#include "llvm/ADT/SetVector.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/ADT/Statistic.h"
-#include "llvm/Analysis/AssumptionTracker.h"
+#include "llvm/Analysis/AssumptionCache.h"
#include "llvm/Analysis/Loads.h"
#include "llvm/Analysis/PtrUseVisitor.h"
#include "llvm/Analysis/ValueTracking.h"
const_iterator end() const { return Slices.end(); }
/// @}
+ /// \brief Erase a range of slices.
+ void erase(iterator Start, iterator Stop) { Slices.erase(Start, Stop); }
+
+ /// \brief Insert new slices for this alloca.
+ ///
+ /// This moves the slices into the alloca's slices collection, and re-sorts
+ /// everything so that the usual ordering properties of the alloca's slices
+ /// hold.
+ void insert(ArrayRef<Slice> NewSlices) {
+ int OldSize = Slices.size();
+ Slices.append(NewSlices.begin(), NewSlices.end());
+ auto SliceI = Slices.begin() + OldSize;
+ std::sort(SliceI, Slices.end());
+ std::inplace_merge(Slices.begin(), SliceI, Slices.end());
+ }
+
// Forward declare an iterator to befriend it.
class partition_iterator;
// by writing out the code here where we have tho underlying allocation
// size readily available.
APInt GEPOffset = Offset;
+ const DataLayout &DL = GEPI.getModule()->getDataLayout();
for (gep_type_iterator GTI = gep_type_begin(GEPI),
GTE = gep_type_end(GEPI);
GTI != GTE; ++GTI) {
void handleLoadOrStore(Type *Ty, Instruction &I, const APInt &Offset,
uint64_t Size, bool IsVolatile) {
- // We allow splitting of loads and stores where the type is an integer type
- // and cover the entire alloca. This prevents us from splitting over
- // eagerly.
- // FIXME: In the great blue eventually, we should eagerly split all integer
- // loads and stores, and then have a separate step that merges adjacent
- // alloca partitions into a single partition suitable for integer widening.
- // Or we should skip the merge step and rely on GVN and other passes to
- // merge adjacent loads and stores that survive mem2reg.
- bool IsSplittable =
- Ty->isIntegerTy() && !IsVolatile && Offset == 0 && Size >= AllocSize;
+ // We allow splitting of non-volatile loads and stores where the type is an
+ // integer type. These may be used to implement 'memcpy' or other "transfer
+ // of bits" patterns.
+ bool IsSplittable = Ty->isIntegerTy() && !IsVolatile;
insertUse(I, Offset, Size, IsSplittable);
}
if (!IsOffsetKnown)
return PI.setAborted(&LI);
+ const DataLayout &DL = LI.getModule()->getDataLayout();
uint64_t Size = DL.getTypeStoreSize(LI.getType());
return handleLoadOrStore(LI.getType(), LI, Offset, Size, LI.isVolatile());
}
if (!IsOffsetKnown)
return PI.setAborted(&SI);
+ const DataLayout &DL = SI.getModule()->getDataLayout();
uint64_t Size = DL.getTypeStoreSize(ValOp->getType());
// If this memory access can be shown to *statically* extend outside the
SmallVector<std::pair<Instruction *, Instruction *>, 4> Uses;
Visited.insert(Root);
Uses.push_back(std::make_pair(cast<Instruction>(*U), Root));
+ const DataLayout &DL = Root->getModule()->getDataLayout();
// If there are no loads or stores, the access is dead. We mark that as
// a size zero access.
Size = 0;
void AllocaSlices::print(raw_ostream &OS, const_iterator I,
StringRef Indent) const {
printSlice(OS, I, Indent);
+ OS << "\n";
printUse(OS, I, Indent);
}
StringRef Indent) const {
OS << Indent << "[" << I->beginOffset() << "," << I->endOffset() << ")"
<< " slice #" << (I - begin())
- << (I->isSplittable() ? " (splittable)" : "") << "\n";
+ << (I->isSplittable() ? " (splittable)" : "");
}
void AllocaSlices::printUse(raw_ostream &OS, const_iterator I,
} else {
continue;
}
- Instruction *DbgVal =
- DIB.insertDbgValueIntrinsic(Arg, 0, DIVariable(DVI->getVariable()),
- DIExpression(DVI->getExpression()), Inst);
- DbgVal->setDebugLoc(DVI->getDebugLoc());
+ DIB.insertDbgValueIntrinsic(Arg, 0, DIVariable(DVI->getVariable()),
+ DIExpression(DVI->getExpression()),
+ DVI->getDebugLoc(), Inst);
}
}
};
const bool RequiresDomTree;
LLVMContext *C;
- const DataLayout *DL;
DominatorTree *DT;
- AssumptionTracker *AT;
+ AssumptionCache *AC;
/// \brief Worklist of alloca instructions to simplify.
///
public:
SROA(bool RequiresDomTree = true)
: FunctionPass(ID), RequiresDomTree(RequiresDomTree), C(nullptr),
- DL(nullptr), DT(nullptr) {
+ DT(nullptr) {
initializeSROAPass(*PassRegistry::getPassRegistry());
}
bool runOnFunction(Function &F) override;
friend class PHIOrSelectSpeculator;
friend class AllocaSliceRewriter;
- bool rewritePartition(AllocaInst &AI, AllocaSlices &AS,
- AllocaSlices::Partition &P);
+ bool presplitLoadsAndStores(AllocaInst &AI, AllocaSlices &AS);
+ AllocaInst *rewritePartition(AllocaInst &AI, AllocaSlices &AS,
+ AllocaSlices::Partition &P);
bool splitAlloca(AllocaInst &AI, AllocaSlices &AS);
bool runOnAlloca(AllocaInst &AI);
void clobberUse(Use &U);
INITIALIZE_PASS_BEGIN(SROA, "sroa", "Scalar Replacement Of Aggregates", false,
false)
-INITIALIZE_PASS_DEPENDENCY(AssumptionTracker)
+INITIALIZE_PASS_DEPENDENCY(AssumptionCacheTracker)
INITIALIZE_PASS_DEPENDENCY(DominatorTreeWrapperPass)
INITIALIZE_PASS_END(SROA, "sroa", "Scalar Replacement Of Aggregates", false,
false)
///
/// FIXME: This should be hoisted into a generic utility, likely in
/// Transforms/Util/Local.h
-static bool isSafePHIToSpeculate(PHINode &PN, const DataLayout *DL = nullptr) {
+static bool isSafePHIToSpeculate(PHINode &PN) {
// 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.
if (!HaveLoad)
return false;
+ const DataLayout &DL = PN.getModule()->getDataLayout();
+
// 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.
// is already a load in the block, then we can move the load to the pred
// block.
if (InVal->isDereferenceablePointer(DL) ||
- isSafeToLoadUnconditionally(InVal, TI, MaxAlign, DL))
+ isSafeToLoadUnconditionally(InVal, TI, MaxAlign))
continue;
return false;
///
/// 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 *DL = nullptr) {
+static bool isSafeSelectToSpeculate(SelectInst &SI) {
Value *TValue = SI.getTrueValue();
Value *FValue = SI.getFalseValue();
+ const DataLayout &DL = SI.getModule()->getDataLayout();
bool TDerefable = TValue->isDereferenceablePointer(DL);
bool FDerefable = FValue->isDereferenceablePointer(DL);
// absolutely (e.g. allocas) or at this point because we can see other
// accesses to it.
if (!TDerefable &&
- !isSafeToLoadUnconditionally(TValue, LI, LI->getAlignment(), DL))
+ !isSafeToLoadUnconditionally(TValue, LI, LI->getAlignment()))
return false;
if (!FDerefable &&
- !isSafeToLoadUnconditionally(FValue, LI, LI->getAlignment(), DL))
+ !isSafeToLoadUnconditionally(FValue, LI, LI->getAlignment()))
return false;
}
if (Indices.size() == 1 && cast<ConstantInt>(Indices.back())->isZero())
return BasePtr;
- return IRB.CreateInBoundsGEP(BasePtr, Indices, NamePrefix + "sroa_idx");
+ return IRB.CreateInBoundsGEP(nullptr, BasePtr, Indices,
+ NamePrefix + "sroa_idx");
}
/// \brief Get a natural GEP off of the BasePtr walking through Ty toward
// We may end up computing an offset pointer that has the wrong type. If we
// never are able to compute one directly that has the correct type, we'll
- // fall back to it, so keep it around here.
+ // fall back to it, so keep it and the base it was computed from around here.
Value *OffsetPtr = nullptr;
+ Value *OffsetBasePtr;
// Remember any i8 pointer we come across to re-use if we need to do a raw
// byte offset.
Indices.clear();
if (Value *P = getNaturalGEPWithOffset(IRB, DL, Ptr, Offset, TargetTy,
Indices, NamePrefix)) {
- if (P->getType() == PointerTy) {
- // Zap any offset pointer that we ended up computing in previous rounds.
- if (OffsetPtr && OffsetPtr->use_empty())
- if (Instruction *I = dyn_cast<Instruction>(OffsetPtr))
- I->eraseFromParent();
+ // If we have a new natural pointer at the offset, clear out any old
+ // offset pointer we computed. Unless it is the base pointer or
+ // a non-instruction, we built a GEP we don't need. Zap it.
+ if (OffsetPtr && OffsetPtr != OffsetBasePtr)
+ if (Instruction *I = dyn_cast<Instruction>(OffsetPtr)) {
+ assert(I->use_empty() && "Built a GEP with uses some how!");
+ I->eraseFromParent();
+ }
+ OffsetPtr = P;
+ OffsetBasePtr = Ptr;
+ // If we also found a pointer of the right type, we're done.
+ if (P->getType() == PointerTy)
return P;
- }
- if (!OffsetPtr) {
- OffsetPtr = P;
- }
}
// Stash this pointer if we've found an i8*.
OffsetPtr = Int8PtrOffset == 0
? Int8Ptr
- : IRB.CreateInBoundsGEP(Int8Ptr, IRB.getInt(Int8PtrOffset),
+ : IRB.CreateInBoundsGEP(IRB.getInt8Ty(), Int8Ptr,
+ IRB.getInt(Int8PtrOffset),
NamePrefix + "sroa_raw_idx");
}
Ptr = OffsetPtr;
return Ptr;
}
+/// \brief Compute the adjusted alignment for a load or store from an offset.
+static unsigned getAdjustedAlignment(Instruction *I, uint64_t Offset,
+ const DataLayout &DL) {
+ unsigned Alignment;
+ Type *Ty;
+ if (auto *LI = dyn_cast<LoadInst>(I)) {
+ Alignment = LI->getAlignment();
+ Ty = LI->getType();
+ } else if (auto *SI = dyn_cast<StoreInst>(I)) {
+ Alignment = SI->getAlignment();
+ Ty = SI->getValueOperand()->getType();
+ } else {
+ llvm_unreachable("Only loads and stores are allowed!");
+ }
+
+ if (!Alignment)
+ Alignment = DL.getABITypeAlignment(Ty);
+
+ return MinAlign(Alignment, Offset);
+}
+
/// \brief Test whether we can convert a value from the old to the new type.
///
/// This predicate should be used to guard calls to convertValue in order to
BeginOffset < NewAllocaBeginOffset || EndOffset > NewAllocaEndOffset;
DEBUG(dbgs() << " rewriting " << (IsSplit ? "split " : ""));
DEBUG(AS.printSlice(dbgs(), I, ""));
+ DEBUG(dbgs() << "\n");
// Compute the intersecting offset range.
assert(BeginOffset < NewAllocaEndOffset);
// LI only used for this computation.
Value *Placeholder =
new LoadInst(UndefValue::get(LI.getType()->getPointerTo()));
- V = insertInteger(DL, IRB, Placeholder, V, NewBeginOffset, "insert");
+ V = insertInteger(DL, IRB, Placeholder, V, NewBeginOffset - BeginOffset,
+ "insert");
LI.replaceAllUsesWith(V);
Placeholder->replaceAllUsesWith(&LI);
delete Placeholder;
DL.getTypeStoreSizeInBits(V->getType()) &&
"Non-byte-multiple bit width");
IntegerType *NarrowTy = Type::getIntNTy(SI.getContext(), SliceSize * 8);
- V = extractInteger(DL, IRB, V, NarrowTy, NewBeginOffset, "extract");
+ V = extractInteger(DL, IRB, V, NarrowTy, NewBeginOffset - BeginOffset,
+ "extract");
}
if (VecTy)
void emitFunc(Type *Ty, Value *&Agg, const Twine &Name) {
assert(Ty->isSingleValueType());
// Load the single value and insert it using the indices.
- Value *GEP = IRB.CreateInBoundsGEP(Ptr, GEPIndices, Name + ".gep");
+ Value *GEP =
+ IRB.CreateInBoundsGEP(nullptr, Ptr, GEPIndices, Name + ".gep");
Value *Load = IRB.CreateLoad(GEP, Name + ".load");
Agg = IRB.CreateInsertValue(Agg, Load, Indices, Name + ".insert");
DEBUG(dbgs() << " to: " << *Load << "\n");
// Extract the single value and store it using the indices.
Value *Store = IRB.CreateStore(
IRB.CreateExtractValue(Agg, Indices, Name + ".extract"),
- IRB.CreateInBoundsGEP(Ptr, GEPIndices, Name + ".gep"));
+ IRB.CreateInBoundsGEP(nullptr, Ptr, GEPIndices, Name + ".gep"));
(void)Store;
DEBUG(dbgs() << " to: " << *Store << "\n");
}
return SubTy;
}
+/// \brief Pre-split loads and stores to simplify rewriting.
+///
+/// We want to break up the splittable load+store pairs as much as
+/// possible. This is important to do as a preprocessing step, as once we
+/// start rewriting the accesses to partitions of the alloca we lose the
+/// necessary information to correctly split apart paired loads and stores
+/// which both point into this alloca. The case to consider is something like
+/// the following:
+///
+/// %a = alloca [12 x i8]
+/// %gep1 = getelementptr [12 x i8]* %a, i32 0, i32 0
+/// %gep2 = getelementptr [12 x i8]* %a, i32 0, i32 4
+/// %gep3 = getelementptr [12 x i8]* %a, i32 0, i32 8
+/// %iptr1 = bitcast i8* %gep1 to i64*
+/// %iptr2 = bitcast i8* %gep2 to i64*
+/// %fptr1 = bitcast i8* %gep1 to float*
+/// %fptr2 = bitcast i8* %gep2 to float*
+/// %fptr3 = bitcast i8* %gep3 to float*
+/// store float 0.0, float* %fptr1
+/// store float 1.0, float* %fptr2
+/// %v = load i64* %iptr1
+/// store i64 %v, i64* %iptr2
+/// %f1 = load float* %fptr2
+/// %f2 = load float* %fptr3
+///
+/// Here we want to form 3 partitions of the alloca, each 4 bytes large, and
+/// promote everything so we recover the 2 SSA values that should have been
+/// there all along.
+///
+/// \returns true if any changes are made.
+bool SROA::presplitLoadsAndStores(AllocaInst &AI, AllocaSlices &AS) {
+ DEBUG(dbgs() << "Pre-splitting loads and stores\n");
+
+ // Track the loads and stores which are candidates for pre-splitting here, in
+ // the order they first appear during the partition scan. These give stable
+ // iteration order and a basis for tracking which loads and stores we
+ // actually split.
+ SmallVector<LoadInst *, 4> Loads;
+ SmallVector<StoreInst *, 4> Stores;
+
+ // We need to accumulate the splits required of each load or store where we
+ // can find them via a direct lookup. This is important to cross-check loads
+ // and stores against each other. We also track the slice so that we can kill
+ // all the slices that end up split.
+ struct SplitOffsets {
+ Slice *S;
+ std::vector<uint64_t> Splits;
+ };
+ SmallDenseMap<Instruction *, SplitOffsets, 8> SplitOffsetsMap;
+
+ // Track loads out of this alloca which cannot, for any reason, be pre-split.
+ // This is important as we also cannot pre-split stores of those loads!
+ // FIXME: This is all pretty gross. It means that we can be more aggressive
+ // in pre-splitting when the load feeding the store happens to come from
+ // a separate alloca. Put another way, the effectiveness of SROA would be
+ // decreased by a frontend which just concatenated all of its local allocas
+ // into one big flat alloca. But defeating such patterns is exactly the job
+ // SROA is tasked with! Sadly, to not have this discrepancy we would have
+ // change store pre-splitting to actually force pre-splitting of the load
+ // that feeds it *and all stores*. That makes pre-splitting much harder, but
+ // maybe it would make it more principled?
+ SmallPtrSet<LoadInst *, 8> UnsplittableLoads;
+
+ DEBUG(dbgs() << " Searching for candidate loads and stores\n");
+ for (auto &P : AS.partitions()) {
+ for (Slice &S : P) {
+ Instruction *I = cast<Instruction>(S.getUse()->getUser());
+ if (!S.isSplittable() ||S.endOffset() <= P.endOffset()) {
+ // If this was a load we have to track that it can't participate in any
+ // pre-splitting!
+ if (auto *LI = dyn_cast<LoadInst>(I))
+ UnsplittableLoads.insert(LI);
+ continue;
+ }
+ assert(P.endOffset() > S.beginOffset() &&
+ "Empty or backwards partition!");
+
+ // Determine if this is a pre-splittable slice.
+ if (auto *LI = dyn_cast<LoadInst>(I)) {
+ assert(!LI->isVolatile() && "Cannot split volatile loads!");
+
+ // The load must be used exclusively to store into other pointers for
+ // us to be able to arbitrarily pre-split it. The stores must also be
+ // simple to avoid changing semantics.
+ auto IsLoadSimplyStored = [](LoadInst *LI) {
+ for (User *LU : LI->users()) {
+ auto *SI = dyn_cast<StoreInst>(LU);
+ if (!SI || !SI->isSimple())
+ return false;
+ }
+ return true;
+ };
+ if (!IsLoadSimplyStored(LI)) {
+ UnsplittableLoads.insert(LI);
+ continue;
+ }
+
+ Loads.push_back(LI);
+ } else if (auto *SI = dyn_cast<StoreInst>(S.getUse()->getUser())) {
+ if (!SI ||
+ S.getUse() != &SI->getOperandUse(SI->getPointerOperandIndex()))
+ continue;
+ auto *StoredLoad = dyn_cast<LoadInst>(SI->getValueOperand());
+ if (!StoredLoad || !StoredLoad->isSimple())
+ continue;
+ assert(!SI->isVolatile() && "Cannot split volatile stores!");
+
+ Stores.push_back(SI);
+ } else {
+ // Other uses cannot be pre-split.
+ continue;
+ }
+
+ // Record the initial split.
+ DEBUG(dbgs() << " Candidate: " << *I << "\n");
+ auto &Offsets = SplitOffsetsMap[I];
+ assert(Offsets.Splits.empty() &&
+ "Should not have splits the first time we see an instruction!");
+ Offsets.S = &S;
+ Offsets.Splits.push_back(P.endOffset() - S.beginOffset());
+ }
+
+ // Now scan the already split slices, and add a split for any of them which
+ // we're going to pre-split.
+ for (Slice *S : P.splitSliceTails()) {
+ auto SplitOffsetsMapI =
+ SplitOffsetsMap.find(cast<Instruction>(S->getUse()->getUser()));
+ if (SplitOffsetsMapI == SplitOffsetsMap.end())
+ continue;
+ auto &Offsets = SplitOffsetsMapI->second;
+
+ assert(Offsets.S == S && "Found a mismatched slice!");
+ assert(!Offsets.Splits.empty() &&
+ "Cannot have an empty set of splits on the second partition!");
+ assert(Offsets.Splits.back() ==
+ P.beginOffset() - Offsets.S->beginOffset() &&
+ "Previous split does not end where this one begins!");
+
+ // Record each split. The last partition's end isn't needed as the size
+ // of the slice dictates that.
+ if (S->endOffset() > P.endOffset())
+ Offsets.Splits.push_back(P.endOffset() - Offsets.S->beginOffset());
+ }
+ }
+
+ // We may have split loads where some of their stores are split stores. For
+ // such loads and stores, we can only pre-split them if their splits exactly
+ // match relative to their starting offset. We have to verify this prior to
+ // any rewriting.
+ Stores.erase(
+ std::remove_if(Stores.begin(), Stores.end(),
+ [&UnsplittableLoads, &SplitOffsetsMap](StoreInst *SI) {
+ // Lookup the load we are storing in our map of split
+ // offsets.
+ auto *LI = cast<LoadInst>(SI->getValueOperand());
+ // If it was completely unsplittable, then we're done,
+ // and this store can't be pre-split.
+ if (UnsplittableLoads.count(LI))
+ return true;
+
+ auto LoadOffsetsI = SplitOffsetsMap.find(LI);
+ if (LoadOffsetsI == SplitOffsetsMap.end())
+ return false; // Unrelated loads are definitely safe.
+ auto &LoadOffsets = LoadOffsetsI->second;
+
+ // Now lookup the store's offsets.
+ auto &StoreOffsets = SplitOffsetsMap[SI];
+
+ // If the relative offsets of each split in the load and
+ // store match exactly, then we can split them and we
+ // don't need to remove them here.
+ if (LoadOffsets.Splits == StoreOffsets.Splits)
+ return false;
+
+ DEBUG(dbgs()
+ << " Mismatched splits for load and store:\n"
+ << " " << *LI << "\n"
+ << " " << *SI << "\n");
+
+ // We've found a store and load that we need to split
+ // with mismatched relative splits. Just give up on them
+ // and remove both instructions from our list of
+ // candidates.
+ UnsplittableLoads.insert(LI);
+ return true;
+ }),
+ Stores.end());
+ // Now we have to go *back* through all te stores, because a later store may
+ // have caused an earlier store's load to become unsplittable and if it is
+ // unsplittable for the later store, then we can't rely on it being split in
+ // the earlier store either.
+ Stores.erase(std::remove_if(Stores.begin(), Stores.end(),
+ [&UnsplittableLoads](StoreInst *SI) {
+ auto *LI =
+ cast<LoadInst>(SI->getValueOperand());
+ return UnsplittableLoads.count(LI);
+ }),
+ Stores.end());
+ // Once we've established all the loads that can't be split for some reason,
+ // filter any that made it into our list out.
+ Loads.erase(std::remove_if(Loads.begin(), Loads.end(),
+ [&UnsplittableLoads](LoadInst *LI) {
+ return UnsplittableLoads.count(LI);
+ }),
+ Loads.end());
+
+
+ // If no loads or stores are left, there is no pre-splitting to be done for
+ // this alloca.
+ if (Loads.empty() && Stores.empty())
+ return false;
+
+ // From here on, we can't fail and will be building new accesses, so rig up
+ // an IR builder.
+ IRBuilderTy IRB(&AI);
+
+ // Collect the new slices which we will merge into the alloca slices.
+ SmallVector<Slice, 4> NewSlices;
+
+ // Track any allocas we end up splitting loads and stores for so we iterate
+ // on them.
+ SmallPtrSet<AllocaInst *, 4> ResplitPromotableAllocas;
+
+ // At this point, we have collected all of the loads and stores we can
+ // pre-split, and the specific splits needed for them. We actually do the
+ // splitting in a specific order in order to handle when one of the loads in
+ // the value operand to one of the stores.
+ //
+ // First, we rewrite all of the split loads, and just accumulate each split
+ // load in a parallel structure. We also build the slices for them and append
+ // them to the alloca slices.
+ SmallDenseMap<LoadInst *, std::vector<LoadInst *>, 1> SplitLoadsMap;
+ std::vector<LoadInst *> SplitLoads;
+ const DataLayout &DL = AI.getModule()->getDataLayout();
+ for (LoadInst *LI : Loads) {
+ SplitLoads.clear();
+
+ IntegerType *Ty = cast<IntegerType>(LI->getType());
+ uint64_t LoadSize = Ty->getBitWidth() / 8;
+ assert(LoadSize > 0 && "Cannot have a zero-sized integer load!");
+
+ auto &Offsets = SplitOffsetsMap[LI];
+ assert(LoadSize == Offsets.S->endOffset() - Offsets.S->beginOffset() &&
+ "Slice size should always match load size exactly!");
+ uint64_t BaseOffset = Offsets.S->beginOffset();
+ assert(BaseOffset + LoadSize > BaseOffset &&
+ "Cannot represent alloca access size using 64-bit integers!");
+
+ Instruction *BasePtr = cast<Instruction>(LI->getPointerOperand());
+ IRB.SetInsertPoint(BasicBlock::iterator(LI));
+
+ DEBUG(dbgs() << " Splitting load: " << *LI << "\n");
+
+ uint64_t PartOffset = 0, PartSize = Offsets.Splits.front();
+ int Idx = 0, Size = Offsets.Splits.size();
+ for (;;) {
+ auto *PartTy = Type::getIntNTy(Ty->getContext(), PartSize * 8);
+ auto *PartPtrTy = PartTy->getPointerTo(LI->getPointerAddressSpace());
+ LoadInst *PLoad = IRB.CreateAlignedLoad(
+ getAdjustedPtr(IRB, DL, BasePtr,
+ APInt(DL.getPointerSizeInBits(), PartOffset),
+ PartPtrTy, BasePtr->getName() + "."),
+ getAdjustedAlignment(LI, PartOffset, DL), /*IsVolatile*/ false,
+ LI->getName());
+
+ // Append this load onto the list of split loads so we can find it later
+ // to rewrite the stores.
+ SplitLoads.push_back(PLoad);
+
+ // Now build a new slice for the alloca.
+ NewSlices.push_back(
+ Slice(BaseOffset + PartOffset, BaseOffset + PartOffset + PartSize,
+ &PLoad->getOperandUse(PLoad->getPointerOperandIndex()),
+ /*IsSplittable*/ false));
+ DEBUG(dbgs() << " new slice [" << NewSlices.back().beginOffset()
+ << ", " << NewSlices.back().endOffset() << "): " << *PLoad
+ << "\n");
+
+ // See if we've handled all the splits.
+ if (Idx >= Size)
+ break;
+
+ // Setup the next partition.
+ PartOffset = Offsets.Splits[Idx];
+ ++Idx;
+ PartSize = (Idx < Size ? Offsets.Splits[Idx] : LoadSize) - PartOffset;
+ }
+
+ // Now that we have the split loads, do the slow walk over all uses of the
+ // load and rewrite them as split stores, or save the split loads to use
+ // below if the store is going to be split there anyways.
+ bool DeferredStores = false;
+ for (User *LU : LI->users()) {
+ StoreInst *SI = cast<StoreInst>(LU);
+ if (!Stores.empty() && SplitOffsetsMap.count(SI)) {
+ DeferredStores = true;
+ DEBUG(dbgs() << " Deferred splitting of store: " << *SI << "\n");
+ continue;
+ }
+
+ Value *StoreBasePtr = SI->getPointerOperand();
+ IRB.SetInsertPoint(BasicBlock::iterator(SI));
+
+ DEBUG(dbgs() << " Splitting store of load: " << *SI << "\n");
+
+ for (int Idx = 0, Size = SplitLoads.size(); Idx < Size; ++Idx) {
+ LoadInst *PLoad = SplitLoads[Idx];
+ uint64_t PartOffset = Idx == 0 ? 0 : Offsets.Splits[Idx - 1];
+ auto *PartPtrTy =
+ PLoad->getType()->getPointerTo(SI->getPointerAddressSpace());
+
+ StoreInst *PStore = IRB.CreateAlignedStore(
+ PLoad, getAdjustedPtr(IRB, DL, StoreBasePtr,
+ APInt(DL.getPointerSizeInBits(), PartOffset),
+ PartPtrTy, StoreBasePtr->getName() + "."),
+ getAdjustedAlignment(SI, PartOffset, DL), /*IsVolatile*/ false);
+ (void)PStore;
+ DEBUG(dbgs() << " +" << PartOffset << ":" << *PStore << "\n");
+ }
+
+ // We want to immediately iterate on any allocas impacted by splitting
+ // this store, and we have to track any promotable alloca (indicated by
+ // a direct store) as needing to be resplit because it is no longer
+ // promotable.
+ if (AllocaInst *OtherAI = dyn_cast<AllocaInst>(StoreBasePtr)) {
+ ResplitPromotableAllocas.insert(OtherAI);
+ Worklist.insert(OtherAI);
+ } else if (AllocaInst *OtherAI = dyn_cast<AllocaInst>(
+ StoreBasePtr->stripInBoundsOffsets())) {
+ Worklist.insert(OtherAI);
+ }
+
+ // Mark the original store as dead.
+ DeadInsts.insert(SI);
+ }
+
+ // Save the split loads if there are deferred stores among the users.
+ if (DeferredStores)
+ SplitLoadsMap.insert(std::make_pair(LI, std::move(SplitLoads)));
+
+ // Mark the original load as dead and kill the original slice.
+ DeadInsts.insert(LI);
+ Offsets.S->kill();
+ }
+
+ // Second, we rewrite all of the split stores. At this point, we know that
+ // all loads from this alloca have been split already. For stores of such
+ // loads, we can simply look up the pre-existing split loads. For stores of
+ // other loads, we split those loads first and then write split stores of
+ // them.
+ for (StoreInst *SI : Stores) {
+ auto *LI = cast<LoadInst>(SI->getValueOperand());
+ IntegerType *Ty = cast<IntegerType>(LI->getType());
+ uint64_t StoreSize = Ty->getBitWidth() / 8;
+ assert(StoreSize > 0 && "Cannot have a zero-sized integer store!");
+
+ auto &Offsets = SplitOffsetsMap[SI];
+ assert(StoreSize == Offsets.S->endOffset() - Offsets.S->beginOffset() &&
+ "Slice size should always match load size exactly!");
+ uint64_t BaseOffset = Offsets.S->beginOffset();
+ assert(BaseOffset + StoreSize > BaseOffset &&
+ "Cannot represent alloca access size using 64-bit integers!");
+
+ Value *LoadBasePtr = LI->getPointerOperand();
+ Instruction *StoreBasePtr = cast<Instruction>(SI->getPointerOperand());
+
+ DEBUG(dbgs() << " Splitting store: " << *SI << "\n");
+
+ // Check whether we have an already split load.
+ auto SplitLoadsMapI = SplitLoadsMap.find(LI);
+ std::vector<LoadInst *> *SplitLoads = nullptr;
+ if (SplitLoadsMapI != SplitLoadsMap.end()) {
+ SplitLoads = &SplitLoadsMapI->second;
+ assert(SplitLoads->size() == Offsets.Splits.size() + 1 &&
+ "Too few split loads for the number of splits in the store!");
+ } else {
+ DEBUG(dbgs() << " of load: " << *LI << "\n");
+ }
+
+ uint64_t PartOffset = 0, PartSize = Offsets.Splits.front();
+ int Idx = 0, Size = Offsets.Splits.size();
+ for (;;) {
+ auto *PartTy = Type::getIntNTy(Ty->getContext(), PartSize * 8);
+ auto *PartPtrTy = PartTy->getPointerTo(SI->getPointerAddressSpace());
+
+ // Either lookup a split load or create one.
+ LoadInst *PLoad;
+ if (SplitLoads) {
+ PLoad = (*SplitLoads)[Idx];
+ } else {
+ IRB.SetInsertPoint(BasicBlock::iterator(LI));
+ PLoad = IRB.CreateAlignedLoad(
+ getAdjustedPtr(IRB, DL, LoadBasePtr,
+ APInt(DL.getPointerSizeInBits(), PartOffset),
+ PartPtrTy, LoadBasePtr->getName() + "."),
+ getAdjustedAlignment(LI, PartOffset, DL), /*IsVolatile*/ false,
+ LI->getName());
+ }
+
+ // And store this partition.
+ IRB.SetInsertPoint(BasicBlock::iterator(SI));
+ StoreInst *PStore = IRB.CreateAlignedStore(
+ PLoad, getAdjustedPtr(IRB, DL, StoreBasePtr,
+ APInt(DL.getPointerSizeInBits(), PartOffset),
+ PartPtrTy, StoreBasePtr->getName() + "."),
+ getAdjustedAlignment(SI, PartOffset, DL), /*IsVolatile*/ false);
+
+ // Now build a new slice for the alloca.
+ NewSlices.push_back(
+ Slice(BaseOffset + PartOffset, BaseOffset + PartOffset + PartSize,
+ &PStore->getOperandUse(PStore->getPointerOperandIndex()),
+ /*IsSplittable*/ false));
+ DEBUG(dbgs() << " new slice [" << NewSlices.back().beginOffset()
+ << ", " << NewSlices.back().endOffset() << "): " << *PStore
+ << "\n");
+ if (!SplitLoads) {
+ DEBUG(dbgs() << " of split load: " << *PLoad << "\n");
+ }
+
+ // See if we've finished all the splits.
+ if (Idx >= Size)
+ break;
+
+ // Setup the next partition.
+ PartOffset = Offsets.Splits[Idx];
+ ++Idx;
+ PartSize = (Idx < Size ? Offsets.Splits[Idx] : StoreSize) - PartOffset;
+ }
+
+ // We want to immediately iterate on any allocas impacted by splitting
+ // this load, which is only relevant if it isn't a load of this alloca and
+ // thus we didn't already split the loads above. We also have to keep track
+ // of any promotable allocas we split loads on as they can no longer be
+ // promoted.
+ if (!SplitLoads) {
+ if (AllocaInst *OtherAI = dyn_cast<AllocaInst>(LoadBasePtr)) {
+ assert(OtherAI != &AI && "We can't re-split our own alloca!");
+ ResplitPromotableAllocas.insert(OtherAI);
+ Worklist.insert(OtherAI);
+ } else if (AllocaInst *OtherAI = dyn_cast<AllocaInst>(
+ LoadBasePtr->stripInBoundsOffsets())) {
+ assert(OtherAI != &AI && "We can't re-split our own alloca!");
+ Worklist.insert(OtherAI);
+ }
+ }
+
+ // Mark the original store as dead now that we've split it up and kill its
+ // slice. Note that we leave the original load in place unless this store
+ // was its ownly use. It may in turn be split up if it is an alloca load
+ // for some other alloca, but it may be a normal load. This may introduce
+ // redundant loads, but where those can be merged the rest of the optimizer
+ // should handle the merging, and this uncovers SSA splits which is more
+ // important. In practice, the original loads will almost always be fully
+ // split and removed eventually, and the splits will be merged by any
+ // trivial CSE, including instcombine.
+ if (LI->hasOneUse()) {
+ assert(*LI->user_begin() == SI && "Single use isn't this store!");
+ DeadInsts.insert(LI);
+ }
+ DeadInsts.insert(SI);
+ Offsets.S->kill();
+ }
+
+ // Remove the killed slices that have ben pre-split.
+ AS.erase(std::remove_if(AS.begin(), AS.end(), [](const Slice &S) {
+ return S.isDead();
+ }), AS.end());
+
+ // Insert our new slices. This will sort and merge them into the sorted
+ // sequence.
+ AS.insert(NewSlices);
+
+ DEBUG(dbgs() << " Pre-split slices:\n");
+#ifndef NDEBUG
+ for (auto I = AS.begin(), E = AS.end(); I != E; ++I)
+ DEBUG(AS.print(dbgs(), I, " "));
+#endif
+
+ // Finally, don't try to promote any allocas that new require re-splitting.
+ // They have already been added to the worklist above.
+ PromotableAllocas.erase(
+ std::remove_if(
+ PromotableAllocas.begin(), PromotableAllocas.end(),
+ [&](AllocaInst *AI) { return ResplitPromotableAllocas.count(AI); }),
+ PromotableAllocas.end());
+
+ return true;
+}
+
/// \brief Rewrite an alloca partition's users.
///
/// This routine drives both of the rewriting goals of the SROA pass. It tries
/// 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::rewritePartition(AllocaInst &AI, AllocaSlices &AS,
- AllocaSlices::Partition &P) {
+AllocaInst *SROA::rewritePartition(AllocaInst &AI, AllocaSlices &AS,
+ AllocaSlices::Partition &P) {
// 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 *SliceTy = nullptr;
+ const DataLayout &DL = AI.getModule()->getDataLayout();
if (Type *CommonUseTy = findCommonType(P.begin(), P.end(), P.endOffset()))
- if (DL->getTypeAllocSize(CommonUseTy) >= P.size())
+ if (DL.getTypeAllocSize(CommonUseTy) >= P.size())
SliceTy = CommonUseTy;
if (!SliceTy)
- if (Type *TypePartitionTy = getTypePartition(*DL, AI.getAllocatedType(),
+ if (Type *TypePartitionTy = getTypePartition(DL, AI.getAllocatedType(),
P.beginOffset(), P.size()))
SliceTy = TypePartitionTy;
if ((!SliceTy || (SliceTy->isArrayTy() &&
SliceTy->getArrayElementType()->isIntegerTy())) &&
- DL->isLegalInteger(P.size() * 8))
+ DL.isLegalInteger(P.size() * 8))
SliceTy = Type::getIntNTy(*C, P.size() * 8);
if (!SliceTy)
SliceTy = ArrayType::get(Type::getInt8Ty(*C), P.size());
- assert(DL->getTypeAllocSize(SliceTy) >= P.size());
+ assert(DL.getTypeAllocSize(SliceTy) >= P.size());
- bool IsIntegerPromotable = isIntegerWideningViable(P, SliceTy, *DL);
+ bool IsIntegerPromotable = isIntegerWideningViable(P, SliceTy, DL);
VectorType *VecTy =
- IsIntegerPromotable ? nullptr : isVectorPromotionViable(P, *DL);
+ IsIntegerPromotable ? nullptr : isVectorPromotionViable(P, DL);
if (VecTy)
SliceTy = VecTy;
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.
+ // FIXME: return nullptr;
} else {
unsigned Alignment = AI.getAlignment();
if (!Alignment) {
// The minimum alignment which users can rely on when the explicit
// alignment is omitted or zero is that required by the ABI for this
// type.
- Alignment = DL->getABITypeAlignment(AI.getAllocatedType());
+ Alignment = DL.getABITypeAlignment(AI.getAllocatedType());
}
Alignment = MinAlign(Alignment, P.beginOffset());
// If we will get at least this much alignment from the type alone, leave
// the alloca's alignment unconstrained.
- if (Alignment <= DL->getABITypeAlignment(SliceTy))
+ if (Alignment <= DL.getABITypeAlignment(SliceTy))
Alignment = 0;
NewAI = new AllocaInst(
SliceTy, nullptr, Alignment,
SmallPtrSet<PHINode *, 8> PHIUsers;
SmallPtrSet<SelectInst *, 8> SelectUsers;
- AllocaSliceRewriter Rewriter(*DL, AS, *this, AI, *NewAI, P.beginOffset(),
+ AllocaSliceRewriter Rewriter(DL, AS, *this, AI, *NewAI, P.beginOffset(),
P.endOffset(), IsIntegerPromotable, VecTy,
PHIUsers, SelectUsers);
bool Promotable = true;
for (SmallPtrSetImpl<PHINode *>::iterator I = PHIUsers.begin(),
E = PHIUsers.end();
I != E; ++I)
- if (!isSafePHIToSpeculate(**I, DL)) {
+ if (!isSafePHIToSpeculate(**I)) {
Promotable = false;
PHIUsers.clear();
SelectUsers.clear();
for (SmallPtrSetImpl<SelectInst *>::iterator I = SelectUsers.begin(),
E = SelectUsers.end();
I != E; ++I)
- if (!isSafeSelectToSpeculate(**I, DL)) {
+ if (!isSafeSelectToSpeculate(**I)) {
Promotable = false;
PHIUsers.clear();
SelectUsers.clear();
PostPromotionWorklist.pop_back();
}
- return true;
+ return NewAI;
}
/// \brief Walks the slices of an alloca and form partitions based on them,
unsigned NumPartitions = 0;
bool Changed = false;
+ const DataLayout &DL = AI.getModule()->getDataLayout();
+
+ // First try to pre-split loads and stores.
+ Changed |= presplitLoadsAndStores(AI, AS);
+
+ // Now that we have identified any pre-splitting opportunities, mark any
+ // splittable (non-whole-alloca) loads and stores as unsplittable. If we fail
+ // to split these during pre-splitting, we want to force them to be
+ // rewritten into a partition.
+ bool IsSorted = true;
+ for (Slice &S : AS) {
+ if (!S.isSplittable())
+ continue;
+ // FIXME: We currently leave whole-alloca splittable loads and stores. This
+ // used to be the only splittable loads and stores and we need to be
+ // confident that the above handling of splittable loads and stores is
+ // completely sufficient before we forcibly disable the remaining handling.
+ if (S.beginOffset() == 0 &&
+ S.endOffset() >= DL.getTypeAllocSize(AI.getAllocatedType()))
+ continue;
+ if (isa<LoadInst>(S.getUse()->getUser()) ||
+ isa<StoreInst>(S.getUse()->getUser())) {
+ S.makeUnsplittable();
+ IsSorted = false;
+ }
+ }
+ if (!IsSorted)
+ std::sort(AS.begin(), AS.end());
+
+ /// \brief Describes the allocas introduced by rewritePartition
+ /// in order to migrate the debug info.
+ struct Piece {
+ AllocaInst *Alloca;
+ uint64_t Offset;
+ uint64_t Size;
+ Piece(AllocaInst *AI, uint64_t O, uint64_t S)
+ : Alloca(AI), Offset(O), Size(S) {}
+ };
+ SmallVector<Piece, 4> Pieces;
- // Rewrite each parttion.
+ // Rewrite each partition.
for (auto &P : AS.partitions()) {
- Changed |= rewritePartition(AI, AS, P);
+ if (AllocaInst *NewAI = rewritePartition(AI, AS, P)) {
+ Changed = true;
+ if (NewAI != &AI) {
+ uint64_t SizeOfByte = 8;
+ uint64_t AllocaSize = DL.getTypeSizeInBits(NewAI->getAllocatedType());
+ // Don't include any padding.
+ uint64_t Size = std::min(AllocaSize, P.size() * SizeOfByte);
+ Pieces.push_back(Piece(NewAI, P.beginOffset() * SizeOfByte, Size));
+ }
+ }
++NumPartitions;
}
MaxPartitionsPerAlloca =
std::max<unsigned>(NumPartitions, MaxPartitionsPerAlloca);
+ // Migrate debug information from the old alloca to the new alloca(s)
+ // and the individial partitions.
+ if (DbgDeclareInst *DbgDecl = FindAllocaDbgDeclare(&AI)) {
+ DIVariable Var(DbgDecl->getVariable());
+ DIExpression Expr(DbgDecl->getExpression());
+ DIBuilder DIB(*AI.getParent()->getParent()->getParent(),
+ /*AllowUnresolved*/ false);
+ bool IsSplit = Pieces.size() > 1;
+ for (auto Piece : Pieces) {
+ // Create a piece expression describing the new partition or reuse AI's
+ // expression if there is only one partition.
+ DIExpression PieceExpr = Expr;
+ if (IsSplit || Expr->isBitPiece()) {
+ // If this alloca is already a scalar replacement of a larger aggregate,
+ // Piece.Offset describes the offset inside the scalar.
+ uint64_t Offset = Expr->isBitPiece() ? Expr->getBitPieceOffset() : 0;
+ uint64_t Start = Offset + Piece.Offset;
+ uint64_t Size = Piece.Size;
+ if (Expr->isBitPiece()) {
+ uint64_t AbsEnd = Expr->getBitPieceOffset() + Expr->getBitPieceSize();
+ if (Start >= AbsEnd)
+ // No need to describe a SROAed padding.
+ continue;
+ Size = std::min(Size, AbsEnd - Start);
+ }
+ PieceExpr = DIB.createBitPieceExpression(Start, Size);
+ }
+
+ // Remove any existing dbg.declare intrinsic describing the same alloca.
+ if (DbgDeclareInst *OldDDI = FindAllocaDbgDeclare(Piece.Alloca))
+ OldDDI->eraseFromParent();
+
+ DIB.insertDeclare(Piece.Alloca, Var, PieceExpr, DbgDecl->getDebugLoc(),
+ &AI);
+ }
+ }
return Changed;
}
AI.eraseFromParent();
return true;
}
+ const DataLayout &DL = AI.getModule()->getDataLayout();
// Skip alloca forms that this analysis can't handle.
if (AI.isArrayAllocation() || !AI.getAllocatedType()->isSized() ||
- DL->getTypeAllocSize(AI.getAllocatedType()) == 0)
+ DL.getTypeAllocSize(AI.getAllocatedType()) == 0)
return false;
bool Changed = false;
// First, split any FCA loads and stores touching this alloca to promote
// better splitting and promotion opportunities.
- AggLoadStoreRewriter AggRewriter(*DL);
+ AggLoadStoreRewriter AggRewriter(DL);
Changed |= AggRewriter.rewrite(AI);
// Build the slices using a recursive instruction-visiting builder.
- AllocaSlices AS(*DL, AI);
+ AllocaSlices AS(DL, AI);
DEBUG(AS.print(dbgs()));
if (AS.isEscaped())
return Changed;
DeadInsts.insert(U);
}
- if (AllocaInst *AI = dyn_cast<AllocaInst>(I))
+ if (AllocaInst *AI = dyn_cast<AllocaInst>(I)) {
DeletedAllocas.insert(AI);
+ if (DbgDeclareInst *DbgDecl = FindAllocaDbgDeclare(AI))
+ DbgDecl->eraseFromParent();
+ }
++NumDeleted;
I->eraseFromParent();
if (DT && !ForceSSAUpdater) {
DEBUG(dbgs() << "Promoting allocas with mem2reg...\n");
- PromoteMemToReg(PromotableAllocas, *DT, nullptr, AT);
+ PromoteMemToReg(PromotableAllocas, *DT, nullptr, AC);
PromotableAllocas.clear();
return true;
}
DEBUG(dbgs() << "SROA function: " << F.getName() << "\n");
C = &F.getContext();
- DataLayoutPass *DLP = getAnalysisIfAvailable<DataLayoutPass>();
- if (!DLP) {
- DEBUG(dbgs() << " Skipping SROA -- no target data!\n");
- return false;
- }
- DL = &DLP->getDataLayout();
DominatorTreeWrapperPass *DTWP =
getAnalysisIfAvailable<DominatorTreeWrapperPass>();
DT = DTWP ? &DTWP->getDomTree() : nullptr;
- AT = &getAnalysis<AssumptionTracker>();
+ AC = &getAnalysis<AssumptionCacheTracker>().getAssumptionCache(F);
BasicBlock &EntryBB = F.getEntryBlock();
for (BasicBlock::iterator I = EntryBB.begin(), E = std::prev(EntryBB.end());
- I != E; ++I)
+ I != E; ++I) {
if (AllocaInst *AI = dyn_cast<AllocaInst>(I))
Worklist.insert(AI);
+ }
bool Changed = false;
// A set of deleted alloca instruction pointers which should be removed from
}
void SROA::getAnalysisUsage(AnalysisUsage &AU) const {
- AU.addRequired<AssumptionTracker>();
+ AU.addRequired<AssumptionCacheTracker>();
if (RequiresDomTree)
AU.addRequired<DominatorTreeWrapperPass>();
AU.setPreservesCFG();
projects / oota-llvm.git / blobdiff