//===----------------------------------------------------------------------===//
#include "InstCombineInternal.h"
+#include "llvm/ADT/SmallString.h"
#include "llvm/ADT/Statistic.h"
#include "llvm/Analysis/Loads.h"
#include "llvm/IR/DataLayout.h"
continue;
}
- if (CallSite CS = I) {
+ if (auto CS = CallSite(I)) {
// If this is the function being called then we treat it like a load and
// ignore it.
if (CS.isCallee(&U))
continue;
+ unsigned DataOpNo = CS.getDataOperandNo(&U);
+ bool IsArgOperand = CS.isArgOperand(&U);
+
// Inalloca arguments are clobbered by the call.
- unsigned ArgNo = CS.getArgumentNo(&U);
- if (CS.isInAllocaArgument(ArgNo))
+ if (IsArgOperand && CS.isInAllocaArgument(DataOpNo))
return false;
// If this is a readonly/readnone call site, then we know it is just a
// load (but one that potentially returns the value itself), so we can
// ignore it if we know that the value isn't captured.
if (CS.onlyReadsMemory() &&
- (CS.getInstruction()->use_empty() || CS.doesNotCapture(ArgNo)))
+ (CS.getInstruction()->use_empty() || CS.doesNotCapture(DataOpNo)))
continue;
// If this is being passed as a byval argument, the caller is making a
// copy, so it is only a read of the alloca.
- if (CS.isByValArgument(ArgNo))
+ if (IsArgOperand && CS.isByValArgument(DataOpNo))
continue;
}
// Scan to the end of the allocation instructions, to skip over a block of
// allocas if possible...also skip interleaved debug info
//
- BasicBlock::iterator It = New;
+ BasicBlock::iterator It(New);
while (isa<AllocaInst>(*It) || isa<DbgInfoIntrinsic>(*It))
++It;
///
/// Note that this will create all of the instructions with whatever insert
/// point the \c InstCombiner currently is using.
-static LoadInst *combineLoadToNewType(InstCombiner &IC, LoadInst &LI, Type *NewTy) {
+static LoadInst *combineLoadToNewType(InstCombiner &IC, LoadInst &LI, Type *NewTy,
+ const Twine &Suffix = "") {
Value *Ptr = LI.getPointerOperand();
unsigned AS = LI.getPointerAddressSpace();
SmallVector<std::pair<unsigned, MDNode *>, 8> MD;
LoadInst *NewLoad = IC.Builder->CreateAlignedLoad(
IC.Builder->CreateBitCast(Ptr, NewTy->getPointerTo(AS)),
- LI.getAlignment(), LI.getName());
+ LI.getAlignment(), LI.getName() + Suffix);
MDBuilder MDB(NewLoad->getContext());
for (const auto &MDPair : MD) {
unsigned ID = MDPair.first;
MDB.createRange(NonNullInt, NullInt));
}
break;
-
+ case LLVMContext::MD_align:
+ case LLVMContext::MD_dereferenceable:
+ case LLVMContext::MD_dereferenceable_or_null:
+ // These only directly apply if the new type is also a pointer.
+ if (NewTy->isPointerTy())
+ NewLoad->setMetadata(ID, N);
+ break;
case LLVMContext::MD_range:
// FIXME: It would be nice to propagate this in some way, but the type
// conversions make it hard. If the new type is a pointer, we could
case LLVMContext::MD_invariant_load:
case LLVMContext::MD_nonnull:
case LLVMContext::MD_range:
+ case LLVMContext::MD_align:
+ case LLVMContext::MD_dereferenceable:
+ case LLVMContext::MD_dereferenceable_or_null:
// These don't apply for stores.
break;
}
}
// Fold away bit casts of the loaded value by loading the desired type.
+ // We can do this for BitCastInsts as well as casts from and to pointer types,
+ // as long as those are noops (i.e., the source or dest type have the same
+ // bitwidth as the target's pointers).
if (LI.hasOneUse())
- if (auto *BC = dyn_cast<BitCastInst>(LI.user_back())) {
- LoadInst *NewLoad = combineLoadToNewType(IC, LI, BC->getDestTy());
- BC->replaceAllUsesWith(NewLoad);
- IC.EraseInstFromFunction(*BC);
- return &LI;
+ if (auto* CI = dyn_cast<CastInst>(LI.user_back())) {
+ if (CI->isNoopCast(DL)) {
+ LoadInst *NewLoad = combineLoadToNewType(IC, LI, CI->getDestTy());
+ CI->replaceAllUsesWith(NewLoad);
+ IC.EraseInstFromFunction(*CI);
+ return &LI;
+ }
}
// FIXME: We should also canonicalize loads of vectors when their elements are
return nullptr;
}
+static Instruction *unpackLoadToAggregate(InstCombiner &IC, LoadInst &LI) {
+ // FIXME: We could probably with some care handle both volatile and atomic
+ // stores here but it isn't clear that this is important.
+ if (!LI.isSimple())
+ return nullptr;
+
+ Type *T = LI.getType();
+ if (!T->isAggregateType())
+ return nullptr;
+
+ assert(LI.getAlignment() && "Alignment must be set at this point");
+
+ if (auto *ST = dyn_cast<StructType>(T)) {
+ // If the struct only have one element, we unpack.
+ unsigned Count = ST->getNumElements();
+ if (Count == 1) {
+ LoadInst *NewLoad = combineLoadToNewType(IC, LI, ST->getTypeAtIndex(0U),
+ ".unpack");
+ return IC.ReplaceInstUsesWith(LI, IC.Builder->CreateInsertValue(
+ UndefValue::get(T), NewLoad, 0, LI.getName()));
+ }
+
+ // We don't want to break loads with padding here as we'd loose
+ // the knowledge that padding exists for the rest of the pipeline.
+ const DataLayout &DL = IC.getDataLayout();
+ auto *SL = DL.getStructLayout(ST);
+ if (SL->hasPadding())
+ return nullptr;
+
+ auto Name = LI.getName();
+ SmallString<16> LoadName = Name;
+ LoadName += ".unpack";
+ SmallString<16> EltName = Name;
+ EltName += ".elt";
+ auto *Addr = LI.getPointerOperand();
+ Value *V = UndefValue::get(T);
+ auto *IdxType = Type::getInt32Ty(ST->getContext());
+ auto *Zero = ConstantInt::get(IdxType, 0);
+ for (unsigned i = 0; i < Count; i++) {
+ Value *Indices[2] = {
+ Zero,
+ ConstantInt::get(IdxType, i),
+ };
+ auto *Ptr = IC.Builder->CreateInBoundsGEP(ST, Addr, makeArrayRef(Indices), EltName);
+ auto *L = IC.Builder->CreateAlignedLoad(Ptr, LI.getAlignment(),
+ LoadName);
+ V = IC.Builder->CreateInsertValue(V, L, i);
+ }
+
+ V->setName(Name);
+ return IC.ReplaceInstUsesWith(LI, V);
+ }
+
+ if (auto *AT = dyn_cast<ArrayType>(T)) {
+ // If the array only have one element, we unpack.
+ if (AT->getNumElements() == 1) {
+ LoadInst *NewLoad = combineLoadToNewType(IC, LI, AT->getElementType(),
+ ".unpack");
+ return IC.ReplaceInstUsesWith(LI, IC.Builder->CreateInsertValue(
+ UndefValue::get(T), NewLoad, 0, LI.getName()));
+ }
+ }
+
+ return nullptr;
+}
+
// If we can determine that all possible objects pointed to by the provided
// pointer value are, not only dereferenceable, but also definitively less than
// or equal to the provided maximum size, then return true. Otherwise, return
}
if (PHINode *PN = dyn_cast<PHINode>(P)) {
- for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i)
- Worklist.push_back(PN->getIncomingValue(i));
+ for (Value *IncValue : PN->incoming_values())
+ Worklist.push_back(IncValue);
continue;
}
return false;
SmallVector<Value *, 4> Ops(GEPI->idx_begin(), GEPI->idx_begin() + Idx);
- Type *AllocTy =
- GetElementPtrInst::getIndexedType(GEPI->getOperand(0)->getType(), Ops);
+ Type *AllocTy = GetElementPtrInst::getIndexedType(
+ cast<PointerType>(GEPI->getOperand(0)->getType()->getScalarType())
+ ->getElementType(),
+ Ops);
if (!AllocTy || !AllocTy->isSized())
return false;
const DataLayout &DL = IC.getDataLayout();
// FIXME: If the GEP is not inbounds, and there are extra indices after the
// one we'll replace, those could cause the address computation to wrap
// (rendering the IsAllNonNegative() check below insufficient). We can do
- // better, ignoring zero indicies (and other indicies we can prove small
+ // better, ignoring zero indices (and other indices we can prove small
// enough not to wrap).
if (Idx+1 != GEPI->getNumOperands() && !GEPI->isInBounds())
return false;
// FIXME: Some of it is okay for atomic loads; needs refactoring.
if (!LI.isSimple()) return nullptr;
+ if (Instruction *Res = unpackLoadToAggregate(*this, LI))
+ return Res;
+
// Do really simple store-to-load forwarding and load CSE, to catch cases
// where there are several consecutive memory accesses to the same location,
// separated by a few arithmetic operations.
- BasicBlock::iterator BBI = &LI;
- if (Value *AvailableVal = FindAvailableLoadedValue(Op, LI.getParent(), BBI,6))
+ BasicBlock::iterator BBI(LI);
+ AAMDNodes AATags;
+ if (Value *AvailableVal =
+ FindAvailableLoadedValue(Op, LI.getParent(), BBI,
+ DefMaxInstsToScan, AA, &AATags)) {
+ if (LoadInst *NLI = dyn_cast<LoadInst>(AvailableVal)) {
+ unsigned KnownIDs[] = {
+ LLVMContext::MD_tbaa, LLVMContext::MD_alias_scope,
+ LLVMContext::MD_noalias, LLVMContext::MD_range,
+ LLVMContext::MD_invariant_load, LLVMContext::MD_nonnull,
+ LLVMContext::MD_invariant_group, LLVMContext::MD_align,
+ LLVMContext::MD_dereferenceable,
+ LLVMContext::MD_dereferenceable_or_null};
+ combineMetadata(NLI, &LI, KnownIDs);
+ };
+
return ReplaceInstUsesWith(
LI, Builder->CreateBitOrPointerCast(AvailableVal, LI.getType(),
LI.getName() + ".cast"));
+ }
// load(gep null, ...) -> unreachable
if (GetElementPtrInst *GEPI = dyn_cast<GetElementPtrInst>(Op)) {
}
// load (select (cond, null, P)) -> load P
- if (isa<ConstantPointerNull>(SI->getOperand(1)) &&
+ if (isa<ConstantPointerNull>(SI->getOperand(1)) &&
LI.getPointerAddressSpace() == 0) {
LI.setOperand(0, SI->getOperand(2));
return &LI;
///
/// \returns true if the store was successfully combined away. This indicates
/// the caller must erase the store instruction. We have to let the caller erase
-/// the store instruction sas otherwise there is no way to signal whether it was
+/// the store instruction as otherwise there is no way to signal whether it was
/// combined or not: IC.EraseInstFromFunction returns a null pointer.
static bool combineStoreToValueType(InstCombiner &IC, StoreInst &SI) {
// FIXME: We could probably with some care handle both volatile and atomic
if (!T->isAggregateType())
return false;
- if (StructType *ST = dyn_cast<StructType>(T)) {
+ if (auto *ST = dyn_cast<StructType>(T)) {
// If the struct only have one element, we unpack.
- if (ST->getNumElements() == 1) {
+ unsigned Count = ST->getNumElements();
+ if (Count == 1) {
+ V = IC.Builder->CreateExtractValue(V, 0);
+ combineStoreToNewValue(IC, SI, V);
+ return true;
+ }
+
+ // We don't want to break loads with padding here as we'd loose
+ // the knowledge that padding exists for the rest of the pipeline.
+ const DataLayout &DL = IC.getDataLayout();
+ auto *SL = DL.getStructLayout(ST);
+ if (SL->hasPadding())
+ return false;
+
+ SmallString<16> EltName = V->getName();
+ EltName += ".elt";
+ auto *Addr = SI.getPointerOperand();
+ SmallString<16> AddrName = Addr->getName();
+ AddrName += ".repack";
+ auto *IdxType = Type::getInt32Ty(ST->getContext());
+ auto *Zero = ConstantInt::get(IdxType, 0);
+ for (unsigned i = 0; i < Count; i++) {
+ Value *Indices[2] = {
+ Zero,
+ ConstantInt::get(IdxType, i),
+ };
+ auto *Ptr = IC.Builder->CreateInBoundsGEP(ST, Addr, makeArrayRef(Indices), AddrName);
+ auto *Val = IC.Builder->CreateExtractValue(V, i, EltName);
+ IC.Builder->CreateStore(Val, Ptr);
+ }
+
+ return true;
+ }
+
+ if (auto *AT = dyn_cast<ArrayType>(T)) {
+ // If the array only have one element, we unpack.
+ if (AT->getNumElements() == 1) {
V = IC.Builder->CreateExtractValue(V, 0);
combineStoreToNewValue(IC, SI, V);
return true;
return &SI;
}
- // Don't hack volatile/atomic stores.
- // FIXME: Some bits are legal for atomic stores; needs refactoring.
- if (!SI.isSimple()) return nullptr;
+ // Don't hack volatile/ordered stores.
+ // FIXME: Some bits are legal for ordered atomic stores; needs refactoring.
+ if (!SI.isUnordered()) return nullptr;
// If the RHS is an alloca with a single use, zapify the store, making the
// alloca dead.
// Do really simple DSE, to catch cases where there are several consecutive
// stores to the same location, separated by a few arithmetic operations. This
// situation often occurs with bitfield accesses.
- BasicBlock::iterator BBI = &SI;
+ BasicBlock::iterator BBI(SI);
for (unsigned ScanInsts = 6; BBI != SI.getParent()->begin() && ScanInsts;
--ScanInsts) {
--BBI;
if (StoreInst *PrevSI = dyn_cast<StoreInst>(BBI)) {
// Prev store isn't volatile, and stores to the same location?
- if (PrevSI->isSimple() && equivalentAddressValues(PrevSI->getOperand(1),
+ if (PrevSI->isUnordered() && equivalentAddressValues(PrevSI->getOperand(1),
SI.getOperand(1))) {
++NumDeadStore;
++BBI;
// the pointer we're loading and is producing the pointer we're storing,
// then *this* store is dead (X = load P; store X -> P).
if (LoadInst *LI = dyn_cast<LoadInst>(BBI)) {
- if (LI == Val && equivalentAddressValues(LI->getOperand(0), Ptr) &&
- LI->isSimple())
+ if (LI == Val && equivalentAddressValues(LI->getOperand(0), Ptr)) {
+ assert(SI.isUnordered() && "can't eliminate ordering operation");
return EraseInstFromFunction(SI);
+ }
// Otherwise, this is a load from some other location. Stores before it
// may not be dead.
if (isa<UndefValue>(Val))
return EraseInstFromFunction(SI);
+ // The code below needs to be audited and adjusted for unordered atomics
+ if (!SI.isSimple())
+ return nullptr;
+
// If this store is the last instruction in the basic block (possibly
// excepting debug info instructions), and if the block ends with an
// unconditional branch, try to move it to the successor block.
- BBI = &SI;
+ BBI = SI.getIterator();
do {
++BBI;
} while (isa<DbgInfoIntrinsic>(BBI) ||
return false;
// Verify that the other block ends in a branch and is not otherwise empty.
- BasicBlock::iterator BBI = OtherBB->getTerminator();
+ BasicBlock::iterator BBI(OtherBB->getTerminator());
BranchInst *OtherBr = dyn_cast<BranchInst>(BBI);
if (!OtherBr || BBI == OtherBB->begin())
return false;
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