);
+ ShouldContinue = true;
+ break;
+ }
+ case S_Use:
+ SomeSuccHasSame = true;
+ break;
+ case S_Stop:
+ case S_Release:
+ case S_MovableRelease:
+ if (!S.IsKnownSafe() && !SuccSRRIKnownSafe)
+ AllSuccsHaveSame = false;
+ else
+ NotAllSeqEqualButKnownSafe = true;
+ break;
+ case S_Retain:
+ llvm_unreachable("bottom-up pointer in retain state!");
+ case S_None:
+ llvm_unreachable("This should have been handled earlier.");
+ }
+}
+
+/// If we have a Top Down pointer in the S_CanRelease state, make sure that
+/// there are no CFG hazards by checking the states of various bottom up
+/// pointers.
+static void CheckForCanReleaseCFGHazard(const Sequence SuccSSeq,
+ const bool SuccSRRIKnownSafe,
+ PtrState &S,
+ bool &SomeSuccHasSame,
+ bool &AllSuccsHaveSame,
+ bool &NotAllSeqEqualButKnownSafe) {
+ switch (SuccSSeq) {
+ case S_CanRelease:
+ SomeSuccHasSame = true;
+ break;
+ case S_Stop:
+ case S_Release:
+ case S_MovableRelease:
+ case S_Use:
+ if (!S.IsKnownSafe() && !SuccSRRIKnownSafe)
+ AllSuccsHaveSame = false;
+ else
+ NotAllSeqEqualButKnownSafe = true;
+ break;
+ case S_Retain:
+ llvm_unreachable("bottom-up pointer in retain state!");
+ case S_None:
+ llvm_unreachable("This should have been handled earlier.");
+ }
}
/// Check for critical edges, loop boundaries, irreducible control flow, or
// If any top-down local-use or possible-dec has a succ which is earlier in
// the sequence, forget it.
for (BBState::ptr_iterator I = MyStates.top_down_ptr_begin(),
- E = MyStates.top_down_ptr_end(); I != E; ++I)
- switch (I->second.GetSeq()) {
- default: break;
- case S_Use: {
- const Value *Arg = I->first;
- const TerminatorInst *TI = cast<TerminatorInst>(&BB->back());
- bool SomeSuccHasSame = false;
- bool AllSuccsHaveSame = true;
- PtrState &S = I->second;
- succ_const_iterator SI(TI), SE(TI, false);
-
- for (; SI != SE; ++SI) {
- Sequence SuccSSeq = S_None;
- bool SuccSRRIKnownSafe = false;
- // If VisitBottomUp has pointer information for this successor, take
- // what we know about it.
- DenseMap<const BasicBlock *, BBState>::iterator BBI =
- BBStates.find(*SI);
- assert(BBI != BBStates.end());
- const PtrState &SuccS = BBI->second.getPtrBottomUpState(Arg);
- SuccSSeq = SuccS.GetSeq();
- SuccSRRIKnownSafe = SuccS.RRI.KnownSafe;
- switch (SuccSSeq) {
- case S_None:
- case S_CanRelease: {
- if (!S.RRI.KnownSafe && !SuccSRRIKnownSafe) {
- S.ClearSequenceProgress();
- break;
- }
- continue;
- }
- case S_Use:
- SomeSuccHasSame = true;
- break;
- case S_Stop:
- case S_Release:
- case S_MovableRelease:
- if (!S.RRI.KnownSafe && !SuccSRRIKnownSafe)
- AllSuccsHaveSame = false;
- break;
- case S_Retain:
- llvm_unreachable("bottom-up pointer in retain state!");
- }
- }
- // If the state at the other end of any of the successor edges
- // matches the current state, require all edges to match. This
- // guards against loops in the middle of a sequence.
- if (SomeSuccHasSame && !AllSuccsHaveSame)
+ E = MyStates.top_down_ptr_end(); I != E; ++I) {
+ PtrState &S = I->second;
+ const Sequence Seq = I->second.GetSeq();
+
+ // We only care about S_Retain, S_CanRelease, and S_Use.
+ if (Seq == S_None)
+ continue;
+
+ // Make sure that if extra top down states are added in the future that this
+ // code is updated to handle it.
+ assert((Seq == S_Retain || Seq == S_CanRelease || Seq == S_Use) &&
+ "Unknown top down sequence state.");
+
+ const Value *Arg = I->first;
+ const TerminatorInst *TI = cast<TerminatorInst>(&BB->back());
+ bool SomeSuccHasSame = false;
+ bool AllSuccsHaveSame = true;
+ bool NotAllSeqEqualButKnownSafe = false;
+
+ succ_const_iterator SI(TI), SE(TI, false);
+
+ for (; SI != SE; ++SI) {
+ // If VisitBottomUp has pointer information for this successor, take
+ // what we know about it.
+ const DenseMap<const BasicBlock *, BBState>::iterator BBI =
+ BBStates.find(*SI);
+ assert(BBI != BBStates.end());
+ const PtrState &SuccS = BBI->second.getPtrBottomUpState(Arg);
+ const Sequence SuccSSeq = SuccS.GetSeq();
+
+ // If bottom up, the pointer is in an S_None state, clear the sequence
+ // progress since the sequence in the bottom up state finished
+ // suggesting a mismatch in between retains/releases. This is true for
+ // all three cases that we are handling here: S_Retain, S_Use, and
+ // S_CanRelease.
+ if (SuccSSeq == S_None) {
S.ClearSequenceProgress();
- break;
- }
- case S_CanRelease: {
- const Value *Arg = I->first;
- const TerminatorInst *TI = cast<TerminatorInst>(&BB->back());
- bool SomeSuccHasSame = false;
- bool AllSuccsHaveSame = true;
- PtrState &S = I->second;
- succ_const_iterator SI(TI), SE(TI, false);
-
- for (; SI != SE; ++SI) {
- Sequence SuccSSeq = S_None;
- bool SuccSRRIKnownSafe = false;
- // If VisitBottomUp has pointer information for this successor, take
- // what we know about it.
- DenseMap<const BasicBlock *, BBState>::iterator BBI =
- BBStates.find(*SI);
- assert(BBI != BBStates.end());
- const PtrState &SuccS = BBI->second.getPtrBottomUpState(Arg);
- SuccSSeq = SuccS.GetSeq();
- SuccSRRIKnownSafe = SuccS.RRI.KnownSafe;
- switch (SuccSSeq) {
- case S_None: {
- if (!S.RRI.KnownSafe && !SuccSRRIKnownSafe) {
- S.ClearSequenceProgress();
- break;
- }
+ continue;
+ }
+
+ // If we have S_Use or S_CanRelease, perform our check for cfg hazard
+ // checks.
+ const bool SuccSRRIKnownSafe = SuccS.IsKnownSafe();
+
+ // *NOTE* We do not use Seq from above here since we are allowing for
+ // S.GetSeq() to change while we are visiting basic blocks.
+ switch(S.GetSeq()) {
+ case S_Use: {
+ bool ShouldContinue = false;
+ CheckForUseCFGHazard(SuccSSeq, SuccSRRIKnownSafe, S, SomeSuccHasSame,
+ AllSuccsHaveSame, NotAllSeqEqualButKnownSafe,
+ ShouldContinue);
+ if (ShouldContinue)
continue;
- }
- case S_CanRelease:
- SomeSuccHasSame = true;
- break;
- case S_Stop:
- case S_Release:
- case S_MovableRelease:
- case S_Use:
- if (!S.RRI.KnownSafe && !SuccSRRIKnownSafe)
- AllSuccsHaveSame = false;
- break;
- case S_Retain:
- llvm_unreachable("bottom-up pointer in retain state!");
- }
+ break;
+ }
+ case S_CanRelease: {
+ CheckForCanReleaseCFGHazard(SuccSSeq, SuccSRRIKnownSafe, S,
+ SomeSuccHasSame, AllSuccsHaveSame,
+ NotAllSeqEqualButKnownSafe);
+ break;
+ }
+ case S_Retain:
+ case S_None:
+ case S_Stop:
+ case S_Release:
+ case S_MovableRelease:
+ break;
}
- // If the state at the other end of any of the successor edges
- // matches the current state, require all edges to match. This
- // guards against loops in the middle of a sequence.
- if (SomeSuccHasSame && !AllSuccsHaveSame)
- S.ClearSequenceProgress();
- break;
}
+
+ // If the state at the other end of any of the successor edges
+ // matches the current state, require all edges to match. This
+ // guards against loops in the middle of a sequence.
+ if (SomeSuccHasSame && !AllSuccsHaveSame) {
+ S.ClearSequenceProgress();
+ } else if (NotAllSeqEqualButKnownSafe) {
+ // If we would have cleared the state foregoing the fact that we are known
+ // safe, stop code motion. This is because whether or not it is safe to
+ // remove RR pairs via KnownSafe is an orthogonal concept to whether we
+ // are allowed to perform code motion.
+ S.SetCFGHazardAfflicted(true);
}
+ }
}
bool
InstructionClass Class = GetInstructionClass(Inst);
const Value *Arg = 0;
+ DEBUG(dbgs() << "Class: " << Class << "\n");
+
switch (Class) {
case IC_Release: {
Arg = GetObjCArg(Inst);
// pairs by making PtrState hold a stack of states, but this is
// simple and avoids adding overhead for the non-nested case.
if (S.GetSeq() == S_Release || S.GetSeq() == S_MovableRelease) {
- DEBUG(dbgs() << "ObjCARCOpt::VisitInstructionBottomUp: Found nested "
- "releases (i.e. a release pair)\n");
+ DEBUG(dbgs() << "Found nested releases (i.e. a release pair)\n");
NestingDetected = true;
}
MDNode *ReleaseMetadata = Inst->getMetadata(ImpreciseReleaseMDKind);
- S.ResetSequenceProgress(ReleaseMetadata ? S_MovableRelease : S_Release);
- S.RRI.ReleaseMetadata = ReleaseMetadata;
- S.RRI.KnownSafe = S.IsKnownIncremented();
- S.RRI.IsTailCallRelease = cast<CallInst>(Inst)->isTailCall();
- S.RRI.Calls.insert(Inst);
-
+ Sequence NewSeq = ReleaseMetadata ? S_MovableRelease : S_Release;
+ ANNOTATE_BOTTOMUP(Inst, Arg, S.GetSeq(), NewSeq);
+ S.ResetSequenceProgress(NewSeq);
+ S.SetReleaseMetadata(ReleaseMetadata);
+ S.SetKnownSafe(S.HasKnownPositiveRefCount());
+ S.SetTailCallRelease(cast<CallInst>(Inst)->isTailCall());
+ S.InsertCall(Inst);
S.SetKnownPositiveRefCount();
break;
}
case IC_RetainBlock:
- // An objc_retainBlock call with just a use may need to be kept,
- // because it may be copying a block from the stack to the heap.
- if (!IsRetainBlockOptimizable(Inst))
- break;
- // FALLTHROUGH
+ // In OptimizeIndividualCalls, we have strength reduced all optimizable
+ // objc_retainBlocks to objc_retains. Thus at this point any
+ // objc_retainBlocks that we see are not optimizable.
+ break;
case IC_Retain:
case IC_RetainRV: {
Arg = GetObjCArg(Inst);
PtrState &S = MyStates.getPtrBottomUpState(Arg);
S.SetKnownPositiveRefCount();
- switch (S.GetSeq()) {
+ Sequence OldSeq = S.GetSeq();
+ switch (OldSeq) {
case S_Stop:
case S_Release:
case S_MovableRelease:
case S_Use:
- S.RRI.ReverseInsertPts.clear();
+ // If OldSeq is not S_Use or OldSeq is S_Use and we are tracking an
+ // imprecise release, clear our reverse insertion points.
+ if (OldSeq != S_Use || S.IsTrackingImpreciseReleases())
+ S.ClearReverseInsertPts();
// FALL THROUGH
case S_CanRelease:
// Don't do retain+release tracking for IC_RetainRV, because it's
// better to let it remain as the first instruction after a call.
- if (Class != IC_RetainRV) {
- S.RRI.IsRetainBlock = Class == IC_RetainBlock;
- Retains[Inst] = S.RRI;
- }
+ if (Class != IC_RetainRV)
+ Retains[Inst] = S.GetRRInfo();
S.ClearSequenceProgress();
break;
case S_None:
case S_Retain:
llvm_unreachable("bottom-up pointer in retain state!");
}
- return NestingDetected;
+ ANNOTATE_BOTTOMUP(Inst, Arg, OldSeq, S.GetSeq());
+ // A retain moving bottom up can be a use.
+ break;
}
case IC_AutoreleasepoolPop:
// Conservatively, clear MyStates for all known pointers.
case IC_None:
// These are irrelevant.
return NestingDetected;
+ case IC_User:
+ // If we have a store into an alloca of a pointer we are tracking, the
+ // pointer has multiple owners implying that we must be more conservative.
+ //
+ // This comes up in the context of a pointer being ``KnownSafe''. In the
+ // presense of a block being initialized, the frontend will emit the
+ // objc_retain on the original pointer and the release on the pointer loaded
+ // from the alloca. The optimizer will through the provenance analysis
+ // realize that the two are related, but since we only require KnownSafe in
+ // one direction, will match the inner retain on the original pointer with
+ // the guard release on the original pointer. This is fixed by ensuring that
+ // in the presense of allocas we only unconditionally remove pointers if
+ // both our retain and our release are KnownSafe.
+ if (StoreInst *SI = dyn_cast<StoreInst>(Inst)) {
+ if (AreAnyUnderlyingObjectsAnAlloca(SI->getPointerOperand())) {
+ BBState::ptr_iterator I = MyStates.findPtrBottomUpState(
+ StripPointerCastsAndObjCCalls(SI->getValueOperand()));
+ if (I != MyStates.bottom_up_ptr_end())
+ MultiOwnersSet.insert(I->first);
+ }
+ }
+ break;
default:
break;
}
// Check for possible releases.
if (CanAlterRefCount(Inst, Ptr, PA, Class)) {
- S.ClearRefCount();
+ DEBUG(dbgs() << "CanAlterRefCount: Seq: " << Seq << "; " << *Ptr
+ << "\n");
+ S.ClearKnownPositiveRefCount();
switch (Seq) {
case S_Use:
S.SetSeq(S_CanRelease);
+ ANNOTATE_BOTTOMUP(Inst, Ptr, Seq, S.GetSeq());
continue;
case S_CanRelease:
case S_Release:
case S_Release:
case S_MovableRelease:
if (CanUse(Inst, Ptr, PA, Class)) {
- assert(S.RRI.ReverseInsertPts.empty());
+ DEBUG(dbgs() << "CanUse: Seq: " << Seq << "; " << *Ptr
+ << "\n");
+ assert(!S.HasReverseInsertPts());
// If this is an invoke instruction, we're scanning it as part of
// one of its successor blocks, since we can't insert code after it
// in its own block, and we don't want to split critical edges.
if (isa<InvokeInst>(Inst))
- S.RRI.ReverseInsertPts.insert(BB->getFirstInsertionPt());
+ S.InsertReverseInsertPt(BB->getFirstInsertionPt());
else
- S.RRI.ReverseInsertPts.insert(llvm::next(BasicBlock::iterator(Inst)));
+ S.InsertReverseInsertPt(llvm::next(BasicBlock::iterator(Inst)));
S.SetSeq(S_Use);
- } else if (Seq == S_Release &&
- (Class == IC_User || Class == IC_CallOrUser)) {
+ ANNOTATE_BOTTOMUP(Inst, Ptr, Seq, S_Use);
+ } else if (Seq == S_Release && IsUser(Class)) {
+ DEBUG(dbgs() << "PreciseReleaseUse: Seq: " << Seq << "; " << *Ptr
+ << "\n");
// Non-movable releases depend on any possible objc pointer use.
S.SetSeq(S_Stop);
- assert(S.RRI.ReverseInsertPts.empty());
+ ANNOTATE_BOTTOMUP(Inst, Ptr, S_Release, S_Stop);
+ assert(!S.HasReverseInsertPts());
// As above; handle invoke specially.
if (isa<InvokeInst>(Inst))
- S.RRI.ReverseInsertPts.insert(BB->getFirstInsertionPt());
+ S.InsertReverseInsertPt(BB->getFirstInsertionPt());
else
- S.RRI.ReverseInsertPts.insert(llvm::next(BasicBlock::iterator(Inst)));
+ S.InsertReverseInsertPt(llvm::next(BasicBlock::iterator(Inst)));
}
break;
case S_Stop:
- if (CanUse(Inst, Ptr, PA, Class))
+ if (CanUse(Inst, Ptr, PA, Class)) {
+ DEBUG(dbgs() << "PreciseStopUse: Seq: " << Seq << "; " << *Ptr
+ << "\n");
S.SetSeq(S_Use);
+ ANNOTATE_BOTTOMUP(Inst, Ptr, Seq, S_Use);
+ }
break;
case S_CanRelease:
case S_Use:
ObjCARCOpt::VisitBottomUp(BasicBlock *BB,
DenseMap<const BasicBlock *, BBState> &BBStates,
MapVector<Value *, RRInfo> &Retains) {
+
+ DEBUG(dbgs() << "\n== ObjCARCOpt::VisitBottomUp ==\n");
+
bool NestingDetected = false;
BBState &MyStates = BBStates[BB];
}
}
+ // If ARC Annotations are enabled, output the current state of pointers at the
+ // bottom of the basic block.
+ ANNOTATE_BOTTOMUP_BBEND(MyStates, BB);
+
// Visit all the instructions, bottom-up.
for (BasicBlock::iterator I = BB->end(), E = BB->begin(); I != E; --I) {
Instruction *Inst = llvm::prior(I);
if (isa<InvokeInst>(Inst))
continue;
- DEBUG(dbgs() << "ObjCARCOpt::VisitButtonUp: Visiting " << *Inst << "\n");
+ DEBUG(dbgs() << "Visiting " << *Inst << "\n");
NestingDetected |= VisitInstructionBottomUp(Inst, BB, Retains, MyStates);
}
NestingDetected |= VisitInstructionBottomUp(II, BB, Retains, MyStates);
}
+ // If ARC Annotations are enabled, output the current state of pointers at the
+ // top of the basic block.
+ ANNOTATE_BOTTOMUP_BBSTART(MyStates, BB);
+
return NestingDetected;
}
switch (Class) {
case IC_RetainBlock:
- // An objc_retainBlock call with just a use may need to be kept,
- // because it may be copying a block from the stack to the heap.
- if (!IsRetainBlockOptimizable(Inst))
- break;
- // FALLTHROUGH
+ // In OptimizeIndividualCalls, we have strength reduced all optimizable
+ // objc_retainBlocks to objc_retains. Thus at this point any
+ // objc_retainBlocks that we see are not optimizable.
+ break;
case IC_Retain:
case IC_RetainRV: {
Arg = GetObjCArg(Inst);
if (S.GetSeq() == S_Retain)
NestingDetected = true;
+ ANNOTATE_TOPDOWN(Inst, Arg, S.GetSeq(), S_Retain);
S.ResetSequenceProgress(S_Retain);
- S.RRI.IsRetainBlock = Class == IC_RetainBlock;
- S.RRI.KnownSafe = S.IsKnownIncremented();
- S.RRI.Calls.insert(Inst);
+ S.SetKnownSafe(S.HasKnownPositiveRefCount());
+ S.InsertCall(Inst);
}
S.SetKnownPositiveRefCount();
Arg = GetObjCArg(Inst);
PtrState &S = MyStates.getPtrTopDownState(Arg);
- S.ClearRefCount();
+ S.ClearKnownPositiveRefCount();
- switch (S.GetSeq()) {
+ Sequence OldSeq = S.GetSeq();
+
+ MDNode *ReleaseMetadata = Inst->getMetadata(ImpreciseReleaseMDKind);
+
+ switch (OldSeq) {
case S_Retain:
case S_CanRelease:
- S.RRI.ReverseInsertPts.clear();
+ if (OldSeq == S_Retain || ReleaseMetadata != 0)
+ S.ClearReverseInsertPts();
// FALL THROUGH
case S_Use:
- S.RRI.ReleaseMetadata = Inst->getMetadata(ImpreciseReleaseMDKind);
- S.RRI.IsTailCallRelease = cast<CallInst>(Inst)->isTailCall();
- Releases[Inst] = S.RRI;
+ S.SetReleaseMetadata(ReleaseMetadata);
+ S.SetTailCallRelease(cast<CallInst>(Inst)->isTailCall());
+ Releases[Inst] = S.GetRRInfo();
+ ANNOTATE_TOPDOWN(Inst, Arg, S.GetSeq(), S_None);
S.ClearSequenceProgress();
break;
case S_None:
// Check for possible releases.
if (CanAlterRefCount(Inst, Ptr, PA, Class)) {
- S.ClearRefCount();
+ DEBUG(dbgs() << "CanAlterRefCount: Seq: " << Seq << "; " << *Ptr
+ << "\n");
+ S.ClearKnownPositiveRefCount();
switch (Seq) {
case S_Retain:
S.SetSeq(S_CanRelease);
- assert(S.RRI.ReverseInsertPts.empty());
- S.RRI.ReverseInsertPts.insert(Inst);
+ ANNOTATE_TOPDOWN(Inst, Ptr, Seq, S_CanRelease);
+ assert(!S.HasReverseInsertPts());
+ S.InsertReverseInsertPt(Inst);
// One call can't cause a transition from S_Retain to S_CanRelease
// and S_CanRelease to S_Use. If we've made the first transition,
// Check for possible direct uses.
switch (Seq) {
case S_CanRelease:
- if (CanUse(Inst, Ptr, PA, Class))
+ if (CanUse(Inst, Ptr, PA, Class)) {
+ DEBUG(dbgs() << "CanUse: Seq: " << Seq << "; " << *Ptr
+ << "\n");
S.SetSeq(S_Use);
+ ANNOTATE_TOPDOWN(Inst, Ptr, Seq, S_Use);
+ }
break;
case S_Retain:
case S_Use:
ObjCARCOpt::VisitTopDown(BasicBlock *BB,
DenseMap<const BasicBlock *, BBState> &BBStates,
DenseMap<Value *, RRInfo> &Releases) {
+ DEBUG(dbgs() << "\n== ObjCARCOpt::VisitTopDown ==\n");
bool NestingDetected = false;
BBState &MyStates = BBStates[BB];
}
}
+ // If ARC Annotations are enabled, output the current state of pointers at the
+ // top of the basic block.
+ ANNOTATE_TOPDOWN_BBSTART(MyStates, BB);
+
// Visit all the instructions, top-down.
for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ++I) {
Instruction *Inst = I;
- DEBUG(dbgs() << "ObjCARCOpt::VisitTopDown: Visiting " << *Inst << "\n");
+ DEBUG(dbgs() << "Visiting " << *Inst << "\n");
NestingDetected |= VisitInstructionTopDown(Inst, Releases, MyStates);
}
+ // If ARC Annotations are enabled, output the current state of pointers at the
+ // bottom of the basic block.
+ ANNOTATE_TOPDOWN_BBEND(MyStates, BB);
+
+#ifdef ARC_ANNOTATIONS
+ if (!(EnableARCAnnotations && DisableCheckForCFGHazards))
+#endif
CheckForCFGHazards(BB, BBStates, MyStates);
return NestingDetected;
}
Type *ArgTy = Arg->getType();
Type *ParamTy = PointerType::getUnqual(Type::getInt8Ty(ArgTy->getContext()));
+ DEBUG(dbgs() << "== ObjCARCOpt::MoveCalls ==\n");
+
// Insert the new retain and release calls.
for (SmallPtrSet<Instruction *, 2>::const_iterator
PI = ReleasesToMove.ReverseInsertPts.begin(),
Instruction *InsertPt = *PI;
Value *MyArg = ArgTy == ParamTy ? Arg :
new BitCastInst(Arg, ParamTy, "", InsertPt);
- CallInst *Call =
- CallInst::Create(RetainsToMove.IsRetainBlock ?
- getRetainBlockCallee(M) : getRetainCallee(M),
- MyArg, "", InsertPt);
+ Constant *Decl = EP.get(ARCRuntimeEntryPoints::EPT_Retain);
+ CallInst *Call = CallInst::Create(Decl, MyArg, "", InsertPt);
Call->setDoesNotThrow();
- if (RetainsToMove.IsRetainBlock)
- Call->setMetadata(CopyOnEscapeMDKind,
- MDNode::get(M->getContext(), ArrayRef<Value *>()));
- else
- Call->setTailCall();
+ Call->setTailCall();
- DEBUG(dbgs() << "ObjCARCOpt::MoveCalls: Inserting new Release: " << *Call
- << "\n"
- " At insertion point: " << *InsertPt
- << "\n");
+ DEBUG(dbgs() << "Inserting new Retain: " << *Call << "\n"
+ "At insertion point: " << *InsertPt << "\n");
}
for (SmallPtrSet<Instruction *, 2>::const_iterator
PI = RetainsToMove.ReverseInsertPts.begin(),
Instruction *InsertPt = *PI;
Value *MyArg = ArgTy == ParamTy ? Arg :
new BitCastInst(Arg, ParamTy, "", InsertPt);
- CallInst *Call = CallInst::Create(getReleaseCallee(M), MyArg,
- "", InsertPt);
+ Constant *Decl = EP.get(ARCRuntimeEntryPoints::EPT_Release);
+ CallInst *Call = CallInst::Create(Decl, MyArg, "", InsertPt);
// Attach a clang.imprecise_release metadata tag, if appropriate.
if (MDNode *M = ReleasesToMove.ReleaseMetadata)
Call->setMetadata(ImpreciseReleaseMDKind, M);
if (ReleasesToMove.IsTailCallRelease)
Call->setTailCall();
- DEBUG(dbgs() << "ObjCARCOpt::MoveCalls: Inserting new Retain: " << *Call
- << "\n"
- " At insertion point: " << *InsertPt
- << "\n");
+ DEBUG(dbgs() << "Inserting new Release: " << *Call << "\n"
+ "At insertion point: " << *InsertPt << "\n");
}
// Delete the original retain and release calls.
Instruction *OrigRetain = *AI;
Retains.blot(OrigRetain);
DeadInsts.push_back(OrigRetain);
- DEBUG(dbgs() << "ObjCARCOpt::MoveCalls: Deleting retain: " << *OrigRetain <<
- "\n");
+ DEBUG(dbgs() << "Deleting retain: " << *OrigRetain << "\n");
}
for (SmallPtrSet<Instruction *, 2>::const_iterator
AI = ReleasesToMove.Calls.begin(),
Instruction *OrigRelease = *AI;
Releases.erase(OrigRelease);
DeadInsts.push_back(OrigRelease);
- DEBUG(dbgs() << "ObjCARCOpt::MoveCalls: Deleting release: " << *OrigRelease
- << "\n");
+ DEBUG(dbgs() << "Deleting release: " << *OrigRelease << "\n");
}
+
}
bool
MapVector<Value *, RRInfo> &Retains,
DenseMap<Value *, RRInfo> &Releases,
Module *M,
- SmallVector<Instruction *, 4> &NewRetains,
- SmallVector<Instruction *, 4> &NewReleases,
- SmallVector<Instruction *, 8> &DeadInsts,
+ SmallVectorImpl<Instruction *> &NewRetains,
+ SmallVectorImpl<Instruction *> &NewReleases,
+ SmallVectorImpl<Instruction *> &DeadInsts,
RRInfo &RetainsToMove,
RRInfo &ReleasesToMove,
Value *Arg,
bool KnownSafe,
bool &AnyPairsCompletelyEliminated) {
// If a pair happens in a region where it is known that the reference count
- // is already incremented, we can similarly ignore possible decrements.
+ // is already incremented, we can similarly ignore possible decrements unless
+ // we are dealing with a retainable object with multiple provenance sources.
bool KnownSafeTD = true, KnownSafeBU = true;
+ bool MultipleOwners = false;
+ bool CFGHazardAfflicted = false;
// Connect the dots between the top-down-collected RetainsToMove and
// bottom-up-collected ReleasesToMove to form sets of related calls.
unsigned OldCount = 0;
unsigned NewCount = 0;
bool FirstRelease = true;
- bool FirstRetain = true;
for (;;) {
for (SmallVectorImpl<Instruction *>::const_iterator
NI = NewRetains.begin(), NE = NewRetains.end(); NI != NE; ++NI) {
assert(It != Retains.end());
const RRInfo &NewRetainRRI = It->second;
KnownSafeTD &= NewRetainRRI.KnownSafe;
+ MultipleOwners =
+ MultipleOwners || MultiOwnersSet.count(GetObjCArg(NewRetain));
for (SmallPtrSet<Instruction *, 2>::const_iterator
LI = NewRetainRRI.Calls.begin(),
LE = NewRetainRRI.Calls.end(); LI != LE; ++LI) {
const RRInfo &NewRetainReleaseRRI = Jt->second;
assert(NewRetainReleaseRRI.Calls.count(NewRetain));
if (ReleasesToMove.Calls.insert(NewRetainRelease)) {
- OldDelta -=
- BBStates[NewRetainRelease->getParent()].GetAllPathCount();
+
+ // If we overflow when we compute the path count, don't remove/move
+ // anything.
+ const BBState &NRRBBState = BBStates[NewRetainRelease->getParent()];
+ unsigned PathCount;
+ if (NRRBBState.GetAllPathCountWithOverflow(PathCount))
+ return false;
+ OldDelta -= PathCount;
// Merge the ReleaseMetadata and IsTailCallRelease values.
if (FirstRelease) {
RE = NewRetainReleaseRRI.ReverseInsertPts.end();
RI != RE; ++RI) {
Instruction *RIP = *RI;
- if (ReleasesToMove.ReverseInsertPts.insert(RIP))
- NewDelta -= BBStates[RIP->getParent()].GetAllPathCount();
+ if (ReleasesToMove.ReverseInsertPts.insert(RIP)) {
+ // If we overflow when we compute the path count, don't
+ // remove/move anything.
+ const BBState &RIPBBState = BBStates[RIP->getParent()];
+ if (RIPBBState.GetAllPathCountWithOverflow(PathCount))
+ return false;
+ NewDelta -= PathCount;
+ }
}
NewReleases.push_back(NewRetainRelease);
}
assert(It != Releases.end());
const RRInfo &NewReleaseRRI = It->second;
KnownSafeBU &= NewReleaseRRI.KnownSafe;
+ CFGHazardAfflicted |= NewReleaseRRI.CFGHazardAfflicted;
for (SmallPtrSet<Instruction *, 2>::const_iterator
LI = NewReleaseRRI.Calls.begin(),
LE = NewReleaseRRI.Calls.end(); LI != LE; ++LI) {
const RRInfo &NewReleaseRetainRRI = Jt->second;
assert(NewReleaseRetainRRI.Calls.count(NewRelease));
if (RetainsToMove.Calls.insert(NewReleaseRetain)) {
- unsigned PathCount =
- BBStates[NewReleaseRetain->getParent()].GetAllPathCount();
- OldDelta += PathCount;
- OldCount += PathCount;
- // Merge the IsRetainBlock values.
- if (FirstRetain) {
- RetainsToMove.IsRetainBlock = NewReleaseRetainRRI.IsRetainBlock;
- FirstRetain = false;
- } else if (ReleasesToMove.IsRetainBlock !=
- NewReleaseRetainRRI.IsRetainBlock)
- // It's not possible to merge the sequences if one uses
- // objc_retain and the other uses objc_retainBlock.
+ // If we overflow when we compute the path count, don't remove/move
+ // anything.
+ const BBState &NRRBBState = BBStates[NewReleaseRetain->getParent()];
+ unsigned PathCount;
+ if (NRRBBState.GetAllPathCountWithOverflow(PathCount))
return false;
+ OldDelta += PathCount;
+ OldCount += PathCount;
// Collect the optimal insertion points.
if (!KnownSafe)
RI != RE; ++RI) {
Instruction *RIP = *RI;
if (RetainsToMove.ReverseInsertPts.insert(RIP)) {
- PathCount = BBStates[RIP->getParent()].GetAllPathCount();
+ // If we overflow when we compute the path count, don't
+ // remove/move anything.
+ const BBState &RIPBBState = BBStates[RIP->getParent()];
+ if (RIPBBState.GetAllPathCountWithOverflow(PathCount))
+ return false;
NewDelta += PathCount;
NewCount += PathCount;
}
if (NewRetains.empty()) break;
}
- // If the pointer is known incremented or nested, we can safely delete the
- // pair regardless of what's between them.
- if (KnownSafeTD || KnownSafeBU) {
+ // If the pointer is known incremented in 1 direction and we do not have
+ // MultipleOwners, we can safely remove the retain/releases. Otherwise we need
+ // to be known safe in both directions.
+ bool UnconditionallySafe = (KnownSafeTD && KnownSafeBU) ||
+ ((KnownSafeTD || KnownSafeBU) && !MultipleOwners);
+ if (UnconditionallySafe) {
RetainsToMove.ReverseInsertPts.clear();
ReleasesToMove.ReverseInsertPts.clear();
NewCount = 0;
// less aggressive solution which is.
if (NewDelta != 0)
return false;
+
+ // At this point, we are not going to remove any RR pairs, but we still are
+ // able to move RR pairs. If one of our pointers is afflicted with
+ // CFGHazards, we cannot perform such code motion so exit early.
+ const bool WillPerformCodeMotion = RetainsToMove.ReverseInsertPts.size() ||
+ ReleasesToMove.ReverseInsertPts.size();
+ if (CFGHazardAfflicted && WillPerformCodeMotion)
+ return false;
}
// Determine whether the original call points are balanced in the retain and
if (OldDelta != 0)
return false;
+#ifdef ARC_ANNOTATIONS
+ // Do not move calls if ARC annotations are requested.
+ if (EnableARCAnnotations)
+ return false;
+#endif // ARC_ANNOTATIONS
+
Changed = true;
assert(OldCount != 0 && "Unreachable code?");
NumRRs += OldCount - NewCount;
MapVector<Value *, RRInfo> &Retains,
DenseMap<Value *, RRInfo> &Releases,
Module *M) {
+ DEBUG(dbgs() << "\n== ObjCARCOpt::PerformCodePlacement ==\n");
+
bool AnyPairsCompletelyEliminated = false;
RRInfo RetainsToMove;
RRInfo ReleasesToMove;
Instruction *Retain = cast<Instruction>(V);
- DEBUG(dbgs() << "ObjCARCOpt::PerformCodePlacement: Visiting: " << *Retain
- << "\n");
+ DEBUG(dbgs() << "Visiting: " << *Retain << "\n");
Value *Arg = GetObjCArg(Retain);
/// Weak pointer optimizations.
void ObjCARCOpt::OptimizeWeakCalls(Function &F) {
+ DEBUG(dbgs() << "\n== ObjCARCOpt::OptimizeWeakCalls ==\n");
+
// First, do memdep-style RLE and S2L optimizations. We can't use memdep
// itself because it uses AliasAnalysis and we need to do provenance
// queries instead.
for (inst_iterator I = inst_begin(&F), E = inst_end(&F); I != E; ) {
Instruction *Inst = &*I++;
- DEBUG(dbgs() << "ObjCARCOpt::OptimizeWeakCalls: Visiting: " << *Inst <<
- "\n");
+ DEBUG(dbgs() << "Visiting: " << *Inst << "\n");
InstructionClass Class = GetBasicInstructionClass(Inst);
if (Class != IC_LoadWeak && Class != IC_LoadWeakRetained)
Changed = true;
// If the load has a builtin retain, insert a plain retain for it.
if (Class == IC_LoadWeakRetained) {
- CallInst *CI =
- CallInst::Create(getRetainCallee(F.getParent()), EarlierCall,
- "", Call);
+ Constant *Decl = EP.get(ARCRuntimeEntryPoints::EPT_Retain);
+ CallInst *CI = CallInst::Create(Decl, EarlierCall, "", Call);
CI->setTailCall();
}
// Zap the fully redundant load.
Changed = true;
// If the load has a builtin retain, insert a plain retain for it.
if (Class == IC_LoadWeakRetained) {
- CallInst *CI =
- CallInst::Create(getRetainCallee(F.getParent()), EarlierCall,
- "", Call);
+ Constant *Decl = EP.get(ARCRuntimeEntryPoints::EPT_Retain);
+ CallInst *CI = CallInst::Create(Decl, EarlierCall, "", Call);
CI->setTailCall();
}
// Zap the fully redundant load.
goto clobbered;
case IC_AutoreleasepoolPush:
case IC_None:
+ case IC_IntrinsicUser:
case IC_User:
// Weak pointers are only modified through the weak entry points
// (and arbitrary calls, which could call the weak entry points).
done:;
}
}
-
- DEBUG(dbgs() << "ObjCARCOpt::OptimizeWeakCalls: Finished List.\n\n");
-
}
/// Identify program paths which execute sequences of retains and releases which
/// can be eliminated.
bool ObjCARCOpt::OptimizeSequences(Function &F) {
- /// Releases, Retains - These are used to store the results of the main flow
- /// analysis. These use Value* as the key instead of Instruction* so that the
- /// map stays valid when we get around to rewriting code and calls get
- /// replaced by arguments.
+ // Releases, Retains - These are used to store the results of the main flow
+ // analysis. These use Value* as the key instead of Instruction* so that the
+ // map stays valid when we get around to rewriting code and calls get
+ // replaced by arguments.
DenseMap<Value *, RRInfo> Releases;
MapVector<Value *, RRInfo> Retains;
- /// This is used during the traversal of the function to track the
- /// states for each identified object at each block.
+ // This is used during the traversal of the function to track the
+ // states for each identified object at each block.
DenseMap<const BasicBlock *, BBState> BBStates;
// Analyze the CFG of the function, and all instructions.
bool NestingDetected = Visit(F, BBStates, Retains, Releases);
// Transform.
- return PerformCodePlacement(BBStates, Retains, Releases, F.getParent()) &&
- NestingDetected;
+ bool AnyPairsCompletelyEliminated = PerformCodePlacement(BBStates, Retains,
+ Releases,
+ F.getParent());
+
+ // Cleanup.
+ MultiOwnersSet.clear();
+
+ return AnyPairsCompletelyEliminated && NestingDetected;
+}
+
+/// Check if there is a dependent call earlier that does not have anything in
+/// between the Retain and the call that can affect the reference count of their
+/// shared pointer argument. Note that Retain need not be in BB.
+static bool
+HasSafePathToPredecessorCall(const Value *Arg, Instruction *Retain,
+ SmallPtrSet<Instruction *, 4> &DepInsts,
+ SmallPtrSet<const BasicBlock *, 4> &Visited,
+ ProvenanceAnalysis &PA) {
+ FindDependencies(CanChangeRetainCount, Arg, Retain->getParent(), Retain,
+ DepInsts, Visited, PA);
+ if (DepInsts.size() != 1)
+ return false;
+
+ CallInst *Call =
+ dyn_cast_or_null<CallInst>(*DepInsts.begin());
+
+ // Check that the pointer is the return value of the call.
+ if (!Call || Arg != Call)
+ return false;
+
+ // Check that the call is a regular call.
+ InstructionClass Class = GetBasicInstructionClass(Call);
+ if (Class != IC_CallOrUser && Class != IC_Call)
+ return false;
+
+ return true;
+}
+
+/// Find a dependent retain that precedes the given autorelease for which there
+/// is nothing in between the two instructions that can affect the ref count of
+/// Arg.
+static CallInst *
+FindPredecessorRetainWithSafePath(const Value *Arg, BasicBlock *BB,
+ Instruction *Autorelease,
+ SmallPtrSet<Instruction *, 4> &DepInsts,
+ SmallPtrSet<const BasicBlock *, 4> &Visited,
+ ProvenanceAnalysis &PA) {
+ FindDependencies(CanChangeRetainCount, Arg,
+ BB, Autorelease, DepInsts, Visited, PA);
+ if (DepInsts.size() != 1)
+ return 0;
+
+ CallInst *Retain =
+ dyn_cast_or_null<CallInst>(*DepInsts.begin());
+
+ // Check that we found a retain with the same argument.
+ if (!Retain ||
+ !IsRetain(GetBasicInstructionClass(Retain)) ||
+ GetObjCArg(Retain) != Arg) {
+ return 0;
+ }
+
+ return Retain;
+}
+
+/// Look for an ``autorelease'' instruction dependent on Arg such that there are
+/// no instructions dependent on Arg that need a positive ref count in between
+/// the autorelease and the ret.
+static CallInst *
+FindPredecessorAutoreleaseWithSafePath(const Value *Arg, BasicBlock *BB,
+ ReturnInst *Ret,
+ SmallPtrSet<Instruction *, 4> &DepInsts,
+ SmallPtrSet<const BasicBlock *, 4> &V,
+ ProvenanceAnalysis &PA) {
+ FindDependencies(NeedsPositiveRetainCount, Arg,
+ BB, Ret, DepInsts, V, PA);
+ if (DepInsts.size() != 1)
+ return 0;
+
+ CallInst *Autorelease =
+ dyn_cast_or_null<CallInst>(*DepInsts.begin());
+ if (!Autorelease)
+ return 0;
+ InstructionClass AutoreleaseClass = GetBasicInstructionClass(Autorelease);
+ if (!IsAutorelease(AutoreleaseClass))
+ return 0;
+ if (GetObjCArg(Autorelease) != Arg)
+ return 0;
+
+ return Autorelease;
}
/// Look for this pattern:
/// ret i8* %3
/// \endcode
/// And delete the retain and autorelease.
-///
-/// Otherwise if it's just this:
-/// \code
-/// %3 = call i8* @objc_autorelease(i8* %2)
-/// ret i8* %3
-/// \endcode
-/// convert the autorelease to autoreleaseRV.
void ObjCARCOpt::OptimizeReturns(Function &F) {
if (!F.getReturnType()->isPointerTy())
return;
+ DEBUG(dbgs() << "\n== ObjCARCOpt::OptimizeReturns ==\n");
+
SmallPtrSet<Instruction *, 4> DependingInstructions;
SmallPtrSet<const BasicBlock *, 4> Visited;
for (Function::iterator FI = F.begin(), FE = F.end(); FI != FE; ++FI) {
BasicBlock *BB = FI;
ReturnInst *Ret = dyn_cast<ReturnInst>(&BB->back());
- DEBUG(dbgs() << "ObjCARCOpt::OptimizeReturns: Visiting: " << *Ret << "\n");
+ DEBUG(dbgs() << "Visiting: " << *Ret << "\n");
- if (!Ret) continue;
+ if (!Ret)
+ continue;
const Value *Arg = StripPointerCastsAndObjCCalls(Ret->getOperand(0));
- FindDependencies(NeedsPositiveRetainCount, Arg,
- BB, Ret, DependingInstructions, Visited, PA);
- if (DependingInstructions.size() != 1)
- goto next_block;
-
- {
- CallInst *Autorelease =
- dyn_cast_or_null<CallInst>(*DependingInstructions.begin());
- if (!Autorelease)
- goto next_block;
- InstructionClass AutoreleaseClass = GetBasicInstructionClass(Autorelease);
- if (!IsAutorelease(AutoreleaseClass))
- goto next_block;
- if (GetObjCArg(Autorelease) != Arg)
- goto next_block;
-
- DependingInstructions.clear();
- Visited.clear();
-
- // Check that there is nothing that can affect the reference
- // count between the autorelease and the retain.
- FindDependencies(CanChangeRetainCount, Arg,
- BB, Autorelease, DependingInstructions, Visited, PA);
- if (DependingInstructions.size() != 1)
- goto next_block;
-
- {
- CallInst *Retain =
- dyn_cast_or_null<CallInst>(*DependingInstructions.begin());
-
- // Check that we found a retain with the same argument.
- if (!Retain ||
- !IsRetain(GetBasicInstructionClass(Retain)) ||
- GetObjCArg(Retain) != Arg)
- goto next_block;
-
- DependingInstructions.clear();
- Visited.clear();
-
- // Convert the autorelease to an autoreleaseRV, since it's
- // returning the value.
- if (AutoreleaseClass == IC_Autorelease) {
- DEBUG(dbgs() << "ObjCARCOpt::OptimizeReturns: Converting autorelease "
- "=> autoreleaseRV since it's returning a value.\n"
- " In: " << *Autorelease
- << "\n");
- Autorelease->setCalledFunction(getAutoreleaseRVCallee(F.getParent()));
- DEBUG(dbgs() << " Out: " << *Autorelease
- << "\n");
- Autorelease->setTailCall(); // Always tail call autoreleaseRV.
- AutoreleaseClass = IC_AutoreleaseRV;
- }
-
- // Check that there is nothing that can affect the reference
- // count between the retain and the call.
- // Note that Retain need not be in BB.
- FindDependencies(CanChangeRetainCount, Arg, Retain->getParent(), Retain,
- DependingInstructions, Visited, PA);
- if (DependingInstructions.size() != 1)
- goto next_block;
- {
- CallInst *Call =
- dyn_cast_or_null<CallInst>(*DependingInstructions.begin());
+ // Look for an ``autorelease'' instruction that is a predecessor of Ret and
+ // dependent on Arg such that there are no instructions dependent on Arg
+ // that need a positive ref count in between the autorelease and Ret.
+ CallInst *Autorelease =
+ FindPredecessorAutoreleaseWithSafePath(Arg, BB, Ret,
+ DependingInstructions, Visited,
+ PA);
+ DependingInstructions.clear();
+ Visited.clear();
- // Check that the pointer is the return value of the call.
- if (!Call || Arg != Call)
- goto next_block;
+ if (!Autorelease)
+ continue;
- // Check that the call is a regular call.
- InstructionClass Class = GetBasicInstructionClass(Call);
- if (Class != IC_CallOrUser && Class != IC_Call)
- goto next_block;
+ CallInst *Retain =
+ FindPredecessorRetainWithSafePath(Arg, BB, Autorelease,
+ DependingInstructions, Visited, PA);
+ DependingInstructions.clear();
+ Visited.clear();
- // If so, we can zap the retain and autorelease.
- Changed = true;
- ++NumRets;
- DEBUG(dbgs() << "ObjCARCOpt::OptimizeReturns: Erasing: " << *Retain
- << "\n Erasing: "
- << *Autorelease << "\n");
- EraseInstruction(Retain);
- EraseInstruction(Autorelease);
- }
- }
- }
+ if (!Retain)
+ continue;
- next_block:
+ // Check that there is nothing that can affect the reference count
+ // between the retain and the call. Note that Retain need not be in BB.
+ bool HasSafePathToCall = HasSafePathToPredecessorCall(Arg, Retain,
+ DependingInstructions,
+ Visited, PA);
DependingInstructions.clear();
Visited.clear();
+
+ if (!HasSafePathToCall)
+ continue;
+
+ // If so, we can zap the retain and autorelease.
+ Changed = true;
+ ++NumRets;
+ DEBUG(dbgs() << "Erasing: " << *Retain << "\nErasing: "
+ << *Autorelease << "\n");
+ EraseInstruction(Retain);
+ EraseInstruction(Autorelease);
}
+}
- DEBUG(dbgs() << "ObjCARCOpt::OptimizeReturns: Finished List.\n\n");
+#ifndef NDEBUG
+void
+ObjCARCOpt::GatherStatistics(Function &F, bool AfterOptimization) {
+ llvm::Statistic &NumRetains =
+ AfterOptimization? NumRetainsAfterOpt : NumRetainsBeforeOpt;
+ llvm::Statistic &NumReleases =
+ AfterOptimization? NumReleasesAfterOpt : NumReleasesBeforeOpt;
+ for (inst_iterator I = inst_begin(&F), E = inst_end(&F); I != E; ) {
+ Instruction *Inst = &*I++;
+ switch (GetBasicInstructionClass(Inst)) {
+ default:
+ break;
+ case IC_Retain:
+ ++NumRetains;
+ break;
+ case IC_Release:
+ ++NumReleases;
+ break;
+ }
+ }
}
+#endif
bool ObjCARCOpt::doInitialization(Module &M) {
if (!EnableARCOpts)
M.getContext().getMDKindID("clang.arc.copy_on_escape");
NoObjCARCExceptionsMDKind =
M.getContext().getMDKindID("clang.arc.no_objc_arc_exceptions");
+#ifdef ARC_ANNOTATIONS
+ ARCAnnotationBottomUpMDKind =
+ M.getContext().getMDKindID("llvm.arc.annotation.bottomup");
+ ARCAnnotationTopDownMDKind =
+ M.getContext().getMDKindID("llvm.arc.annotation.topdown");
+ ARCAnnotationProvenanceSourceMDKind =
+ M.getContext().getMDKindID("llvm.arc.annotation.provenancesource");
+#endif // ARC_ANNOTATIONS
// Intuitively, objc_retain and others are nocapture, however in practice
// they are not, because they return their argument value. And objc_release
// calls finalizers which can have arbitrary side effects.
- // These are initialized lazily.
- RetainRVCallee = 0;
- AutoreleaseRVCallee = 0;
- ReleaseCallee = 0;
- RetainCallee = 0;
- RetainBlockCallee = 0;
- AutoreleaseCallee = 0;
+ // Initialize our runtime entry point cache.
+ EP.Initialize(&M);
return false;
}
Changed = false;
- DEBUG(dbgs() << "ObjCARCOpt: Visiting Function: " << F.getName() << "\n");
+ DEBUG(dbgs() << "<<< ObjCARCOpt: Visiting Function: " << F.getName() << " >>>"
+ "\n");
PA.setAA(&getAnalysis<AliasAnalysis>());
+#ifndef NDEBUG
+ if (AreStatisticsEnabled()) {
+ GatherStatistics(F, false);
+ }
+#endif
+
// This pass performs several distinct transformations. As a compile-time aid
// when compiling code that isn't ObjC, skip these if the relevant ObjC
// library functions aren't declared.
- // Preliminary optimizations. This also computs UsedInThisFunction.
+ // Preliminary optimizations. This also computes UsedInThisFunction.
OptimizeIndividualCalls(F);
// Optimizations for weak pointers.
(1 << IC_AutoreleaseRV)))
OptimizeReturns(F);
+ // Gather statistics after optimization.
+#ifndef NDEBUG
+ if (AreStatisticsEnabled()) {
+ GatherStatistics(F, true);
+ }
+#endif
+
DEBUG(dbgs() << "\n");
return Changed;
/// @}
///
-/// \defgroup ARCContract ARC Contraction.
-/// @{
-
-// TODO: ObjCARCContract could insert PHI nodes when uses aren't
-// dominated by single calls.
-
-#include "llvm/Analysis/Dominators.h"
-#include "llvm/IR/InlineAsm.h"
-#include "llvm/IR/Operator.h"
-
-STATISTIC(NumStoreStrongs, "Number objc_storeStrong calls formed");
-
-namespace {
- /// \brief Late ARC optimizations
- ///
- /// These change the IR in a way that makes it difficult to be analyzed by
- /// ObjCARCOpt, so it's run late.
- class ObjCARCContract : public FunctionPass {
- bool Changed;
- AliasAnalysis *AA;
- DominatorTree *DT;
- ProvenanceAnalysis PA;
-
- /// A flag indicating whether this optimization pass should run.
- bool Run;
-
- /// Declarations for ObjC runtime functions, for use in creating calls to
- /// them. These are initialized lazily to avoid cluttering up the Module
- /// with unused declarations.
-
- /// Declaration for objc_storeStrong().
- Constant *StoreStrongCallee;
- /// Declaration for objc_retainAutorelease().
- Constant *RetainAutoreleaseCallee;
- /// Declaration for objc_retainAutoreleaseReturnValue().
- Constant *RetainAutoreleaseRVCallee;
-
- /// The inline asm string to insert between calls and RetainRV calls to make
- /// the optimization work on targets which need it.
- const MDString *RetainRVMarker;
-
- /// The set of inserted objc_storeStrong calls. If at the end of walking the
- /// function we have found no alloca instructions, these calls can be marked
- /// "tail".
- SmallPtrSet<CallInst *, 8> StoreStrongCalls;
-
- Constant *getStoreStrongCallee(Module *M);
- Constant *getRetainAutoreleaseCallee(Module *M);
- Constant *getRetainAutoreleaseRVCallee(Module *M);
-
- bool ContractAutorelease(Function &F, Instruction *Autorelease,
- InstructionClass Class,
- SmallPtrSet<Instruction *, 4>
- &DependingInstructions,
- SmallPtrSet<const BasicBlock *, 4>
- &Visited);
-
- void ContractRelease(Instruction *Release,
- inst_iterator &Iter);
-
- virtual void getAnalysisUsage(AnalysisUsage &AU) const;
- virtual bool doInitialization(Module &M);
- virtual bool runOnFunction(Function &F);
-
- public:
- static char ID;
- ObjCARCContract() : FunctionPass(ID) {
- initializeObjCARCContractPass(*PassRegistry::getPassRegistry());
- }
- };
-}
-
-char ObjCARCContract::ID = 0;
-INITIALIZE_PASS_BEGIN(ObjCARCContract,
- "objc-arc-contract", "ObjC ARC contraction", false, false)
-INITIALIZE_AG_DEPENDENCY(AliasAnalysis)
-INITIALIZE_PASS_DEPENDENCY(DominatorTree)
-INITIALIZE_PASS_END(ObjCARCContract,
- "objc-arc-contract", "ObjC ARC contraction", false, false)
-
-Pass *llvm::createObjCARCContractPass() {
- return new ObjCARCContract();
-}
-
-void ObjCARCContract::getAnalysisUsage(AnalysisUsage &AU) const {
- AU.addRequired<AliasAnalysis>();
- AU.addRequired<DominatorTree>();
- AU.setPreservesCFG();
-}
-
-Constant *ObjCARCContract::getStoreStrongCallee(Module *M) {
- if (!StoreStrongCallee) {
- LLVMContext &C = M->getContext();
- Type *I8X = PointerType::getUnqual(Type::getInt8Ty(C));
- Type *I8XX = PointerType::getUnqual(I8X);
- Type *Params[] = { I8XX, I8X };
-
- AttributeSet Attr = AttributeSet()
- .addAttribute(M->getContext(), AttributeSet::FunctionIndex,
- Attribute::NoUnwind)
- .addAttribute(M->getContext(), 1, Attribute::NoCapture);
-
- StoreStrongCallee =
- M->getOrInsertFunction(
- "objc_storeStrong",
- FunctionType::get(Type::getVoidTy(C), Params, /*isVarArg=*/false),
- Attr);
- }
- return StoreStrongCallee;
-}
-
-Constant *ObjCARCContract::getRetainAutoreleaseCallee(Module *M) {
- if (!RetainAutoreleaseCallee) {
- LLVMContext &C = M->getContext();
- Type *I8X = PointerType::getUnqual(Type::getInt8Ty(C));
- Type *Params[] = { I8X };
- FunctionType *FTy = FunctionType::get(I8X, Params, /*isVarArg=*/false);
- AttributeSet Attribute =
- AttributeSet().addAttribute(M->getContext(), AttributeSet::FunctionIndex,
- Attribute::NoUnwind);
- RetainAutoreleaseCallee =
- M->getOrInsertFunction("objc_retainAutorelease", FTy, Attribute);
- }
- return RetainAutoreleaseCallee;
-}
-
-Constant *ObjCARCContract::getRetainAutoreleaseRVCallee(Module *M) {
- if (!RetainAutoreleaseRVCallee) {
- LLVMContext &C = M->getContext();
- Type *I8X = PointerType::getUnqual(Type::getInt8Ty(C));
- Type *Params[] = { I8X };
- FunctionType *FTy = FunctionType::get(I8X, Params, /*isVarArg=*/false);
- AttributeSet Attribute =
- AttributeSet().addAttribute(M->getContext(), AttributeSet::FunctionIndex,
- Attribute::NoUnwind);
- RetainAutoreleaseRVCallee =
- M->getOrInsertFunction("objc_retainAutoreleaseReturnValue", FTy,
- Attribute);
- }
- return RetainAutoreleaseRVCallee;
-}
-
-/// Merge an autorelease with a retain into a fused call.
-bool
-ObjCARCContract::ContractAutorelease(Function &F, Instruction *Autorelease,
- InstructionClass Class,
- SmallPtrSet<Instruction *, 4>
- &DependingInstructions,
- SmallPtrSet<const BasicBlock *, 4>
- &Visited) {
- const Value *Arg = GetObjCArg(Autorelease);
-
- // Check that there are no instructions between the retain and the autorelease
- // (such as an autorelease_pop) which may change the count.
- CallInst *Retain = 0;
- if (Class == IC_AutoreleaseRV)
- FindDependencies(RetainAutoreleaseRVDep, Arg,
- Autorelease->getParent(), Autorelease,
- DependingInstructions, Visited, PA);
- else
- FindDependencies(RetainAutoreleaseDep, Arg,
- Autorelease->getParent(), Autorelease,
- DependingInstructions, Visited, PA);
-
- Visited.clear();
- if (DependingInstructions.size() != 1) {
- DependingInstructions.clear();
- return false;
- }
-
- Retain = dyn_cast_or_null<CallInst>(*DependingInstructions.begin());
- DependingInstructions.clear();
-
- if (!Retain ||
- GetBasicInstructionClass(Retain) != IC_Retain ||
- GetObjCArg(Retain) != Arg)
- return false;
-
- Changed = true;
- ++NumPeeps;
-
- DEBUG(dbgs() << "ObjCARCContract::ContractAutorelease: Fusing "
- "retain/autorelease. Erasing: " << *Autorelease << "\n"
- " Old Retain: "
- << *Retain << "\n");
-
- if (Class == IC_AutoreleaseRV)
- Retain->setCalledFunction(getRetainAutoreleaseRVCallee(F.getParent()));
- else
- Retain->setCalledFunction(getRetainAutoreleaseCallee(F.getParent()));
-
- DEBUG(dbgs() << " New Retain: "
- << *Retain << "\n");
-
- EraseInstruction(Autorelease);
- return true;
-}
-
-/// Attempt to merge an objc_release with a store, load, and objc_retain to form
-/// an objc_storeStrong. This can be a little tricky because the instructions
-/// don't always appear in order, and there may be unrelated intervening
-/// instructions.
-void ObjCARCContract::ContractRelease(Instruction *Release,
- inst_iterator &Iter) {
- LoadInst *Load = dyn_cast<LoadInst>(GetObjCArg(Release));
- if (!Load || !Load->isSimple()) return;
-
- // For now, require everything to be in one basic block.
- BasicBlock *BB = Release->getParent();
- if (Load->getParent() != BB) return;
-
- // Walk down to find the store and the release, which may be in either order.
- BasicBlock::iterator I = Load, End = BB->end();
- ++I;
- AliasAnalysis::Location Loc = AA->getLocation(Load);
- StoreInst *Store = 0;
- bool SawRelease = false;
- for (; !Store || !SawRelease; ++I) {
- if (I == End)
- return;
-
- Instruction *Inst = I;
- if (Inst == Release) {
- SawRelease = true;
- continue;
- }
-
- InstructionClass Class = GetBasicInstructionClass(Inst);
-
- // Unrelated retains are harmless.
- if (IsRetain(Class))
- continue;
-
- if (Store) {
- // The store is the point where we're going to put the objc_storeStrong,
- // so make sure there are no uses after it.
- if (CanUse(Inst, Load, PA, Class))
- return;
- } else if (AA->getModRefInfo(Inst, Loc) & AliasAnalysis::Mod) {
- // We are moving the load down to the store, so check for anything
- // else which writes to the memory between the load and the store.
- Store = dyn_cast<StoreInst>(Inst);
- if (!Store || !Store->isSimple()) return;
- if (Store->getPointerOperand() != Loc.Ptr) return;
- }
- }
-
- Value *New = StripPointerCastsAndObjCCalls(Store->getValueOperand());
-
- // Walk up to find the retain.
- I = Store;
- BasicBlock::iterator Begin = BB->begin();
- while (I != Begin && GetBasicInstructionClass(I) != IC_Retain)
- --I;
- Instruction *Retain = I;
- if (GetBasicInstructionClass(Retain) != IC_Retain) return;
- if (GetObjCArg(Retain) != New) return;
-
- Changed = true;
- ++NumStoreStrongs;
-
- LLVMContext &C = Release->getContext();
- Type *I8X = PointerType::getUnqual(Type::getInt8Ty(C));
- Type *I8XX = PointerType::getUnqual(I8X);
-
- Value *Args[] = { Load->getPointerOperand(), New };
- if (Args[0]->getType() != I8XX)
- Args[0] = new BitCastInst(Args[0], I8XX, "", Store);
- if (Args[1]->getType() != I8X)
- Args[1] = new BitCastInst(Args[1], I8X, "", Store);
- CallInst *StoreStrong =
- CallInst::Create(getStoreStrongCallee(BB->getParent()->getParent()),
- Args, "", Store);
- StoreStrong->setDoesNotThrow();
- StoreStrong->setDebugLoc(Store->getDebugLoc());
-
- // We can't set the tail flag yet, because we haven't yet determined
- // whether there are any escaping allocas. Remember this call, so that
- // we can set the tail flag once we know it's safe.
- StoreStrongCalls.insert(StoreStrong);
-
- if (&*Iter == Store) ++Iter;
- Store->eraseFromParent();
- Release->eraseFromParent();
- EraseInstruction(Retain);
- if (Load->use_empty())
- Load->eraseFromParent();
-}
-
-bool ObjCARCContract::doInitialization(Module &M) {
- // If nothing in the Module uses ARC, don't do anything.
- Run = ModuleHasARC(M);
- if (!Run)
- return false;
-
- // These are initialized lazily.
- StoreStrongCallee = 0;
- RetainAutoreleaseCallee = 0;
- RetainAutoreleaseRVCallee = 0;
-
- // Initialize RetainRVMarker.
- RetainRVMarker = 0;
- if (NamedMDNode *NMD =
- M.getNamedMetadata("clang.arc.retainAutoreleasedReturnValueMarker"))
- if (NMD->getNumOperands() == 1) {
- const MDNode *N = NMD->getOperand(0);
- if (N->getNumOperands() == 1)
- if (const MDString *S = dyn_cast<MDString>(N->getOperand(0)))
- RetainRVMarker = S;
- }
-
- return false;
-}
-
-bool ObjCARCContract::runOnFunction(Function &F) {
- if (!EnableARCOpts)
- return false;
-
- // If nothing in the Module uses ARC, don't do anything.
- if (!Run)
- return false;
-
- Changed = false;
- AA = &getAnalysis<AliasAnalysis>();
- DT = &getAnalysis<DominatorTree>();
-
- PA.setAA(&getAnalysis<AliasAnalysis>());
-
- // Track whether it's ok to mark objc_storeStrong calls with the "tail"
- // keyword. Be conservative if the function has variadic arguments.
- // It seems that functions which "return twice" are also unsafe for the
- // "tail" argument, because they are setjmp, which could need to
- // return to an earlier stack state.
- bool TailOkForStoreStrongs = !F.isVarArg() &&
- !F.callsFunctionThatReturnsTwice();
-
- // For ObjC library calls which return their argument, replace uses of the
- // argument with uses of the call return value, if it dominates the use. This
- // reduces register pressure.
- SmallPtrSet<Instruction *, 4> DependingInstructions;
- SmallPtrSet<const BasicBlock *, 4> Visited;
- for (inst_iterator I = inst_begin(&F), E = inst_end(&F); I != E; ) {
- Instruction *Inst = &*I++;
-
- DEBUG(dbgs() << "ObjCARCContract: Visiting: " << *Inst << "\n");
-
- // Only these library routines return their argument. In particular,
- // objc_retainBlock does not necessarily return its argument.
- InstructionClass Class = GetBasicInstructionClass(Inst);
- switch (Class) {
- case IC_Retain:
- case IC_FusedRetainAutorelease:
- case IC_FusedRetainAutoreleaseRV:
- break;
- case IC_Autorelease:
- case IC_AutoreleaseRV:
- if (ContractAutorelease(F, Inst, Class, DependingInstructions, Visited))
- continue;
- break;
- case IC_RetainRV: {
- // If we're compiling for a target which needs a special inline-asm
- // marker to do the retainAutoreleasedReturnValue optimization,
- // insert it now.
- if (!RetainRVMarker)
- break;
- BasicBlock::iterator BBI = Inst;
- BasicBlock *InstParent = Inst->getParent();
-
- // Step up to see if the call immediately precedes the RetainRV call.
- // If it's an invoke, we have to cross a block boundary. And we have
- // to carefully dodge no-op instructions.
- do {
- if (&*BBI == InstParent->begin()) {
- BasicBlock *Pred = InstParent->getSinglePredecessor();
- if (!Pred)
- goto decline_rv_optimization;
- BBI = Pred->getTerminator();
- break;
- }
- --BBI;
- } while (isNoopInstruction(BBI));
-
- if (&*BBI == GetObjCArg(Inst)) {
- DEBUG(dbgs() << "ObjCARCContract: Adding inline asm marker for "
- "retainAutoreleasedReturnValue optimization.\n");
- Changed = true;
- InlineAsm *IA =
- InlineAsm::get(FunctionType::get(Type::getVoidTy(Inst->getContext()),
- /*isVarArg=*/false),
- RetainRVMarker->getString(),
- /*Constraints=*/"", /*hasSideEffects=*/true);
- CallInst::Create(IA, "", Inst);
- }
- decline_rv_optimization:
- break;
- }
- case IC_InitWeak: {
- // objc_initWeak(p, null) => *p = null
- CallInst *CI = cast<CallInst>(Inst);
- if (isNullOrUndef(CI->getArgOperand(1))) {
- Value *Null =
- ConstantPointerNull::get(cast<PointerType>(CI->getType()));
- Changed = true;
- new StoreInst(Null, CI->getArgOperand(0), CI);
-
- DEBUG(dbgs() << "OBJCARCContract: Old = " << *CI << "\n"
- << " New = " << *Null << "\n");
-
- CI->replaceAllUsesWith(Null);
- CI->eraseFromParent();
- }
- continue;
- }
- case IC_Release:
- ContractRelease(Inst, I);
- continue;
- case IC_User:
- // Be conservative if the function has any alloca instructions.
- // Technically we only care about escaping alloca instructions,
- // but this is sufficient to handle some interesting cases.
- if (isa<AllocaInst>(Inst))
- TailOkForStoreStrongs = false;
- continue;
- default:
- continue;
- }
-
- DEBUG(dbgs() << "ObjCARCContract: Finished List.\n\n");
-
- // Don't use GetObjCArg because we don't want to look through bitcasts
- // and such; to do the replacement, the argument must have type i8*.
- const Value *Arg = cast<CallInst>(Inst)->getArgOperand(0);
- for (;;) {
- // If we're compiling bugpointed code, don't get in trouble.
- if (!isa<Instruction>(Arg) && !isa<Argument>(Arg))
- break;
- // Look through the uses of the pointer.
- for (Value::const_use_iterator UI = Arg->use_begin(), UE = Arg->use_end();
- UI != UE; ) {
- Use &U = UI.getUse();
- unsigned OperandNo = UI.getOperandNo();
- ++UI; // Increment UI now, because we may unlink its element.
-
- // If the call's return value dominates a use of the call's argument
- // value, rewrite the use to use the return value. We check for
- // reachability here because an unreachable call is considered to
- // trivially dominate itself, which would lead us to rewriting its
- // argument in terms of its return value, which would lead to
- // infinite loops in GetObjCArg.
- if (DT->isReachableFromEntry(U) && DT->dominates(Inst, U)) {
- Changed = true;
- Instruction *Replacement = Inst;
- Type *UseTy = U.get()->getType();
- if (PHINode *PHI = dyn_cast<PHINode>(U.getUser())) {
- // For PHI nodes, insert the bitcast in the predecessor block.
- unsigned ValNo = PHINode::getIncomingValueNumForOperand(OperandNo);
- BasicBlock *BB = PHI->getIncomingBlock(ValNo);
- if (Replacement->getType() != UseTy)
- Replacement = new BitCastInst(Replacement, UseTy, "",
- &BB->back());
- // While we're here, rewrite all edges for this PHI, rather
- // than just one use at a time, to minimize the number of
- // bitcasts we emit.
- for (unsigned i = 0, e = PHI->getNumIncomingValues(); i != e; ++i)
- if (PHI->getIncomingBlock(i) == BB) {
- // Keep the UI iterator valid.
- if (&PHI->getOperandUse(
- PHINode::getOperandNumForIncomingValue(i)) ==
- &UI.getUse())
- ++UI;
- PHI->setIncomingValue(i, Replacement);
- }
- } else {
- if (Replacement->getType() != UseTy)
- Replacement = new BitCastInst(Replacement, UseTy, "",
- cast<Instruction>(U.getUser()));
- U.set(Replacement);
- }
- }
- }
-
- // If Arg is a no-op casted pointer, strip one level of casts and iterate.
- if (const BitCastInst *BI = dyn_cast<BitCastInst>(Arg))
- Arg = BI->getOperand(0);
- else if (isa<GEPOperator>(Arg) &&
- cast<GEPOperator>(Arg)->hasAllZeroIndices())
- Arg = cast<GEPOperator>(Arg)->getPointerOperand();
- else if (isa<GlobalAlias>(Arg) &&
- !cast<GlobalAlias>(Arg)->mayBeOverridden())
- Arg = cast<GlobalAlias>(Arg)->getAliasee();
- else
- break;
- }
- }
-
- // If this function has no escaping allocas or suspicious vararg usage,
- // objc_storeStrong calls can be marked with the "tail" keyword.
- if (TailOkForStoreStrongs)
- for (SmallPtrSet<CallInst *, 8>::iterator I = StoreStrongCalls.begin(),
- E = StoreStrongCalls.end(); I != E; ++I)
- (*I)->setTailCall();
- StoreStrongCalls.clear();
-
- return Changed;
-}
-
-/// @}
-///
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