diff options
Diffstat (limited to 'lib/Transforms/Scalar')
| -rw-r--r-- | lib/Transforms/Scalar/ObjCARC.cpp | 351 |
1 files changed, 198 insertions, 153 deletions
diff --git a/lib/Transforms/Scalar/ObjCARC.cpp b/lib/Transforms/Scalar/ObjCARC.cpp index 1c054f9..32e4b9c 100644 --- a/lib/Transforms/Scalar/ObjCARC.cpp +++ b/lib/Transforms/Scalar/ObjCARC.cpp @@ -1849,6 +1849,19 @@ namespace { SmallVectorImpl<Instruction *> &DeadInsts, Module *M); + bool ConnectTDBUTraversals(DenseMap<const BasicBlock *, BBState> &BBStates, + MapVector<Value *, RRInfo> &Retains, + DenseMap<Value *, RRInfo> &Releases, + Module *M, + SmallVector<Instruction *, 4> &NewRetains, + SmallVector<Instruction *, 4> &NewReleases, + SmallVector<Instruction *, 8> &DeadInsts, + RRInfo &RetainsToMove, + RRInfo &ReleasesToMove, + Value *Arg, + bool KnownSafe, + bool &AnyPairsCompletelyEliminated); + bool PerformCodePlacement(DenseMap<const BasicBlock *, BBState> &BBStates, MapVector<Value *, RRInfo> &Retains, DenseMap<Value *, RRInfo> &Releases, @@ -3398,6 +3411,179 @@ void ObjCARCOpt::MoveCalls(Value *Arg, } } +bool +ObjCARCOpt::ConnectTDBUTraversals(DenseMap<const BasicBlock *, BBState> + &BBStates, + MapVector<Value *, RRInfo> &Retains, + DenseMap<Value *, RRInfo> &Releases, + Module *M, + SmallVector<Instruction *, 4> &NewRetains, + SmallVector<Instruction *, 4> &NewReleases, + SmallVector<Instruction *, 8> &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. + bool KnownSafeTD = true, KnownSafeBU = true; + + // Connect the dots between the top-down-collected RetainsToMove and + // bottom-up-collected ReleasesToMove to form sets of related calls. + // This is an iterative process so that we connect multiple releases + // to multiple retains if needed. + unsigned OldDelta = 0; + unsigned NewDelta = 0; + 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) { + Instruction *NewRetain = *NI; + MapVector<Value *, RRInfo>::const_iterator It = Retains.find(NewRetain); + assert(It != Retains.end()); + const RRInfo &NewRetainRRI = It->second; + KnownSafeTD &= NewRetainRRI.KnownSafe; + for (SmallPtrSet<Instruction *, 2>::const_iterator + LI = NewRetainRRI.Calls.begin(), + LE = NewRetainRRI.Calls.end(); LI != LE; ++LI) { + Instruction *NewRetainRelease = *LI; + DenseMap<Value *, RRInfo>::const_iterator Jt = + Releases.find(NewRetainRelease); + if (Jt == Releases.end()) + return false; + const RRInfo &NewRetainReleaseRRI = Jt->second; + assert(NewRetainReleaseRRI.Calls.count(NewRetain)); + if (ReleasesToMove.Calls.insert(NewRetainRelease)) { + OldDelta -= + BBStates[NewRetainRelease->getParent()].GetAllPathCount(); + + // Merge the ReleaseMetadata and IsTailCallRelease values. + if (FirstRelease) { + ReleasesToMove.ReleaseMetadata = + NewRetainReleaseRRI.ReleaseMetadata; + ReleasesToMove.IsTailCallRelease = + NewRetainReleaseRRI.IsTailCallRelease; + FirstRelease = false; + } else { + if (ReleasesToMove.ReleaseMetadata != + NewRetainReleaseRRI.ReleaseMetadata) + ReleasesToMove.ReleaseMetadata = 0; + if (ReleasesToMove.IsTailCallRelease != + NewRetainReleaseRRI.IsTailCallRelease) + ReleasesToMove.IsTailCallRelease = false; + } + + // Collect the optimal insertion points. + if (!KnownSafe) + for (SmallPtrSet<Instruction *, 2>::const_iterator + RI = NewRetainReleaseRRI.ReverseInsertPts.begin(), + RE = NewRetainReleaseRRI.ReverseInsertPts.end(); + RI != RE; ++RI) { + Instruction *RIP = *RI; + if (ReleasesToMove.ReverseInsertPts.insert(RIP)) + NewDelta -= BBStates[RIP->getParent()].GetAllPathCount(); + } + NewReleases.push_back(NewRetainRelease); + } + } + } + NewRetains.clear(); + if (NewReleases.empty()) break; + + // Back the other way. + for (SmallVectorImpl<Instruction *>::const_iterator + NI = NewReleases.begin(), NE = NewReleases.end(); NI != NE; ++NI) { + Instruction *NewRelease = *NI; + DenseMap<Value *, RRInfo>::const_iterator It = + Releases.find(NewRelease); + assert(It != Releases.end()); + const RRInfo &NewReleaseRRI = It->second; + KnownSafeBU &= NewReleaseRRI.KnownSafe; + for (SmallPtrSet<Instruction *, 2>::const_iterator + LI = NewReleaseRRI.Calls.begin(), + LE = NewReleaseRRI.Calls.end(); LI != LE; ++LI) { + Instruction *NewReleaseRetain = *LI; + MapVector<Value *, RRInfo>::const_iterator Jt = + Retains.find(NewReleaseRetain); + if (Jt == Retains.end()) + return false; + 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. + return false; + + // Collect the optimal insertion points. + if (!KnownSafe) + for (SmallPtrSet<Instruction *, 2>::const_iterator + RI = NewReleaseRetainRRI.ReverseInsertPts.begin(), + RE = NewReleaseRetainRRI.ReverseInsertPts.end(); + RI != RE; ++RI) { + Instruction *RIP = *RI; + if (RetainsToMove.ReverseInsertPts.insert(RIP)) { + PathCount = BBStates[RIP->getParent()].GetAllPathCount(); + NewDelta += PathCount; + NewCount += PathCount; + } + } + NewRetains.push_back(NewReleaseRetain); + } + } + } + NewReleases.clear(); + 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) { + RetainsToMove.ReverseInsertPts.clear(); + ReleasesToMove.ReverseInsertPts.clear(); + NewCount = 0; + } else { + // Determine whether the new insertion points we computed preserve the + // balance of retain and release calls through the program. + // TODO: If the fully aggressive solution isn't valid, try to find a + // less aggressive solution which is. + if (NewDelta != 0) + return false; + } + + // Determine whether the original call points are balanced in the retain and + // release calls through the program. If not, conservatively don't touch + // them. + // TODO: It's theoretically possible to do code motion in this case, as + // long as the existing imbalances are maintained. + if (OldDelta != 0) + return false; + + Changed = true; + assert(OldCount != 0 && "Unreachable code?"); + NumRRs += OldCount - NewCount; + + // Set to true if we completely removed any RR pairs. + AnyPairsCompletelyEliminated |= NewCount == 0; + + // We can move calls! + return true; +} + /// Identify pairings between the retains and releases, and delete and/or move /// them. bool @@ -3440,164 +3626,23 @@ ObjCARCOpt::PerformCodePlacement(DenseMap<const BasicBlock *, BBState> if (GV->isConstant()) KnownSafe = true; - // If a pair happens in a region where it is known that the reference count - // is already incremented, we can similarly ignore possible decrements. - bool KnownSafeTD = true, KnownSafeBU = true; - // Connect the dots between the top-down-collected RetainsToMove and // bottom-up-collected ReleasesToMove to form sets of related calls. - // This is an iterative process so that we connect multiple releases - // to multiple retains if needed. - unsigned OldDelta = 0; - unsigned NewDelta = 0; - unsigned OldCount = 0; - unsigned NewCount = 0; - bool FirstRelease = true; - bool FirstRetain = true; NewRetains.push_back(Retain); - for (;;) { - for (SmallVectorImpl<Instruction *>::const_iterator - NI = NewRetains.begin(), NE = NewRetains.end(); NI != NE; ++NI) { - Instruction *NewRetain = *NI; - MapVector<Value *, RRInfo>::const_iterator It = Retains.find(NewRetain); - assert(It != Retains.end()); - const RRInfo &NewRetainRRI = It->second; - KnownSafeTD &= NewRetainRRI.KnownSafe; - for (SmallPtrSet<Instruction *, 2>::const_iterator - LI = NewRetainRRI.Calls.begin(), - LE = NewRetainRRI.Calls.end(); LI != LE; ++LI) { - Instruction *NewRetainRelease = *LI; - DenseMap<Value *, RRInfo>::const_iterator Jt = - Releases.find(NewRetainRelease); - if (Jt == Releases.end()) - goto next_retain; - const RRInfo &NewRetainReleaseRRI = Jt->second; - assert(NewRetainReleaseRRI.Calls.count(NewRetain)); - if (ReleasesToMove.Calls.insert(NewRetainRelease)) { - OldDelta -= - BBStates[NewRetainRelease->getParent()].GetAllPathCount(); - - // Merge the ReleaseMetadata and IsTailCallRelease values. - if (FirstRelease) { - ReleasesToMove.ReleaseMetadata = - NewRetainReleaseRRI.ReleaseMetadata; - ReleasesToMove.IsTailCallRelease = - NewRetainReleaseRRI.IsTailCallRelease; - FirstRelease = false; - } else { - if (ReleasesToMove.ReleaseMetadata != - NewRetainReleaseRRI.ReleaseMetadata) - ReleasesToMove.ReleaseMetadata = 0; - if (ReleasesToMove.IsTailCallRelease != - NewRetainReleaseRRI.IsTailCallRelease) - ReleasesToMove.IsTailCallRelease = false; - } - - // Collect the optimal insertion points. - if (!KnownSafe) - for (SmallPtrSet<Instruction *, 2>::const_iterator - RI = NewRetainReleaseRRI.ReverseInsertPts.begin(), - RE = NewRetainReleaseRRI.ReverseInsertPts.end(); - RI != RE; ++RI) { - Instruction *RIP = *RI; - if (ReleasesToMove.ReverseInsertPts.insert(RIP)) - NewDelta -= BBStates[RIP->getParent()].GetAllPathCount(); - } - NewReleases.push_back(NewRetainRelease); - } - } - } - NewRetains.clear(); - if (NewReleases.empty()) break; - - // Back the other way. - for (SmallVectorImpl<Instruction *>::const_iterator - NI = NewReleases.begin(), NE = NewReleases.end(); NI != NE; ++NI) { - Instruction *NewRelease = *NI; - DenseMap<Value *, RRInfo>::const_iterator It = - Releases.find(NewRelease); - assert(It != Releases.end()); - const RRInfo &NewReleaseRRI = It->second; - KnownSafeBU &= NewReleaseRRI.KnownSafe; - for (SmallPtrSet<Instruction *, 2>::const_iterator - LI = NewReleaseRRI.Calls.begin(), - LE = NewReleaseRRI.Calls.end(); LI != LE; ++LI) { - Instruction *NewReleaseRetain = *LI; - MapVector<Value *, RRInfo>::const_iterator Jt = - Retains.find(NewReleaseRetain); - if (Jt == Retains.end()) - goto next_retain; - 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. - goto next_retain; - - // Collect the optimal insertion points. - if (!KnownSafe) - for (SmallPtrSet<Instruction *, 2>::const_iterator - RI = NewReleaseRetainRRI.ReverseInsertPts.begin(), - RE = NewReleaseRetainRRI.ReverseInsertPts.end(); - RI != RE; ++RI) { - Instruction *RIP = *RI; - if (RetainsToMove.ReverseInsertPts.insert(RIP)) { - PathCount = BBStates[RIP->getParent()].GetAllPathCount(); - NewDelta += PathCount; - NewCount += PathCount; - } - } - NewRetains.push_back(NewReleaseRetain); - } - } - } - NewReleases.clear(); - 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) { - RetainsToMove.ReverseInsertPts.clear(); - ReleasesToMove.ReverseInsertPts.clear(); - NewCount = 0; - } else { - // Determine whether the new insertion points we computed preserve the - // balance of retain and release calls through the program. - // TODO: If the fully aggressive solution isn't valid, try to find a - // less aggressive solution which is. - if (NewDelta != 0) - goto next_retain; + bool PerformMoveCalls = + ConnectTDBUTraversals(BBStates, Retains, Releases, M, NewRetains, + NewReleases, DeadInsts, RetainsToMove, + ReleasesToMove, Arg, KnownSafe, + AnyPairsCompletelyEliminated); + + if (PerformMoveCalls) { + // Ok, everything checks out and we're all set. Let's move/delete some + // code! + MoveCalls(Arg, RetainsToMove, ReleasesToMove, + Retains, Releases, DeadInsts, M); } - // Determine whether the original call points are balanced in the retain and - // release calls through the program. If not, conservatively don't touch - // them. - // TODO: It's theoretically possible to do code motion in this case, as - // long as the existing imbalances are maintained. - if (OldDelta != 0) - goto next_retain; - - // 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, - Retains, Releases, DeadInsts, M); - - next_retain: + // Clean up state for next retain. NewReleases.clear(); NewRetains.clear(); RetainsToMove.clear(); |