// This file also defines a simple ARC-aware AliasAnalysis.
//
// WARNING: This file knows about certain library functions. It recognizes them
-// by name, and hardwires knowedge of their semantics.
+// by name, and hardwires knowledge of their semantics.
//
// WARNING: This file knows about how certain Objective-C library functions are
// used. Naive LLVM IR transformations which would otherwise be
//===----------------------------------------------------------------------===//
#define DEBUG_TYPE "objc-arc"
-#include "llvm/Function.h"
-#include "llvm/Intrinsics.h"
-#include "llvm/GlobalVariable.h"
-#include "llvm/DerivedTypes.h"
-#include "llvm/Module.h"
-#include "llvm/Analysis/ValueTracking.h"
-#include "llvm/Transforms/Utils/Local.h"
-#include "llvm/Support/CallSite.h"
+#include "llvm/Support/raw_ostream.h"
#include "llvm/Support/CommandLine.h"
-#include "llvm/ADT/StringSwitch.h"
#include "llvm/ADT/DenseMap.h"
-#include "llvm/ADT/STLExtras.h"
using namespace llvm;
// A handy option to enable/disable all optimizations in this file.
}
#endif
- ValueT &operator[](KeyT Arg) {
+ ValueT &operator[](const KeyT &Arg) {
std::pair<typename MapTy::iterator, bool> Pair =
Map.insert(std::make_pair(Arg, size_t(0)));
if (Pair.second) {
- Pair.first->second = Vector.size();
+ size_t Num = Vector.size();
+ Pair.first->second = Num;
Vector.push_back(std::make_pair(Arg, ValueT()));
- return Vector.back().second;
+ return Vector[Num].second;
}
return Vector[Pair.first->second].second;
}
std::pair<typename MapTy::iterator, bool> Pair =
Map.insert(std::make_pair(InsertPair.first, size_t(0)));
if (Pair.second) {
- Pair.first->second = Vector.size();
+ size_t Num = Vector.size();
+ Pair.first->second = Num;
Vector.push_back(InsertPair);
- return std::make_pair(llvm::prior(Vector.end()), true);
+ return std::make_pair(Vector.begin() + Num, true);
}
return std::make_pair(Vector.begin() + Pair.first->second, false);
}
- const_iterator find(KeyT Key) const {
+ const_iterator find(const KeyT &Key) const {
typename MapTy::const_iterator It = Map.find(Key);
if (It == Map.end()) return Vector.end();
return Vector.begin() + It->second;
/// from the vector, it just zeros out the key in the vector. This leaves
/// iterators intact, but clients must be prepared for zeroed-out keys when
/// iterating.
- void blot(KeyT Key) {
+ void blot(const KeyT &Key) {
typename MapTy::iterator It = Map.find(Key);
if (It == Map.end()) return;
Vector[It->second].first = KeyT();
// ARC Utilities.
//===----------------------------------------------------------------------===//
+#include "llvm/Intrinsics.h"
+#include "llvm/Module.h"
+#include "llvm/Analysis/ValueTracking.h"
+#include "llvm/Transforms/Utils/Local.h"
+#include "llvm/Support/CallSite.h"
+#include "llvm/ADT/StringSwitch.h"
+
namespace {
/// InstructionClass - A simple classification for instructions.
enum InstructionClass {
IC_MoveWeak, ///< objc_moveWeak (derived)
IC_CopyWeak, ///< objc_copyWeak (derived)
IC_DestroyWeak, ///< objc_destroyWeak (derived)
+ IC_StoreStrong, ///< objc_storeStrong (derived)
IC_CallOrUser, ///< could call objc_release and/or "use" pointers
IC_Call, ///< could call objc_release
IC_User, ///< could "use" a pointer
Arg->hasNestAttr() ||
Arg->hasStructRetAttr())
return false;
- // Only consider values with pointer types, and not function pointers.
+ // Only consider values with pointer types.
+ // It seemes intuitive to exclude function pointer types as well, since
+ // functions are never reference-counted, however clang occasionally
+ // bitcasts reference-counted pointers to function-pointer type
+ // temporarily.
PointerType *Ty = dyn_cast<PointerType>(Op->getType());
- if (!Ty || isa<FunctionType>(Ty->getElementType()))
+ if (!Ty)
return false;
// Conservatively assume anything else is a potential use.
return true;
return StringSwitch<InstructionClass>(F->getName())
.Case("objc_storeWeak", IC_StoreWeak)
.Case("objc_initWeak", IC_InitWeak)
+ .Case("objc_storeStrong", IC_StoreStrong)
.Default(IC_CallOrUser);
// Second argument is i8**.
if (PointerType *Pte1 = dyn_cast<PointerType>(ETy1))
// 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 0: break;
- case Intrinsic::bswap: case Intrinsic::ctpop:
- case Intrinsic::ctlz: case Intrinsic::cttz:
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:
- for (Function::const_arg_iterator AI = F->arg_begin(),
- AE = F->arg_end(); AI != AE; ++AI)
- if (IsPotentialUse(AI))
- return IC_User;
- return IC_None;
+ break;
}
}
return GetCallSiteClass(CI);
}
// Otherwise, be conservative.
- return IC_User;
+ return isa<InvokeInst>(V) ? IC_CallOrUser : IC_User;
}
-/// IsRetain - Test if the the given class is objc_retain or
+/// IsRetain - Test if the given class is objc_retain or
/// equivalent.
static bool IsRetain(InstructionClass Class) {
return Class == IC_Retain ||
Class == IC_RetainRV;
}
-/// IsAutorelease - Test if the the given class is objc_autorelease or
+/// IsAutorelease - Test if the given class is objc_autorelease or
/// equivalent.
static bool IsAutorelease(InstructionClass Class) {
return Class == IC_Autorelease ||
Class == IC_AutoreleasepoolPop;
}
-/// EraseInstruction - Erase the given instruction. ObjC calls return their
+/// EraseInstruction - 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) {
return Arg;
}
- // If we found an identifiable object but it has multiple uses, but they
- // are trivial uses, we can still consider this to be a single-use
- // value.
+ // If we found an identifiable object but it has multiple uses, but they are
+ // trivial uses, we can still consider this to be a single-use value.
if (IsObjCIdentifiedObject(Arg)) {
for (Value::const_use_iterator UI = Arg->use_begin(), UE = Arg->use_end();
UI != UE; ++UI) {
M.getNamedValue("objc_unretainedPointer");
}
+/// DoesObjCBlockEscape - Test whether the given pointer, which is an
+/// Objective C block pointer, does not "escape". 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) {
+ // Walk the def-use chains.
+ SmallVector<const Value *, 4> Worklist;
+ Worklist.push_back(BlockPtr);
+ do {
+ const Value *V = Worklist.pop_back_val();
+ for (Value::const_use_iterator UI = V->use_begin(), UE = V->use_end();
+ UI != UE; ++UI) {
+ const User *UUser = *UI;
+ // Special - Use by a call (callee or argument) is not considered
+ // to be an escape.
+ switch (GetBasicInstructionClass(UUser)) {
+ case IC_StoreWeak:
+ case IC_InitWeak:
+ case IC_StoreStrong:
+ case IC_Autorelease:
+ case IC_AutoreleaseRV:
+ // These special functions make copies of their pointer arguments.
+ return true;
+ case IC_User:
+ case IC_None:
+ // Use by an instruction which copies the value is an escape if the
+ // result is an escape.
+ if (isa<BitCastInst>(UUser) || isa<GetElementPtrInst>(UUser) ||
+ isa<PHINode>(UUser) || isa<SelectInst>(UUser)) {
+ Worklist.push_back(UUser);
+ continue;
+ }
+ // Use by a load is not an escape.
+ if (isa<LoadInst>(UUser))
+ continue;
+ // Use by a store is not an escape if the use is the address.
+ if (const StoreInst *SI = dyn_cast<StoreInst>(UUser))
+ if (V != SI->getValueOperand())
+ continue;
+ break;
+ default:
+ // Regular calls and other stuff are not considered escapes.
+ continue;
+ }
+ // Otherwise, conservatively assume an escape.
+ return true;
+ }
+ } while (!Worklist.empty());
+
+ // No escapes found.
+ return false;
+}
+
//===----------------------------------------------------------------------===//
// ARC AliasAnalysis.
//===----------------------------------------------------------------------===//
/// specified pass info.
virtual void *getAdjustedAnalysisPointer(const void *PI) {
if (PI == &AliasAnalysis::ID)
- return (AliasAnalysis*)this;
+ return static_cast<AliasAnalysis *>(this);
return this;
}
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, becuase it updates
+ // Note that this doesn't include objc_retainBlock, because it updates
// pointers when it copies block data.
return NoModRef;
default:
// These calls return their argument verbatim, as a low-level
// optimization. However, this makes high-level optimizations
// harder. Undo any uses of this optimization that the front-end
- // emitted here. We'll redo them in a later pass.
+ // emitted here. We'll redo them in the contract pass.
Changed = true;
Inst->replaceAllUsesWith(cast<CallInst>(Inst)->getArgOperand(0));
break;
return Changed;
}
+//===----------------------------------------------------------------------===//
+// ARC autorelease pool elimination.
+//===----------------------------------------------------------------------===//
+
+#include "llvm/Constants.h"
+#include "llvm/ADT/STLExtras.h"
+
+namespace {
+ /// ObjCARCAPElim - Autorelease pool elimination.
+ class ObjCARCAPElim : public ModulePass {
+ virtual void getAnalysisUsage(AnalysisUsage &AU) const;
+ virtual bool runOnModule(Module &M);
+
+ static bool MayAutorelease(ImmutableCallSite CS, unsigned Depth = 0);
+ static bool OptimizeBB(BasicBlock *BB);
+
+ public:
+ static char ID;
+ ObjCARCAPElim() : ModulePass(ID) {
+ initializeObjCARCAPElimPass(*PassRegistry::getPassRegistry());
+ }
+ };
+}
+
+char ObjCARCAPElim::ID = 0;
+INITIALIZE_PASS(ObjCARCAPElim,
+ "objc-arc-apelim",
+ "ObjC ARC autorelease pool elimination",
+ false, false)
+
+Pass *llvm::createObjCARCAPElimPass() {
+ return new ObjCARCAPElim();
+}
+
+void ObjCARCAPElim::getAnalysisUsage(AnalysisUsage &AU) const {
+ AU.setPreservesCFG();
+}
+
+/// MayAutorelease - Interprocedurally determine if calls made by the
+/// given call site can possibly produce autoreleases.
+bool ObjCARCAPElim::MayAutorelease(ImmutableCallSite CS, unsigned Depth) {
+ if (const Function *Callee = CS.getCalledFunction()) {
+ if (Callee->isDeclaration() || Callee->mayBeOverridden())
+ return true;
+ for (Function::const_iterator I = Callee->begin(), E = Callee->end();
+ I != E; ++I) {
+ const BasicBlock *BB = I;
+ for (BasicBlock::const_iterator J = BB->begin(), F = BB->end();
+ J != F; ++J)
+ if (ImmutableCallSite JCS = ImmutableCallSite(J))
+ // This recursion depth limit is arbitrary. It's just great
+ // enough to cover known interesting testcases.
+ if (Depth < 3 &&
+ !JCS.onlyReadsMemory() &&
+ MayAutorelease(JCS, Depth + 1))
+ return true;
+ }
+ return false;
+ }
+
+ return true;
+}
+
+bool ObjCARCAPElim::OptimizeBB(BasicBlock *BB) {
+ bool Changed = false;
+
+ Instruction *Push = 0;
+ for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ) {
+ Instruction *Inst = I++;
+ switch (GetBasicInstructionClass(Inst)) {
+ case IC_AutoreleasepoolPush:
+ Push = Inst;
+ break;
+ case IC_AutoreleasepoolPop:
+ // If this pop matches a push and nothing in between can autorelease,
+ // zap the pair.
+ if (Push && cast<CallInst>(Inst)->getArgOperand(0) == Push) {
+ Changed = true;
+ Inst->eraseFromParent();
+ Push->eraseFromParent();
+ }
+ Push = 0;
+ break;
+ case IC_CallOrUser:
+ if (MayAutorelease(ImmutableCallSite(Inst)))
+ Push = 0;
+ break;
+ default:
+ break;
+ }
+ }
+
+ return Changed;
+}
+
+bool ObjCARCAPElim::runOnModule(Module &M) {
+ if (!EnableARCOpts)
+ return false;
+
+ // If nothing in the Module uses ARC, don't do anything.
+ if (!ModuleHasARC(M))
+ return false;
+
+ // Find the llvm.global_ctors variable, as the first step in
+ // identifying the global constructors. In theory, unnecessary autorelease
+ // pools could occur anywhere, but in practice it's pretty rare. Global
+ // ctors are a place where autorelease pools get inserted automatically,
+ // so it's pretty common for them to be unnecessary, and it's pretty
+ // profitable to eliminate them.
+ GlobalVariable *GV = M.getGlobalVariable("llvm.global_ctors");
+ if (!GV)
+ return false;
+
+ assert(GV->hasDefinitiveInitializer() &&
+ "llvm.global_ctors is uncooperative!");
+
+ bool Changed = false;
+
+ // Dig the constructor functions out of GV's initializer.
+ ConstantArray *Init = cast<ConstantArray>(GV->getInitializer());
+ for (User::op_iterator OI = Init->op_begin(), OE = Init->op_end();
+ OI != OE; ++OI) {
+ Value *Op = *OI;
+ // llvm.global_ctors is an array of pairs where the second members
+ // are constructor functions.
+ Function *F = dyn_cast<Function>(cast<ConstantStruct>(Op)->getOperand(1));
+ // If the user used a constructor function with the wrong signature and
+ // it got bitcasted or whatever, look the other way.
+ if (!F)
+ continue;
+ // Only look at function definitions.
+ if (F->isDeclaration())
+ continue;
+ // Only look at functions with one basic block.
+ if (llvm::next(F->begin()) != F->end())
+ continue;
+ // Ok, a single-block constructor function definition. Try to optimize it.
+ Changed |= OptimizeBB(F->begin());
+ }
+
+ return Changed;
+}
+
//===----------------------------------------------------------------------===//
// ARC optimization.
//===----------------------------------------------------------------------===//
// TODO: Delete release+retain pairs (rare).
-#include "llvm/GlobalAlias.h"
-#include "llvm/Constants.h"
#include "llvm/LLVMContext.h"
-#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/CFG.h"
-#include "llvm/ADT/PostOrderIterator.h"
#include "llvm/ADT/Statistic.h"
+#include "llvm/ADT/SmallPtrSet.h"
STATISTIC(NumNoops, "Number of no-op objc calls eliminated");
STATISTIC(NumPartialNoops, "Number of partially no-op objc calls eliminated");
bool relatedSelect(const SelectInst *A, const Value *B);
bool relatedPHI(const PHINode *A, const Value *B);
- // Do not implement.
- void operator=(const ProvenanceAnalysis &);
- ProvenanceAnalysis(const ProvenanceAnalysis &);
+ void operator=(const ProvenanceAnalysis &) LLVM_DELETED_FUNCTION;
+ ProvenanceAnalysis(const ProvenanceAnalysis &) LLVM_DELETED_FUNCTION;
public:
ProvenanceAnalysis() {}
// 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()) {
- if (related(A->getTrueValue(), SB->getTrueValue()))
- return true;
- if (related(A->getFalseValue(), SB->getFalseValue()))
- return true;
- return false;
- }
+ if (A->getCondition() == SB->getCondition())
+ return related(A->getTrueValue(), SB->getTrueValue()) ||
+ related(A->getFalseValue(), SB->getFalseValue());
// Check both arms of the Select node individually.
- if (related(A->getTrueValue(), B))
- return true;
- if (related(A->getFalseValue(), B))
- return true;
-
- // The arms both checked out.
- return false;
+ return related(A->getTrueValue(), B) ||
+ related(A->getFalseValue(), B);
}
bool ProvenanceAnalysis::relatedPHI(const PHINode *A, const Value *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) {
- // If both pointers have provenance, they can be directly compared.
- if (A != B)
- return false;
- } else {
- if (isa<LoadInst>(B))
- return isStoredObjCPointer(A);
+ // 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 && isa<LoadInst>(A))
+ } else if (BIsIdentified) {
+ // Check for an obvious escape.
+ if (isa<LoadInst>(A))
return isStoredObjCPointer(B);
}
/// opposed to objc_retain calls).
bool IsRetainBlock;
- /// CopyOnEscape - True if this the Calls are objc_retainBlock calls
- /// which all have the !clang.arc.copy_on_escape metadata.
- bool CopyOnEscape;
-
/// IsTailCallRelease - True of the objc_release calls are all marked
/// with the "tail" keyword.
bool IsTailCallRelease;
- /// Partial - True of 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;
-
/// ReleaseMetadata - If the Calls are objc_release calls and they all have
/// a clang.imprecise_release tag, this is the metadata tag.
MDNode *ReleaseMetadata;
SmallPtrSet<Instruction *, 2> ReverseInsertPts;
RRInfo() :
- KnownSafe(false), IsRetainBlock(false), CopyOnEscape(false),
- IsTailCallRelease(false), Partial(false),
+ KnownSafe(false), IsRetainBlock(false),
+ IsTailCallRelease(false),
ReleaseMetadata(0) {}
void clear();
void RRInfo::clear() {
KnownSafe = false;
IsRetainBlock = false;
- CopyOnEscape = false;
IsTailCallRelease = false;
- Partial = false;
ReleaseMetadata = 0;
Calls.clear();
ReverseInsertPts.clear();
/// PtrState - This class summarizes several per-pointer runtime properties
/// which are propogated through the flow graph.
class PtrState {
- /// RefCount - The known minimum number of reference count increments.
- unsigned RefCount;
+ /// KnownPositiveRefCount - True if the reference count is known to
+ /// be incremented.
+ bool KnownPositiveRefCount;
- /// NestCount - The known minimum level of retain+release nesting.
- unsigned NestCount;
+ /// Partial - True of 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;
/// Seq - The current position in the sequence.
- Sequence Seq;
+ Sequence Seq : 8;
public:
/// RRI - Unidirectional information about the current sequence.
/// TODO: Encapsulate this better.
RRInfo RRI;
- PtrState() : RefCount(0), NestCount(0), Seq(S_None) {}
-
- void SetAtLeastOneRefCount() {
- if (RefCount == 0) RefCount = 1;
- }
+ PtrState() : KnownPositiveRefCount(false), Partial(false),
+ Seq(S_None) {}
- void IncrementRefCount() {
- if (RefCount != UINT_MAX) ++RefCount;
+ void SetKnownPositiveRefCount() {
+ KnownPositiveRefCount = true;
}
- void DecrementRefCount() {
- if (RefCount != 0) --RefCount;
+ void ClearRefCount() {
+ KnownPositiveRefCount = false;
}
bool IsKnownIncremented() const {
- return RefCount > 0;
- }
-
- void IncrementNestCount() {
- if (NestCount != UINT_MAX) ++NestCount;
- }
-
- void DecrementNestCount() {
- if (NestCount != 0) --NestCount;
- }
-
- bool IsKnownNested() const {
- return NestCount > 0;
+ return KnownPositiveRefCount;
}
void SetSeq(Sequence NewSeq) {
}
void ClearSequenceProgress() {
- Seq = S_None;
+ ResetSequenceProgress(S_None);
+ }
+
+ void ResetSequenceProgress(Sequence NewSeq) {
+ Seq = NewSeq;
+ Partial = false;
RRI.clear();
}
void
PtrState::Merge(const PtrState &Other, bool TopDown) {
Seq = MergeSeqs(Seq, Other.Seq, TopDown);
- RefCount = std::min(RefCount, Other.RefCount);
- NestCount = std::min(NestCount, Other.NestCount);
+ KnownPositiveRefCount = KnownPositiveRefCount && Other.KnownPositiveRefCount;
// We can't merge a plain objc_retain with an objc_retainBlock.
if (RRI.IsRetainBlock != Other.RRI.IsRetainBlock)
// If we're not in a sequence (anymore), drop all associated state.
if (Seq == S_None) {
+ Partial = false;
RRI.clear();
- } else if (RRI.Partial || Other.RRI.Partial) {
+ } else if (Partial || Other.Partial) {
// If we're doing a merge on a path that's previously seen a partial
// merge, conservatively drop the sequence, to avoid doing partial
// RR elimination. If the branch predicates for the two merge differ,
// mixing them is unsafe.
- Seq = S_None;
- RRI.clear();
+ ClearSequenceProgress();
} else {
// Conservatively merge the ReleaseMetadata information.
if (RRI.ReleaseMetadata != Other.RRI.ReleaseMetadata)
RRI.ReleaseMetadata = 0;
- RRI.CopyOnEscape = RRI.CopyOnEscape && Other.RRI.CopyOnEscape;
RRI.KnownSafe = RRI.KnownSafe && Other.RRI.KnownSafe;
- RRI.IsTailCallRelease = RRI.IsTailCallRelease && Other.RRI.IsTailCallRelease;
+ 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.
- RRI.Partial = RRI.ReverseInsertPts.size() !=
- Other.RRI.ReverseInsertPts.size();
+ 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)
- RRI.Partial |= RRI.ReverseInsertPts.insert(*I);
+ Partial |= RRI.ReverseInsertPts.insert(*I);
}
}
/// known about a pointer at the top of each block.
MapTy PerPtrBottomUp;
+ /// Preds, Succs - Effective successors and predecessors of the current
+ /// block (this ignores ignorable edges and ignored backedges).
+ SmallVector<BasicBlock *, 2> Preds;
+ SmallVector<BasicBlock *, 2> Succs;
+
public:
BBState() : TopDownPathCount(0), BottomUpPathCount(0) {}
/// 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 {
+ assert(TopDownPathCount != 0);
+ assert(BottomUpPathCount != 0);
return TopDownPathCount * BottomUpPathCount;
}
- /// IsVisitedTopDown - Test whether the block for this BBState has been
- /// visited by the top-down portion of the algorithm.
- bool isVisitedTopDown() const {
- return TopDownPathCount != 0;
- }
+ // 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(); }
+
+ void addSucc(BasicBlock *Succ) { Succs.push_back(Succ); }
+ void addPred(BasicBlock *Pred) { Preds.push_back(Pred); }
+
+ bool isExit() const { return Succs.empty(); }
};
}
// loop backedge. Loop backedges are special.
TopDownPathCount += Other.TopDownPathCount;
+ // Check for overflow. If we have overflow, fall back to conservative behavior.
+ if (TopDownPathCount < Other.TopDownPathCount) {
+ clearTopDownPointers();
+ return;
+ }
+
// For each entry in the other set, if our set has an entry with the same key,
// merge the entries. Otherwise, copy the entry and merge it with an empty
// entry.
// loop backedge. Loop backedges are special.
BottomUpPathCount += Other.BottomUpPathCount;
+ // Check for overflow. If we have overflow, fall back to conservative behavior.
+ if (BottomUpPathCount < Other.BottomUpPathCount) {
+ clearBottomUpPointers();
+ return;
+ }
+
// For each entry in the other set, if our set has an entry with the
// same key, merge the entries. Otherwise, copy the entry and merge
// it with an empty entry.
/// metadata.
unsigned ImpreciseReleaseMDKind;
- /// CopyOnEscape - The Metadata Kind for clang.arc.copy_on_escape
+ /// CopyOnEscapeMDKind - The Metadata Kind for clang.arc.copy_on_escape
/// metadata.
unsigned CopyOnEscapeMDKind;
+ /// NoObjCARCExceptionsMDKind - 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 *getRetainBlockCallee(Module *M);
Constant *getAutoreleaseCallee(Module *M);
+ bool IsRetainBlockOptimizable(const Instruction *Inst);
+
void OptimizeRetainCall(Function &F, Instruction *Retain);
bool OptimizeRetainRVCall(Function &F, Instruction *RetainRV);
void OptimizeAutoreleaseRVCall(Function &F, Instruction *AutoreleaseRV);
void CheckForCFGHazards(const BasicBlock *BB,
DenseMap<const BasicBlock *, BBState> &BBStates,
BBState &MyStates) const;
+ bool VisitInstructionBottomUp(Instruction *Inst,
+ BasicBlock *BB,
+ MapVector<Value *, RRInfo> &Retains,
+ BBState &MyStates);
bool VisitBottomUp(BasicBlock *BB,
DenseMap<const BasicBlock *, BBState> &BBStates,
MapVector<Value *, RRInfo> &Retains);
+ bool VisitInstructionTopDown(Instruction *Inst,
+ DenseMap<Value *, RRInfo> &Releases,
+ BBState &MyStates);
bool VisitTopDown(BasicBlock *BB,
DenseMap<const BasicBlock *, BBState> &BBStates,
DenseMap<Value *, RRInfo> &Releases);
AU.setPreservesCFG();
}
+bool ObjCARCOpt::IsRetainBlockOptimizable(const Instruction *Inst) {
+ // Without the magic metadata tag, we have to assume this might be an
+ // objc_retainBlock call inserted to convert a block pointer to an id,
+ // in which case it really is needed.
+ if (!Inst->getMetadata(CopyOnEscapeMDKind))
+ return false;
+
+ // If the pointer "escapes" (not including being used in a call),
+ // the copy may be needed.
+ if (DoesObjCBlockEscape(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));
- std::vector<Type *> Params;
- Params.push_back(I8X);
- FunctionType *FTy =
- FunctionType::get(I8X, Params, /*isVarArg=*/false);
- AttrListPtr Attributes;
- Attributes.addAttr(~0u, Attribute::NoUnwind);
+ Type *Params[] = { I8X };
+ FunctionType *FTy = FunctionType::get(I8X, Params, /*isVarArg=*/false);
+ Attributes::Builder B;
+ B.addAttribute(Attributes::NoUnwind);
+ AttrListPtr Attributes =
+ AttrListPtr().addAttr(M->getContext(), AttrListPtr::FunctionIndex,
+ Attributes::get(M->getContext(), B));
RetainRVCallee =
M->getOrInsertFunction("objc_retainAutoreleasedReturnValue", FTy,
Attributes);
if (!AutoreleaseRVCallee) {
LLVMContext &C = M->getContext();
Type *I8X = PointerType::getUnqual(Type::getInt8Ty(C));
- std::vector<Type *> Params;
- Params.push_back(I8X);
- FunctionType *FTy =
- FunctionType::get(I8X, Params, /*isVarArg=*/false);
- AttrListPtr Attributes;
- Attributes.addAttr(~0u, Attribute::NoUnwind);
+ Type *Params[] = { I8X };
+ FunctionType *FTy = FunctionType::get(I8X, Params, /*isVarArg=*/false);
+ Attributes::Builder B;
+ B.addAttribute(Attributes::NoUnwind);
+ AttrListPtr Attributes =
+ AttrListPtr().addAttr(M->getContext(), AttrListPtr::FunctionIndex,
+ Attributes::get(C, B));
AutoreleaseRVCallee =
M->getOrInsertFunction("objc_autoreleaseReturnValue", FTy,
Attributes);
Constant *ObjCARCOpt::getReleaseCallee(Module *M) {
if (!ReleaseCallee) {
LLVMContext &C = M->getContext();
- std::vector<Type *> Params;
- Params.push_back(PointerType::getUnqual(Type::getInt8Ty(C)));
- AttrListPtr Attributes;
- Attributes.addAttr(~0u, Attribute::NoUnwind);
+ Type *Params[] = { PointerType::getUnqual(Type::getInt8Ty(C)) };
+ Attributes::Builder B;
+ B.addAttribute(Attributes::NoUnwind);
+ AttrListPtr Attributes =
+ AttrListPtr().addAttr(M->getContext(), AttrListPtr::FunctionIndex,
+ Attributes::get(C, B));
ReleaseCallee =
M->getOrInsertFunction(
"objc_release",
Constant *ObjCARCOpt::getRetainCallee(Module *M) {
if (!RetainCallee) {
LLVMContext &C = M->getContext();
- std::vector<Type *> Params;
- Params.push_back(PointerType::getUnqual(Type::getInt8Ty(C)));
- AttrListPtr Attributes;
- Attributes.addAttr(~0u, Attribute::NoUnwind);
+ Type *Params[] = { PointerType::getUnqual(Type::getInt8Ty(C)) };
+ Attributes::Builder B;
+ B.addAttribute(Attributes::NoUnwind);
+ AttrListPtr Attributes =
+ AttrListPtr().addAttr(M->getContext(), AttrListPtr::FunctionIndex,
+ Attributes::get(C, B));
RetainCallee =
M->getOrInsertFunction(
"objc_retain",
Constant *ObjCARCOpt::getRetainBlockCallee(Module *M) {
if (!RetainBlockCallee) {
LLVMContext &C = M->getContext();
- std::vector<Type *> Params;
- Params.push_back(PointerType::getUnqual(Type::getInt8Ty(C)));
- AttrListPtr Attributes;
+ 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),
- Attributes);
+ AttrListPtr());
}
return RetainBlockCallee;
}
Constant *ObjCARCOpt::getAutoreleaseCallee(Module *M) {
if (!AutoreleaseCallee) {
LLVMContext &C = M->getContext();
- std::vector<Type *> Params;
- Params.push_back(PointerType::getUnqual(Type::getInt8Ty(C)));
- AttrListPtr Attributes;
- Attributes.addAttr(~0u, Attribute::NoUnwind);
+ Type *Params[] = { PointerType::getUnqual(Type::getInt8Ty(C)) };
+ Attributes::Builder B;
+ B.addAttribute(Attributes::NoUnwind);
+ AttrListPtr Attributes =
+ AttrListPtr().addAttr(M->getContext(), AttrListPtr::FunctionIndex,
+ Attributes::get(C, B));
AutoreleaseCallee =
M->getOrInsertFunction(
"objc_autorelease",
return AutoreleaseCallee;
}
+/// IsPotentialUse - Test whether the given value is possible a
+/// reference-counted pointer, including tests which utilize AliasAnalysis.
+static bool IsPotentialUse(const Value *Op, AliasAnalysis &AA) {
+ // First make the rudimentary check.
+ if (!IsPotentialUse(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;
+}
+
/// CanAlterRefCount - Test whether the given instruction can result in a
/// reference count modification (positive or negative) for the pointer's
/// object.
for (ImmutableCallSite::arg_iterator I = CS.arg_begin(), E = CS.arg_end();
I != E; ++I) {
const Value *Op = *I;
- if (IsPotentialUse(Op) && PA.related(Ptr, Op))
+ if (IsPotentialUse(Op, *PA.getAA()) && PA.related(Ptr, Op))
return true;
}
return false;
// 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 (!IsPotentialUse(ICI->getOperand(1)))
+ if (!IsPotentialUse(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 (IsPotentialUse(Op) && PA.related(Ptr, Op))
+ if (IsPotentialUse(Op, *PA.getAA()) && PA.related(Ptr, Op))
return true;
}
return false;
const Value *Op = GetUnderlyingObjCPtr(SI->getPointerOperand());
// If we can't tell what the underlying object was, assume there is a
// dependence.
- return IsPotentialUse(Op) && PA.related(Op, Ptr);
+ return IsPotentialUse(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 (IsPotentialUse(Op) && PA.related(Ptr, Op))
+ if (IsPotentialUse(Op, *PA.getAA()) && PA.related(Ptr, Op))
return true;
}
return false;
/// use here.
enum DependenceKind {
NeedsPositiveRetainCount,
+ AutoreleasePoolBoundary,
CanChangeRetainCount,
RetainAutoreleaseDep, ///< Blocks objc_retainAutorelease.
RetainAutoreleaseRVDep, ///< Blocks objc_retainAutoreleaseReturnValue.
}
}
+ 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 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;
// Nothing else matters for objc_retainAutorelease formation.
return false;
}
- break;
case RetainAutoreleaseRVDep: {
InstructionClass Class = GetBasicInstructionClass(Inst);
// retainAutoreleaseReturnValue formation.
return CanInterruptRV(Class);
}
- break;
}
case RetainRVDep:
}
llvm_unreachable("Invalid dependence flavor");
- return true;
}
/// FindDependencies - Walk up the CFG from StartPos (which is in StartBB) and
/// objc_retainAutoreleasedReturnValue if the operand is a return value.
void
ObjCARCOpt::OptimizeRetainCall(Function &F, Instruction *Retain) {
- CallSite CS(GetObjCArg(Retain));
- Instruction *Call = CS.getInstruction();
+ 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::iterator I = Call;
+ BasicBlock::const_iterator I = Call;
++I;
while (isNoopInstruction(I)) ++I;
if (&*I != Retain)
}
/// OptimizeRetainRVCall - 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.
+/// 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.
bool
ObjCARCOpt::OptimizeRetainRVCall(Function &F, Instruction *RetainRV) {
- // Check for the argument being from an immediately preceding call.
- Value *Arg = GetObjCArg(RetainRV);
- CallSite CS(Arg);
- if (Instruction *Call = CS.getInstruction())
+ // Check for the argument being from an immediately preceding call or invoke.
+ const Value *Arg = GetObjCArg(RetainRV);
+ ImmutableCallSite CS(Arg);
+ if (const Instruction *Call = CS.getInstruction()) {
if (Call->getParent() == RetainRV->getParent()) {
- BasicBlock::iterator I = Call;
+ BasicBlock::const_iterator I = Call;
++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;
+ if (&*I == RetainRV)
+ return false;
+ }
}
+ }
// Check for being preceded by an objc_autoreleaseReturnValue on the same
// pointer. In this case, we can delete the pair.
case IC_DestroyWeak: {
CallInst *CI = cast<CallInst>(Inst);
if (isNullOrUndef(CI->getArgOperand(0))) {
+ Changed = true;
Type *Ty = CI->getArgOperand(0)->getType();
new StoreInst(UndefValue::get(cast<PointerType>(Ty)->getElementType()),
Constant::getNullValue(Ty),
CallInst *CI = cast<CallInst>(Inst);
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()),
Constant::getNullValue(Ty),
// Check that there is nothing that cares about the reference
// count between the call and the phi.
- FindDependencies(NeedsPositiveRetainCount, Arg,
- Inst->getParent(), Inst,
- DependingInstructions, Visited, PA);
+ switch (Class) {
+ case IC_Retain:
+ case IC_RetainBlock:
+ // These can always be moved up.
+ break;
+ case IC_Release:
+ // These can't be moved across things that care about the retain
+ // count.
+ FindDependencies(NeedsPositiveRetainCount, Arg,
+ Inst->getParent(), Inst,
+ DependingInstructions, Visited, PA);
+ break;
+ case IC_Autorelease:
+ // These can't be moved across autorelease pool scope boundaries.
+ FindDependencies(AutoreleasePoolBoundary, Arg,
+ Inst->getParent(), Inst,
+ DependingInstructions, Visited, PA);
+ break;
+ case IC_RetainRV:
+ case IC_AutoreleaseRV:
+ // Don't move these; the RV optimization depends on the autoreleaseRV
+ // being tail called, and the retainRV being immediately after a call
+ // (which might still happen if we get lucky with codegen layout, but
+ // it's not worth taking the chance).
+ continue;
+ default:
+ llvm_unreachable("Invalid dependence flavor");
+ }
+
if (DependingInstructions.size() == 1 &&
*DependingInstructions.begin() == PN) {
Changed = true;
BBState &MyStates) const {
// If any top-down local-use or possible-dec has a succ which is earlier in
// the sequence, forget it.
- for (BBState::ptr_const_iterator I = MyStates.top_down_ptr_begin(),
+ 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;
const TerminatorInst *TI = cast<TerminatorInst>(&BB->back());
bool SomeSuccHasSame = false;
bool AllSuccsHaveSame = true;
- PtrState &S = MyStates.getPtrTopDownState(Arg);
- for (succ_const_iterator SI(TI), SE(TI, false); SI != SE; ++SI) {
- PtrState &SuccS = BBStates[*SI].getPtrBottomUpState(Arg);
- switch (SuccS.GetSeq()) {
+ PtrState &S = I->second;
+ succ_const_iterator SI(TI), SE(TI, false);
+
+ // If the terminator is an invoke marked with the
+ // clang.arc.no_objc_arc_exceptions metadata, the unwind edge can be
+ // ignored, for ARC purposes.
+ if (isa<InvokeInst>(TI) && TI->getMetadata(NoObjCARCExceptionsMDKind))
+ --SE;
+
+ 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 && !SuccS.RRI.KnownSafe)
+ if (!S.RRI.KnownSafe && !SuccSRRIKnownSafe) {
S.ClearSequenceProgress();
+ break;
+ }
continue;
}
case S_Use:
case S_Stop:
case S_Release:
case S_MovableRelease:
- if (!S.RRI.KnownSafe && !SuccS.RRI.KnownSafe)
+ if (!S.RRI.KnownSafe && !SuccSRRIKnownSafe)
AllSuccsHaveSame = false;
break;
case S_Retain:
const TerminatorInst *TI = cast<TerminatorInst>(&BB->back());
bool SomeSuccHasSame = false;
bool AllSuccsHaveSame = true;
- PtrState &S = MyStates.getPtrTopDownState(Arg);
- for (succ_const_iterator SI(TI), SE(TI, false); SI != SE; ++SI) {
- PtrState &SuccS = BBStates[*SI].getPtrBottomUpState(Arg);
- switch (SuccS.GetSeq()) {
+ PtrState &S = I->second;
+ succ_const_iterator SI(TI), SE(TI, false);
+
+ // If the terminator is an invoke marked with the
+ // clang.arc.no_objc_arc_exceptions metadata, the unwind edge can be
+ // ignored, for ARC purposes.
+ if (isa<InvokeInst>(TI) && TI->getMetadata(NoObjCARCExceptionsMDKind))
+ --SE;
+
+ 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 && !SuccS.RRI.KnownSafe)
+ if (!S.RRI.KnownSafe && !SuccSRRIKnownSafe) {
S.ClearSequenceProgress();
+ break;
+ }
continue;
}
case S_CanRelease:
case S_Release:
case S_MovableRelease:
case S_Use:
- if (!S.RRI.KnownSafe && !SuccS.RRI.KnownSafe)
+ if (!S.RRI.KnownSafe && !SuccSRRIKnownSafe)
AllSuccsHaveSame = false;
break;
case S_Retain:
}
}
+bool
+ObjCARCOpt::VisitInstructionBottomUp(Instruction *Inst,
+ BasicBlock *BB,
+ MapVector<Value *, RRInfo> &Retains,
+ BBState &MyStates) {
+ bool NestingDetected = false;
+ InstructionClass Class = GetInstructionClass(Inst);
+ const Value *Arg = 0;
+
+ switch (Class) {
+ case IC_Release: {
+ Arg = GetObjCArg(Inst);
+
+ PtrState &S = MyStates.getPtrBottomUpState(Arg);
+
+ // If we see two releases in a row on the same pointer. If so, make
+ // a note, and we'll cicle back to revisit it after we've
+ // hopefully eliminated the second release, which may allow us to
+ // eliminate the first release too.
+ // Theoretically we could implement removal of nested retain+release
+ // 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)
+ 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);
+
+ 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
+ case IC_Retain:
+ case IC_RetainRV: {
+ Arg = GetObjCArg(Inst);
+
+ PtrState &S = MyStates.getPtrBottomUpState(Arg);
+ S.SetKnownPositiveRefCount();
+
+ switch (S.GetSeq()) {
+ case S_Stop:
+ case S_Release:
+ case S_MovableRelease:
+ case S_Use:
+ S.RRI.ReverseInsertPts.clear();
+ // 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;
+ }
+ S.ClearSequenceProgress();
+ break;
+ case S_None:
+ break;
+ case S_Retain:
+ llvm_unreachable("bottom-up pointer in retain state!");
+ }
+ return NestingDetected;
+ }
+ case IC_AutoreleasepoolPop:
+ // Conservatively, clear MyStates for all known pointers.
+ MyStates.clearBottomUpPointers();
+ return NestingDetected;
+ case IC_AutoreleasepoolPush:
+ case IC_None:
+ // These are irrelevant.
+ return NestingDetected;
+ default:
+ break;
+ }
+
+ // Consider any other possible effects of this instruction on each
+ // pointer being tracked.
+ for (BBState::ptr_iterator MI = MyStates.bottom_up_ptr_begin(),
+ ME = MyStates.bottom_up_ptr_end(); MI != ME; ++MI) {
+ const Value *Ptr = MI->first;
+ if (Ptr == Arg)
+ continue; // Handled above.
+ PtrState &S = MI->second;
+ Sequence Seq = S.GetSeq();
+
+ // Check for possible releases.
+ if (CanAlterRefCount(Inst, Ptr, PA, Class)) {
+ S.ClearRefCount();
+ switch (Seq) {
+ case S_Use:
+ S.SetSeq(S_CanRelease);
+ continue;
+ case S_CanRelease:
+ case S_Release:
+ case S_MovableRelease:
+ case S_Stop:
+ case S_None:
+ break;
+ case S_Retain:
+ llvm_unreachable("bottom-up pointer in retain state!");
+ }
+ }
+
+ // Check for possible direct uses.
+ switch (Seq) {
+ case S_Release:
+ case S_MovableRelease:
+ if (CanUse(Inst, Ptr, PA, Class)) {
+ assert(S.RRI.ReverseInsertPts.empty());
+ // 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());
+ else
+ S.RRI.ReverseInsertPts.insert(llvm::next(BasicBlock::iterator(Inst)));
+ S.SetSeq(S_Use);
+ } else if (Seq == S_Release &&
+ (Class == IC_User || Class == IC_CallOrUser)) {
+ // Non-movable releases depend on any possible objc pointer use.
+ S.SetSeq(S_Stop);
+ assert(S.RRI.ReverseInsertPts.empty());
+ // As above; handle invoke specially.
+ if (isa<InvokeInst>(Inst))
+ S.RRI.ReverseInsertPts.insert(BB->getFirstInsertionPt());
+ else
+ S.RRI.ReverseInsertPts.insert(llvm::next(BasicBlock::iterator(Inst)));
+ }
+ break;
+ case S_Stop:
+ if (CanUse(Inst, Ptr, PA, Class))
+ S.SetSeq(S_Use);
+ break;
+ case S_CanRelease:
+ case S_Use:
+ case S_None:
+ break;
+ case S_Retain:
+ llvm_unreachable("bottom-up pointer in retain state!");
+ }
+ }
+
+ return NestingDetected;
+}
+
bool
ObjCARCOpt::VisitBottomUp(BasicBlock *BB,
DenseMap<const BasicBlock *, BBState> &BBStates,
// Merge the states from each successor to compute the initial state
// for the current block.
- const TerminatorInst *TI = cast<TerminatorInst>(&BB->back());
- succ_const_iterator SI(TI), SE(TI, false);
- if (SI == SE)
- MyStates.SetAsExit();
- else
- do {
- const BasicBlock *Succ = *SI++;
- if (Succ == BB)
- continue;
- DenseMap<const BasicBlock *, BBState>::iterator I = BBStates.find(Succ);
- // If we haven't seen this node yet, then we've found a CFG cycle.
- // Be optimistic here; it's CheckForCFGHazards' job detect trouble.
- if (I == BBStates.end())
- continue;
- MyStates.InitFromSucc(I->second);
- while (SI != SE) {
- Succ = *SI++;
- if (Succ != BB) {
- I = BBStates.find(Succ);
- if (I != BBStates.end())
- MyStates.MergeSucc(I->second);
- }
- }
- break;
- } while (SI != SE);
+ BBState::edge_iterator SI(MyStates.succ_begin()),
+ SE(MyStates.succ_end());
+ if (SI != SE) {
+ const BasicBlock *Succ = *SI;
+ DenseMap<const BasicBlock *, BBState>::iterator I = BBStates.find(Succ);
+ assert(I != BBStates.end());
+ MyStates.InitFromSucc(I->second);
+ ++SI;
+ for (; SI != SE; ++SI) {
+ Succ = *SI;
+ I = BBStates.find(Succ);
+ assert(I != BBStates.end());
+ MyStates.MergeSucc(I->second);
+ }
+ }
// Visit all the instructions, bottom-up.
for (BasicBlock::iterator I = BB->end(), E = BB->begin(); I != E; --I) {
Instruction *Inst = llvm::prior(I);
- InstructionClass Class = GetInstructionClass(Inst);
- const Value *Arg = 0;
- switch (Class) {
- case IC_Release: {
- Arg = GetObjCArg(Inst);
+ // Invoke instructions are visited as part of their successors (below).
+ if (isa<InvokeInst>(Inst))
+ continue;
+
+ NestingDetected |= VisitInstructionBottomUp(Inst, BB, Retains, MyStates);
+ }
- PtrState &S = MyStates.getPtrBottomUpState(Arg);
+ // If there's a predecessor with an invoke, visit the invoke as if it were
+ // part of this block, since we can't insert code after an invoke in its own
+ // block, and we don't want to split critical edges.
+ for (BBState::edge_iterator PI(MyStates.pred_begin()),
+ PE(MyStates.pred_end()); PI != PE; ++PI) {
+ BasicBlock *Pred = *PI;
+ if (InvokeInst *II = dyn_cast<InvokeInst>(&Pred->back()))
+ NestingDetected |= VisitInstructionBottomUp(II, BB, Retains, MyStates);
+ }
- // If we see two releases in a row on the same pointer. If so, make
+ return NestingDetected;
+}
+
+bool
+ObjCARCOpt::VisitInstructionTopDown(Instruction *Inst,
+ DenseMap<Value *, RRInfo> &Releases,
+ BBState &MyStates) {
+ bool NestingDetected = false;
+ InstructionClass Class = GetInstructionClass(Inst);
+ const Value *Arg = 0;
+
+ 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
+ case IC_Retain:
+ case IC_RetainRV: {
+ Arg = GetObjCArg(Inst);
+
+ PtrState &S = MyStates.getPtrTopDownState(Arg);
+
+ // 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) {
+ // If we see two retains in a row on the same pointer. If so, make
// a note, and we'll cicle back to revisit it after we've
- // hopefully eliminated the second release, which may allow us to
- // eliminate the first release too.
+ // hopefully eliminated the second retain, which may allow us to
+ // eliminate the first retain too.
// Theoretically we could implement removal of nested retain+release
// 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)
+ if (S.GetSeq() == S_Retain)
NestingDetected = true;
- S.RRI.clear();
-
- MDNode *ReleaseMetadata = Inst->getMetadata(ImpreciseReleaseMDKind);
- S.SetSeq(ReleaseMetadata ? S_MovableRelease : S_Release);
- S.RRI.ReleaseMetadata = ReleaseMetadata;
- S.RRI.KnownSafe = S.IsKnownNested() || S.IsKnownIncremented();
- S.RRI.IsTailCallRelease = cast<CallInst>(Inst)->isTailCall();
+ S.ResetSequenceProgress(S_Retain);
+ S.RRI.IsRetainBlock = Class == IC_RetainBlock;
+ S.RRI.KnownSafe = S.IsKnownIncremented();
S.RRI.Calls.insert(Inst);
+ }
+
+ S.SetKnownPositiveRefCount();
- S.IncrementRefCount();
- S.IncrementNestCount();
+ // A retain can be a potential use; procede to the generic checking
+ // code below.
+ break;
+ }
+ case IC_Release: {
+ Arg = GetObjCArg(Inst);
+
+ PtrState &S = MyStates.getPtrTopDownState(Arg);
+ S.ClearRefCount();
+
+ switch (S.GetSeq()) {
+ case S_Retain:
+ case S_CanRelease:
+ S.RRI.ReverseInsertPts.clear();
+ // FALL THROUGH
+ case S_Use:
+ S.RRI.ReleaseMetadata = Inst->getMetadata(ImpreciseReleaseMDKind);
+ S.RRI.IsTailCallRelease = cast<CallInst>(Inst)->isTailCall();
+ Releases[Inst] = S.RRI;
+ S.ClearSequenceProgress();
+ break;
+ case S_None:
break;
+ case S_Stop:
+ case S_Release:
+ case S_MovableRelease:
+ llvm_unreachable("top-down pointer in release state!");
}
- case IC_RetainBlock:
- case IC_Retain:
- case IC_RetainRV: {
- Arg = GetObjCArg(Inst);
-
- PtrState &S = MyStates.getPtrBottomUpState(Arg);
- S.DecrementRefCount();
- S.SetAtLeastOneRefCount();
- S.DecrementNestCount();
-
- // An non-copy-on-escape objc_retainBlock call with just a use still
- // needs to be kept, because it may be copying a block from the stack
- // to the heap.
- if (Class == IC_RetainBlock &&
- !Inst->getMetadata(CopyOnEscapeMDKind) &&
- S.GetSeq() == S_Use)
+ break;
+ }
+ case IC_AutoreleasepoolPop:
+ // Conservatively, clear MyStates for all known pointers.
+ MyStates.clearTopDownPointers();
+ return NestingDetected;
+ case IC_AutoreleasepoolPush:
+ case IC_None:
+ // These are irrelevant.
+ return NestingDetected;
+ default:
+ break;
+ }
+
+ // Consider any other possible effects of this instruction on each
+ // pointer being tracked.
+ for (BBState::ptr_iterator MI = MyStates.top_down_ptr_begin(),
+ ME = MyStates.top_down_ptr_end(); MI != ME; ++MI) {
+ const Value *Ptr = MI->first;
+ if (Ptr == Arg)
+ continue; // Handled above.
+ PtrState &S = MI->second;
+ Sequence Seq = S.GetSeq();
+
+ // Check for possible releases.
+ if (CanAlterRefCount(Inst, Ptr, PA, Class)) {
+ S.ClearRefCount();
+ switch (Seq) {
+ case S_Retain:
S.SetSeq(S_CanRelease);
+ assert(S.RRI.ReverseInsertPts.empty());
+ S.RRI.ReverseInsertPts.insert(Inst);
- switch (S.GetSeq()) {
- case S_Stop:
- case S_Release:
- case S_MovableRelease:
+ // 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,
+ // we're done.
+ continue;
case S_Use:
- S.RRI.ReverseInsertPts.clear();
- // 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;
- if (S.RRI.IsRetainBlock)
- S.RRI.CopyOnEscape = !!Inst->getMetadata(CopyOnEscapeMDKind);
- Retains[Inst] = S.RRI;
- }
- S.ClearSequenceProgress();
- break;
case S_None:
break;
- case S_Retain:
- llvm_unreachable("bottom-up pointer in retain state!");
- }
- continue;
- }
- case IC_AutoreleasepoolPop:
- // Conservatively, clear MyStates for all known pointers.
- MyStates.clearBottomUpPointers();
- continue;
- case IC_AutoreleasepoolPush:
- case IC_None:
- // These are irrelevant.
- continue;
- default:
- break;
- }
-
- // Consider any other possible effects of this instruction on each
- // pointer being tracked.
- for (BBState::ptr_iterator MI = MyStates.bottom_up_ptr_begin(),
- ME = MyStates.bottom_up_ptr_end(); MI != ME; ++MI) {
- const Value *Ptr = MI->first;
- if (Ptr == Arg)
- continue; // Handled above.
- PtrState &S = MI->second;
- Sequence Seq = S.GetSeq();
-
- // Check for possible releases.
- if (CanAlterRefCount(Inst, Ptr, PA, Class)) {
- S.DecrementRefCount();
- switch (Seq) {
- case S_Use:
- S.SetSeq(S_CanRelease);
- continue;
- case S_CanRelease:
- case S_Release:
- case S_MovableRelease:
- case S_Stop:
- case S_None:
- break;
- case S_Retain:
- llvm_unreachable("bottom-up pointer in retain state!");
- }
- }
-
- // Check for possible direct uses.
- switch (Seq) {
+ case S_Stop:
case S_Release:
case S_MovableRelease:
- if (CanUse(Inst, Ptr, PA, Class)) {
- assert(S.RRI.ReverseInsertPts.empty());
- S.RRI.ReverseInsertPts.insert(Inst);
- S.SetSeq(S_Use);
- } else if (Seq == S_Release &&
- (Class == IC_User || Class == IC_CallOrUser)) {
- // Non-movable releases depend on any possible objc pointer use.
- S.SetSeq(S_Stop);
- assert(S.RRI.ReverseInsertPts.empty());
- S.RRI.ReverseInsertPts.insert(Inst);
- }
- break;
- case S_Stop:
- if (CanUse(Inst, Ptr, PA, Class))
- S.SetSeq(S_Use);
- break;
- case S_CanRelease:
- case S_Use:
- case S_None:
- break;
- case S_Retain:
- llvm_unreachable("bottom-up pointer in retain state!");
+ llvm_unreachable("top-down pointer in release state!");
}
}
+
+ // Check for possible direct uses.
+ switch (Seq) {
+ case S_CanRelease:
+ if (CanUse(Inst, Ptr, PA, Class))
+ S.SetSeq(S_Use);
+ break;
+ case S_Retain:
+ case S_Use:
+ case S_None:
+ break;
+ case S_Stop:
+ case S_Release:
+ case S_MovableRelease:
+ llvm_unreachable("top-down pointer in release state!");
+ }
}
return NestingDetected;
// Merge the states from each predecessor to compute the initial state
// for the current block.
- const_pred_iterator PI(BB), PE(BB, false);
- if (PI == PE)
- MyStates.SetAsEntry();
- else
- do {
- const BasicBlock *Pred = *PI++;
- if (Pred == BB)
- continue;
- DenseMap<const BasicBlock *, BBState>::iterator I = BBStates.find(Pred);
+ BBState::edge_iterator PI(MyStates.pred_begin()),
+ PE(MyStates.pred_end());
+ if (PI != PE) {
+ const BasicBlock *Pred = *PI;
+ DenseMap<const BasicBlock *, BBState>::iterator I = BBStates.find(Pred);
+ assert(I != BBStates.end());
+ MyStates.InitFromPred(I->second);
+ ++PI;
+ for (; PI != PE; ++PI) {
+ Pred = *PI;
+ I = BBStates.find(Pred);
assert(I != BBStates.end());
- // If we haven't seen this node yet, then we've found a CFG cycle.
- // Be optimistic here; it's CheckForCFGHazards' job detect trouble.
- if (!I->second.isVisitedTopDown())
- continue;
- MyStates.InitFromPred(I->second);
- while (PI != PE) {
- Pred = *PI++;
- if (Pred != BB) {
- I = BBStates.find(Pred);
- assert(I != BBStates.end());
- if (I->second.isVisitedTopDown())
- MyStates.MergePred(I->second);
- }
- }
- break;
- } while (PI != PE);
+ MyStates.MergePred(I->second);
+ }
+ }
// Visit all the instructions, top-down.
for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ++I) {
Instruction *Inst = I;
- InstructionClass Class = GetInstructionClass(Inst);
- const Value *Arg = 0;
+ NestingDetected |= VisitInstructionTopDown(Inst, Releases, MyStates);
+ }
- switch (Class) {
- case IC_RetainBlock:
- case IC_Retain:
- case IC_RetainRV: {
- Arg = GetObjCArg(Inst);
+ CheckForCFGHazards(BB, BBStates, MyStates);
+ return NestingDetected;
+}
- PtrState &S = MyStates.getPtrTopDownState(Arg);
+static void
+ComputePostOrders(Function &F,
+ SmallVectorImpl<BasicBlock *> &PostOrder,
+ SmallVectorImpl<BasicBlock *> &ReverseCFGPostOrder,
+ unsigned NoObjCARCExceptionsMDKind,
+ DenseMap<const BasicBlock *, BBState> &BBStates) {
+ /// Visited - The visited set, for doing DFS walks.
+ SmallPtrSet<BasicBlock *, 16> Visited;
- // 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) {
- // If we see two retains in a row on the same pointer. If so, make
- // a note, and we'll cicle back to revisit it after we've
- // hopefully eliminated the second retain, which may allow us to
- // eliminate the first retain too.
- // Theoretically we could implement removal of nested retain+release
- // 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_Retain)
- NestingDetected = true;
-
- S.SetSeq(S_Retain);
- S.RRI.clear();
- S.RRI.IsRetainBlock = Class == IC_RetainBlock;
- if (S.RRI.IsRetainBlock)
- S.RRI.CopyOnEscape = !!Inst->getMetadata(CopyOnEscapeMDKind);
- // Don't check S.IsKnownIncremented() here because it's not
- // sufficient.
- S.RRI.KnownSafe = S.IsKnownNested();
- S.RRI.Calls.insert(Inst);
+ // Do DFS, computing the PostOrder.
+ SmallPtrSet<BasicBlock *, 16> OnStack;
+ SmallVector<std::pair<BasicBlock *, succ_iterator>, 16> SuccStack;
+
+ // Functions always have exactly one entry block, and we don't have
+ // any other block that we treat like an entry block.
+ BasicBlock *EntryBB = &F.getEntryBlock();
+ BBState &MyStates = BBStates[EntryBB];
+ MyStates.SetAsEntry();
+ TerminatorInst *EntryTI = cast<TerminatorInst>(&EntryBB->back());
+ SuccStack.push_back(std::make_pair(EntryBB, succ_iterator(EntryTI)));
+ Visited.insert(EntryBB);
+ OnStack.insert(EntryBB);
+ do {
+ dfs_next_succ:
+ BasicBlock *CurrBB = SuccStack.back().first;
+ TerminatorInst *TI = cast<TerminatorInst>(&CurrBB->back());
+ succ_iterator SE(TI, false);
+
+ // If the terminator is an invoke marked with the
+ // clang.arc.no_objc_arc_exceptions metadata, the unwind edge can be
+ // ignored, for ARC purposes.
+ if (isa<InvokeInst>(TI) && TI->getMetadata(NoObjCARCExceptionsMDKind))
+ --SE;
+
+ while (SuccStack.back().second != SE) {
+ BasicBlock *SuccBB = *SuccStack.back().second++;
+ if (Visited.insert(SuccBB)) {
+ TerminatorInst *TI = cast<TerminatorInst>(&SuccBB->back());
+ SuccStack.push_back(std::make_pair(SuccBB, succ_iterator(TI)));
+ BBStates[CurrBB].addSucc(SuccBB);
+ BBState &SuccStates = BBStates[SuccBB];
+ SuccStates.addPred(CurrBB);
+ OnStack.insert(SuccBB);
+ goto dfs_next_succ;
}
- S.SetAtLeastOneRefCount();
- S.IncrementRefCount();
- S.IncrementNestCount();
- continue;
+ if (!OnStack.count(SuccBB)) {
+ BBStates[CurrBB].addSucc(SuccBB);
+ BBStates[SuccBB].addPred(CurrBB);
+ }
}
- case IC_Release: {
- Arg = GetObjCArg(Inst);
+ OnStack.erase(CurrBB);
+ PostOrder.push_back(CurrBB);
+ SuccStack.pop_back();
+ } while (!SuccStack.empty());
- PtrState &S = MyStates.getPtrTopDownState(Arg);
- S.DecrementRefCount();
- S.DecrementNestCount();
+ Visited.clear();
- switch (S.GetSeq()) {
- case S_Retain:
- case S_CanRelease:
- S.RRI.ReverseInsertPts.clear();
- // FALL THROUGH
- case S_Use:
- S.RRI.ReleaseMetadata = Inst->getMetadata(ImpreciseReleaseMDKind);
- S.RRI.IsTailCallRelease = cast<CallInst>(Inst)->isTailCall();
- Releases[Inst] = S.RRI;
- S.ClearSequenceProgress();
- break;
- case S_None:
- break;
- case S_Stop:
- case S_Release:
- case S_MovableRelease:
- llvm_unreachable("top-down pointer in release state!");
- }
- break;
- }
- case IC_AutoreleasepoolPop:
- // Conservatively, clear MyStates for all known pointers.
- MyStates.clearTopDownPointers();
- continue;
- case IC_AutoreleasepoolPush:
- case IC_None:
- // These are irrelevant.
+ // Do reverse-CFG DFS, computing the reverse-CFG PostOrder.
+ // Functions may have many exits, and there also blocks which we treat
+ // as exits due to ignored edges.
+ SmallVector<std::pair<BasicBlock *, BBState::edge_iterator>, 16> PredStack;
+ for (Function::iterator I = F.begin(), E = F.end(); I != E; ++I) {
+ BasicBlock *ExitBB = I;
+ BBState &MyStates = BBStates[ExitBB];
+ if (!MyStates.isExit())
continue;
- default:
- break;
- }
- // Consider any other possible effects of this instruction on each
- // pointer being tracked.
- for (BBState::ptr_iterator MI = MyStates.top_down_ptr_begin(),
- ME = MyStates.top_down_ptr_end(); MI != ME; ++MI) {
- const Value *Ptr = MI->first;
- if (Ptr == Arg)
- continue; // Handled above.
- PtrState &S = MI->second;
- Sequence Seq = S.GetSeq();
-
- // Check for possible releases.
- if (CanAlterRefCount(Inst, Ptr, PA, Class)) {
- S.DecrementRefCount();
- switch (Seq) {
- case S_Retain:
- S.SetSeq(S_CanRelease);
- assert(S.RRI.ReverseInsertPts.empty());
- S.RRI.ReverseInsertPts.insert(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,
- // we're done.
- continue;
- case S_Use:
- case S_CanRelease:
- case S_None:
- break;
- case S_Stop:
- case S_Release:
- case S_MovableRelease:
- llvm_unreachable("top-down pointer in release state!");
- }
- }
+ MyStates.SetAsExit();
- // Check for possible direct uses.
- switch (Seq) {
- case S_CanRelease:
- if (CanUse(Inst, Ptr, PA, Class))
- S.SetSeq(S_Use);
- break;
- case S_Retain:
- // A non-copy-on-scape objc_retainBlock call may be responsible for
- // copying the block data from the stack to the heap. Model this by
- // moving it straight from S_Retain to S_Use.
- if (S.RRI.IsRetainBlock &&
- !S.RRI.CopyOnEscape &&
- CanUse(Inst, Ptr, PA, Class)) {
- assert(S.RRI.ReverseInsertPts.empty());
- S.RRI.ReverseInsertPts.insert(Inst);
- S.SetSeq(S_Use);
+ PredStack.push_back(std::make_pair(ExitBB, MyStates.pred_begin()));
+ Visited.insert(ExitBB);
+ while (!PredStack.empty()) {
+ reverse_dfs_next_succ:
+ BBState::edge_iterator PE = BBStates[PredStack.back().first].pred_end();
+ while (PredStack.back().second != PE) {
+ BasicBlock *BB = *PredStack.back().second++;
+ if (Visited.insert(BB)) {
+ PredStack.push_back(std::make_pair(BB, BBStates[BB].pred_begin()));
+ goto reverse_dfs_next_succ;
}
- break;
- case S_Use:
- case S_None:
- break;
- case S_Stop:
- case S_Release:
- case S_MovableRelease:
- llvm_unreachable("top-down pointer in release state!");
}
+ ReverseCFGPostOrder.push_back(PredStack.pop_back_val().first);
}
}
-
- CheckForCFGHazards(BB, BBStates, MyStates);
- return NestingDetected;
}
// Visit - Visit the function both top-down and bottom-up.
DenseMap<const BasicBlock *, BBState> &BBStates,
MapVector<Value *, RRInfo> &Retains,
DenseMap<Value *, RRInfo> &Releases) {
- // Use reverse-postorder on the reverse CFG for bottom-up, because we
- // magically know that loops will be well behaved, i.e. they won't repeatedly
- // call retain on a single pointer without doing a release. We can't use
- // ReversePostOrderTraversal here because we want to walk up from each
- // function exit point.
- SmallPtrSet<BasicBlock *, 16> Visited;
- SmallVector<std::pair<BasicBlock *, pred_iterator>, 16> Stack;
- SmallVector<BasicBlock *, 16> Order;
- for (Function::iterator I = F.begin(), E = F.end(); I != E; ++I) {
- BasicBlock *BB = I;
- if (BB->getTerminator()->getNumSuccessors() == 0)
- Stack.push_back(std::make_pair(BB, pred_begin(BB)));
- }
- while (!Stack.empty()) {
- pred_iterator End = pred_end(Stack.back().first);
- while (Stack.back().second != End) {
- BasicBlock *BB = *Stack.back().second++;
- if (Visited.insert(BB))
- Stack.push_back(std::make_pair(BB, pred_begin(BB)));
- }
- Order.push_back(Stack.pop_back_val().first);
- }
+
+ // Use reverse-postorder traversals, because we magically know that loops
+ // will be well behaved, i.e. they won't repeatedly call retain on a single
+ // pointer without doing a release. We can't use the ReversePostOrderTraversal
+ // class here because we want the reverse-CFG postorder to consider each
+ // function exit point, and we want to ignore selected cycle edges.
+ SmallVector<BasicBlock *, 16> PostOrder;
+ SmallVector<BasicBlock *, 16> ReverseCFGPostOrder;
+ ComputePostOrders(F, PostOrder, ReverseCFGPostOrder,
+ NoObjCARCExceptionsMDKind,
+ BBStates);
+
+ // Use reverse-postorder on the reverse CFG for bottom-up.
bool BottomUpNestingDetected = false;
for (SmallVectorImpl<BasicBlock *>::const_reverse_iterator I =
- Order.rbegin(), E = Order.rend(); I != E; ++I) {
- BasicBlock *BB = *I;
- BottomUpNestingDetected |= VisitBottomUp(BB, BBStates, Retains);
- }
+ ReverseCFGPostOrder.rbegin(), E = ReverseCFGPostOrder.rend();
+ I != E; ++I)
+ BottomUpNestingDetected |= VisitBottomUp(*I, BBStates, Retains);
- // Use regular reverse-postorder for top-down.
+ // Use reverse-postorder for top-down.
bool TopDownNestingDetected = false;
- typedef ReversePostOrderTraversal<Function *> RPOTType;
- RPOTType RPOT(&F);
- for (RPOTType::rpo_iterator I = RPOT.begin(), E = RPOT.end(); I != E; ++I) {
- BasicBlock *BB = *I;
- TopDownNestingDetected |= VisitTopDown(BB, BBStates, Releases);
- }
+ for (SmallVectorImpl<BasicBlock *>::const_reverse_iterator I =
+ PostOrder.rbegin(), E = PostOrder.rend();
+ I != E; ++I)
+ TopDownNestingDetected |= VisitTopDown(*I, BBStates, Releases);
return TopDownNestingDetected && BottomUpNestingDetected;
}
getRetainBlockCallee(M) : getRetainCallee(M),
MyArg, "", InsertPt);
Call->setDoesNotThrow();
- if (RetainsToMove.CopyOnEscape)
+ if (RetainsToMove.IsRetainBlock)
Call->setMetadata(CopyOnEscapeMDKind,
MDNode::get(M->getContext(), ArrayRef<Value *>()));
- if (!RetainsToMove.IsRetainBlock)
+ else
Call->setTailCall();
}
for (SmallPtrSet<Instruction *, 2>::const_iterator
PI = RetainsToMove.ReverseInsertPts.begin(),
PE = RetainsToMove.ReverseInsertPts.end(); PI != PE; ++PI) {
- Instruction *LastUse = *PI;
- Instruction *InsertPts[] = { 0, 0, 0 };
- if (InvokeInst *II = dyn_cast<InvokeInst>(LastUse)) {
- // We can't insert code immediately after an invoke instruction, so
- // insert code at the beginning of both successor blocks instead.
- // The invoke's return value isn't available in the unwind block,
- // but our releases will never depend on it, because they must be
- // paired with retains from before the invoke.
- InsertPts[0] = II->getNormalDest()->getFirstInsertionPt();
- InsertPts[1] = II->getUnwindDest()->getFirstInsertionPt();
- } else {
- // Insert code immediately after the last use.
- InsertPts[0] = llvm::next(BasicBlock::iterator(LastUse));
- }
-
- for (Instruction **I = InsertPts; *I; ++I) {
- Instruction *InsertPt = *I;
- Value *MyArg = ArgTy == ParamTy ? Arg :
- new BitCastInst(Arg, ParamTy, "", InsertPt);
- CallInst *Call = CallInst::Create(getReleaseCallee(M), MyArg,
- "", InsertPt);
- // Attach a clang.imprecise_release metadata tag, if appropriate.
- if (MDNode *M = ReleasesToMove.ReleaseMetadata)
- Call->setMetadata(ImpreciseReleaseMDKind, M);
- Call->setDoesNotThrow();
- if (ReleasesToMove.IsTailCallRelease)
- Call->setTailCall();
- }
+ Instruction *InsertPt = *PI;
+ Value *MyArg = ArgTy == ParamTy ? Arg :
+ new BitCastInst(Arg, ParamTy, "", InsertPt);
+ CallInst *Call = CallInst::Create(getReleaseCallee(M), MyArg,
+ "", InsertPt);
+ // Attach a clang.imprecise_release metadata tag, if appropriate.
+ if (MDNode *M = ReleasesToMove.ReleaseMetadata)
+ Call->setMetadata(ImpreciseReleaseMDKind, M);
+ Call->setDoesNotThrow();
+ if (ReleasesToMove.IsTailCallRelease)
+ Call->setTailCall();
}
// Delete the original retain and release calls.
}
}
+/// PerformCodePlacement - Identify pairings between the retains and releases,
+/// and delete and/or move them.
bool
ObjCARCOpt::PerformCodePlacement(DenseMap<const BasicBlock *, BBState>
&BBStates,
SmallVector<Instruction *, 4> NewReleases;
SmallVector<Instruction *, 8> DeadInsts;
+ // Visit each retain.
for (MapVector<Value *, RRInfo>::const_iterator I = Retains.begin(),
E = Retains.end(); I != E; ++I) {
Value *V = I->first;
Instruction *Retain = cast<Instruction>(V);
Value *Arg = GetObjCArg(Retain);
- // If the object being released is in static storage, we know it's
+ // If the object being released is in static or stack storage, we know it's
// not being managed by ObjC reference counting, so we can delete pairs
// regardless of what possible decrements or uses lie between them.
- bool KnownSafe = isa<Constant>(Arg);
-
- // Same for stack storage, unless this is a non-copy-on-escape
- // objc_retainBlock call, which is responsible for copying the block data
- // from the stack to the heap.
- if ((!I->second.IsRetainBlock || I->second.CopyOnEscape) &&
- isa<AllocaInst>(Arg))
- KnownSafe = true;
+ bool KnownSafe = isa<Constant>(Arg) || isa<AllocaInst>(Arg);
// A constant pointer can't be pointing to an object on the heap. It may
// be reference-counted, but it won't be deleted.
// Merge the IsRetainBlock values.
if (FirstRetain) {
RetainsToMove.IsRetainBlock = NewReleaseRetainRRI.IsRetainBlock;
- RetainsToMove.CopyOnEscape = NewReleaseRetainRRI.CopyOnEscape;
FirstRetain = false;
} else if (ReleasesToMove.IsRetainBlock !=
NewReleaseRetainRRI.IsRetainBlock)
// objc_retain and the other uses objc_retainBlock.
goto next_retain;
- // Merge the CopyOnEscape values.
- RetainsToMove.CopyOnEscape &= NewReleaseRetainRRI.CopyOnEscape;
-
// Collect the optimal insertion points.
if (!KnownSafe)
for (SmallPtrSet<Instruction *, 2>::const_iterator
// Ok, everything checks out and we're all set. Let's move some code!
Changed = true;
+ assert(OldCount != 0 && "Unreachable code?");
AnyPairsCompletelyEliminated = NewCount == 0;
NumRRs += OldCount - NewCount;
MoveCalls(Arg, RetainsToMove, ReleasesToMove,
if (AllocaInst *Alloca = dyn_cast<AllocaInst>(Arg)) {
for (Value::use_iterator UI = Alloca->use_begin(),
UE = Alloca->use_end(); UI != UE; ++UI) {
- Instruction *UserInst = cast<Instruction>(*UI);
+ const Instruction *UserInst = cast<Instruction>(*UI);
switch (GetBasicInstructionClass(UserInst)) {
case IC_InitWeak:
case IC_StoreWeak:
for (Value::use_iterator UI = Alloca->use_begin(),
UE = Alloca->use_end(); UI != UE; ) {
CallInst *UserInst = cast<CallInst>(*UI++);
- if (!UserInst->use_empty())
- UserInst->replaceAllUsesWith(UserInst->getArgOperand(0));
+ switch (GetBasicInstructionClass(UserInst)) {
+ case IC_InitWeak:
+ case IC_StoreWeak:
+ // These functions return their second argument.
+ UserInst->replaceAllUsesWith(UserInst->getArgOperand(1));
+ break;
+ case IC_DestroyWeak:
+ // No return value.
+ break;
+ default:
+ llvm_unreachable("alloca really is used!");
+ }
UserInst->eraseFromParent();
}
Alloca->eraseFromParent();
}
/// OptimizeReturns - Look for this pattern:
-///
+/// \code
/// %call = call i8* @something(...)
/// %2 = call i8* @objc_retain(i8* %call)
/// %3 = call i8* @objc_autorelease(i8* %2)
/// 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())
dyn_cast_or_null<CallInst>(*DependingInstructions.begin());
if (!Autorelease)
goto next_block;
- InstructionClass AutoreleaseClass =
- GetBasicInstructionClass(Autorelease);
+ InstructionClass AutoreleaseClass = GetBasicInstructionClass(Autorelease);
if (!IsAutorelease(AutoreleaseClass))
goto next_block;
if (GetObjCArg(Autorelease) != Arg)
if (!EnableARCOpts)
return false;
+ // If nothing in the Module uses ARC, don't do anything.
Run = ModuleHasARC(M);
if (!Run)
return false;
M.getContext().getMDKindID("clang.imprecise_release");
CopyOnEscapeMDKind =
M.getContext().getMDKindID("clang.arc.copy_on_escape");
+ NoObjCARCExceptionsMDKind =
+ M.getContext().getMDKindID("clang.arc.no_objc_arc_exceptions");
// Intuitively, objc_retain and others are nocapture, however in practice
// they are not, because they return their argument value. And objc_release
- // calls finalizers.
+ // calls finalizers which can have arbitrary side effects.
// These are initialized lazily.
RetainRVCallee = 0;
while (OptimizeSequences(F)) {}
// Optimizations if objc_autorelease is used.
- if (UsedInThisFunction &
- ((1 << IC_Autorelease) | (1 << IC_AutoreleaseRV)))
+ if (UsedInThisFunction & ((1 << IC_Autorelease) |
+ (1 << IC_AutoreleaseRV)))
OptimizeReturns(F);
return Changed;
/// RetainRV calls to make the optimization work on targets which need it.
const MDString *RetainRVMarker;
+ /// StoreStrongCalls - 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);
LLVMContext &C = M->getContext();
Type *I8X = PointerType::getUnqual(Type::getInt8Ty(C));
Type *I8XX = PointerType::getUnqual(I8X);
- std::vector<Type *> Params;
- Params.push_back(I8XX);
- Params.push_back(I8X);
+ Type *Params[] = { I8XX, I8X };
- AttrListPtr Attributes;
- Attributes.addAttr(~0u, Attribute::NoUnwind);
- Attributes.addAttr(1, Attribute::NoCapture);
+ Attributes::Builder BNoUnwind;
+ BNoUnwind.addAttribute(Attributes::NoUnwind);
+ Attributes::Builder BNoCapture;
+ BNoCapture.addAttribute(Attributes::NoCapture);
+ AttrListPtr Attributes = AttrListPtr()
+ .addAttr(M->getContext(), AttrListPtr::FunctionIndex,
+ Attributes::get(C, BNoUnwind))
+ .addAttr(M->getContext(), 1, Attributes::get(C, BNoCapture));
StoreStrongCallee =
M->getOrInsertFunction(
if (!RetainAutoreleaseCallee) {
LLVMContext &C = M->getContext();
Type *I8X = PointerType::getUnqual(Type::getInt8Ty(C));
- std::vector<Type *> Params;
- Params.push_back(I8X);
- FunctionType *FTy =
- FunctionType::get(I8X, Params, /*isVarArg=*/false);
- AttrListPtr Attributes;
- Attributes.addAttr(~0u, Attribute::NoUnwind);
+ Type *Params[] = { I8X };
+ FunctionType *FTy = FunctionType::get(I8X, Params, /*isVarArg=*/false);
+ Attributes::Builder B;
+ B.addAttribute(Attributes::NoUnwind);
+ AttrListPtr Attributes =
+ AttrListPtr().addAttr(M->getContext(), AttrListPtr::FunctionIndex,
+ Attributes::get(C, B));
RetainAutoreleaseCallee =
M->getOrInsertFunction("objc_retainAutorelease", FTy, Attributes);
}
if (!RetainAutoreleaseRVCallee) {
LLVMContext &C = M->getContext();
Type *I8X = PointerType::getUnqual(Type::getInt8Ty(C));
- std::vector<Type *> Params;
- Params.push_back(I8X);
- FunctionType *FTy =
- FunctionType::get(I8X, Params, /*isVarArg=*/false);
- AttrListPtr Attributes;
- Attributes.addAttr(~0u, Attribute::NoUnwind);
+ Type *Params[] = { I8X };
+ FunctionType *FTy = FunctionType::get(I8X, Params, /*isVarArg=*/false);
+ Attributes::Builder B;
+ B.addAttribute(Attributes::NoUnwind);
+ AttrListPtr Attributes =
+ AttrListPtr().addAttr(M->getContext(), AttrListPtr::FunctionIndex,
+ Attributes::get(C, B));
RetainAutoreleaseRVCallee =
M->getOrInsertFunction("objc_retainAutoreleaseReturnValue", FTy,
Attributes);
return RetainAutoreleaseRVCallee;
}
-/// ContractAutorelease - Merge an autorelease with a retain into a fused
-/// call.
+/// ContractAutorelease - Merge an autorelease with a retain into a fused call.
bool
ObjCARCContract::ContractAutorelease(Function &F, Instruction *Autorelease,
InstructionClass Class,
BasicBlock *BB = Release->getParent();
if (Load->getParent() != BB) return;
- // Walk down to find the store.
+ // 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);
- while (I != End &&
- (&*I == Release ||
- IsRetain(GetBasicInstructionClass(I)) ||
- !(AA->getModRefInfo(I, Loc) & AliasAnalysis::Mod)))
- ++I;
- StoreInst *Store = dyn_cast<StoreInst>(I);
- if (!Store || !Store->isSimple()) return;
- if (Store->getPointerOperand() != Loc.Ptr) return;
+ 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());
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();
}
bool ObjCARCContract::doInitialization(Module &M) {
+ // If nothing in the Module uses ARC, don't do anything.
Run = ModuleHasARC(M);
if (!Run)
return false;
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.
if (!RetainRVMarker)
break;
BasicBlock::iterator BBI = Inst;
- --BBI;
- while (isNoopInstruction(BBI)) --BBI;
+ 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)) {
+ Changed = true;
InlineAsm *IA =
InlineAsm::get(FunctionType::get(Type::getVoidTy(Inst->getContext()),
/*isVarArg=*/false),
/*Constraints=*/"", /*hasSideEffects=*/true);
CallInst::Create(IA, "", Inst);
}
+ decline_rv_optimization:
break;
}
case IC_InitWeak: {
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;
}
Use &U = UI.getUse();
unsigned OperandNo = UI.getOperandNo();
++UI; // Increment UI now, because we may unlink its element.
- if (Instruction *UserInst = dyn_cast<Instruction>(U.getUser()))
- if (Inst != UserInst && DT->dominates(Inst, UserInst)) {
- Changed = true;
- Instruction *Replacement = Inst;
- Type *UseTy = U.get()->getType();
- if (PHINode *PHI = dyn_cast<PHINode>(UserInst)) {
- // 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());
- 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, "", UserInst);
- U.set(Replacement);
- }
+
+ // 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 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) &&
}
}
+ // 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;
}
projects / oota-llvm.git / blobdiff