diff options
Diffstat (limited to 'lib/Transforms/ObjCARC/ObjCARCOpts.cpp')
| -rw-r--r-- | lib/Transforms/ObjCARC/ObjCARCOpts.cpp | 48 |
1 files changed, 40 insertions, 8 deletions
diff --git a/lib/Transforms/ObjCARC/ObjCARCOpts.cpp b/lib/Transforms/ObjCARC/ObjCARCOpts.cpp index 91490d1b2d..e6e1ff95aa 100644 --- a/lib/Transforms/ObjCARC/ObjCARCOpts.cpp +++ b/lib/Transforms/ObjCARC/ObjCARCOpts.cpp @@ -455,8 +455,13 @@ namespace { /// sequence. SmallPtrSet<Instruction *, 2> ReverseInsertPts; + /// If this is true, we cannot perform code motion but can still remove + /// retain/release pairs. + bool CFGHazardAfflicted; + RRInfo() : - KnownSafe(false), IsTailCallRelease(false), ReleaseMetadata(0) {} + KnownSafe(false), IsTailCallRelease(false), ReleaseMetadata(0), + CFGHazardAfflicted(false) {} void clear(); @@ -472,6 +477,7 @@ void RRInfo::clear() { ReleaseMetadata = 0; Calls.clear(); ReverseInsertPts.clear(); + CFGHazardAfflicted = false; } namespace { @@ -559,6 +565,7 @@ PtrState::Merge(const PtrState &Other, bool TopDown) { RRI.IsTailCallRelease = RRI.IsTailCallRelease && Other.RRI.IsTailCallRelease; RRI.Calls.insert(Other.RRI.Calls.begin(), Other.RRI.Calls.end()); + RRI.CFGHazardAfflicted |= Other.RRI.CFGHazardAfflicted; // Merge the insert point sets. If there are any differences, // that makes this a partial merge. @@ -1690,6 +1697,7 @@ static void CheckForUseCFGHazard(const Sequence SuccSSeq, PtrState &S, bool &SomeSuccHasSame, bool &AllSuccsHaveSame, + bool &NotAllSeqEqualButKnownSafe, bool &ShouldContinue) { switch (SuccSSeq) { case S_CanRelease: { @@ -1697,6 +1705,7 @@ static void CheckForUseCFGHazard(const Sequence SuccSSeq, S.ClearSequenceProgress(); break; } + S.RRI.CFGHazardAfflicted = true; ShouldContinue = true; break; } @@ -1708,6 +1717,8 @@ static void CheckForUseCFGHazard(const Sequence SuccSSeq, case S_MovableRelease: if (!S.RRI.KnownSafe && !SuccSRRIKnownSafe) AllSuccsHaveSame = false; + else + NotAllSeqEqualButKnownSafe = true; break; case S_Retain: llvm_unreachable("bottom-up pointer in retain state!"); @@ -1723,7 +1734,8 @@ static void CheckForCanReleaseCFGHazard(const Sequence SuccSSeq, const bool SuccSRRIKnownSafe, PtrState &S, bool &SomeSuccHasSame, - bool &AllSuccsHaveSame) { + bool &AllSuccsHaveSame, + bool &NotAllSeqEqualButKnownSafe) { switch (SuccSSeq) { case S_CanRelease: SomeSuccHasSame = true; @@ -1734,6 +1746,8 @@ static void CheckForCanReleaseCFGHazard(const Sequence SuccSSeq, case S_Use: if (!S.RRI.KnownSafe && !SuccSRRIKnownSafe) AllSuccsHaveSame = false; + else + NotAllSeqEqualButKnownSafe = true; break; case S_Retain: llvm_unreachable("bottom-up pointer in retain state!"); @@ -1769,6 +1783,7 @@ ObjCARCOpt::CheckForCFGHazards(const BasicBlock *BB, const TerminatorInst *TI = cast<TerminatorInst>(&BB->back()); bool SomeSuccHasSame = false; bool AllSuccsHaveSame = true; + bool NotAllSeqEqualButKnownSafe = false; succ_const_iterator SI(TI), SE(TI, false); @@ -1800,17 +1815,17 @@ ObjCARCOpt::CheckForCFGHazards(const BasicBlock *BB, switch(S.GetSeq()) { case S_Use: { bool ShouldContinue = false; - CheckForUseCFGHazard(SuccSSeq, SuccSRRIKnownSafe, S, - SomeSuccHasSame, AllSuccsHaveSame, + CheckForUseCFGHazard(SuccSSeq, SuccSRRIKnownSafe, S, SomeSuccHasSame, + AllSuccsHaveSame, NotAllSeqEqualButKnownSafe, ShouldContinue); if (ShouldContinue) continue; break; } case S_CanRelease: { - CheckForCanReleaseCFGHazard(SuccSSeq, SuccSRRIKnownSafe, - S, SomeSuccHasSame, - AllSuccsHaveSame); + CheckForCanReleaseCFGHazard(SuccSSeq, SuccSRRIKnownSafe, S, + SomeSuccHasSame, AllSuccsHaveSame, + NotAllSeqEqualButKnownSafe); break; } case S_Retain: @@ -1825,8 +1840,15 @@ ObjCARCOpt::CheckForCFGHazards(const BasicBlock *BB, // If the state at the other end of any of the successor edges // matches the current state, require all edges to match. This // guards against loops in the middle of a sequence. - if (SomeSuccHasSame && !AllSuccsHaveSame) + if (SomeSuccHasSame && !AllSuccsHaveSame) { S.ClearSequenceProgress(); + } else if (NotAllSeqEqualButKnownSafe) { + // If we would have cleared the state foregoing the fact that we are known + // safe, stop code motion. This is because whether or not it is safe to + // remove RR pairs via KnownSafe is an orthogonal concept to whether we + // are allowed to perform code motion. + S.RRI.CFGHazardAfflicted = true; + } } } @@ -2489,6 +2511,7 @@ ObjCARCOpt::ConnectTDBUTraversals(DenseMap<const BasicBlock *, BBState> // we are dealing with a retainable object with multiple provenance sources. bool KnownSafeTD = true, KnownSafeBU = true; bool MultipleOwners = false; + bool CFGHazardAfflicted = false; // Connect the dots between the top-down-collected RetainsToMove and // bottom-up-collected ReleasesToMove to form sets of related calls. @@ -2565,6 +2588,7 @@ ObjCARCOpt::ConnectTDBUTraversals(DenseMap<const BasicBlock *, BBState> assert(It != Releases.end()); const RRInfo &NewReleaseRRI = It->second; KnownSafeBU &= NewReleaseRRI.KnownSafe; + CFGHazardAfflicted |= NewReleaseRRI.CFGHazardAfflicted; for (SmallPtrSet<Instruction *, 2>::const_iterator LI = NewReleaseRRI.Calls.begin(), LE = NewReleaseRRI.Calls.end(); LI != LE; ++LI) { @@ -2618,6 +2642,14 @@ ObjCARCOpt::ConnectTDBUTraversals(DenseMap<const BasicBlock *, BBState> // less aggressive solution which is. if (NewDelta != 0) return false; + + // At this point, we are not going to remove any RR pairs, but we still are + // able to move RR pairs. If one of our pointers is afflicted with + // CFGHazards, we cannot perform such code motion so exit early. + const bool WillPerformCodeMotion = RetainsToMove.ReverseInsertPts.size() || + ReleasesToMove.ReverseInsertPts.size(); + if (CFGHazardAfflicted && WillPerformCodeMotion) + return false; } // Determine whether the original call points are balanced in the retain and |