- 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);