diff options
Diffstat (limited to 'lib')
| -rw-r--r-- | lib/Transforms/Scalar/SROA.cpp | 2227 |
1 files changed, 1255 insertions, 972 deletions
diff --git a/lib/Transforms/Scalar/SROA.cpp b/lib/Transforms/Scalar/SROA.cpp index 985e57c..717c3f4 100644 --- a/lib/Transforms/Scalar/SROA.cpp +++ b/lib/Transforms/Scalar/SROA.cpp @@ -47,7 +47,6 @@ #include "llvm/InstVisitor.h" #include "llvm/Pass.h" #include "llvm/Support/CommandLine.h" -#include "llvm/Support/Compiler.h" #include "llvm/Support/Debug.h" #include "llvm/Support/ErrorHandling.h" #include "llvm/Support/MathExtras.h" @@ -111,40 +110,17 @@ typedef llvm::IRBuilder<false, ConstantFolder, } namespace { -/// \brief A partition of an alloca. -/// -/// This structure represents a contiguous partition of the alloca. These are -/// formed by examining the uses of the alloca. During formation, they may -/// overlap but once an AllocaPartitioning is built, the Partitions within it -/// are all disjoint. The partition also contains a chain of uses of that -/// partition. -class Partition { +/// \brief A common base class for representing a half-open byte range. +struct ByteRange { /// \brief The beginning offset of the range. uint64_t BeginOffset; /// \brief The ending offset, not included in the range. uint64_t EndOffset; - /// \brief Storage for both the use of this partition and whether it can be - /// split. - PointerIntPair<Use *, 1, bool> PartitionUseAndIsSplittable; - -public: - Partition() : BeginOffset(), EndOffset() {} - Partition(uint64_t BeginOffset, uint64_t EndOffset, Use *U, bool IsSplittable) - : BeginOffset(BeginOffset), EndOffset(EndOffset), - PartitionUseAndIsSplittable(U, IsSplittable) {} - - uint64_t beginOffset() const { return BeginOffset; } - uint64_t endOffset() const { return EndOffset; } - - bool isSplittable() const { return PartitionUseAndIsSplittable.getInt(); } - void makeUnsplittable() { PartitionUseAndIsSplittable.setInt(false); } - - Use *getUse() const { return PartitionUseAndIsSplittable.getPointer(); } - - bool isDead() const { return getUse() == 0; } - void kill() { PartitionUseAndIsSplittable.setPointer(0); } + ByteRange() : BeginOffset(), EndOffset() {} + ByteRange(uint64_t BeginOffset, uint64_t EndOffset) + : BeginOffset(BeginOffset), EndOffset(EndOffset) {} /// \brief Support for ordering ranges. /// @@ -152,39 +128,101 @@ public: /// always increasing, and within equal start offsets, the end offsets are /// decreasing. Thus the spanning range comes first in a cluster with the /// same start position. - bool operator<(const Partition &RHS) const { - if (beginOffset() < RHS.beginOffset()) return true; - if (beginOffset() > RHS.beginOffset()) return false; - if (isSplittable() != RHS.isSplittable()) return !isSplittable(); - if (endOffset() > RHS.endOffset()) return true; + bool operator<(const ByteRange &RHS) const { + if (BeginOffset < RHS.BeginOffset) return true; + if (BeginOffset > RHS.BeginOffset) return false; + if (EndOffset > RHS.EndOffset) return true; return false; } /// \brief Support comparison with a single offset to allow binary searches. - friend LLVM_ATTRIBUTE_UNUSED bool operator<(const Partition &LHS, - uint64_t RHSOffset) { - return LHS.beginOffset() < RHSOffset; + friend bool operator<(const ByteRange &LHS, uint64_t RHSOffset) { + return LHS.BeginOffset < RHSOffset; } + friend LLVM_ATTRIBUTE_UNUSED bool operator<(uint64_t LHSOffset, - const Partition &RHS) { - return LHSOffset < RHS.beginOffset(); + const ByteRange &RHS) { + return LHSOffset < RHS.BeginOffset; } - bool operator==(const Partition &RHS) const { - return isSplittable() == RHS.isSplittable() && - beginOffset() == RHS.beginOffset() && endOffset() == RHS.endOffset(); + bool operator==(const ByteRange &RHS) const { + return BeginOffset == RHS.BeginOffset && EndOffset == RHS.EndOffset; } - bool operator!=(const Partition &RHS) const { return !operator==(RHS); } + bool operator!=(const ByteRange &RHS) const { return !operator==(RHS); } }; -} // end anonymous namespace -namespace llvm { -template <typename T> struct isPodLike; -template <> struct isPodLike<Partition> { - static const bool value = true; +/// \brief A partition of an alloca. +/// +/// This structure represents a contiguous partition of the alloca. These are +/// formed by examining the uses of the alloca. During formation, they may +/// overlap but once an AllocaPartitioning is built, the Partitions within it +/// are all disjoint. +struct Partition : public ByteRange { + /// \brief Whether this partition is splittable into smaller partitions. + /// + /// We flag partitions as splittable when they are formed entirely due to + /// accesses by trivially splittable operations such as memset and memcpy. + bool IsSplittable; + + /// \brief Test whether a partition has been marked as dead. + bool isDead() const { + if (BeginOffset == UINT64_MAX) { + assert(EndOffset == UINT64_MAX); + return true; + } + return false; + } + + /// \brief Kill a partition. + /// This is accomplished by setting both its beginning and end offset to + /// the maximum possible value. + void kill() { + assert(!isDead() && "He's Dead, Jim!"); + BeginOffset = EndOffset = UINT64_MAX; + } + + Partition() : ByteRange(), IsSplittable() {} + Partition(uint64_t BeginOffset, uint64_t EndOffset, bool IsSplittable) + : ByteRange(BeginOffset, EndOffset), IsSplittable(IsSplittable) {} +}; + +/// \brief A particular use of a partition of the alloca. +/// +/// This structure is used to associate uses of a partition with it. They +/// mark the range of bytes which are referenced by a particular instruction, +/// and includes a handle to the user itself and the pointer value in use. +/// The bounds of these uses are determined by intersecting the bounds of the +/// memory use itself with a particular partition. As a consequence there is +/// intentionally overlap between various uses of the same partition. +class PartitionUse : public ByteRange { + /// \brief Combined storage for both the Use* and split state. + PointerIntPair<Use*, 1, bool> UsePtrAndIsSplit; + +public: + PartitionUse() : ByteRange(), UsePtrAndIsSplit() {} + PartitionUse(uint64_t BeginOffset, uint64_t EndOffset, Use *U, + bool IsSplit) + : ByteRange(BeginOffset, EndOffset), UsePtrAndIsSplit(U, IsSplit) {} + + /// \brief The use in question. Provides access to both user and used value. + /// + /// Note that this may be null if the partition use is *dead*, that is, it + /// should be ignored. + Use *getUse() const { return UsePtrAndIsSplit.getPointer(); } + + /// \brief Set the use for this partition use range. + void setUse(Use *U) { UsePtrAndIsSplit.setPointer(U); } + + /// \brief Whether this use is split across multiple partitions. + bool isSplit() const { return UsePtrAndIsSplit.getInt(); } }; } +namespace llvm { +template <> struct isPodLike<Partition> : llvm::true_type {}; +template <> struct isPodLike<PartitionUse> : llvm::true_type {}; +} + namespace { /// \brief Alloca partitioning representation. /// @@ -219,6 +257,46 @@ public: const_iterator end() const { return Partitions.end(); } /// @} + /// \brief Support for iterating over and manipulating a particular + /// partition's uses. + /// + /// The iteration support provided for uses is more limited, but also + /// includes some manipulation routines to support rewriting the uses of + /// partitions during SROA. + /// @{ + typedef SmallVectorImpl<PartitionUse>::iterator use_iterator; + use_iterator use_begin(unsigned Idx) { return Uses[Idx].begin(); } + use_iterator use_begin(const_iterator I) { return Uses[I - begin()].begin(); } + use_iterator use_end(unsigned Idx) { return Uses[Idx].end(); } + use_iterator use_end(const_iterator I) { return Uses[I - begin()].end(); } + + typedef SmallVectorImpl<PartitionUse>::const_iterator const_use_iterator; + const_use_iterator use_begin(unsigned Idx) const { return Uses[Idx].begin(); } + const_use_iterator use_begin(const_iterator I) const { + return Uses[I - begin()].begin(); + } + const_use_iterator use_end(unsigned Idx) const { return Uses[Idx].end(); } + const_use_iterator use_end(const_iterator I) const { + return Uses[I - begin()].end(); + } + + unsigned use_size(unsigned Idx) const { return Uses[Idx].size(); } + unsigned use_size(const_iterator I) const { return Uses[I - begin()].size(); } + const PartitionUse &getUse(unsigned PIdx, unsigned UIdx) const { + return Uses[PIdx][UIdx]; + } + const PartitionUse &getUse(const_iterator I, unsigned UIdx) const { + return Uses[I - begin()][UIdx]; + } + + void use_push_back(unsigned Idx, const PartitionUse &PU) { + Uses[Idx].push_back(PU); + } + void use_push_back(const_iterator I, const PartitionUse &PU) { + Uses[I - begin()].push_back(PU); + } + /// @} + /// \brief Allow iterating the dead users for this alloca. /// /// These are instructions which will never actually use the alloca as they @@ -242,12 +320,66 @@ public: dead_op_iterator dead_op_end() const { return DeadOperands.end(); } /// @} + /// \brief MemTransferInst auxiliary data. + /// This struct provides some auxiliary data about memory transfer + /// intrinsics such as memcpy and memmove. These intrinsics can use two + /// different ranges within the same alloca, and provide other challenges to + /// correctly represent. We stash extra data to help us untangle this + /// after the partitioning is complete. + struct MemTransferOffsets { + /// The destination begin and end offsets when the destination is within + /// this alloca. If the end offset is zero the destination is not within + /// this alloca. + uint64_t DestBegin, DestEnd; + + /// The source begin and end offsets when the source is within this alloca. + /// If the end offset is zero, the source is not within this alloca. + uint64_t SourceBegin, SourceEnd; + + /// Flag for whether an alloca is splittable. + bool IsSplittable; + }; + MemTransferOffsets getMemTransferOffsets(MemTransferInst &II) const { + return MemTransferInstData.lookup(&II); + } + + /// \brief Map from a PHI or select operand back to a partition. + /// + /// When manipulating PHI nodes or selects, they can use more than one + /// partition of an alloca. We store a special mapping to allow finding the + /// partition referenced by each of these operands, if any. + iterator findPartitionForPHIOrSelectOperand(Use *U) { + SmallDenseMap<Use *, std::pair<unsigned, unsigned> >::const_iterator MapIt + = PHIOrSelectOpMap.find(U); + if (MapIt == PHIOrSelectOpMap.end()) + return end(); + + return begin() + MapIt->second.first; + } + + /// \brief Map from a PHI or select operand back to the specific use of + /// a partition. + /// + /// Similar to mapping these operands back to the partitions, this maps + /// directly to the use structure of that partition. + use_iterator findPartitionUseForPHIOrSelectOperand(Use *U) { + SmallDenseMap<Use *, std::pair<unsigned, unsigned> >::const_iterator MapIt + = PHIOrSelectOpMap.find(U); + assert(MapIt != PHIOrSelectOpMap.end()); + return Uses[MapIt->second.first].begin() + MapIt->second.second; + } + + /// \brief Compute a common type among the uses of a particular partition. + /// + /// This routines walks all of the uses of a particular partition and tries + /// to find a common type between them. Untyped operations such as memset and + /// memcpy are ignored. + Type *getCommonType(iterator I) const; + #if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP) void print(raw_ostream &OS, const_iterator I, StringRef Indent = " ") const; - void printPartition(raw_ostream &OS, const_iterator I, - StringRef Indent = " ") const; - void printUse(raw_ostream &OS, const_iterator I, - StringRef Indent = " ") const; + void printUsers(raw_ostream &OS, const_iterator I, + StringRef Indent = " ") const; void print(raw_ostream &OS) const; void LLVM_ATTRIBUTE_NOINLINE LLVM_ATTRIBUTE_USED dump(const_iterator I) const; void LLVM_ATTRIBUTE_NOINLINE LLVM_ATTRIBUTE_USED dump() const; @@ -257,6 +389,8 @@ private: template <typename DerivedT, typename RetT = void> class BuilderBase; class PartitionBuilder; friend class AllocaPartitioning::PartitionBuilder; + class UseBuilder; + friend class AllocaPartitioning::UseBuilder; #if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP) /// \brief Handle to alloca instruction to simplify method interfaces. @@ -280,6 +414,14 @@ private: /// expected to always have this as a disjoint space. SmallVector<Partition, 8> Partitions; + /// \brief The uses of the partitions. + /// + /// This is essentially a mapping from each partition to a list of uses of + /// that partition. The mapping is done with a Uses vector that has the exact + /// same number of entries as the partition vector. Each entry is itself + /// a vector of the uses. + SmallVector<SmallVector<PartitionUse, 2>, 8> Uses; + /// \brief Instructions which will become dead if we rewrite the alloca. /// /// Note that these are not separated by partition. This is because we expect @@ -297,6 +439,26 @@ private: /// want to swap this particular input for undef to simplify the use lists of /// the alloca. SmallVector<Use *, 8> DeadOperands; + + /// \brief The underlying storage for auxiliary memcpy and memset info. + SmallDenseMap<MemTransferInst *, MemTransferOffsets, 4> MemTransferInstData; + + /// \brief A side datastructure used when building up the partitions and uses. + /// + /// This mapping is only really used during the initial building of the + /// partitioning so that we can retain information about PHI and select nodes + /// processed. + SmallDenseMap<Instruction *, std::pair<uint64_t, bool> > PHIOrSelectSizes; + + /// \brief Auxiliary information for particular PHI or select operands. + SmallDenseMap<Use *, std::pair<unsigned, unsigned>, 4> PHIOrSelectOpMap; + + /// \brief A utility routine called from the constructor. + /// + /// This does what it says on the tin. It is the key of the alloca partition + /// splitting and merging. After it is called we have the desired disjoint + /// collection of partitions. + void splitAndMergePartitions(); }; } @@ -327,10 +489,6 @@ class AllocaPartitioning::PartitionBuilder AllocaPartitioning &P; SmallDenseMap<Instruction *, unsigned> MemTransferPartitionMap; - SmallDenseMap<Instruction *, uint64_t> PHIOrSelectSizes; - - /// \brief Set to de-duplicate dead instructions found in the use walk. - SmallPtrSet<Instruction *, 4> VisitedDeadInsts; public: PartitionBuilder(const DataLayout &DL, AllocaInst &AI, AllocaPartitioning &P) @@ -339,11 +497,6 @@ public: P(P) {} private: - void markAsDead(Instruction &I) { - if (VisitedDeadInsts.insert(&I)) - P.DeadUsers.push_back(&I); - } - void insertUse(Instruction &I, const APInt &Offset, uint64_t Size, bool IsSplittable = false) { // Completely skip uses which have a zero size or start either before or @@ -354,7 +507,7 @@ private: << AllocSize << " byte alloca:\n" << " alloca: " << P.AI << "\n" << " use: " << I << "\n"); - return markAsDead(I); + return; } uint64_t BeginOffset = Offset.getZExtValue(); @@ -375,21 +528,8 @@ private: EndOffset = AllocSize; } - P.Partitions.push_back(Partition(BeginOffset, EndOffset, U, IsSplittable)); - } - - void visitBitCastInst(BitCastInst &BC) { - if (BC.use_empty()) - return markAsDead(BC); - - return Base::visitBitCastInst(BC); - } - - void visitGetElementPtrInst(GetElementPtrInst &GEPI) { - if (GEPI.use_empty()) - return markAsDead(GEPI); - - return Base::visitGetElementPtrInst(GEPI); + Partition New(BeginOffset, EndOffset, IsSplittable); + P.Partitions.push_back(New); } void handleLoadOrStore(Type *Ty, Instruction &I, const APInt &Offset, @@ -442,7 +582,7 @@ private: << " byte alloca:\n" << " alloca: " << P.AI << "\n" << " use: " << SI << "\n"); - return markAsDead(SI); + return; } assert((!SI.isSimple() || ValOp->getType()->isSingleValueType()) && @@ -457,7 +597,7 @@ private: if ((Length && Length->getValue() == 0) || (IsOffsetKnown && !Offset.isNegative() && Offset.uge(AllocSize))) // Zero-length mem transfer intrinsics can be ignored entirely. - return markAsDead(II); + return; if (!IsOffsetKnown) return PI.setAborted(&II); @@ -473,7 +613,7 @@ private: if ((Length && Length->getValue() == 0) || (IsOffsetKnown && !Offset.isNegative() && Offset.uge(AllocSize))) // Zero-length mem transfer intrinsics can be ignored entirely. - return markAsDead(II); + return; if (!IsOffsetKnown) return PI.setAborted(&II); @@ -482,44 +622,63 @@ private: uint64_t Size = Length ? Length->getLimitedValue() : AllocSize - RawOffset; - // Check for the special case where the same exact value is used for both - // source and dest. - if (*U == II.getRawDest() && *U == II.getRawSource()) { - // For non-volatile transfers this is a no-op. - if (!II.isVolatile()) - return markAsDead(II); + MemTransferOffsets &Offsets = P.MemTransferInstData[&II]; - return insertUse(II, Offset, Size, /*IsSplittable=*/false);; + // Only intrinsics with a constant length can be split. + Offsets.IsSplittable = Length; + + if (*U == II.getRawDest()) { + Offsets.DestBegin = RawOffset; + Offsets.DestEnd = RawOffset + Size; + } + if (*U == II.getRawSource()) { + Offsets.SourceBegin = RawOffset; + Offsets.SourceEnd = RawOffset + Size; } - // If we have seen both source and destination for a mem transfer, then - // they both point to the same alloca. - bool Inserted; - SmallDenseMap<Instruction *, unsigned>::iterator MTPI; - llvm::tie(MTPI, Inserted) = - MemTransferPartitionMap.insert(std::make_pair(&II, P.Partitions.size())); - unsigned PrevIdx = MTPI->second; - if (!Inserted) { - Partition &PrevP = P.Partitions[PrevIdx]; + // If we have set up end offsets for both the source and the destination, + // we have found both sides of this transfer pointing at the same alloca. + bool SeenBothEnds = Offsets.SourceEnd && Offsets.DestEnd; + if (SeenBothEnds && II.getRawDest() != II.getRawSource()) { + unsigned PrevIdx = MemTransferPartitionMap[&II]; // Check if the begin offsets match and this is a non-volatile transfer. // In that case, we can completely elide the transfer. - if (!II.isVolatile() && PrevP.beginOffset() == RawOffset) { - PrevP.kill(); - return markAsDead(II); + if (!II.isVolatile() && Offsets.SourceBegin == Offsets.DestBegin) { + P.Partitions[PrevIdx].kill(); + return; } // Otherwise we have an offset transfer within the same alloca. We can't // split those. - PrevP.makeUnsplittable(); + P.Partitions[PrevIdx].IsSplittable = Offsets.IsSplittable = false; + } else if (SeenBothEnds) { + // Handle the case where this exact use provides both ends of the + // operation. + assert(II.getRawDest() == II.getRawSource()); + + // For non-volatile transfers this is a no-op. + if (!II.isVolatile()) + return; + + // Otherwise just suppress splitting. + Offsets.IsSplittable = false; } - // Insert the use now that we've fixed up the splittable nature. - insertUse(II, Offset, Size, /*IsSplittable=*/Inserted && Length); - // Check that we ended up with a valid index in the map. - assert(P.Partitions[PrevIdx].getUse()->getUser() == &II && - "Map index doesn't point back to a partition with this user."); + // Insert the use now that we've fixed up the splittable nature. + insertUse(II, Offset, Size, Offsets.IsSplittable); + + // Setup the mapping from intrinsic to partition of we've not seen both + // ends of this transfer. + if (!SeenBothEnds) { + unsigned NewIdx = P.Partitions.size() - 1; + bool Inserted + = MemTransferPartitionMap.insert(std::make_pair(&II, NewIdx)).second; + assert(Inserted && + "Already have intrinsic in map but haven't seen both ends"); + (void)Inserted; + } } // Disable SRoA for any intrinsics except for lifetime invariants. @@ -588,45 +747,33 @@ private: void visitPHINode(PHINode &PN) { if (PN.use_empty()) - return markAsDead(PN); + return; if (!IsOffsetKnown) return PI.setAborted(&PN); // See if we already have computed info on this node. - uint64_t &PHISize = PHIOrSelectSizes[&PN]; - if (!PHISize) { - // This is a new PHI node, check for an unsafe use of the PHI node. - if (Instruction *UnsafeI = hasUnsafePHIOrSelectUse(&PN, PHISize)) - return PI.setAborted(UnsafeI); - } - - // For PHI and select operands outside the alloca, we can't nuke the entire - // phi or select -- the other side might still be relevant, so we special - // case them here and use a separate structure to track the operands - // themselves which should be replaced with undef. - // FIXME: This should instead be escaped in the event we're instrumenting - // for address sanitization. - if ((Offset.isNegative() && (-Offset).uge(PHISize)) || - (!Offset.isNegative() && Offset.uge(AllocSize))) { - P.DeadOperands.push_back(U); + std::pair<uint64_t, bool> &PHIInfo = P.PHIOrSelectSizes[&PN]; + if (PHIInfo.first) { + PHIInfo.second = true; + insertUse(PN, Offset, PHIInfo.first); return; } - insertUse(PN, Offset, PHISize); + // Check for an unsafe use of the PHI node. + if (Instruction *UnsafeI = hasUnsafePHIOrSelectUse(&PN, PHIInfo.first)) + return PI.setAborted(UnsafeI); + + insertUse(PN, Offset, PHIInfo.first); } void visitSelectInst(SelectInst &SI) { if (SI.use_empty()) - return markAsDead(SI); + return; if (Value *Result = foldSelectInst(SI)) { if (Result == *U) // If the result of the constant fold will be the pointer, recurse // through the select as if we had RAUW'ed it. enqueueUsers(SI); - else - // Otherwise the operand to the select is dead, and we can replace it - // with undef. - P.DeadOperands.push_back(U); return; } @@ -634,38 +781,316 @@ private: return PI.setAborted(&SI); // See if we already have computed info on this node. - uint64_t &SelectSize = PHIOrSelectSizes[&SI]; - if (!SelectSize) { - // This is a new Select, check for an unsafe use of it. - if (Instruction *UnsafeI = hasUnsafePHIOrSelectUse(&SI, SelectSize)) - return PI.setAborted(UnsafeI); + std::pair<uint64_t, bool> &SelectInfo = P.PHIOrSelectSizes[&SI]; + if (SelectInfo.first) { + SelectInfo.second = true; + insertUse(SI, Offset, SelectInfo.first); + return; + } + + // Check for an unsafe use of the PHI node. + if (Instruction *UnsafeI = hasUnsafePHIOrSelectUse(&SI, SelectInfo.first)) + return PI.setAborted(UnsafeI); + + insertUse(SI, Offset, SelectInfo.first); + } + + /// \brief Disable SROA entirely if there are unhandled users of the alloca. + void visitInstruction(Instruction &I) { + PI.setAborted(&I); + } +}; + +/// \brief Use adder for the alloca partitioning. +/// +/// This class adds the uses of an alloca to all of the partitions which they +/// use. For splittable partitions, this can end up doing essentially a linear +/// walk of the partitions, but the number of steps remains bounded by the +/// total result instruction size: +/// - The number of partitions is a result of the number unsplittable +/// instructions using the alloca. +/// - The number of users of each partition is at worst the total number of +/// splittable instructions using the alloca. +/// Thus we will produce N * M instructions in the end, where N are the number +/// of unsplittable uses and M are the number of splittable. This visitor does +/// the exact same number of updates to the partitioning. +/// +/// In the more common case, this visitor will leverage the fact that the +/// partition space is pre-sorted, and do a logarithmic search for the +/// partition needed, making the total visit a classical ((N + M) * log(N)) +/// complexity operation. +class AllocaPartitioning::UseBuilder : public PtrUseVisitor<UseBuilder> { + friend class PtrUseVisitor<UseBuilder>; + friend class InstVisitor<UseBuilder>; + typedef PtrUseVisitor<UseBuilder> Base; + + const uint64_t AllocSize; + AllocaPartitioning &P; + + /// \brief Set to de-duplicate dead instructions found in the use walk. + SmallPtrSet<Instruction *, 4> VisitedDeadInsts; + +public: + UseBuilder(const DataLayout &TD, AllocaInst &AI, AllocaPartitioning &P) + : PtrUseVisitor<UseBuilder>(TD), + AllocSize(TD.getTypeAllocSize(AI.getAllocatedType())), + P(P) {} + +private: + void markAsDead(Instruction &I) { + if (VisitedDeadInsts.insert(&I)) + P.DeadUsers.push_back(&I); + } + + void insertUse(Instruction &User, const APInt &Offset, uint64_t Size) { + // If the use has a zero size or extends outside of the allocation, record + // it as a dead use for elimination later. + if (Size == 0 || Offset.isNegative() || Offset.uge(AllocSize)) + return markAsDead(User); + + uint64_t BeginOffset = Offset.getZExtValue(); + uint64_t EndOffset = BeginOffset + Size; + + // Clamp the end offset to the end of the allocation. Note that this is + // formulated to handle even the case where "BeginOffset + Size" overflows. + assert(AllocSize >= BeginOffset); // Established above. + if (Size > AllocSize - BeginOffset) + EndOffset = AllocSize; + + // NB: This only works if we have zero overlapping partitions. + iterator I = std::lower_bound(P.begin(), P.end(), BeginOffset); + if (I != P.begin() && llvm::prior(I)->EndOffset > BeginOffset) + I = llvm::prior(I); + iterator E = P.end(); + bool IsSplit = llvm::next(I) != E && llvm::next(I)->BeginOffset < EndOffset; + for (; I != E && I->BeginOffset < EndOffset; ++I) { + PartitionUse NewPU(std::max(I->BeginOffset, BeginOffset), + std::min(I->EndOffset, EndOffset), U, IsSplit); + P.use_push_back(I, NewPU); + if (isa<PHINode>(U->getUser()) || isa<SelectInst>(U->getUser())) + P.PHIOrSelectOpMap[U] + = std::make_pair(I - P.begin(), P.Uses[I - P.begin()].size() - 1); } + } + + void visitBitCastInst(BitCastInst &BC) { + if (BC.use_empty()) + return markAsDead(BC); + + return Base::visitBitCastInst(BC); + } + + void visitGetElementPtrInst(GetElementPtrInst &GEPI) { + if (GEPI.use_empty()) + return markAsDead(GEPI); + + return Base::visitGetElementPtrInst(GEPI); + } + + void visitLoadInst(LoadInst &LI) { + assert(IsOffsetKnown); + uint64_t Size = DL.getTypeStoreSize(LI.getType()); + insertUse(LI, Offset, Size); + } + + void visitStoreInst(StoreInst &SI) { + assert(IsOffsetKnown); + uint64_t Size = DL.getTypeStoreSize(SI.getOperand(0)->getType()); + + // If this memory access can be shown to *statically* extend outside the + // bounds of of the allocation, it's behavior is undefined, so simply + // ignore it. Note that this is more strict than the generic clamping + // behavior of insertUse. + if (Offset.isNegative() || Size > AllocSize || + Offset.ugt(AllocSize - Size)) + return markAsDead(SI); + + insertUse(SI, Offset, Size); + } + + void visitMemSetInst(MemSetInst &II) { + ConstantInt *Length = dyn_cast<ConstantInt>(II.getLength()); + if ((Length && Length->getValue() == 0) || + (IsOffsetKnown && !Offset.isNegative() && Offset.uge(AllocSize))) + return markAsDead(II); + + assert(IsOffsetKnown); + insertUse(II, Offset, Length ? Length->getLimitedValue() + : AllocSize - Offset.getLimitedValue()); + } + + void visitMemTransferInst(MemTransferInst &II) { + ConstantInt *Length = dyn_cast<ConstantInt>(II.getLength()); + if ((Length && Length->getValue() == 0) || + (IsOffsetKnown && !Offset.isNegative() && Offset.uge(AllocSize))) + return markAsDead(II); + + assert(IsOffsetKnown); + uint64_t Size = Length ? Length->getLimitedValue() + : AllocSize - Offset.getLimitedValue(); + + const MemTransferOffsets &Offsets = P.MemTransferInstData[&II]; + if (!II.isVolatile() && Offsets.DestEnd && Offsets.SourceEnd && + Offsets.DestBegin == Offsets.SourceBegin) + return markAsDead(II); // Skip identity transfers without side-effects. + + insertUse(II, Offset, Size); + } + + void visitIntrinsicInst(IntrinsicInst &II) { + assert(IsOffsetKnown); + assert(II.getIntrinsicID() == Intrinsic::lifetime_start || + II.getIntrinsicID() == Intrinsic::lifetime_end); + + ConstantInt *Length = cast<ConstantInt>(II.getArgOperand(0)); + insertUse(II, Offset, std::min(Length->getLimitedValue(), + AllocSize - Offset.getLimitedValue())); + } + + void insertPHIOrSelect(Instruction &User, const APInt &Offset) { + uint64_t Size = P.PHIOrSelectSizes.lookup(&User).first; // For PHI and select operands outside the alloca, we can't nuke the entire // phi or select -- the other side might still be relevant, so we special // case them here and use a separate structure to track the operands // themselves which should be replaced with undef. - // FIXME: This should instead be escaped in the event we're instrumenting - // for address sanitization. - if ((Offset.isNegative() && Offset.uge(SelectSize)) || + if ((Offset.isNegative() && Offset.uge(Size)) || (!Offset.isNegative() && Offset.uge(AllocSize))) { P.DeadOperands.push_back(U); return; } - insertUse(SI, Offset, SelectSize); + insertUse(User, Offset, Size); } - /// \brief Disable SROA entirely if there are unhandled users of the alloca. + void visitPHINode(PHINode &PN) { + if (PN.use_empty()) + return markAsDead(PN); + + assert(IsOffsetKnown); + insertPHIOrSelect(PN, Offset); + } + + void visitSelectInst(SelectInst &SI) { + if (SI.use_empty()) + return markAsDead(SI); + + if (Value *Result = foldSelectInst(SI)) { + if (Result == *U) + // If the result of the constant fold will be the pointer, recurse + // through the select as if we had RAUW'ed it. + enqueueUsers(SI); + else + // Otherwise the operand to the select is dead, and we can replace it + // with undef. + P.DeadOperands.push_back(U); + + return; + } + + assert(IsOffsetKnown); + insertPHIOrSelect(SI, Offset); + } + + /// \brief Unreachable, we've already visited the alloca once. void visitInstruction(Instruction &I) { - PI.setAborted(&I); + llvm_unreachable("Unhandled instruction in use builder."); } }; -namespace { -struct IsPartitionDead { - bool operator()(const Partition &P) { return P.isDead(); } -}; +void AllocaPartitioning::splitAndMergePartitions() { + size_t NumDeadPartitions = 0; + + // Track the range of splittable partitions that we pass when accumulating + // overlapping unsplittable partitions. + uint64_t SplitEndOffset = 0ull; + + Partition New(0ull, 0ull, false); + + for (unsigned i = 0, j = i, e = Partitions.size(); i != e; i = j) { + ++j; + + if (!Partitions[i].IsSplittable || New.BeginOffset == New.EndOffset) { + assert(New.BeginOffset == New.EndOffset); + New = Partitions[i]; + } else { + assert(New.IsSplittable); + New.EndOffset = std::max(New.EndOffset, Partitions[i].EndOffset); + } + assert(New.BeginOffset != New.EndOffset); + + // Scan the overlapping partitions. + while (j != e && New.EndOffset > Partitions[j].BeginOffset) { + // If the new partition we are forming is splittable, stop at the first + // unsplittable partition. + if (New.IsSplittable && !Partitions[j].IsSplittable) + break; + + // Grow the new partition to include any equally splittable range. 'j' is + // always equally splittable when New is splittable, but when New is not + // splittable, we may subsume some (or part of some) splitable partition + // without growing the new one. + if (New.IsSplittable == Partitions[j].IsSplittable) { + New.EndOffset = std::max(New.EndOffset, Partitions[j].EndOffset); + } else { + assert(!New.IsSplittable); + assert(Partitions[j].IsSplittable); + SplitEndOffset = std::max(SplitEndOffset, Partitions[j].EndOffset); + } + + Partitions[j].kill(); + ++NumDeadPartitions; + ++j; + } + + // If the new partition is splittable, chop off the end as soon as the + // unsplittable subsequent partition starts and ensure we eventually cover + // the splittable area. + if (j != e && New.IsSplittable) { + SplitEndOffset = std::max(SplitEndOffset, New.EndOffset); + New.EndOffset = std::min(New.EndOffset, Partitions[j].BeginOffset); + } + + // Add the new partition if it differs from the original one and is + // non-empty. We can end up with an empty partition here if it was + // splittable but there is an unsplittable one that starts at the same + // offset. + if (New != Partitions[i]) { + if (New.BeginOffset != New.EndOffset) + Partitions.push_back(New); + // Mark the old one for removal. + Partitions[i].kill(); + ++NumDeadPartitions; + } + + New.BeginOffset = New.EndOffset; + if (!New.IsSplittable) { + New.EndOffset = std::max(New.EndOffset, SplitEndOffset); + if (j != e && !Partitions[j].IsSplittable) + New.EndOffset = std::min(New.EndOffset, Partitions[j].BeginOffset); + New.IsSplittable = true; + // If there is a trailing splittable partition which won't be fused into + // the next splittable partition go ahead and add it onto the partitions + // list. + if (New.BeginOffset < New.EndOffset && + (j == e || !Partitions[j].IsSplittable || + New.EndOffset < Partitions[j].BeginOffset)) { + Partitions.push_back(New); + New.BeginOffset = New.EndOffset = 0ull; + } + } + } + + // Re-sort the partitions now that they have been split and merged into + // disjoint set of partitions. Also remove any of the dead partitions we've + // replaced in the process. + std::sort(Partitions.begin(), Partitions.end()); + if (NumDeadPartitions) { + assert(Partitions.back().isDead()); + assert((ptrdiff_t)NumDeadPartitions == + std::count(Partitions.begin(), Partitions.end(), Partitions.back())); + } + Partitions.erase(Partitions.end() - NumDeadPartitions, Partitions.end()); } AllocaPartitioning::AllocaPartitioning(const DataLayout &TD, AllocaInst &AI) @@ -689,37 +1114,122 @@ AllocaPartitioning::AllocaPartitioning(const DataLayout &TD, AllocaInst &AI) // and the sizes to be in descending order. std::sort(Partitions.begin(), Partitions.end()); - Partitions.erase( - std::remove_if(Partitions.begin(), Partitions.end(), IsPartitionDead()), - Partitions.end()); + // Remove any partitions from the back which are marked as dead. + while (!Partitions.empty() && Partitions.back().isDead()) + Partitions.pop_back(); + + if (Partitions.size() > 1) { + // Intersect splittability for all partitions with equal offsets and sizes. + // Then remove all but the first so that we have a sequence of non-equal but + // potentially overlapping partitions. + for (iterator I = Partitions.begin(), J = I, E = Partitions.end(); I != E; + I = J) { + ++J; + while (J != E && *I == *J) { + I->IsSplittable &= J->IsSplittable; + ++J; + } + } + Partitions.erase(std::unique(Partitions.begin(), Partitions.end()), + Partitions.end()); + + // Split splittable and merge unsplittable partitions into a disjoint set + // of partitions over the used space of the allocation. + splitAndMergePartitions(); + } // Record how many partitions we end up with. NumAllocaPartitions += Partitions.size(); MaxPartitionsPerAlloca = std::max<unsigned>(Partitions.size(), MaxPartitionsPerAlloca); - NumAllocaPartitionUses += Partitions.size(); - MaxPartitionUsesPerAlloca = - std::max<unsigned>(Partitions.size(), MaxPartitionUsesPerAlloca); + // Now build up the user lists for each of these disjoint partitions by + // re-walking the recursive users of the alloca. + Uses.resize(Partitions.size()); + UseBuilder UB(TD, AI, *this); + PtrI = UB.visitPtr(AI); + assert(!PtrI.isEscaped() && "Previously analyzed pointer now escapes!"); + assert(!PtrI.isAborted() && "Early aborted the visit of the pointer."); + + unsigned NumUses = 0; +#if !defined(NDEBUG) || defined(LLVM_ENABLE_STATS) + for (unsigned Idx = 0, Size = Uses.size(); Idx != Size; ++Idx) + NumUses += Uses[Idx].size(); +#endif + NumAllocaPartitionUses += NumUses; + MaxPartitionUsesPerAlloca = std::max<unsigned>(NumUses, MaxPartitionUsesPerAlloca); +} + +Type *AllocaPartitioning::getCommonType(iterator I) const { + Type *Ty = 0; + for (const_use_iterator UI = use_begin(I), UE = use_end(I); UI != UE; ++UI) { + Use *U = UI->getUse(); + if (!U) + continue; // Skip dead uses. + if (isa<IntrinsicInst>(*U->getUser())) + continue; + if (UI->BeginOffset != I->BeginOffset || UI->EndOffset != I->EndOffset) + continue; + + Type *UserTy = 0; + if (LoadInst *LI = dyn_cast<LoadInst>(U->getUser())) + UserTy = LI->getType(); + else if (StoreInst *SI = dyn_cast<StoreInst>(U->getUser())) + UserTy = SI->getValueOperand()->getType(); + else + return 0; // Bail if we have weird uses. + + if (IntegerType *ITy = dyn_cast<IntegerType>(UserTy)) { + // If the type is larger than the partition, skip it. We only encounter + // this for split integer operations where we want to use the type of the + // entity causing the split. + if (ITy->getBitWidth() > (I->EndOffset - I->BeginOffset)*8) + continue; + + // If we have found an integer type use covering the alloca, use that + // regardless of the other types, as integers are often used for a "bucket + // of bits" type. + return ITy; + } + + if (Ty && Ty != UserTy) + return 0; + + Ty = UserTy; + } + return Ty; } #if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP) void AllocaPartitioning::print(raw_ostream &OS, const_iterator I, StringRef Indent) const { - printPartition(OS, I, Indent); - printUse(OS, I, Indent); -} - -void AllocaPartitioning::printPartition(raw_ostream &OS, const_iterator I, - StringRef Indent) const { - OS << Indent << "[" << I->beginOffset() << "," << I->endOffset() << ")" - << " partition #" << (I - begin()) - << (I->isSplittable() ? " (splittable)" : "") << "\n"; + OS << Indent << "partition #" << (I - begin()) + << " [" << I->BeginOffset << "," << I->EndOffset << ")" + << (I->IsSplittable ? " (splittable)" : "") + << (Uses[I - begin()].empty() ? " (zero uses)" : "") + << "\n"; } -void AllocaPartitioning::printUse(raw_ostream &OS, const_iterator I, - StringRef Indent) const { - OS << Indent << " used by: " << *I->getUse()->getUser() << "\n"; +void AllocaPartitioning::printUsers(raw_ostream &OS, const_iterator I, + StringRef Indent) const { + for (const_use_iterator UI = use_begin(I), UE = use_end(I); UI != UE; ++UI) { + if (!UI->getUse()) + continue; // Skip dead uses. + OS << Indent << " [" << UI->BeginOffset << "," << UI->EndOffset << ") " + << "used by: " << *UI->getUse()->getUser() << "\n"; + if (MemTransferInst *II = + dyn_cast<MemTransferInst>(UI->getUse()->getUser())) { + const MemTransferOffsets &MTO = MemTransferInstData.lookup(II); + bool IsDest; + if (!MTO.IsSplittable) + IsDest = UI->BeginOffset == MTO.DestBegin; + else + IsDest = MTO.DestBegin != 0u; + OS << Indent << " (original " << (IsDest ? "dest" : "source") << ": " + << "[" << (IsDest ? MTO.DestBegin : MTO.SourceBegin) + << "," << (IsDest ? MTO.DestEnd : MTO.SourceEnd) << ")\n"; + } + } } void AllocaPartitioning::print(raw_ostream &OS) const { @@ -731,8 +1241,10 @@ void AllocaPartitioning::print(raw_ostream &OS) const { } OS << "Partitioning of alloca: " << AI << "\n"; - for (const_iterator I = begin(), E = end(); I != E; ++I) + for (const_iterator I = begin(), E = end(); I != E; ++I) { print(OS, I); + printUsers(OS, I); + } } void AllocaPartitioning::dump(const_iterator I) const { print(dbgs(), I); } @@ -740,6 +1252,7 @@ void AllocaPartitioning::dump() const { print(dbgs()); } #endif // !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP) + namespace { /// \brief Implementation of LoadAndStorePromoter for promoting allocas. /// @@ -877,21 +1390,6 @@ class SROA : public FunctionPass { /// \brief A collection of alloca instructions we can directly promote. std::vector<AllocaInst *> PromotableAllocas; - /// \brief A worklist of PHIs to speculate prior to promoting allocas. - /// - /// All of these PHIs have been checked for the safety of speculation and by - /// being speculated will allow promoting allocas currently in the promotable - /// queue. - SetVector<PHINode *, SmallVector<PHINode *, 2> > SpeculatablePHIs; - - /// \brief A worklist of select instructions to speculate prior to promoting - /// allocas. - /// - /// All of these select instructions have been checked for the safety of - /// speculation and by being speculated will allow promoting allocas - /// currently in the promotable queue. - SetVector<SelectInst *, SmallVector<SelectInst *, 2> > SpeculatableSelects; - public: SROA(bool RequiresDomTree = true) : FunctionPass(ID), RequiresDomTree(RequiresDomTree), @@ -909,11 +1407,9 @@ private: friend class AllocaPartitionRewriter; friend class AllocaPartitionVectorRewriter; - bool rewritePartitions(AllocaInst &AI, AllocaPartitioning &P, - AllocaPartitioning::iterator B, - AllocaPartitioning::iterator E, - int64_t BeginOffset, int64_t EndOffset, - ArrayRef<AllocaPartitioning::iterator> SplitUses); + bool rewriteAllocaPartition(AllocaInst &AI, + AllocaPartitioning &P, + AllocaPartitioning::iterator PI); bool splitAlloca(AllocaInst &AI, AllocaPartitioning &P); bool runOnAlloca(AllocaInst &AI); void deleteDeadInstructions(SmallPtrSet<AllocaInst *, 4> &DeletedAllocas); @@ -933,247 +1429,286 @@ INITIALIZE_PASS_DEPENDENCY(DominatorTree) INITIALIZE_PASS_END(SROA, "sroa", "Scalar Replacement Of Aggregates", false, false) -/// Walk a range of a partitioning looking for a common type to cover this -/// sequence of partition uses. -static Type *findCommonType(AllocaPartitioning::const_iterator B, - AllocaPartitioning::const_iterator E, - uint64_t EndOffset) { - Type *Ty = 0; - for (AllocaPartitioning::const_iterator I = B; I != E; ++I) { - Use *U = I->getUse(); - if (isa<IntrinsicInst>(*U->getUser())) - continue; - if (I->beginOffset() != B->beginOffset() || I->endOffset() != EndOffset) - continue; +namespace { +/// \brief Visitor to speculate PHIs and Selects where possible. +class PHIOrSelectSpeculator : public InstVisitor<PHIOrSelectSpeculator> { + // Befriend the base class so it can delegate to private visit methods. + friend class llvm::InstVisitor<PHIOrSelectSpeculator>; - Type *UserTy = 0; - if (LoadInst *LI = dyn_cast<LoadInst>(U->getUser())) - UserTy = LI->getType(); - else if (StoreInst *SI = dyn_cast<StoreInst>(U->getUser())) - UserTy = SI->getValueOperand()->getType(); - else - return 0; // Bail if we have weird uses. + const DataLayout &TD; + AllocaPartitioning &P; + SROA &Pass; - if (IntegerType *ITy = dyn_cast<IntegerType>(UserTy)) { - // If the type is larger than the partition, skip it. We only encounter - // this for split integer operations where we want to use the type of - // the - // entity causing the split. - if (ITy->getBitWidth() / 8 > (EndOffset - B->beginOffset())) - continue; +public: + PHIOrSelectSpeculator(const DataLayout &TD, AllocaPartitioning &P, SROA &Pass) + : TD(TD), P(P), Pass(Pass) {} + + /// \brief Visit the users of an alloca partition and rewrite them. + void visitUsers(AllocaPartitioning::const_iterator PI) { + // Note that we need to use an index here as the underlying vector of uses + // may be grown during speculation. However, we never need to re-visit the + // new uses, and so we can use the initial size bound. + for (unsigned Idx = 0, Size = P.use_size(PI); Idx != Size; ++Idx) { + const PartitionUse &PU = P.getUse(PI, Idx); + if (!PU.getUse()) + continue; // Skip dead use. + + visit(cast<Instruction>(PU.getUse()->getUser())); + } + } - // If we have found an integer type use covering the alloca, use that - // regardless of the other types, as integers are often used for a - // "bucket - // of bits" type. - return ITy; +private: + // By default, skip this instruction. + void visitInstruction(Instruction &I) {} + + /// PHI instructions that use an alloca and are subsequently loaded can be + /// rewritten to load both input pointers in the pred blocks and then PHI the + /// results, allowing the load of the alloca to be promoted. + /// From this: + /// %P2 = phi [i32* %Alloca, i32* %Other] + /// %V = load i32* %P2 + /// to: + /// %V1 = load i32* %Alloca -> will be mem2reg'd + /// ... + /// %V2 = load i32* %Other + /// ... + /// %V = phi [i32 %V1, i32 %V2] + /// + /// We can do this to a select if its only uses are loads and if the operands + /// to the select can be loaded unconditionally. + /// + /// FIXME: This should be hoisted into a generic utility, likely in + /// Transforms/Util/Local.h + bool isSafePHIToSpeculate(PHINode &PN, SmallVectorImpl<LoadInst *> &Loads) { + // For now, we can only do this promotion if the load is in the same block + // as the PHI, and if there are no stores between the phi and load. + // TODO: Allow recursive phi users. + // TODO: Allow stores. + BasicBlock *BB = PN.getParent(); + unsigned MaxAlign = 0; + for (Value::use_iterator UI = PN.use_begin(), UE = PN.use_end(); + UI != UE; ++UI) { + LoadInst *LI = dyn_cast<LoadInst>(*UI); + if (LI == 0 || !LI->isSimple()) return false; + + // For now we only allow loads in the same block as the PHI. This is + // a common case that happens when instcombine merges two loads through + // a PHI. + if (LI->getParent() != BB) return false; + + // Ensure that there are no instructions between the PHI and the load that + // could store. + for (BasicBlock::iterator BBI = &PN; &*BBI != LI; ++BBI) + if (BBI->mayWriteToMemory()) + return false; + + MaxAlign = std::max(MaxAlign, LI->getAlignment()); + Loads.push_back(LI); } - if (Ty && Ty != UserTy) - return 0; + // We can only transform this if it is safe to push the loads into the + // predecessor blocks. The only thing to watch out for is that we can't put + // a possibly trapping load in the predecessor if it is a critical edge. + for (unsigned Idx = 0, Num = PN.getNumIncomingValues(); Idx != Num; ++Idx) { + TerminatorInst *TI = PN.getIncomingBlock(Idx)->getTerminator(); + Value *InVal = PN.getIncomingValue(Idx); + + // If the value is produced by the terminator of the predecessor (an + // invoke) or it has side-effects, there is no valid place to put a load + // in the predecessor. + if (TI == InVal || TI->mayHaveSideEffects()) + return false; - Ty = UserTy; - } - return Ty; -} + // If the predecessor has a single successor, then the edge isn't + // critical. + if (TI->getNumSuccessors() == 1) + continue; -/// PHI instructions that use an alloca and are subsequently loaded can be -/// rewritten to load both input pointers in the pred blocks and then PHI the -/// results, allowing the load of the alloca to be promoted. -/// From this: -/// %P2 = phi [i32* %Alloca, i32* %Other] -/// %V = load i32* %P2 -/// to: -/// %V1 = load i32* %Alloca -> will be mem2reg'd -/// ... -/// %V2 = load i32* %Other -/// ... -/// %V = phi [i32 %V1, i32 %V2] -/// -/// We can do this to a select if its only uses are loads and if the operands -/// to the select can be loaded unconditionally. -/// -/// FIXME: This should be hoisted into a generic utility, likely in -/// Transforms/Util/Local.h -static bool isSafePHIToSpeculate(PHINode &PN, - const DataLayout *TD = 0) { - // For now, we can only do this promotion if the load is in the same block - // as the PHI, and if there are no stores between the phi and load. - // TODO: Allow recursive phi users. - // TODO: Allow stores. - BasicBlock *BB = PN.getParent(); - unsigned MaxAlign = 0; - bool HaveLoad = false; - for (Value::use_iterator UI = PN.use_begin(), UE = PN.use_end(); UI != UE; - ++UI) { - LoadInst *LI = dyn_cast<LoadInst>(*UI); - if (LI == 0 || !LI->isSimple()) - return false; + // If this pointer is always safe to load, or if we can prove that there + // is already a load in the block, then we can move the load to the pred + // block. + if (InVal->isDereferenceablePointer() || + isSafeToLoadUnconditionally(InVal, TI, MaxAlign, &TD)) + continue; - // For now we only allow loads in the same block as the PHI. This is - // a common case that happens when instcombine merges two loads through - // a PHI. - if (LI->getParent() != BB) return false; + } - // Ensure that there are no instructions between the PHI and the load that - // could store. - for (BasicBlock::iterator BBI = &PN; &*BBI != LI; ++BBI) - if (BBI->mayWriteToMemory()) - return false; - - MaxAlign = std::max(MaxAlign, LI->getAlignment()); - HaveLoad = true; + return true; } - if (!HaveLoad) - return false; + void visitPHINode(PHINode &PN) { + DEBUG(dbgs() << " original: " << PN << "\n"); - // We can only transform this if it is safe to push the loads into the - // predecessor blocks. The only thing to watch out for is that we can't put - // a possibly trapping load in the predecessor if it is a critical edge. - for (unsigned Idx = 0, Num = PN.getNumIncomingValues(); Idx != Num; ++Idx) { - TerminatorInst *TI = PN.getIncomingBlock(Idx)->getTerminator(); - Value *InVal = PN.getIncomingValue(Idx); - - // If the value is produced by the terminator of the predecessor (an - // invoke) or it has side-effects, there is no valid place to put a load - // in the predecessor. - if (TI == InVal || TI->mayHaveSideEffects()) - return false; + SmallVector<LoadInst *, 4> Loads; + if (!isSafePHIToSpeculate(PN, Loads)) + return; - // If the predecessor has a single successor, then the edge isn't - // critical. - if (TI->getNumSuccessors() == 1) - continue; + assert(!Loads.empty()); - // If this pointer is always safe to load, or if we can prove that there - // is already a load in the block, then we can move the load to the pred - // block. - if (InVal->isDereferenceablePointer() || - isSafeToLoadUnconditionally(InVal, TI, MaxAlign, TD)) - continue; + Type *LoadTy = cast<PointerType>(PN.getType())->getElementType(); + IRBuilderTy PHIBuilder(&PN); + PHINode *NewPN = PHIBuilder.CreatePHI(LoadTy, PN.getNumIncomingValues(), + PN.getName() + ".sroa.speculated"); - return false; - } + // Get the TBAA tag and alignment to use from one of the loads. It doesn't + // matter which one we get and if any differ. + LoadInst *SomeLoad = cast<LoadInst>(Loads.back()); + MDNode *TBAATag = SomeLoad->getMetadata(LLVMContext::MD_tbaa); + unsigned Align = SomeLoad->getAlignment(); - return true; -} + // Rewrite all loads of the PN to use the new PHI. + do { + LoadInst *LI = Loads.pop_back_val(); + LI->replaceAllUsesWith(NewPN); + Pass.DeadInsts.insert(LI); + } while (!Loads.empty()); + + // Inject loads into all of the pred blocks. + for (unsigned Idx = 0, Num = PN.getNumIncomingValues(); Idx != Num; ++Idx) { + BasicBlock *Pred = PN.getIncomingBlock(Idx); + TerminatorInst *TI = Pred->getTerminator(); + Use *InUse = &PN.getOperandUse(PN.getOperandNumForIncomingValue(Idx)); + Value *InVal = PN.getIncomingValue(Idx); + IRBuilderTy PredBuilder(TI); + + LoadInst *Load + = PredBuilder.CreateLoad(InVal, (PN.getName() + ".sroa.speculate.load." + + Pred->getName())); + ++NumLoadsSpeculated; + Load->setAlignment(Align); + if (TBAATag) + Load->setMetadata(LLVMContext::MD_tbaa, TBAATag); + NewPN->addIncoming(Load, Pred); + + Instruction *Ptr = dyn_cast<Instruction>(InVal); + if (!Ptr) + // No uses to rewrite. + continue; -static void speculatePHINodeLoads(PHINode &PN) { - DEBUG(dbgs() << " original: " << PN << "\n"); - - Type *LoadTy = cast<PointerType>(PN.getType())->getElementType(); - IRBuilderTy PHIBuilder(&PN); - PHINode *NewPN = PHIBuilder.CreatePHI(LoadTy, PN.getNumIncomingValues(), - PN.getName() + ".sroa.speculated"); - - // Get the TBAA tag and alignment to use from one of the loads. It doesn't - // matter which one we get and if any differ. - LoadInst *SomeLoad = cast<LoadInst>(*PN.use_begin()); - MDNode *TBAATag = SomeLoad->getMetadata(LLVMContext::MD_tbaa); - unsigned Align = SomeLoad->getAlignment(); - - // Rewrite all loads of the PN to use the new PHI. - while (!PN.use_empty()) { - LoadInst *LI = cast<LoadInst>(*PN.use_begin()); - LI->replaceAllUsesWith(NewPN); - LI->eraseFromParent(); - } - - // Inject loads into all of the pred blocks. - for (unsigned Idx = 0, Num = PN.getNumIncomingValues(); Idx != Num; ++Idx) { - BasicBlock *Pred = PN.getIncomingBlock(Idx); - TerminatorInst *TI = Pred->getTerminator(); - Value *InVal = PN.getIncomingValue(Idx); - IRBuilderTy PredBuilder(TI); - - LoadInst *Load = PredBuilder.CreateLoad( - InVal, (PN.getName() + ".sroa.speculate.load." + Pred->getName())); - ++NumLoadsSpeculated; - Load->setAlignment(Align); - if (TBAATag) - Load->setMetadata(LLVMContext::MD_tbaa, TBAATag); - NewPN->addIncoming(Load, Pred); - } - - DEBUG(dbgs() << " speculated to: " << *NewPN << "\n"); - PN.eraseFromParent(); -} + // Try to lookup and rewrite any partition uses corresponding to this phi + // input. + AllocaPartitioning::iterator PI + = P.findPartitionForPHIOrSelectOperand(InUse); + if (PI == P.end()) + continue; -/// Select instructions that use an alloca and are subsequently loaded can be -/// rewritten to load both input pointers and then select between the result, -/// allowing the load of the alloca to be promoted. -/// From this: -/// %P2 = select i1 %cond, i32* %Alloca, i32* %Other -/// %V = load i32* %P2 -/// to: -/// %V1 = load i32* %Alloca -> will be mem2reg'd -/// %V2 = load i32* %Other -/// %V = select i1 %cond, i32 %V1, i32 %V2 -/// -/// We can do this to a select if its only uses are loads and if the operand -/// to the select can be loaded unconditionally. -static bool isSafeSelectToSpeculate(SelectInst &SI, const DataLayout *TD = 0) { - Value *TValue = SI.getTrueValue(); - Value *FValue = SI.getFalseValue(); - bool TDerefable = TValue->isDereferenceablePointer(); - bool FDerefable = FValue->isDereferenceablePointer(); - - for (Value::use_iterator UI = SI.use_begin(), UE = SI.use_end(); UI != UE; - ++UI) { - LoadInst *LI = dyn_cast<LoadInst>(*UI); - if (LI == 0 || !LI->isSimple()) - return false; + // Replace the Use in the PartitionUse for this operand with the Use + // inside the load. + AllocaPartitioning::use_iterator UI + = P.findPartitionUseForPHIOrSelectOperand(InUse); + assert(isa<PHINode>(*UI->getUse()->getUser())); + UI->setUse(&Load->getOperandUse(Load->getPointerOperandIndex())); + } + DEBUG(dbgs() << " speculated to: " << *NewPN << "\n"); + } + + /// Select instructions that use an alloca and are subsequently loaded can be + /// rewritten to load both input pointers and then select between the result, + /// allowing the load of the alloca to be promoted. + /// From this: + /// %P2 = select i1 %cond, i32* %Alloca, i32* %Other + /// %V = load i32* %P2 + /// to: + /// %V1 = load i32* %Alloca -> will be mem2reg'd + /// %V2 = load i32* %Other + /// %V = select i1 %cond, i32 %V1, i32 %V2 + /// + /// We can do this to a select if its only uses are loads and if the operand + /// to the select can be loaded unconditionally. + bool isSafeSelectToSpeculate(SelectInst &SI, + SmallVectorImpl<LoadInst *> &Loads) { + Value *TValue = SI.getTrueValue(); + Value *FValue = SI.getFalseValue(); + bool TDerefable = TValue->isDereferenceablePointer(); + bool FDerefable = FValue->isDereferenceablePointer(); + + for (Value::use_iterator UI = SI.use_begin(), UE = SI.use_end(); + UI != UE; ++UI) { + LoadInst *LI = dyn_cast<LoadInst>(*UI); + if (LI == 0 || !LI->isSimple()) return false; + + // Both operands to the select need to be dereferencable, either + // absolutely (e.g. allocas) or at this point because we can see other + // accesses to it. + if (!TDerefable && !isSafeToLoadUnconditionally(TValue, LI, + LI->getAlignment(), &TD)) + return false; + if (!FDerefable && !isSafeToLoadUnconditionally(FValue, LI, + LI->getAlignment(), &TD)) + return false; + Loads.push_back(LI); + } - // Both operands to the select need to be dereferencable, either - // absolutely (e.g. allocas) or at this point because we can see other - // accesses to it. - if (!TDerefable && - !isSafeToLoadUnconditionally(TValue, LI, LI->getAlignment(), TD)) - return false; - if (!FDerefable && - !isSafeToLoadUnconditionally(FValue, LI, LI->getAlignment(), TD)) - return false; + return true; } - return true; -} + void visitSelectInst(SelectInst &SI) { + DEBUG(dbgs() << " original: " << SI << "\n"); + + // If the select isn't safe to speculate, just use simple logic to emit it. + SmallVector<LoadInst *, 4> Loads; + if (!isSafeSelectToSpeculate(SI, Loads)) + return; -static void speculateSelectInstLoads(SelectInst &SI) { - DEBUG(dbgs() << " original: " << SI << "\n"); + IRBuilderTy IRB(&SI); + Use *Ops[2] = { &SI.getOperandUse(1), &SI.getOperandUse(2) }; + AllocaPartitioning::iterator PIs[2]; + PartitionUse PUs[2]; + for (unsigned i = 0, e = 2; i != e; ++i) { + PIs[i] = P.findPartitionForPHIOrSelectOperand(Ops[i]); + if (PIs[i] != P.end()) { + // If the pointer is within the partitioning, remove the select from + // its uses. We'll add in the new loads below. + AllocaPartitioning::use_iterator UI + = P.findPartitionUseForPHIOrSelectOperand(Ops[i]); + PUs[i] = *UI; + // Clear out the use here so that the offsets into the use list remain + // stable but this use is ignored when rewriting. + UI->setUse(0); + } + } - IRBuilderTy IRB(&SI); - Value *TV = SI.getTrueValue(); - Value *FV = SI.getFalseValue(); - // Replace the loads of the select with a select of two loads. - while (!SI.use_empty()) { - LoadInst *LI = cast<LoadInst>(*SI.use_begin()); - assert(LI->isSimple() && "We only speculate simple loads"); + Value *TV = SI.getTrueValue(); + Value *FV = SI.getFalseValue(); + // Replace the loads of the select with a select of two loads. + while (!Loads.empty()) { + LoadInst *LI = Loads.pop_back_val(); - IRB.SetInsertPoint(LI); - LoadInst *TL = + IRB.SetInsertPoint(LI); + LoadInst *TL = IRB.CreateLoad(TV, LI->getName() + ".sroa.speculate.load.true"); - LoadInst *FL = + LoadInst *FL = IRB.CreateLoad(FV, LI->getName() + ".sroa.speculate.load.false"); - NumLoadsSpeculated += 2; + NumLoadsSpeculated += 2; + + // Transfer alignment and TBAA info if present. + TL->setAlignment(LI->getAlignment()); + FL->setAlignment(LI->getAlignment()); + if (MDNode *Tag = LI->getMetadata(LLVMContext::MD_tbaa)) { + TL->setMetadata(LLVMContext::MD_tbaa, Tag); + FL->setMetadata(LLVMContext::MD_tbaa, Tag); + } - // Transfer alignment and TBAA info if present. - TL->setAlignment(LI->getAlignment()); - FL->setAlignment(LI->getAlignment()); - if (MDNode *Tag = LI->getMetadata(LLVMContext::MD_tbaa)) { - TL->setMetadata(LLVMContext::MD_tbaa, Tag); - FL->setMetadata(LLVMContext::MD_tbaa, Tag); - } + Value *V = IRB.CreateSelect(SI.getCondition(), TL, FL, + LI->getName() + ".sroa.speculated"); - Value *V = IRB.CreateSelect(SI.getCondition(), TL, FL, - LI->getName() + ".sroa.speculated"); + LoadInst *Loads[2] = { TL, FL }; + for (unsigned i = 0, e = 2; i != e; ++i) { + if (PIs[i] != P.end()) { + Use *LoadUse = &Loads[i]->getOperandUse(0); + assert(PUs[i].getUse()->get() == LoadUse->get()); + PUs[i].setUse(LoadUse); + P.use_push_back(PIs[i], PUs[i]); + } + } - DEBUG(dbgs() << " speculated to: " << *V << "\n"); - LI->replaceAllUsesWith(V); - LI->eraseFromParent(); + DEBUG(dbgs() << " speculated to: " << *V << "\n"); + LI->replaceAllUsesWith(V); + Pass.DeadInsts.insert(LI); + } } - SI.eraseFromParent(); +}; } /// \brief Build a GEP out of a base pointer and indices. @@ -1489,73 +2024,6 @@ static Value *convertValue(const DataLayout &DL, IRBuilderTy &IRB, Value *V, return IRB.CreateBitCast(V, Ty); } -/// \brief Test whether the given partition use can be promoted to a vector. -/// -/// This function is called to test each entry in a partioning which is slated -/// for a single partition. -static bool isVectorPromotionViableForPartitioning( - const DataLayout &TD, AllocaPartitioning &P, - uint64_t PartitionBeginOffset, uint64_t PartitionEndOffset, VectorType *Ty, - uint64_t ElementSize, AllocaPartitioning::const_iterator I) { - // First validate the partitioning offsets. - uint64_t BeginOffset = - std::max(I->beginOffset(), PartitionBeginOffset) - PartitionBeginOffset; - uint64_t BeginIndex = BeginOffset / ElementSize; - if (BeginIndex * ElementSize != BeginOffset || - BeginIndex >= Ty->getNumElements()) - return false; - uint64_t EndOffset = - std::min(I->endOffset(), PartitionEndOffset) - PartitionBeginOffset; - uint64_t EndIndex = EndOffset / ElementSize; - if (EndIndex * ElementSize != EndOffset || EndIndex > Ty->getNumElements()) - return false; - - assert(EndIndex > BeginIndex && "Empty vector!"); - uint64_t NumElements = EndIndex - BeginIndex; - Type *PartitionTy = - (NumElements == 1) ? Ty->getElementType() - : VectorType::get(Ty->getElementType(), NumElements); - - Type *SplitIntTy = - Type::getIntNTy(Ty->getContext(), NumElements * ElementSize * 8); - - Use *U = I->getUse(); - - if (MemIntrinsic *MI = dyn_cast<MemIntrinsic>(U->getUser())) { - if (MI->isVolatile()) - return false; - if (!I->isSplittable()) - return false; // Skip any unsplittable intrinsics. - } else if (U->get()->getType()->getPointerElementType()->isStructTy()) { - // Disable vector promotion when there are loads or stores of an FCA. - return false; - } else if (LoadInst *LI = dyn_cast<LoadInst>(U->getUser())) { - if (LI->isVolatile()) - return false; - Type *LTy = LI->getType(); - if (PartitionBeginOffset > I->beginOffset() || - PartitionEndOffset < I->endOffset()) { - assert(LTy->isIntegerTy()); - LTy = SplitIntTy; - } - if (!canConvertValue(TD, PartitionTy, LTy)) - return false; - } else if (StoreInst *SI = dyn_cast<StoreInst>(U->getUser())) { - if (SI->isVolatile()) - return false; - Type *STy = SI->getValueOperand()->getType(); - if (PartitionBeginOffset > I->beginOffset() || - PartitionEndOffset < I->endOffset()) { - assert(STy->isIntegerTy()); - STy = SplitIntTy; - } - if (!canConvertValue(TD, STy, PartitionTy)) - return false; - } - - return true; -} - /// \brief Test whether the given alloca partition can be promoted to a vector. /// /// This is a quick test to check whether we can rewrite a particular alloca @@ -1564,11 +2032,13 @@ static bool isVectorPromotionViableForPartitioning( /// SSA value. We only can ensure this for a limited set of operations, and we /// don't want to do the rewrites unless we are confident that the result will /// be promotable, so we have an early test here. -static bool isVectorPromotionViable( - const DataLayout &TD, Type *AllocaTy, AllocaPartitioning &P, - uint64_t PartitionBeginOffset, uint64_t PartitionEndOffset, - AllocaPartitioning::const_iterator I, AllocaPartitioning::const_iterator E, - ArrayRef<AllocaPartitioning::iterator> SplitUses) { +static bool isVectorPromotionViable(const DataLayout &TD, + Type *AllocaTy, + AllocaPartitioning &P, + uint64_t PartitionBeginOffset, + uint64_t PartitionEndOffset, + AllocaPartitioning::const_use_iterator I, + AllocaPartitioning::const_use_iterator E) { VectorType *Ty = dyn_cast<VectorType>(AllocaTy); if (!Ty) return false; @@ -1583,85 +2053,54 @@ static bool isVectorPromotionViable( "vector size not a multiple of element size?"); ElementSize /= 8; - for (; I != E; ++I) - if (!isVectorPromotionViableForPartitioning( - TD, P, PartitionBeginOffset, PartitionEndOffset, Ty, ElementSize, - I)) - return false; + for (; I != E; ++I) { + Use *U = I->getUse(); + if (!U) + continue; // Skip dead use. - for (ArrayRef<AllocaPartitioning::iterator>::const_iterator - SUI = SplitUses.begin(), - SUE = SplitUses.end(); - SUI != SUE; ++SUI) - if (!isVectorPromotionViableForPartitioning( - TD, P, PartitionBeginOffset, PartitionEndOffset, Ty, ElementSize, - *SUI)) + uint64_t BeginOffset = I->BeginOffset - PartitionBeginOffset; + uint64_t BeginIndex = BeginOffset / ElementSize; + if (BeginIndex * ElementSize != BeginOffset || + BeginIndex >= Ty->getNumElements()) + return false; + uint64_t EndOffset = I->EndOffset - PartitionBeginOffset; + uint64_t EndIndex = EndOffset / ElementSize; + if (EndIndex * ElementSize != EndOffset || + EndIndex > Ty->getNumElements()) return false; - return true; -} - -/// \brief Test whether a partitioning slice of an alloca is a valid set of -/// operations for integer widening. -/// -/// This implements the necessary checking for the \c isIntegerWideningViable -/// test below on a single partitioning slice of the alloca. -static bool isIntegerWideningViableForPartitioning( - const DataLayout &TD, Type *AllocaTy, uint64_t AllocBeginOffset, - uint64_t Size, AllocaPartitioning &P, AllocaPartitioning::const_iterator I, - bool &WholeAllocaOp) { - uint64_t RelBegin = I->beginOffset() - AllocBeginOffset; - uint64_t RelEnd = I->endOffset() - AllocBeginOffset; - - // We can't reasonably handle cases where the load or store extends past - // the end of the aloca's type and into its padding. - if (RelEnd > Size) - return false; - - Use *U = I->getUse(); + assert(EndIndex > BeginIndex && "Empty vector!"); + uint64_t NumElements = EndIndex - BeginIndex; + Type *PartitionTy + = (NumElements == 1) ? Ty->getElementType() + : VectorType::get(Ty->getElementType(), NumElements); - if (LoadInst *LI = dyn_cast<LoadInst>(U->getUser())) { - if (LI->isVolatile()) - return false; - if (RelBegin == 0 && RelEnd == Size) - WholeAllocaOp = true; - if (IntegerType *ITy = dyn_cast<IntegerType>(LI->getType())) { - if (ITy->getBitWidth() < TD.getTypeStoreSizeInBits(ITy)) + if (MemIntrinsic *MI = dyn_cast<MemIntrinsic>(U->getUser())) { + if (MI->isVolatile()) return false; - } else if (RelBegin != 0 || RelEnd != Size || - !canConvertValue(TD, AllocaTy, LI->getType())) { - // Non-integer loads need to be convertible from the alloca type so that - // they are promotable. - return false; - } - } else if (StoreInst *SI = dyn_cast<StoreInst>(U->getUser())) { - Type *ValueTy = SI->getValueOperand()->getType(); - if (SI->isVolatile()) + if (MemTransferInst *MTI = dyn_cast<MemTransferInst>(U->getUser())) { + const AllocaPartitioning::MemTransferOffsets &MTO + = P.getMemTransferOffsets(*MTI); + if (!MTO.IsSplittable) + return false; + } + } else if (U->get()->getType()->getPointerElementType()->isStructTy()) { + // Disable vector promotion when there are loads or stores of an FCA. return false; - if (RelBegin == 0 && RelEnd == Size) - WholeAllocaOp = true; - if (IntegerType *ITy = dyn_cast<IntegerType>(ValueTy)) { - if (ITy->getBitWidth() < TD.getTypeStoreSizeInBits(ITy)) + } else if (LoadInst *LI = dyn_cast<LoadInst>(U->getUser())) { + if (LI->isVolatile()) return false; - } else if (RelBegin != 0 || RelEnd != Size || - !canConvertValue(TD, ValueTy, AllocaTy)) { - // Non-integer stores need to be convertible to the alloca type so that - // they are promotable. + if (!canConvertValue(TD, PartitionTy, LI->getType())) + return false; + } else if (StoreInst *SI = dyn_cast<StoreInst>(U->getUser())) { + if (SI->isVolatile()) + return false; + if (!canConvertValue(TD, SI->getValueOperand()->getType(), PartitionTy)) + return false; + } else { return false; } - } else if (MemIntrinsic *MI = dyn_cast<MemIntrinsic>(U->getUser())) { - if (MI->isVolatile() || !isa<Constant>(MI->getLength())) - return false; - if (!I->isSplittable()) - return false; // Skip any unsplittable intrinsics. - } else if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(U->getUser())) { - if (II->getIntrinsicID() != Intrinsic::lifetime_start && - II->getIntrinsicID() != Intrinsic::lifetime_end) - return false; - } else { - return false; } - return true; } @@ -1671,12 +2110,12 @@ static bool isIntegerWideningViableForPartitioning( /// This is a quick test to check whether we can rewrite the integer loads and /// stores to a particular alloca into wider loads and stores and be able to /// promote the resulting alloca. -static bool -isIntegerWideningViable(const DataLayout &TD, Type *AllocaTy, - uint64_t AllocBeginOffset, AllocaPartitioning &P, - AllocaPartitioning::const_iterator I, - AllocaPartitioning::const_iterator E, - ArrayRef<AllocaPartitioning::iterator> SplitUses) { +static bool isIntegerWideningViable(const DataLayout &TD, + Type *AllocaTy, + uint64_t AllocBeginOffset, + AllocaPartitioning &P, + AllocaPartitioning::const_use_iterator I, + AllocaPartitioning::const_use_iterator E) { uint64_t SizeInBits = TD.getTypeSizeInBits(AllocaTy); // Don't create integer types larger than the maximum bitwidth. if (SizeInBits > IntegerType::MAX_INT_BITS) @@ -1694,34 +2133,74 @@ isIntegerWideningViable(const DataLayout &TD, Type *AllocaTy, !canConvertValue(TD, IntTy, AllocaTy)) return false; - // If we have no actual uses of this partition, we're forming a fully - // splittable partition. Assume all the operations are easy to widen (they - // are if they're splittable), and just check that it's a good idea to form - // a single integer. - if (I == E) - return TD.isLegalInteger(SizeInBits); - uint64_t Size = TD.getTypeStoreSize(AllocaTy); - // While examining uses, we ensure that the alloca has a covering load or - // store. We don't want to widen the integer operations only to fail to - // promote due to some other unsplittable entry (which we may make splittable - // later). + // Check the uses to ensure the uses are (likely) promotable integer uses. + // Also ensure that the alloca has a covering load or store. We don't want + // to widen the integer operations only to fail to promote due to some other + // unsplittable entry (which we may make splittable later). bool WholeAllocaOp = false; + for (; I != E; ++I) { + Use *U = I->getUse(); + if (!U) + continue; // Skip dead use. - for (; I != E; ++I) - if (!isIntegerWideningViableForPartitioning(TD, AllocaTy, AllocBeginOffset, - Size, P, I, WholeAllocaOp)) - return false; + uint64_t RelBegin = I->BeginOffset - AllocBeginOffset; + uint64_t RelEnd = I->EndOffset - AllocBeginOffset; - for (ArrayRef<AllocaPartitioning::iterator>::const_iterator - SUI = SplitUses.begin(), - SUE = SplitUses.end(); - SUI != SUE; ++SUI) - if (!isIntegerWideningViableForPartitioning(TD, AllocaTy, AllocBeginOffset, - Size, P, *SUI, WholeAllocaOp)) + // We can't reasonably handle cases where the load or store extends past + // the end of the aloca's type and into its padding. + if (RelEnd > Size) return false; + if (LoadInst *LI = dyn_cast<LoadInst>(U->getUser())) { + if (LI->isVolatile()) + return false; + if (RelBegin == 0 && RelEnd == Size) + WholeAllocaOp = true; + if (IntegerType *ITy = dyn_cast<IntegerType>(LI->getType())) { + if (ITy->getBitWidth() < TD.getTypeStoreSizeInBits(ITy)) + return false; + continue; + } + // Non-integer loads need to be convertible from the alloca type so that + // they are promotable. + if (RelBegin != 0 || RelEnd != Size || + !canConvertValue(TD, AllocaTy, LI->getType())) + return false; + } else if (StoreInst *SI = dyn_cast<StoreInst>(U->getUser())) { + Type *ValueTy = SI->getValueOperand()->getType(); + if (SI->isVolatile()) + return false; + if (RelBegin == 0 && RelEnd == Size) + WholeAllocaOp = true; + if (IntegerType *ITy = dyn_cast<IntegerType>(ValueTy)) { + if (ITy->getBitWidth() < TD.getTypeStoreSizeInBits(ITy)) + return false; + continue; + } + // Non-integer stores need to be convertible to the alloca type so that + // they are promotable. + if (RelBegin != 0 || RelEnd != Size || + !canConvertValue(TD, ValueTy, AllocaTy)) + return false; + } else if (MemIntrinsic *MI = dyn_cast<MemIntrinsic>(U->getUser())) { + if (MI->isVolatile() || !isa<Constant>(MI->getLength())) + return false; + if (MemTransferInst *MTI = dyn_cast<MemTransferInst>(U->getUser())) { + const AllocaPartitioning::MemTransferOffsets &MTO + = P.getMemTransferOffsets(*MTI); + if (!MTO.IsSplittable) + return false; + } + } else if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(U->getUser())) { + if (II->getIntrinsicID() != Intrinsic::lifetime_start && + II->getIntrinsicID() != Intrinsic::lifetime_end) + return false; + } else { + return false; + } + } return WholeAllocaOp; } @@ -1866,7 +2345,6 @@ class AllocaPartitionRewriter : public InstVisitor<AllocaPartitionRewriter, bool> { // Befriend the base class so it can delegate to private visit methods. friend class llvm::InstVisitor<AllocaPartitionRewriter, bool>; - typedef llvm::InstVisitor<AllocaPartitionRewriter, bool> Base; const DataLayout &TD; AllocaPartitioning &P; @@ -1896,7 +2374,6 @@ class AllocaPartitionRewriter : public InstVisitor<AllocaPartitionRewriter, // The offset of the partition user currently being rewritten. uint64_t BeginOffset, EndOffset; - bool IsSplittable; bool IsSplit; Use *OldUse; Instruction *OldPtr; @@ -1907,70 +2384,78 @@ class AllocaPartitionRewriter : public InstVisitor<AllocaPartitionRewriter, public: AllocaPartitionRewriter(const DataLayout &TD, AllocaPartitioning &P, + AllocaPartitioning::iterator PI, SROA &Pass, AllocaInst &OldAI, AllocaInst &NewAI, - uint64_t NewBeginOffset, uint64_t NewEndOffset, - bool IsVectorPromotable = false, - bool IsIntegerPromotable = false) - : TD(TD), P(P), Pass(Pass), OldAI(OldAI), NewAI(NewAI), - NewAllocaBeginOffset(NewBeginOffset), NewAllocaEndOffset(NewEndOffset), - NewAllocaTy(NewAI.getAllocatedType()), - VecTy(IsVectorPromotable ? cast<VectorType>(NewAllocaTy) : 0), - ElementTy(VecTy ? VecTy->getElementType() : 0), - ElementSize(VecTy ? TD.getTypeSizeInBits(ElementTy) / 8 : 0), - IntTy(IsIntegerPromotable - ? Type::getIntNTy( - NewAI.getContext(), - TD.getTypeSizeInBits(NewAI.getAllocatedType())) - : 0), - BeginOffset(), EndOffset(), IsSplittable(), IsSplit(), OldUse(), - OldPtr(), IRB(NewAI.getContext(), ConstantFolder()) { - if (VecTy) { - assert((TD.getTypeSizeInBits(ElementTy) % 8) == 0 && - "Only multiple-of-8 sized vector elements are viable"); + uint64_t NewBeginOffset, uint64_t NewEndOffset) + : TD(TD), P(P), Pass(Pass), + OldAI(OldAI), NewAI(NewAI), + NewAllocaBeginOffset(NewBeginOffset), + NewAllocaEndOffset(NewEndOffset), + NewAllocaTy(NewAI.getAllocatedType()), + VecTy(), ElementTy(), ElementSize(), IntTy(), + BeginOffset(), EndOffset(), IsSplit(), OldUse(), OldPtr(), + IRB(NewAI.getContext(), ConstantFolder()) { + } + + /// \brief Visit the users of the alloca partition and rewrite them. + bool visitUsers(AllocaPartitioning::const_use_iterator I, + AllocaPartitioning::const_use_iterator E) { + if (isVectorPromotionViable(TD, NewAI.getAllocatedType(), P, + NewAllocaBeginOffset, NewAllocaEndOffset, + I, E)) { ++NumVectorized; + VecTy = cast<VectorType>(NewAI.getAllocatedType()); + ElementTy = VecTy->getElementType(); + assert((TD.getTypeSizeInBits(VecTy->getScalarType()) % 8) == 0 && + "Only multiple-of-8 sized vector elements are viable"); + ElementSize = TD.getTypeSizeInBits(VecTy->getScalarType()) / 8; + } else if (isIntegerWideningViable(TD, NewAI.getAllocatedType(), + NewAllocaBeginOffset, P, I, E)) { + IntTy = Type::getIntNTy(NewAI.getContext(), + TD.getTypeSizeInBits(NewAI.getAllocatedType())); } - assert((!IsVectorPromotable && !IsIntegerPromotable) || - IsVectorPromotable != IsIntegerPromotable); - } - - bool visit(AllocaPartitioning::const_iterator I) { bool CanSROA = true; - BeginOffset = I->beginOffset(); - EndOffset = I->endOffset(); - IsSplittable = I->isSplittable(); - IsSplit = - BeginOffset < NewAllocaBeginOffset || EndOffset > NewAllocaEndOffset; - - OldUse = I->getUse(); - OldPtr = cast<Instruction>(OldUse->get()); - - Instruction *OldUserI = cast<Instruction>(OldUse->getUser()); - IRB.SetInsertPoint(OldUserI); - IRB.SetCurrentDebugLocation(OldUserI->getDebugLoc()); - IRB.SetNamePrefix(Twine(NewAI.getName()) + "." + Twine(BeginOffset) + "."); - - CanSROA &= visit(cast<Instruction>(OldUse->getUser())); - if (VecTy || IntTy) + for (; I != E; ++I) { + if (!I->getUse()) + continue; // Skip dead uses. + BeginOffset = I->BeginOffset; + EndOffset = I->EndOffset; + IsSplit = I->isSplit(); + OldUse = I->getUse(); + OldPtr = cast<Instruction>(OldUse->get()); + + Instruction *OldUserI = cast<Instruction>(OldUse->getUser()); + IRB.SetInsertPoint(OldUserI); + IRB.SetCurrentDebugLocation(OldUserI->getDebugLoc()); + IRB.SetNamePrefix(Twine(NewAI.getName()) + "." + Twine(BeginOffset) + + "."); + + CanSROA &= visit(cast<Instruction>(OldUse->getUser())); + } + if (VecTy) { + assert(CanSROA); + VecTy = 0; + ElementTy = 0; + ElementSize = 0; + } + if (IntTy) { assert(CanSROA); + IntTy = 0; + } return CanSROA; } private: - // Make sure the other visit overloads are visible. - using Base::visit; - // Every instruction which can end up as a user must have a rewrite rule. bool visitInstruction(Instruction &I) { DEBUG(dbgs() << " !!!! Cannot rewrite: " << I << "\n"); llvm_unreachable("No rewrite rule for this instruction!"); } - Value *getAdjustedAllocaPtr(IRBuilderTy &IRB, uint64_t Offset, - Type *PointerTy) { - assert(Offset >= NewAllocaBeginOffset); - return getAdjustedPtr(IRB, TD, &NewAI, APInt(TD.getPointerSizeInBits(), - Offset - NewAllocaBeginOffset), - PointerTy); + Value *getAdjustedAllocaPtr(IRBuilderTy &IRB, Type *PointerTy) { + assert(BeginOffset >= NewAllocaBeginOffset); + APInt Offset(TD.getPointerSizeInBits(), BeginOffset - NewAllocaBeginOffset); + return getAdjustedPtr(IRB, TD, &NewAI, Offset, PointerTy); } /// \brief Compute suitable alignment to access an offset into the new alloca. @@ -1981,6 +2466,12 @@ private: return MinAlign(NewAIAlign, Offset); } + /// \brief Compute suitable alignment to access this partition of the new + /// alloca. + unsigned getPartitionAlign() { + return getOffsetAlign(BeginOffset - NewAllocaBeginOffset); + } + /// \brief Compute suitable alignment to access a type at an offset of the /// new alloca. /// @@ -1991,6 +2482,14 @@ private: return Align == TD.getABITypeAlignment(Ty) ? 0 : Align; } + /// \brief Compute suitable alignment to access a type at the beginning of + /// this partition of the new alloca. + /// + /// See \c getOffsetTypeAlign for details; this routine delegates to it. + unsigned getPartitionTypeAlign(Type *Ty) { + return getOffsetTypeAlign(Ty, BeginOffset - NewAllocaBeginOffset); + } + unsigned getIndex(uint64_t Offset) { assert(VecTy && "Can only call getIndex when rewriting a vector"); uint64_t RelOffset = Offset - NewAllocaBeginOffset; @@ -2006,10 +2505,9 @@ private: Pass.DeadInsts.insert(I); } - Value *rewriteVectorizedLoadInst(uint64_t NewBeginOffset, - uint64_t NewEndOffset) { - unsigned BeginIndex = getIndex(NewBeginOffset); - unsigned EndIndex = getIndex(NewEndOffset); + Value *rewriteVectorizedLoadInst() { + unsigned BeginIndex = getIndex(BeginOffset); + unsigned EndIndex = getIndex(EndOffset); assert(EndIndex > BeginIndex && "Empty vector!"); Value *V = IRB.CreateAlignedLoad(&NewAI, NewAI.getAlignment(), @@ -2017,16 +2515,15 @@ private: return extractVector(IRB, V, BeginIndex, EndIndex, "vec"); } - Value *rewriteIntegerLoad(LoadInst &LI, uint64_t NewBeginOffset, - uint64_t NewEndOffset) { + Value *rewriteIntegerLoad(LoadInst &LI) { assert(IntTy && "We cannot insert an integer to the alloca"); assert(!LI.isVolatile()); Value *V = IRB.CreateAlignedLoad(&NewAI, NewAI.getAlignment(), "load"); V = convertValue(TD, IRB, V, IntTy); - assert(NewBeginOffset >= NewAllocaBeginOffset && "Out of bounds offset"); - uint64_t Offset = NewBeginOffset - NewAllocaBeginOffset; - if (Offset > 0 || NewEndOffset < NewAllocaEndOffset) + assert(BeginOffset >= NewAllocaBeginOffset && "Out of bounds offset"); + uint64_t Offset = BeginOffset - NewAllocaBeginOffset; + if (Offset > 0 || EndOffset < NewAllocaEndOffset) V = extractInteger(TD, IRB, V, cast<IntegerType>(LI.getType()), Offset, "extract"); return V; @@ -2037,32 +2534,25 @@ private: Value *OldOp = LI.getOperand(0); assert(OldOp == OldPtr); - // Compute the intersecting offset range. - assert(BeginOffset < NewAllocaEndOffset); - assert(EndOffset > NewAllocaBeginOffset); - uint64_t NewBeginOffset = std::max(BeginOffset, NewAllocaBeginOffset); - uint64_t NewEndOffset = std::min(EndOffset, NewAllocaEndOffset); - - uint64_t Size = NewEndOffset - NewBeginOffset; + uint64_t Size = EndOffset - BeginOffset; Type *TargetTy = IsSplit ? Type::getIntNTy(LI.getContext(), Size * 8) : LI.getType(); bool IsPtrAdjusted = false; Value *V; if (VecTy) { - V = rewriteVectorizedLoadInst(NewBeginOffset, NewEndOffset); + V = rewriteVectorizedLoadInst(); } else if (IntTy && LI.getType()->isIntegerTy()) { - V = rewriteIntegerLoad(LI, NewBeginOffset, NewEndOffset); - } else if (NewBeginOffset == NewAllocaBeginOffset && + V = rewriteIntegerLoad(LI); + } else if (BeginOffset == NewAllocaBeginOffset && canConvertValue(TD, NewAllocaTy, LI.getType())) { V = IRB.CreateAlignedLoad(&NewAI, NewAI.getAlignment(), LI.isVolatile(), "load"); } else { Type *LTy = TargetTy->getPointerTo(); - V = IRB.CreateAlignedLoad( - getAdjustedAllocaPtr(IRB, NewBeginOffset, LTy), - getOffsetTypeAlign(TargetTy, NewBeginOffset - NewAllocaBeginOffset), - LI.isVolatile(), "load"); + V = IRB.CreateAlignedLoad(getAdjustedAllocaPtr(IRB, LTy), + getPartitionTypeAlign(TargetTy), + LI.isVolatile(), "load"); IsPtrAdjusted = true; } V = convertValue(TD, IRB, V, TargetTy); @@ -2084,7 +2574,7 @@ private: // LI only used for this computation. Value *Placeholder = new LoadInst(UndefValue::get(LI.getType()->getPointerTo())); - V = insertInteger(TD, IRB, Placeholder, V, NewBeginOffset, + V = insertInteger(TD, IRB, Placeholder, V, BeginOffset, "insert"); LI.replaceAllUsesWith(V); Placeholder->replaceAllUsesWith(&LI); @@ -2099,12 +2589,11 @@ private: return !LI.isVolatile() && !IsPtrAdjusted; } - bool rewriteVectorizedStoreInst(Value *V, StoreInst &SI, Value *OldOp, - uint64_t NewBeginOffset, - uint64_t NewEndOffset) { + bool rewriteVectorizedStoreInst(Value *V, + StoreInst &SI, Value *OldOp) { if (V->getType() != VecTy) { - unsigned BeginIndex = getIndex(NewBeginOffset); - unsigned EndIndex = getIndex(NewEndOffset); + unsigned BeginIndex = getIndex(BeginOffset); + unsigned EndIndex = getIndex(EndOffset); assert(EndIndex > BeginIndex && "Empty vector!"); unsigned NumElements = EndIndex - BeginIndex; assert(NumElements <= VecTy->getNumElements() && "Too many elements!"); @@ -2127,8 +2616,7 @@ private: return true; } - bool rewriteIntegerStore(Value *V, StoreInst &SI, - uint64_t NewBeginOffset, uint64_t NewEndOffset) { + bool rewriteIntegerStore(Value *V, StoreInst &SI) { assert(IntTy && "We cannot extract an integer from the alloca"); assert(!SI.isVolatile()); if (TD.getTypeSizeInBits(V->getType()) != IntTy->getBitWidth()) { @@ -2161,45 +2649,37 @@ private: if (AllocaInst *AI = dyn_cast<AllocaInst>(V->stripInBoundsOffsets())) Pass.PostPromotionWorklist.insert(AI); - // Compute the intersecting offset range. - assert(BeginOffset < NewAllocaEndOffset); - assert(EndOffset > NewAllocaBeginOffset); - uint64_t NewBeginOffset = std::max(BeginOffset, NewAllocaBeginOffset); - uint64_t NewEndOffset = std::min(EndOffset, NewAllocaEndOffset); - - uint64_t Size = NewEndOffset - NewBeginOffset; + uint64_t Size = EndOffset - BeginOffset; if (Size < TD.getTypeStoreSize(V->getType())) { assert(!SI.isVolatile()); + assert(IsSplit && "A seemingly split store isn't splittable"); assert(V->getType()->isIntegerTy() && "Only integer type loads and stores are split"); assert(V->getType()->getIntegerBitWidth() == TD.getTypeStoreSizeInBits(V->getType()) && "Non-byte-multiple bit width"); IntegerType *NarrowTy = Type::getIntNTy(SI.getContext(), Size * 8); - V = extractInteger(TD, IRB, V, NarrowTy, NewBeginOffset, + V = extractInteger(TD, IRB, V, NarrowTy, BeginOffset, "extract"); } if (VecTy) - return rewriteVectorizedStoreInst(V, SI, OldOp, NewBeginOffset, - NewEndOffset); + return rewriteVectorizedStoreInst(V, SI, OldOp); if (IntTy && V->getType()->isIntegerTy()) - return rewriteIntegerStore(V, SI, NewBeginOffset, NewEndOffset); + return rewriteIntegerStore(V, SI); StoreInst *NewSI; - if (NewBeginOffset == NewAllocaBeginOffset && - NewEndOffset == NewAllocaEndOffset && + if (BeginOffset == NewAllocaBeginOffset && + EndOffset == NewAllocaEndOffset && canConvertValue(TD, V->getType(), NewAllocaTy)) { V = convertValue(TD, IRB, V, NewAllocaTy); NewSI = IRB.CreateAlignedStore(V, &NewAI, NewAI.getAlignment(), SI.isVolatile()); } else { - Value *NewPtr = getAdjustedAllocaPtr(IRB, NewBeginOffset, - V->getType()->getPointerTo()); - NewSI = IRB.CreateAlignedStore( - V, NewPtr, getOffsetTypeAlign( - V->getType(), NewBeginOffset - NewAllocaBeginOffset), - SI.isVolatile()); + Value *NewPtr = getAdjustedAllocaPtr(IRB, V->getType()->getPointerTo()); + NewSI = IRB.CreateAlignedStore(V, NewPtr, + getPartitionTypeAlign(V->getType()), + SI.isVolatile()); } (void)NewSI; Pass.DeadInsts.insert(&SI); @@ -2250,12 +2730,9 @@ private: // If the memset has a variable size, it cannot be split, just adjust the // pointer to the new alloca. if (!isa<Constant>(II.getLength())) { - assert(!IsSplit); - assert(BeginOffset >= NewAllocaBeginOffset); - II.setDest( - getAdjustedAllocaPtr(IRB, BeginOffset, II.getRawDest()->getType())); + II.setDest(getAdjustedAllocaPtr(IRB, II.getRawDest()->getType())); Type *CstTy = II.getAlignmentCst()->getType(); - II.setAlignment(ConstantInt::get(CstTy, getOffsetAlign(BeginOffset))); + II.setAlignment(ConstantInt::get(CstTy, getPartitionAlign())); deleteIfTriviallyDead(OldPtr); return false; @@ -2267,27 +2744,21 @@ private: Type *AllocaTy = NewAI.getAllocatedType(); Type *ScalarTy = AllocaTy->getScalarType(); - // Compute the intersecting offset range. - assert(BeginOffset < NewAllocaEndOffset); - assert(EndOffset > NewAllocaBeginOffset); - uint64_t NewBeginOffset = std::max(BeginOffset, NewAllocaBeginOffset); - uint64_t NewEndOffset = std::min(EndOffset, NewAllocaEndOffset); - uint64_t PartitionOffset = NewBeginOffset - NewAllocaBeginOffset; - // If this doesn't map cleanly onto the alloca type, and that type isn't // a single value type, just emit a memset. if (!VecTy && !IntTy && - (BeginOffset > NewAllocaBeginOffset || - EndOffset < NewAllocaEndOffset || + (BeginOffset != NewAllocaBeginOffset || + EndOffset != NewAllocaEndOffset || !AllocaTy->isSingleValueType() || !TD.isLegalInteger(TD.getTypeSizeInBits(ScalarTy)) || TD.getTypeSizeInBits(ScalarTy)%8 != 0)) { Type *SizeTy = II.getLength()->getType(); - Constant *Size = ConstantInt::get(SizeTy, NewEndOffset - NewBeginOffset); - CallInst *New = IRB.CreateMemSet( - getAdjustedAllocaPtr(IRB, NewBeginOffset, II.getRawDest()->getType()), - II.getValue(), Size, getOffsetAlign(PartitionOffset), - II.isVolatile()); + Constant *Size = ConstantInt::get(SizeTy, EndOffset - BeginOffset); + CallInst *New + = IRB.CreateMemSet(getAdjustedAllocaPtr(IRB, + II.getRawDest()->getType()), + II.getValue(), Size, getPartitionAlign(), + II.isVolatile()); (void)New; DEBUG(dbgs() << " to: " << *New << "\n"); return false; @@ -2304,8 +2775,8 @@ private: // If this is a memset of a vectorized alloca, insert it. assert(ElementTy == ScalarTy); - unsigned BeginIndex = getIndex(NewBeginOffset); - unsigned EndIndex = getIndex(NewEndOffset); + unsigned BeginIndex = getIndex(BeginOffset); + unsigned EndIndex = getIndex(EndOffset); assert(EndIndex > BeginIndex && "Empty vector!"); unsigned NumElements = EndIndex - BeginIndex; assert(NumElements <= VecTy->getNumElements() && "Too many elements!"); @@ -2324,7 +2795,7 @@ private: // set integer. assert(!II.isVolatile()); - uint64_t Size = NewEndOffset - NewBeginOffset; + uint64_t Size = EndOffset - BeginOffset; V = getIntegerSplat(II.getValue(), Size); if (IntTy && (BeginOffset != NewAllocaBeginOffset || @@ -2332,7 +2803,8 @@ private: Value *Old = IRB.CreateAlignedLoad(&NewAI, NewAI.getAlignment(), "oldload"); Old = convertValue(TD, IRB, Old, IntTy); - uint64_t Offset = NewBeginOffset - NewAllocaBeginOffset; + assert(BeginOffset >= NewAllocaBeginOffset && "Out of bounds offset"); + uint64_t Offset = BeginOffset - NewAllocaBeginOffset; V = insertInteger(TD, IRB, Old, V, Offset, "insert"); } else { assert(V->getType() == IntTy && @@ -2341,8 +2813,8 @@ private: V = convertValue(TD, IRB, V, AllocaTy); } else { // Established these invariants above. - assert(NewBeginOffset == NewAllocaBeginOffset); - assert(NewEndOffset == NewAllocaEndOffset); + assert(BeginOffset == NewAllocaBeginOffset); + assert(EndOffset == NewAllocaEndOffset); V = getIntegerSplat(II.getValue(), TD.getTypeSizeInBits(ScalarTy) / 8); if (VectorType *AllocaVecTy = dyn_cast<VectorType>(AllocaTy)) @@ -2364,25 +2836,21 @@ private: DEBUG(dbgs() << " original: " << II << "\n"); - // Compute the intersecting offset range. - assert(BeginOffset < NewAllocaEndOffset); - assert(EndOffset > NewAllocaBeginOffset); - uint64_t NewBeginOffset = std::max(BeginOffset, NewAllocaBeginOffset); - uint64_t NewEndOffset = std::min(EndOffset, NewAllocaEndOffset); - assert(II.getRawSource() == OldPtr || II.getRawDest() == OldPtr); bool IsDest = II.getRawDest() == OldPtr; + const AllocaPartitioning::MemTransferOffsets &MTO + = P.getMemTransferOffsets(II); + // Compute the relative offset within the transfer. unsigned IntPtrWidth = TD.getPointerSizeInBits(); - APInt RelOffset(IntPtrWidth, NewBeginOffset - BeginOffset); + APInt RelOffset(IntPtrWidth, BeginOffset - (IsDest ? MTO.DestBegin + : MTO.SourceBegin)); unsigned Align = II.getAlignment(); - uint64_t PartitionOffset = NewBeginOffset - NewAllocaBeginOffset; if (Align > 1) - Align = MinAlign( - RelOffset.zextOrTrunc(64).getZExtValue(), - MinAlign(II.getAlignment(), getOffsetAlign(PartitionOffset))); + Align = MinAlign(RelOffset.zextOrTrunc(64).getZExtValue(), + MinAlign(II.getAlignment(), getPartitionAlign())); // For unsplit intrinsics, we simply modify the source and destination // pointers in place. This isn't just an optimization, it is a matter of @@ -2391,14 +2859,12 @@ private: // a variable length. We may also be dealing with memmove instead of // memcpy, and so simply updating the pointers is the necessary for us to // update both source and dest of a single call. - if (!IsSplittable) { + if (!MTO.IsSplittable) { Value *OldOp = IsDest ? II.getRawDest() : II.getRawSource(); if (IsDest) - II.setDest( - getAdjustedAllocaPtr(IRB, BeginOffset, II.getRawDest()->getType())); + II.setDest(getAdjustedAllocaPtr(IRB, II.getRawDest()->getType())); else - II.setSource(getAdjustedAllocaPtr(IRB, BeginOffset, - II.getRawSource()->getType())); + II.setSource(getAdjustedAllocaPtr(IRB, II.getRawSource()->getType())); Type *CstTy = II.getAlignmentCst()->getType(); II.setAlignment(ConstantInt::get(CstTy, Align)); @@ -2416,21 +2882,24 @@ private: // If this doesn't map cleanly onto the alloca type, and that type isn't // a single value type, just emit a memcpy. bool EmitMemCpy - = !VecTy && !IntTy && (BeginOffset > NewAllocaBeginOffset || - EndOffset < NewAllocaEndOffset || + = !VecTy && !IntTy && (BeginOffset != NewAllocaBeginOffset || + EndOffset != NewAllocaEndOffset || !NewAI.getAllocatedType()->isSingleValueType()); // If we're just going to emit a memcpy, the alloca hasn't changed, and the // size hasn't been shrunk based on analysis of the viable range, this is // a no-op. if (EmitMemCpy && &OldAI == &NewAI) { + uint64_t OrigBegin = IsDest ? MTO.DestBegin : MTO.SourceBegin; + uint64_t OrigEnd = IsDest ? MTO.DestEnd : MTO.SourceEnd; // Ensure the start lines up. - assert(NewBeginOffset == BeginOffset); + assert(BeginOffset == OrigBegin); + (void)OrigBegin; // Rewrite the size as needed. - if (NewEndOffset != EndOffset) + if (EndOffset != OrigEnd) II.setLength(ConstantInt::get(II.getLength()->getType(), - NewEndOffset - NewBeginOffset)); + EndOffset - BeginOffset)); return false; } // Record this instruction for deletion. @@ -2451,11 +2920,11 @@ private: // a single, simple GEP in most cases. OtherPtr = getAdjustedPtr(IRB, TD, OtherPtr, RelOffset, OtherPtrTy); - Value *OurPtr = getAdjustedAllocaPtr( - IRB, NewBeginOffset, - IsDest ? II.getRawDest()->getType() : II.getRawSource()->getType()); + Value *OurPtr + = getAdjustedAllocaPtr(IRB, IsDest ? II.getRawDest()->getType() + : II.getRawSource()->getType()); Type *SizeTy = II.getLength()->getType(); - Constant *Size = ConstantInt::get(SizeTy, NewEndOffset - NewBeginOffset); + Constant *Size = ConstantInt::get(SizeTy, EndOffset - BeginOffset); CallInst *New = IRB.CreateMemCpy(IsDest ? OurPtr : OtherPtr, IsDest ? OtherPtr : OurPtr, @@ -2471,11 +2940,11 @@ private: if (!Align) Align = 1; - bool IsWholeAlloca = NewBeginOffset == NewAllocaBeginOffset && - NewEndOffset == NewAllocaEndOffset; - uint64_t Size = NewEndOffset - NewBeginOffset; - unsigned BeginIndex = VecTy ? getIndex(NewBeginOffset) : 0; - unsigned EndIndex = VecTy ? getIndex(NewEndOffset) : 0; + bool IsWholeAlloca = BeginOffset == NewAllocaBeginOffset && + EndOffset == NewAllocaEndOffset; + uint64_t Size = EndOffset - BeginOffset; + unsigned BeginIndex = VecTy ? getIndex(BeginOffset) : 0; + unsigned EndIndex = VecTy ? getIndex(EndOffset) : 0; unsigned NumElements = EndIndex - BeginIndex; IntegerType *SubIntTy = IntTy ? Type::getIntNTy(IntTy->getContext(), Size*8) : 0; @@ -2506,7 +2975,8 @@ private: Src = IRB.CreateAlignedLoad(&NewAI, NewAI.getAlignment(), "load"); Src = convertValue(TD, IRB, Src, IntTy); - uint64_t Offset = NewBeginOffset - NewAllocaBeginOffset; + assert(BeginOffset >= NewAllocaBeginOffset && "Out of bounds offset"); + uint64_t Offset = BeginOffset - NewAllocaBeginOffset; Src = extractInteger(TD, IRB, Src, SubIntTy, Offset, "extract"); } else { Src = IRB.CreateAlignedLoad(SrcPtr, Align, II.isVolatile(), @@ -2521,7 +2991,8 @@ private: Value *Old = IRB.CreateAlignedLoad(&NewAI, NewAI.getAlignment(), "oldload"); Old = convertValue(TD, IRB, Old, IntTy); - uint64_t Offset = NewBeginOffset - NewAllocaBeginOffset; + assert(BeginOffset >= NewAllocaBeginOffset && "Out of bounds offset"); + uint64_t Offset = BeginOffset - NewAllocaBeginOffset; Src = insertInteger(TD, IRB, Old, Src, Offset, "insert"); Src = convertValue(TD, IRB, Src, NewAllocaTy); } @@ -2539,20 +3010,13 @@ private: DEBUG(dbgs() << " original: " << II << "\n"); assert(II.getArgOperand(1) == OldPtr); - // Compute the intersecting offset range. - assert(BeginOffset < NewAllocaEndOffset); - assert(EndOffset > NewAllocaBeginOffset); - uint64_t NewBeginOffset = std::max(BeginOffset, NewAllocaBeginOffset); - uint64_t NewEndOffset = std::min(EndOffset, NewAllocaEndOffset); - // Record this instruction for deletion. Pass.DeadInsts.insert(&II); ConstantInt *Size = ConstantInt::get(cast<IntegerType>(II.getArgOperand(0)->getType()), - NewEndOffset - NewBeginOffset); - Value *Ptr = - getAdjustedAllocaPtr(IRB, NewBeginOffset, II.getArgOperand(1)->getType()); + EndOffset - BeginOffset); + Value *Ptr = getAdjustedAllocaPtr(IRB, II.getArgOperand(1)->getType()); Value *New; if (II.getIntrinsicID() == Intrinsic::lifetime_start) New = IRB.CreateLifetimeStart(Ptr, Size); @@ -2566,8 +3030,6 @@ private: bool visitPHINode(PHINode &PN) { DEBUG(dbgs() << " original: " << PN << "\n"); - assert(BeginOffset >= NewAllocaBeginOffset && "PHIs are unsplittable"); - assert(EndOffset <= NewAllocaEndOffset && "PHIs are unsplittable"); // We would like to compute a new pointer in only one place, but have it be // as local as possible to the PHI. To do that, we re-use the location of @@ -2577,33 +3039,21 @@ private: PtrBuilder.SetNamePrefix(Twine(NewAI.getName()) + "." + Twine(BeginOffset) + "."); - Value *NewPtr = - getAdjustedAllocaPtr(PtrBuilder, BeginOffset, OldPtr->getType()); + Value *NewPtr = getAdjustedAllocaPtr(PtrBuilder, OldPtr->getType()); // Replace the operands which were using the old pointer. std::replace(PN.op_begin(), PN.op_end(), cast<Value>(OldPtr), NewPtr); DEBUG(dbgs() << " to: " << PN << "\n"); deleteIfTriviallyDead(OldPtr); - - // Check whether we can speculate this PHI node, and if so remember that - // fact and return that this alloca remains viable for promotion to an SSA - // value. - if (isSafePHIToSpeculate(PN, &TD)) { - Pass.SpeculatablePHIs.insert(&PN); - return true; - } - - return false; // PHIs can't be promoted on their own. + return false; } bool visitSelectInst(SelectInst &SI) { DEBUG(dbgs() << " original: " << SI << "\n"); assert((SI.getTrueValue() == OldPtr || SI.getFalseValue() == OldPtr) && "Pointer isn't an operand!"); - assert(BeginOffset >= NewAllocaBeginOffset && "Selects are unsplittable"); - assert(EndOffset <= NewAllocaEndOffset && "Selects are unsplittable"); - Value *NewPtr = getAdjustedAllocaPtr(IRB, BeginOffset, OldPtr->getType()); + Value *NewPtr = getAdjustedAllocaPtr(IRB, OldPtr->getType()); // Replace the operands which were using the old pointer. if (SI.getOperand(1) == OldPtr) SI.setOperand(1, NewPtr); @@ -2612,16 +3062,7 @@ private: DEBUG(dbgs() << " to: " << SI << "\n"); deleteIfTriviallyDead(OldPtr); - - // Check whether we can speculate this select instruction, and if so - // remember that fact and return that this alloca remains viable for - // promotion to an SSA value. - if (isSafeSelectToSpeculate(SI, &TD)) { - Pass.SpeculatableSelects.insert(&SI); - return true; - } - - return false; // Selects can't be promoted on their own. + return false; } }; @@ -2991,52 +3432,57 @@ static Type *getTypePartition(const DataLayout &TD, Type *Ty, /// appropriate new offsets. It also evaluates how successful the rewrite was /// at enabling promotion and if it was successful queues the alloca to be /// promoted. -bool SROA::rewritePartitions(AllocaInst &AI, AllocaPartitioning &P, - AllocaPartitioning::iterator B, - AllocaPartitioning::iterator E, - int64_t BeginOffset, int64_t EndOffset, - ArrayRef<AllocaPartitioning::iterator> SplitUses) { - assert(BeginOffset < EndOffset); - uint64_t PartitionSize = EndOffset - BeginOffset; +bool SROA::rewriteAllocaPartition(AllocaInst &AI, + AllocaPartitioning &P, + AllocaPartitioning::iterator PI) { + uint64_t AllocaSize = PI->EndOffset - PI->BeginOffset; + bool IsLive = false; + for (AllocaPartitioning::use_iterator UI = P.use_begin(PI), + UE = P.use_end(PI); + UI != UE && !IsLive; ++UI) + if (UI->getUse()) + IsLive = true; + if (!IsLive) + return false; // No live uses left of this partition. + + DEBUG(dbgs() << "Speculating PHIs and selects in partition " + << "[" << PI->BeginOffset << "," << PI->EndOffset << ")\n"); + + PHIOrSelectSpeculator Speculator(*TD, P, *this); + DEBUG(dbgs() << " speculating "); + DEBUG(P.print(dbgs(), PI, "")); + Speculator.visitUsers(PI); // Try to compute a friendly type for this partition of the alloca. This // won't always succeed, in which case we fall back to a legal integer type // or an i8 array of an appropriate size. - Type *PartitionTy = 0; - if (Type *CommonUseTy = findCommonType(B, E, EndOffset)) - if (TD->getTypeAllocSize(CommonUseTy) >= PartitionSize) - PartitionTy = CommonUseTy; - if (!PartitionTy) - if (Type *TypePartitionTy = getTypePartition(*TD, AI.getAllocatedType(), - BeginOffset, PartitionSize)) - PartitionTy = TypePartitionTy; - if ((!PartitionTy || (PartitionTy->isArrayTy() && - PartitionTy->getArrayElementType()->isIntegerTy())) && - TD->isLegalInteger(PartitionSize * 8)) - PartitionTy = Type::getIntNTy(*C, PartitionSize * 8); - if (!PartitionTy) - PartitionTy = ArrayType::get(Type::getInt8Ty(*C), PartitionSize); - assert(TD->getTypeAllocSize(PartitionTy) >= PartitionSize); - - bool IsVectorPromotable = isVectorPromotionViable( - *TD, PartitionTy, P, BeginOffset, EndOffset, B, E, SplitUses); - - bool IsIntegerPromotable = - !IsVectorPromotable && - isIntegerWideningViable(*TD, PartitionTy, BeginOffset, P, B, E, - SplitUses); + Type *AllocaTy = 0; + if (Type *PartitionTy = P.getCommonType(PI)) + if (TD->getTypeAllocSize(PartitionTy) >= AllocaSize) + AllocaTy = PartitionTy; + if (!AllocaTy) + if (Type *PartitionTy = getTypePartition(*TD, AI.getAllocatedType(), + PI->BeginOffset, AllocaSize)) + AllocaTy = PartitionTy; + if ((!AllocaTy || + (AllocaTy->isArrayTy() && + AllocaTy->getArrayElementType()->isIntegerTy())) && + TD->isLegalInteger(AllocaSize * 8)) + AllocaTy = Type::getIntNTy(*C, AllocaSize * 8); + if (!AllocaTy) + AllocaTy = ArrayType::get(Type::getInt8Ty(*C), AllocaSize); + assert(TD->getTypeAllocSize(AllocaTy) >= AllocaSize); // Check for the case where we're going to rewrite to a new alloca of the // exact same type as the original, and with the same access offsets. In that // case, re-use the existing alloca, but still run through the rewriter to // perform phi and select speculation. AllocaInst *NewAI; - if (PartitionTy == AI.getAllocatedType()) { - assert(BeginOffset == 0 && + if (AllocaTy == AI.getAllocatedType()) { + assert(PI->BeginOffset == 0 && "Non-zero begin offset but same alloca type"); + assert(PI == P.begin() && "Begin offset is zero on later partition"); NewAI = &AI; - // FIXME: We should be able to bail at this point with "nothing changed". - // FIXME: We might want to defer PHI speculation until after here. } else { unsigned Alignment = AI.getAlignment(); if (!Alignment) { @@ -3045,207 +3491,54 @@ bool SROA::rewritePartitions(AllocaInst &AI, AllocaPartitioning &P, // type. Alignment = TD->getABITypeAlignment(AI.getAllocatedType()); } - Alignment = MinAlign(Alignment, BeginOffset); + Alignment = MinAlign(Alignment, PI->BeginOffset); // If we will get at least this much alignment from the type alone, leave // the alloca's alignment unconstrained. - if (Alignment <= TD->getABITypeAlignment(PartitionTy)) + if (Alignment <= TD->getABITypeAlignment(AllocaTy)) Alignment = 0; - NewAI = new AllocaInst(PartitionTy, 0, Alignment, - AI.getName() + ".sroa." + Twine(B - P.begin()), &AI); + NewAI = new AllocaInst(AllocaTy, 0, Alignment, + AI.getName() + ".sroa." + Twine(PI - P.begin()), + &AI); ++NumNewAllocas; } DEBUG(dbgs() << "Rewriting alloca partition " - << "[" << BeginOffset << "," << EndOffset << ") to: " << *NewAI - << "\n"); + << "[" << PI->BeginOffset << "," << PI->EndOffset << ") to: " + << *NewAI << "\n"); - // Track the high watermark on several worklists that are only relevant for - // promoted allocas. We will reset it to this point if the alloca is not in - // fact scheduled for promotion. + // Track the high watermark of the post-promotion worklist. We will reset it + // to this point if the alloca is not in fact scheduled for promotion. unsigned PPWOldSize = PostPromotionWorklist.size(); - unsigned SPOldSize = SpeculatablePHIs.size(); - unsigned SSOldSize = SpeculatableSelects.size(); - - AllocaPartitionRewriter Rewriter(*TD, P, *this, AI, *NewAI, BeginOffset, - EndOffset, IsVectorPromotable, - IsIntegerPromotable); - bool Promotable = true; - for (ArrayRef<AllocaPartitioning::iterator>::const_iterator - SUI = SplitUses.begin(), - SUE = SplitUses.end(); - SUI != SUE; ++SUI) { - DEBUG(dbgs() << " rewriting split "); - DEBUG(P.printPartition(dbgs(), *SUI, "")); - Promotable &= Rewriter.visit(*SUI); - } - for (AllocaPartitioning::iterator I = B; I != E; ++I) { - DEBUG(dbgs() << " rewriting "); - DEBUG(P.printPartition(dbgs(), I, "")); - Promotable &= Rewriter.visit(I); - } - - if (Promotable && (SpeculatablePHIs.size() > SPOldSize || - SpeculatableSelects.size() > SSOldSize)) { - // If we have a promotable alloca except for some unspeculated loads below - // PHIs or Selects, iterate once. We will speculate the loads and on the - // next iteration rewrite them into a promotable form. - Worklist.insert(NewAI); - } else if (Promotable) { + + AllocaPartitionRewriter Rewriter(*TD, P, PI, *this, AI, *NewAI, + PI->BeginOffset, PI->EndOffset); + DEBUG(dbgs() << " rewriting "); + DEBUG(P.print(dbgs(), PI, "")); + bool Promotable = Rewriter.visitUsers(P.use_begin(PI), P.use_end(PI)); + if (Promotable) { DEBUG(dbgs() << " and queuing for promotion\n"); PromotableAllocas.push_back(NewAI); } else if (NewAI != &AI) { // If we can't promote the alloca, iterate on it to check for new // refinements exposed by splitting the current alloca. Don't iterate on an // alloca which didn't actually change and didn't get promoted. - // FIXME: We should actually track whether the rewriter changed anything. Worklist.insert(NewAI); } // Drop any post-promotion work items if promotion didn't happen. - if (!Promotable) { + if (!Promotable) while (PostPromotionWorklist.size() > PPWOldSize) PostPromotionWorklist.pop_back(); - while (SpeculatablePHIs.size() > SPOldSize) - SpeculatablePHIs.pop_back(); - while (SpeculatableSelects.size() > SSOldSize) - SpeculatableSelects.pop_back(); - } return true; } -namespace { - struct IsPartitionEndLessOrEqualTo { - uint64_t UpperBound; - - IsPartitionEndLessOrEqualTo(uint64_t UpperBound) : UpperBound(UpperBound) {} - - bool operator()(const AllocaPartitioning::iterator &I) { - return I->endOffset() <= UpperBound; - } - }; -} - -static void removeFinishedSplitUses( - SmallVectorImpl<AllocaPartitioning::iterator> &SplitUses, - uint64_t &MaxSplitUseEndOffset, uint64_t Offset) { - if (Offset >= MaxSplitUseEndOffset) { - SplitUses.clear(); - MaxSplitUseEndOffset = 0; - return; - } - - size_t SplitUsesOldSize = SplitUses.size(); - SplitUses.erase(std::remove_if(SplitUses.begin(), SplitUses.end(), - IsPartitionEndLessOrEqualTo(Offset)), - SplitUses.end()); - if (SplitUsesOldSize == SplitUses.size()) - return; - - // Recompute the max. While this is linear, so is remove_if. - MaxSplitUseEndOffset = 0; - for (SmallVectorImpl<AllocaPartitioning::iterator>::iterator - SUI = SplitUses.begin(), - SUE = SplitUses.end(); - SUI != SUE; ++SUI) - MaxSplitUseEndOffset = std::max((*SUI)->endOffset(), MaxSplitUseEndOffset); -} - /// \brief Walks the partitioning of an alloca rewriting uses of each partition. bool SROA::splitAlloca(AllocaInst &AI, AllocaPartitioning &P) { - if (P.begin() == P.end()) - return false; - bool Changed = false; - SmallVector<AllocaPartitioning::iterator, 4> SplitUses; - uint64_t MaxSplitUseEndOffset = 0; - - uint64_t BeginOffset = P.begin()->beginOffset(); - - for (AllocaPartitioning::iterator PI = P.begin(), PJ = llvm::next(PI), - PE = P.end(); - PI != PE; PI = PJ) { - uint64_t MaxEndOffset = PI->endOffset(); - - if (!PI->isSplittable()) { - // When we're forming an unsplittable region, it must always start at he - // first partitioning use and will extend through its end. - assert(BeginOffset == PI->beginOffset()); - - // Rewrite a partition including all of the overlapping uses with this - // unsplittable partition. - while (PJ != PE && PJ->beginOffset() < MaxEndOffset) { - if (!PJ->isSplittable()) - MaxEndOffset = std::max(MaxEndOffset, PJ->endOffset()); - ++PJ; - } - } else { - assert(PI->isSplittable()); // Established above. - - // Collect all of the overlapping splittable partitions. - while (PJ != PE && PJ->beginOffset() < MaxEndOffset && - PJ->isSplittable()) { - MaxEndOffset = std::max(MaxEndOffset, PJ->endOffset()); - ++PJ; - } - - // Back up MaxEndOffset and PJ if we ended the span early when - // encountering an unsplittable partition. - if (PJ != PE && PJ->beginOffset() < MaxEndOffset) { - assert(!PJ->isSplittable()); - MaxEndOffset = PJ->beginOffset(); - } - } - - // Check if we have managed to move the end offset forward yet. If so, - // we'll have to rewrite uses and erase old split uses. - if (BeginOffset < MaxEndOffset) { - // Rewrite a sequence of overlapping partition uses. - Changed |= rewritePartitions(AI, P, PI, PJ, BeginOffset, - MaxEndOffset, SplitUses); - - removeFinishedSplitUses(SplitUses, MaxSplitUseEndOffset, MaxEndOffset); - } - - // Accumulate all the splittable partitions from the [PI,PJ) region which - // overlap going forward. - for (AllocaPartitioning::iterator PII = PI, PIE = PJ; PII != PIE; ++PII) - if (PII->isSplittable() && PII->endOffset() > MaxEndOffset) { - SplitUses.push_back(PII); - MaxSplitUseEndOffset = std::max(PII->endOffset(), MaxSplitUseEndOffset); - } - - // If we have no split uses or no gap in offsets, we're ready to move to - // the next partitioning use. - if (SplitUses.empty() || (PJ != PE && MaxEndOffset == PJ->beginOffset())) { - BeginOffset = PJ->beginOffset(); - continue; - } - - // Even if we have split uses, if the next partitioning use is splittable - // and the split uses reach it, we can simply set up the beginning offset - // to bridge between them. - if (PJ != PE && PJ->isSplittable() && MaxSplitUseEndOffset > PJ->beginOffset()) { - BeginOffset = MaxEndOffset; - continue; - } - - // Otherwise, we have a tail of split uses. Rewrite them with an empty - // range of partitioning uses. - uint64_t PostSplitEndOffset = - PJ == PE ? MaxSplitUseEndOffset : PJ->beginOffset(); - - Changed |= rewritePartitions(AI, P, PJ, PJ, MaxEndOffset, - PostSplitEndOffset, SplitUses); - if (PJ == PE) - break; // Skip the rest, we don't need to do any cleanup. - - removeFinishedSplitUses(SplitUses, MaxSplitUseEndOffset, - PostSplitEndOffset); - - // Now just reset the begin offset for the next iteration. - BeginOffset = PJ->beginOffset(); - } + for (AllocaPartitioning::iterator PI = P.begin(), PE = P.end(); PI != PE; + ++PI) + Changed |= rewriteAllocaPartition(AI, P, PI); return Changed; } @@ -3308,17 +3601,7 @@ bool SROA::runOnAlloca(AllocaInst &AI) { if (P.begin() == P.end()) return Changed; - Changed |= splitAlloca(AI, P); - - DEBUG(dbgs() << " Speculating PHIs\n"); - while (!SpeculatablePHIs.empty()) - speculatePHINodeLoads(*SpeculatablePHIs.pop_back_val()); - - DEBUG(dbgs() << " Speculating Selects\n"); - while (!SpeculatableSelects.empty()) - speculateSelectInstLoads(*SpeculatableSelects.pop_back_val()); - - return Changed; + return splitAlloca(AI, P) || Changed; } /// \brief Delete the dead instructions accumulated in this run. |