diff options
Diffstat (limited to 'lib/Transforms/Scalar/SROA.cpp')
| -rw-r--r-- | lib/Transforms/Scalar/SROA.cpp | 2227 |
1 files changed, 972 insertions, 1255 deletions
diff --git a/lib/Transforms/Scalar/SROA.cpp b/lib/Transforms/Scalar/SROA.cpp index 717c3f449a..985e57cde4 100644 --- a/lib/Transforms/Scalar/SROA.cpp +++ b/lib/Transforms/Scalar/SROA.cpp @@ -47,6 +47,7 @@ #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" @@ -110,17 +111,40 @@ typedef llvm::IRBuilder<false, ConstantFolder, } namespace { -/// \brief A common base class for representing a half-open byte range. -struct ByteRange { +/// \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 The beginning offset of the range. uint64_t BeginOffset; /// \brief The ending offset, not included in the range. uint64_t EndOffset; - ByteRange() : BeginOffset(), EndOffset() {} - ByteRange(uint64_t BeginOffset, uint64_t EndOffset) - : BeginOffset(BeginOffset), EndOffset(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); } /// \brief Support for ordering ranges. /// @@ -128,99 +152,37 @@ struct ByteRange { /// 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 ByteRange &RHS) const { - if (BeginOffset < RHS.BeginOffset) return true; - if (BeginOffset > RHS.BeginOffset) return false; - if (EndOffset > RHS.EndOffset) return true; + 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; return false; } /// \brief Support comparison with a single offset to allow binary searches. - friend bool operator<(const ByteRange &LHS, uint64_t RHSOffset) { - return LHS.BeginOffset < RHSOffset; + friend LLVM_ATTRIBUTE_UNUSED bool operator<(const Partition &LHS, + uint64_t RHSOffset) { + return LHS.beginOffset() < RHSOffset; } - friend LLVM_ATTRIBUTE_UNUSED bool operator<(uint64_t LHSOffset, - const ByteRange &RHS) { - return LHSOffset < RHS.BeginOffset; - } - - bool operator==(const ByteRange &RHS) const { - return BeginOffset == RHS.BeginOffset && EndOffset == RHS.EndOffset; - } - bool operator!=(const ByteRange &RHS) const { return !operator==(RHS); } -}; - -/// \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; + const Partition &RHS) { + return LHSOffset < RHS.beginOffset(); } - /// \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; + bool operator==(const Partition &RHS) const { + return isSplittable() == RHS.isSplittable() && + beginOffset() == RHS.beginOffset() && endOffset() == RHS.endOffset(); } - - 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(); } + bool operator!=(const Partition &RHS) const { return !operator==(RHS); } }; -} +} // end anonymous namespace namespace llvm { -template <> struct isPodLike<Partition> : llvm::true_type {}; -template <> struct isPodLike<PartitionUse> : llvm::true_type {}; +template <typename T> struct isPodLike; +template <> struct isPodLike<Partition> { + static const bool value = true; +}; } namespace { @@ -257,46 +219,6 @@ 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 @@ -320,66 +242,12 @@ 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 printUsers(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 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; @@ -389,8 +257,6 @@ 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. @@ -414,14 +280,6 @@ 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 @@ -439,26 +297,6 @@ 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(); }; } @@ -489,6 +327,10 @@ 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) @@ -497,6 +339,11 @@ 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 @@ -507,7 +354,7 @@ private: << AllocSize << " byte alloca:\n" << " alloca: " << P.AI << "\n" << " use: " << I << "\n"); - return; + return markAsDead(I); } uint64_t BeginOffset = Offset.getZExtValue(); @@ -528,8 +375,21 @@ private: EndOffset = AllocSize; } - Partition New(BeginOffset, EndOffset, IsSplittable); - P.Partitions.push_back(New); + 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); } void handleLoadOrStore(Type *Ty, Instruction &I, const APInt &Offset, @@ -582,7 +442,7 @@ private: << " byte alloca:\n" << " alloca: " << P.AI << "\n" << " use: " << SI << "\n"); - return; + return markAsDead(SI); } assert((!SI.isSimple() || ValOp->getType()->isSingleValueType()) && @@ -597,7 +457,7 @@ private: if ((Length && Length->getValue() == 0) || (IsOffsetKnown && !Offset.isNegative() && Offset.uge(AllocSize))) // Zero-length mem transfer intrinsics can be ignored entirely. - return; + return markAsDead(II); if (!IsOffsetKnown) return PI.setAborted(&II); @@ -613,7 +473,7 @@ private: if ((Length && Length->getValue() == 0) || (IsOffsetKnown && !Offset.isNegative() && Offset.uge(AllocSize))) // Zero-length mem transfer intrinsics can be ignored entirely. - return; + return markAsDead(II); if (!IsOffsetKnown) return PI.setAborted(&II); @@ -622,63 +482,44 @@ private: uint64_t Size = Length ? Length->getLimitedValue() : AllocSize - RawOffset; - MemTransferOffsets &Offsets = P.MemTransferInstData[&II]; - - // Only intrinsics with a constant length can be split. - Offsets.IsSplittable = Length; + // 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); - if (*U == II.getRawDest()) { - Offsets.DestBegin = RawOffset; - Offsets.DestEnd = RawOffset + Size; - } - if (*U == II.getRawSource()) { - Offsets.SourceBegin = RawOffset; - Offsets.SourceEnd = RawOffset + Size; + return insertUse(II, Offset, Size, /*IsSplittable=*/false);; } - // 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]; + // 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]; // 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() && Offsets.SourceBegin == Offsets.DestBegin) { - P.Partitions[PrevIdx].kill(); - return; + if (!II.isVolatile() && PrevP.beginOffset() == RawOffset) { + PrevP.kill(); + return markAsDead(II); } // Otherwise we have an offset transfer within the same alloca. We can't // split those. - 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; + PrevP.makeUnsplittable(); } - // 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; - } + 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."); } // Disable SRoA for any intrinsics except for lifetime invariants. @@ -747,234 +588,36 @@ private: void visitPHINode(PHINode &PN) { if (PN.use_empty()) - return; + return markAsDead(PN); if (!IsOffsetKnown) return PI.setAborted(&PN); // See if we already have computed info on this node. - std::pair<uint64_t, bool> &PHIInfo = P.PHIOrSelectSizes[&PN]; - if (PHIInfo.first) { - PHIInfo.second = true; - insertUse(PN, Offset, PHIInfo.first); - return; - } - - // 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; - 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); - - return; - } - if (!IsOffsetKnown) - return PI.setAborted(&SI); - - // See if we already have computed info on this node. - 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); + 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); } - } - - 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. - if ((Offset.isNegative() && Offset.uge(Size)) || + // 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); return; } - insertUse(User, Offset, Size); - } - - void visitPHINode(PHINode &PN) { - if (PN.use_empty()) - return markAsDead(PN); - - assert(IsOffsetKnown); - insertPHIOrSelect(PN, Offset); + insertUse(PN, Offset, PHISize); } 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 @@ -987,110 +630,42 @@ private: return; } + if (!IsOffsetKnown) + return PI.setAborted(&SI); - assert(IsOffsetKnown); - insertPHIOrSelect(SI, Offset); - } - - /// \brief Unreachable, we've already visited the alloca once. - void visitInstruction(Instruction &I) { - llvm_unreachable("Unhandled instruction in use builder."); - } -}; - -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); + // 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); } - // 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; + // 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)) || + (!Offset.isNegative() && Offset.uge(AllocSize))) { + P.DeadOperands.push_back(U); + return; } - 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; - } - } + insertUse(SI, Offset, SelectSize); } - // 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())); + /// \brief Disable SROA entirely if there are unhandled users of the alloca. + void visitInstruction(Instruction &I) { + PI.setAborted(&I); } - Partitions.erase(Partitions.end() - NumDeadPartitions, Partitions.end()); +}; + +namespace { +struct IsPartitionDead { + bool operator()(const Partition &P) { return P.isDead(); } +}; } AllocaPartitioning::AllocaPartitioning(const DataLayout &TD, AllocaInst &AI) @@ -1114,122 +689,37 @@ AllocaPartitioning::AllocaPartitioning(const DataLayout &TD, AllocaInst &AI) // and the sizes to be in descending order. std::sort(Partitions.begin(), 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(); - } + Partitions.erase( + std::remove_if(Partitions.begin(), Partitions.end(), IsPartitionDead()), + Partitions.end()); // Record how many partitions we end up with. NumAllocaPartitions += Partitions.size(); MaxPartitionsPerAlloca = std::max<unsigned>(Partitions.size(), MaxPartitionsPerAlloca); - // 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; + NumAllocaPartitionUses += Partitions.size(); + MaxPartitionUsesPerAlloca = + std::max<unsigned>(Partitions.size(), MaxPartitionUsesPerAlloca); } #if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP) void AllocaPartitioning::print(raw_ostream &OS, const_iterator I, StringRef Indent) const { - OS << Indent << "partition #" << (I - begin()) - << " [" << I->BeginOffset << "," << I->EndOffset << ")" - << (I->IsSplittable ? " (splittable)" : "") - << (Uses[I - begin()].empty() ? " (zero uses)" : "") - << "\n"; + printPartition(OS, I, Indent); + printUse(OS, I, Indent); } -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::printPartition(raw_ostream &OS, const_iterator I, + StringRef Indent) const { + OS << Indent << "[" << I->beginOffset() << "," << I->endOffset() << ")" + << " partition #" << (I - begin()) + << (I->isSplittable() ? " (splittable)" : "") << "\n"; +} + +void AllocaPartitioning::printUse(raw_ostream &OS, const_iterator I, + StringRef Indent) const { + OS << Indent << " used by: " << *I->getUse()->getUser() << "\n"; } void AllocaPartitioning::print(raw_ostream &OS) const { @@ -1241,10 +731,8 @@ 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); } @@ -1252,7 +740,6 @@ void AllocaPartitioning::dump() const { print(dbgs()); } #endif // !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP) - namespace { /// \brief Implementation of LoadAndStorePromoter for promoting allocas. /// @@ -1390,6 +877,21 @@ 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), @@ -1407,9 +909,11 @@ private: friend class AllocaPartitionRewriter; friend class AllocaPartitionVectorRewriter; - bool rewriteAllocaPartition(AllocaInst &AI, - AllocaPartitioning &P, - AllocaPartitioning::iterator PI); + bool rewritePartitions(AllocaInst &AI, AllocaPartitioning &P, + AllocaPartitioning::iterator B, + AllocaPartitioning::iterator E, + int64_t BeginOffset, int64_t EndOffset, + ArrayRef<AllocaPartitioning::iterator> SplitUses); bool splitAlloca(AllocaInst &AI, AllocaPartitioning &P); bool runOnAlloca(AllocaInst &AI); void deleteDeadInstructions(SmallPtrSet<AllocaInst *, 4> &DeletedAllocas); @@ -1429,286 +933,247 @@ INITIALIZE_PASS_DEPENDENCY(DominatorTree) INITIALIZE_PASS_END(SROA, "sroa", "Scalar Replacement Of Aggregates", false, false) -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>; +/// 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; - const DataLayout &TD; - AllocaPartitioning &P; - SROA &Pass; + 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. -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 (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; -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 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; } - // 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; + if (Ty && Ty != UserTy) + return 0; - // If the predecessor has a single successor, then the edge isn't - // critical. - if (TI->getNumSuccessors() == 1) - continue; + Ty = UserTy; + } + return Ty; +} - // 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; +/// 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; + // 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; - } - return true; + // 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; } - void visitPHINode(PHINode &PN) { - DEBUG(dbgs() << " original: " << PN << "\n"); + if (!HaveLoad) + return false; - SmallVector<LoadInst *, 4> Loads; - if (!isSafePHIToSpeculate(PN, Loads)) - return; + // 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; - assert(!Loads.empty()); + // If the predecessor has a single successor, then the edge isn't + // critical. + if (TI->getNumSuccessors() == 1) + continue; - Type *LoadTy = cast<PointerType>(PN.getType())->getElementType(); - IRBuilderTy PHIBuilder(&PN); - PHINode *NewPN = PHIBuilder.CreatePHI(LoadTy, PN.getNumIncomingValues(), - PN.getName() + ".sroa.speculated"); + // 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; - // 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 false; + } - // 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; + return true; +} - // Try to lookup and rewrite any partition uses corresponding to this phi - // input. - AllocaPartitioning::iterator PI - = P.findPartitionForPHIOrSelectOperand(InUse); - if (PI == P.end()) - 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(); +} - // 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); - } +/// 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; - return true; + // 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; } - 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; + return true; +} - 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); - } - } +static void speculateSelectInstLoads(SelectInst &SI) { + DEBUG(dbgs() << " original: " << SI << "\n"); - 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(); + 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"); - 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; - - // 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); - } + NumLoadsSpeculated += 2; - Value *V = IRB.CreateSelect(SI.getCondition(), TL, FL, - LI->getName() + ".sroa.speculated"); + // 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); + } - 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]); - } - } + Value *V = IRB.CreateSelect(SI.getCondition(), TL, FL, + LI->getName() + ".sroa.speculated"); - DEBUG(dbgs() << " speculated to: " << *V << "\n"); - LI->replaceAllUsesWith(V); - Pass.DeadInsts.insert(LI); - } + DEBUG(dbgs() << " speculated to: " << *V << "\n"); + LI->replaceAllUsesWith(V); + LI->eraseFromParent(); } -}; + SI.eraseFromParent(); } /// \brief Build a GEP out of a base pointer and indices. @@ -2024,6 +1489,73 @@ 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 @@ -2032,13 +1564,11 @@ static Value *convertValue(const DataLayout &DL, IRBuilderTy &IRB, Value *V, /// 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_use_iterator I, - AllocaPartitioning::const_use_iterator E) { +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) { VectorType *Ty = dyn_cast<VectorType>(AllocaTy); if (!Ty) return false; @@ -2053,54 +1583,85 @@ static bool isVectorPromotionViable(const DataLayout &TD, "vector size not a multiple of element size?"); ElementSize /= 8; - for (; I != E; ++I) { - Use *U = I->getUse(); - if (!U) - continue; // Skip dead use. - - uint64_t BeginOffset = I->BeginOffset - PartitionBeginOffset; - uint64_t BeginIndex = BeginOffset / ElementSize; - if (BeginIndex * ElementSize != BeginOffset || - BeginIndex >= Ty->getNumElements()) + for (; I != E; ++I) + if (!isVectorPromotionViableForPartitioning( + TD, P, PartitionBeginOffset, PartitionEndOffset, Ty, ElementSize, + I)) return false; - uint64_t EndOffset = I->EndOffset - PartitionBeginOffset; - uint64_t EndIndex = EndOffset / ElementSize; - if (EndIndex * ElementSize != EndOffset || - EndIndex > Ty->getNumElements()) + + for (ArrayRef<AllocaPartitioning::iterator>::const_iterator + SUI = SplitUses.begin(), + SUE = SplitUses.end(); + SUI != SUE; ++SUI) + if (!isVectorPromotionViableForPartitioning( + TD, P, PartitionBeginOffset, PartitionEndOffset, Ty, ElementSize, + *SUI)) return false; - assert(EndIndex > BeginIndex && "Empty vector!"); - uint64_t NumElements = EndIndex - BeginIndex; - Type *PartitionTy - = (NumElements == 1) ? Ty->getElementType() - : VectorType::get(Ty->getElementType(), NumElements); + return true; +} - if (MemIntrinsic *MI = dyn_cast<MemIntrinsic>(U->getUser())) { - if (MI->isVolatile()) - return false; - 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. +/// \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(); + + if (LoadInst *LI = dyn_cast<LoadInst>(U->getUser())) { + if (LI->isVolatile()) return false; - } else if (LoadInst *LI = dyn_cast<LoadInst>(U->getUser())) { - if (LI->isVolatile()) - return false; - if (!canConvertValue(TD, PartitionTy, LI->getType())) + if (RelBegin == 0 && RelEnd == Size) + WholeAllocaOp = true; + if (IntegerType *ITy = dyn_cast<IntegerType>(LI->getType())) { + if (ITy->getBitWidth() < TD.getTypeStoreSizeInBits(ITy)) return false; - } else if (StoreInst *SI = dyn_cast<StoreInst>(U->getUser())) { - if (SI->isVolatile()) - return false; - if (!canConvertValue(TD, SI->getValueOperand()->getType(), PartitionTy)) + } 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()) + return false; + if (RelBegin == 0 && RelEnd == Size) + WholeAllocaOp = true; + if (IntegerType *ITy = dyn_cast<IntegerType>(ValueTy)) { + if (ITy->getBitWidth() < TD.getTypeStoreSizeInBits(ITy)) return false; - } else { + } 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. 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; } @@ -2110,12 +1671,12 @@ static bool isVectorPromotionViable(const DataLayout &TD, /// 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_use_iterator I, - AllocaPartitioning::const_use_iterator E) { +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) { uint64_t SizeInBits = TD.getTypeSizeInBits(AllocaTy); // Don't create integer types larger than the maximum bitwidth. if (SizeInBits > IntegerType::MAX_INT_BITS) @@ -2133,74 +1694,34 @@ static bool isIntegerWideningViable(const DataLayout &TD, !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); - // 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). + // 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). bool WholeAllocaOp = false; - for (; I != E; ++I) { - Use *U = I->getUse(); - if (!U) - continue; // Skip dead use. - 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) + for (; I != E; ++I) + if (!isIntegerWideningViableForPartitioning(TD, AllocaTy, AllocBeginOffset, + Size, P, I, WholeAllocaOp)) 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 { + for (ArrayRef<AllocaPartitioning::iterator>::const_iterator + SUI = SplitUses.begin(), + SUE = SplitUses.end(); + SUI != SUE; ++SUI) + if (!isIntegerWideningViableForPartitioning(TD, AllocaTy, AllocBeginOffset, + Size, P, *SUI, WholeAllocaOp)) return false; - } - } + return WholeAllocaOp; } @@ -2345,6 +1866,7 @@ 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; @@ -2374,6 +1896,7 @@ 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; @@ -2384,78 +1907,70 @@ 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) - : 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 && + 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"); - 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())); + ++NumVectorized; } + assert((!IsVectorPromotable && !IsIntegerPromotable) || + IsVectorPromotable != IsIntegerPromotable); + } + + bool visit(AllocaPartitioning::const_iterator I) { bool CanSROA = true; - 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) { + 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) 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, Type *PointerTy) { - assert(BeginOffset >= NewAllocaBeginOffset); - APInt Offset(TD.getPointerSizeInBits(), BeginOffset - NewAllocaBeginOffset); - return getAdjustedPtr(IRB, TD, &NewAI, Offset, PointerTy); + Value *getAdjustedAllocaPtr(IRBuilderTy &IRB, uint64_t Offset, + Type *PointerTy) { + assert(Offset >= NewAllocaBeginOffset); + return getAdjustedPtr(IRB, TD, &NewAI, APInt(TD.getPointerSizeInBits(), + Offset - NewAllocaBeginOffset), + PointerTy); } /// \brief Compute suitable alignment to access an offset into the new alloca. @@ -2466,12 +1981,6 @@ 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. /// @@ -2482,14 +1991,6 @@ 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; @@ -2505,9 +2006,10 @@ private: Pass.DeadInsts.insert(I); } - Value *rewriteVectorizedLoadInst() { - unsigned BeginIndex = getIndex(BeginOffset); - unsigned EndIndex = getIndex(EndOffset); + Value *rewriteVectorizedLoadInst(uint64_t NewBeginOffset, + uint64_t NewEndOffset) { + unsigned BeginIndex = getIndex(NewBeginOffset); + unsigned EndIndex = getIndex(NewEndOffset); assert(EndIndex > BeginIndex && "Empty vector!"); Value *V = IRB.CreateAlignedLoad(&NewAI, NewAI.getAlignment(), @@ -2515,15 +2017,16 @@ private: return extractVector(IRB, V, BeginIndex, EndIndex, "vec"); } - Value *rewriteIntegerLoad(LoadInst &LI) { + Value *rewriteIntegerLoad(LoadInst &LI, uint64_t NewBeginOffset, + uint64_t NewEndOffset) { 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(BeginOffset >= NewAllocaBeginOffset && "Out of bounds offset"); - uint64_t Offset = BeginOffset - NewAllocaBeginOffset; - if (Offset > 0 || EndOffset < NewAllocaEndOffset) + assert(NewBeginOffset >= NewAllocaBeginOffset && "Out of bounds offset"); + uint64_t Offset = NewBeginOffset - NewAllocaBeginOffset; + if (Offset > 0 || NewEndOffset < NewAllocaEndOffset) V = extractInteger(TD, IRB, V, cast<IntegerType>(LI.getType()), Offset, "extract"); return V; @@ -2534,25 +2037,32 @@ private: Value *OldOp = LI.getOperand(0); assert(OldOp == OldPtr); - uint64_t Size = EndOffset - BeginOffset; + // 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; Type *TargetTy = IsSplit ? Type::getIntNTy(LI.getContext(), Size * 8) : LI.getType(); bool IsPtrAdjusted = false; Value *V; if (VecTy) { - V = rewriteVectorizedLoadInst(); + V = rewriteVectorizedLoadInst(NewBeginOffset, NewEndOffset); } else if (IntTy && LI.getType()->isIntegerTy()) { - V = rewriteIntegerLoad(LI); - } else if (BeginOffset == NewAllocaBeginOffset && + V = rewriteIntegerLoad(LI, NewBeginOffset, NewEndOffset); + } else if (NewBeginOffset == 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, LTy), - getPartitionTypeAlign(TargetTy), - LI.isVolatile(), "load"); + V = IRB.CreateAlignedLoad( + getAdjustedAllocaPtr(IRB, NewBeginOffset, LTy), + getOffsetTypeAlign(TargetTy, NewBeginOffset - NewAllocaBeginOffset), + LI.isVolatile(), "load"); IsPtrAdjusted = true; } V = convertValue(TD, IRB, V, TargetTy); @@ -2574,7 +2084,7 @@ private: // LI only used for this computation. Value *Placeholder = new LoadInst(UndefValue::get(LI.getType()->getPointerTo())); - V = insertInteger(TD, IRB, Placeholder, V, BeginOffset, + V = insertInteger(TD, IRB, Placeholder, V, NewBeginOffset, "insert"); LI.replaceAllUsesWith(V); Placeholder->replaceAllUsesWith(&LI); @@ -2589,11 +2099,12 @@ private: return !LI.isVolatile() && !IsPtrAdjusted; } - bool rewriteVectorizedStoreInst(Value *V, - StoreInst &SI, Value *OldOp) { + bool rewriteVectorizedStoreInst(Value *V, StoreInst &SI, Value *OldOp, + uint64_t NewBeginOffset, + uint64_t NewEndOffset) { if (V->getType() != VecTy) { - unsigned BeginIndex = getIndex(BeginOffset); - unsigned EndIndex = getIndex(EndOffset); + unsigned BeginIndex = getIndex(NewBeginOffset); + unsigned EndIndex = getIndex(NewEndOffset); assert(EndIndex > BeginIndex && "Empty vector!"); unsigned NumElements = EndIndex - BeginIndex; assert(NumElements <= VecTy->getNumElements() && "Too many elements!"); @@ -2616,7 +2127,8 @@ private: return true; } - bool rewriteIntegerStore(Value *V, StoreInst &SI) { + bool rewriteIntegerStore(Value *V, StoreInst &SI, + uint64_t NewBeginOffset, uint64_t NewEndOffset) { assert(IntTy && "We cannot extract an integer from the alloca"); assert(!SI.isVolatile()); if (TD.getTypeSizeInBits(V->getType()) != IntTy->getBitWidth()) { @@ -2649,37 +2161,45 @@ private: if (AllocaInst *AI = dyn_cast<AllocaInst>(V->stripInBoundsOffsets())) Pass.PostPromotionWorklist.insert(AI); - uint64_t Size = EndOffset - BeginOffset; + // 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; 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, BeginOffset, + V = extractInteger(TD, IRB, V, NarrowTy, NewBeginOffset, "extract"); } if (VecTy) - return rewriteVectorizedStoreInst(V, SI, OldOp); + return rewriteVectorizedStoreInst(V, SI, OldOp, NewBeginOffset, + NewEndOffset); if (IntTy && V->getType()->isIntegerTy()) - return rewriteIntegerStore(V, SI); + return rewriteIntegerStore(V, SI, NewBeginOffset, NewEndOffset); StoreInst *NewSI; - if (BeginOffset == NewAllocaBeginOffset && - EndOffset == NewAllocaEndOffset && + if (NewBeginOffset == NewAllocaBeginOffset && + NewEndOffset == 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, V->getType()->getPointerTo()); - NewSI = IRB.CreateAlignedStore(V, NewPtr, - getPartitionTypeAlign(V->getType()), - SI.isVolatile()); + Value *NewPtr = getAdjustedAllocaPtr(IRB, NewBeginOffset, + V->getType()->getPointerTo()); + NewSI = IRB.CreateAlignedStore( + V, NewPtr, getOffsetTypeAlign( + V->getType(), NewBeginOffset - NewAllocaBeginOffset), + SI.isVolatile()); } (void)NewSI; Pass.DeadInsts.insert(&SI); @@ -2730,9 +2250,12 @@ 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())) { - II.setDest(getAdjustedAllocaPtr(IRB, II.getRawDest()->getType())); + assert(!IsSplit); + assert(BeginOffset >= NewAllocaBeginOffset); + II.setDest( + getAdjustedAllocaPtr(IRB, BeginOffset, II.getRawDest()->getType())); Type *CstTy = II.getAlignmentCst()->getType(); - II.setAlignment(ConstantInt::get(CstTy, getPartitionAlign())); + II.setAlignment(ConstantInt::get(CstTy, getOffsetAlign(BeginOffset))); deleteIfTriviallyDead(OldPtr); return false; @@ -2744,21 +2267,27 @@ 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, EndOffset - BeginOffset); - CallInst *New - = IRB.CreateMemSet(getAdjustedAllocaPtr(IRB, - II.getRawDest()->getType()), - II.getValue(), Size, getPartitionAlign(), - II.isVolatile()); + Constant *Size = ConstantInt::get(SizeTy, NewEndOffset - NewBeginOffset); + CallInst *New = IRB.CreateMemSet( + getAdjustedAllocaPtr(IRB, NewBeginOffset, II.getRawDest()->getType()), + II.getValue(), Size, getOffsetAlign(PartitionOffset), + II.isVolatile()); (void)New; DEBUG(dbgs() << " to: " << *New << "\n"); return false; @@ -2775,8 +2304,8 @@ private: // If this is a memset of a vectorized alloca, insert it. assert(ElementTy == ScalarTy); - unsigned BeginIndex = getIndex(BeginOffset); - unsigned EndIndex = getIndex(EndOffset); + unsigned BeginIndex = getIndex(NewBeginOffset); + unsigned EndIndex = getIndex(NewEndOffset); assert(EndIndex > BeginIndex && "Empty vector!"); unsigned NumElements = EndIndex - BeginIndex; assert(NumElements <= VecTy->getNumElements() && "Too many elements!"); @@ -2795,7 +2324,7 @@ private: // set integer. assert(!II.isVolatile()); - uint64_t Size = EndOffset - BeginOffset; + uint64_t Size = NewEndOffset - NewBeginOffset; V = getIntegerSplat(II.getValue(), Size); if (IntTy && (BeginOffset != NewAllocaBeginOffset || @@ -2803,8 +2332,7 @@ private: Value *Old = IRB.CreateAlignedLoad(&NewAI, NewAI.getAlignment(), "oldload"); Old = convertValue(TD, IRB, Old, IntTy); - assert(BeginOffset >= NewAllocaBeginOffset && "Out of bounds offset"); - uint64_t Offset = BeginOffset - NewAllocaBeginOffset; + uint64_t Offset = NewBeginOffset - NewAllocaBeginOffset; V = insertInteger(TD, IRB, Old, V, Offset, "insert"); } else { assert(V->getType() == IntTy && @@ -2813,8 +2341,8 @@ private: V = convertValue(TD, IRB, V, AllocaTy); } else { // Established these invariants above. - assert(BeginOffset == NewAllocaBeginOffset); - assert(EndOffset == NewAllocaEndOffset); + assert(NewBeginOffset == NewAllocaBeginOffset); + assert(NewEndOffset == NewAllocaEndOffset); V = getIntegerSplat(II.getValue(), TD.getTypeSizeInBits(ScalarTy) / 8); if (VectorType *AllocaVecTy = dyn_cast<VectorType>(AllocaTy)) @@ -2836,21 +2364,25 @@ 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, BeginOffset - (IsDest ? MTO.DestBegin - : MTO.SourceBegin)); + APInt RelOffset(IntPtrWidth, NewBeginOffset - BeginOffset); unsigned Align = II.getAlignment(); + uint64_t PartitionOffset = NewBeginOffset - NewAllocaBeginOffset; if (Align > 1) - Align = MinAlign(RelOffset.zextOrTrunc(64).getZExtValue(), - MinAlign(II.getAlignment(), getPartitionAlign())); + Align = MinAlign( + RelOffset.zextOrTrunc(64).getZExtValue(), + MinAlign(II.getAlignment(), getOffsetAlign(PartitionOffset))); // For unsplit intrinsics, we simply modify the source and destination // pointers in place. This isn't just an optimization, it is a matter of @@ -2859,12 +2391,14 @@ 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 (!MTO.IsSplittable) { + if (!IsSplittable) { Value *OldOp = IsDest ? II.getRawDest() : II.getRawSource(); if (IsDest) - II.setDest(getAdjustedAllocaPtr(IRB, II.getRawDest()->getType())); + II.setDest( + getAdjustedAllocaPtr(IRB, BeginOffset, II.getRawDest()->getType())); else - II.setSource(getAdjustedAllocaPtr(IRB, II.getRawSource()->getType())); + II.setSource(getAdjustedAllocaPtr(IRB, BeginOffset, + II.getRawSource()->getType())); Type *CstTy = II.getAlignmentCst()->getType(); II.setAlignment(ConstantInt::get(CstTy, Align)); @@ -2882,24 +2416,21 @@ 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(BeginOffset == OrigBegin); - (void)OrigBegin; + assert(NewBeginOffset == BeginOffset); // Rewrite the size as needed. - if (EndOffset != OrigEnd) + if (NewEndOffset != EndOffset) II.setLength(ConstantInt::get(II.getLength()->getType(), - EndOffset - BeginOffset)); + NewEndOffset - NewBeginOffset)); return false; } // Record this instruction for deletion. @@ -2920,11 +2451,11 @@ private: // a single, simple GEP in most cases. OtherPtr = getAdjustedPtr(IRB, TD, OtherPtr, RelOffset, OtherPtrTy); - Value *OurPtr - = getAdjustedAllocaPtr(IRB, IsDest ? II.getRawDest()->getType() - : II.getRawSource()->getType()); + Value *OurPtr = getAdjustedAllocaPtr( + IRB, NewBeginOffset, + IsDest ? II.getRawDest()->getType() : II.getRawSource()->getType()); Type *SizeTy = II.getLength()->getType(); - Constant *Size = ConstantInt::get(SizeTy, EndOffset - BeginOffset); + Constant *Size = ConstantInt::get(SizeTy, NewEndOffset - NewBeginOffset); CallInst *New = IRB.CreateMemCpy(IsDest ? OurPtr : OtherPtr, IsDest ? OtherPtr : OurPtr, @@ -2940,11 +2471,11 @@ private: if (!Align) Align = 1; - bool IsWholeAlloca = BeginOffset == NewAllocaBeginOffset && - EndOffset == NewAllocaEndOffset; - uint64_t Size = EndOffset - BeginOffset; - unsigned BeginIndex = VecTy ? getIndex(BeginOffset) : 0; - unsigned EndIndex = VecTy ? getIndex(EndOffset) : 0; + bool IsWholeAlloca = NewBeginOffset == NewAllocaBeginOffset && + NewEndOffset == NewAllocaEndOffset; + uint64_t Size = NewEndOffset - NewBeginOffset; + unsigned BeginIndex = VecTy ? getIndex(NewBeginOffset) : 0; + unsigned EndIndex = VecTy ? getIndex(NewEndOffset) : 0; unsigned NumElements = EndIndex - BeginIndex; IntegerType *SubIntTy = IntTy ? Type::getIntNTy(IntTy->getContext(), Size*8) : 0; @@ -2975,8 +2506,7 @@ private: Src = IRB.CreateAlignedLoad(&NewAI, NewAI.getAlignment(), "load"); Src = convertValue(TD, IRB, Src, IntTy); - assert(BeginOffset >= NewAllocaBeginOffset && "Out of bounds offset"); - uint64_t Offset = BeginOffset - NewAllocaBeginOffset; + uint64_t Offset = NewBeginOffset - NewAllocaBeginOffset; Src = extractInteger(TD, IRB, Src, SubIntTy, Offset, "extract"); } else { Src = IRB.CreateAlignedLoad(SrcPtr, Align, II.isVolatile(), @@ -2991,8 +2521,7 @@ private: Value *Old = IRB.CreateAlignedLoad(&NewAI, NewAI.getAlignment(), "oldload"); Old = convertValue(TD, IRB, Old, IntTy); - assert(BeginOffset >= NewAllocaBeginOffset && "Out of bounds offset"); - uint64_t Offset = BeginOffset - NewAllocaBeginOffset; + uint64_t Offset = NewBeginOffset - NewAllocaBeginOffset; Src = insertInteger(TD, IRB, Old, Src, Offset, "insert"); Src = convertValue(TD, IRB, Src, NewAllocaTy); } @@ -3010,13 +2539,20 @@ 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()), - EndOffset - BeginOffset); - Value *Ptr = getAdjustedAllocaPtr(IRB, II.getArgOperand(1)->getType()); + NewEndOffset - NewBeginOffset); + Value *Ptr = + getAdjustedAllocaPtr(IRB, NewBeginOffset, II.getArgOperand(1)->getType()); Value *New; if (II.getIntrinsicID() == Intrinsic::lifetime_start) New = IRB.CreateLifetimeStart(Ptr, Size); @@ -3030,6 +2566,8 @@ 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 @@ -3039,21 +2577,33 @@ private: PtrBuilder.SetNamePrefix(Twine(NewAI.getName()) + "." + Twine(BeginOffset) + "."); - Value *NewPtr = getAdjustedAllocaPtr(PtrBuilder, OldPtr->getType()); + Value *NewPtr = + getAdjustedAllocaPtr(PtrBuilder, BeginOffset, 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); - return false; + + // 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. } 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, OldPtr->getType()); + Value *NewPtr = getAdjustedAllocaPtr(IRB, BeginOffset, OldPtr->getType()); // Replace the operands which were using the old pointer. if (SI.getOperand(1) == OldPtr) SI.setOperand(1, NewPtr); @@ -3062,7 +2612,16 @@ private: DEBUG(dbgs() << " to: " << SI << "\n"); deleteIfTriviallyDead(OldPtr); - return false; + + // 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. } }; @@ -3432,57 +2991,52 @@ 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::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); +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; // 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 *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); + 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); // 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 (AllocaTy == AI.getAllocatedType()) { - assert(PI->BeginOffset == 0 && + if (PartitionTy == AI.getAllocatedType()) { + assert(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) { @@ -3491,54 +3045,207 @@ bool SROA::rewriteAllocaPartition(AllocaInst &AI, // type. Alignment = TD->getABITypeAlignment(AI.getAllocatedType()); } - Alignment = MinAlign(Alignment, PI->BeginOffset); + Alignment = MinAlign(Alignment, BeginOffset); // If we will get at least this much alignment from the type alone, leave // the alloca's alignment unconstrained. - if (Alignment <= TD->getABITypeAlignment(AllocaTy)) + if (Alignment <= TD->getABITypeAlignment(PartitionTy)) Alignment = 0; - NewAI = new AllocaInst(AllocaTy, 0, Alignment, - AI.getName() + ".sroa." + Twine(PI - P.begin()), - &AI); + NewAI = new AllocaInst(PartitionTy, 0, Alignment, + AI.getName() + ".sroa." + Twine(B - P.begin()), &AI); ++NumNewAllocas; } DEBUG(dbgs() << "Rewriting alloca partition " - << "[" << PI->BeginOffset << "," << PI->EndOffset << ") to: " - << *NewAI << "\n"); + << "[" << BeginOffset << "," << EndOffset << ") to: " << *NewAI + << "\n"); - // 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. + // 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. unsigned PPWOldSize = PostPromotionWorklist.size(); - - 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) { + 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) { 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; - for (AllocaPartitioning::iterator PI = P.begin(), PE = P.end(); PI != PE; - ++PI) - Changed |= rewriteAllocaPartition(AI, P, PI); + 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(); + } return Changed; } @@ -3601,7 +3308,17 @@ bool SROA::runOnAlloca(AllocaInst &AI) { if (P.begin() == P.end()) return Changed; - return splitAlloca(AI, P) || 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; } /// \brief Delete the dead instructions accumulated in this run. |