//
//===----------------------------------------------------------------------===//
+#include "llvm/Analysis/LoopInfo.h"
+#include "llvm/Analysis/ScalarEvolutionExpressions.h"
+#include "llvm/Analysis/ScalarEvolution.h"
#include "llvm/Analysis/VectorUtils.h"
+#include "llvm/IR/GetElementPtrTypeIterator.h"
+#include "llvm/IR/PatternMatch.h"
+#include "llvm/IR/Value.h"
/// \brief Identify if the intrinsic is trivially vectorizable.
/// This method returns true if the intrinsic's argument types are all
return Intrinsic::not_intrinsic;
}
+
+/// \brief Find the operand of the GEP that should be checked for consecutive
+/// stores. This ignores trailing indices that have no effect on the final
+/// pointer.
+unsigned llvm::getGEPInductionOperand(const GetElementPtrInst *Gep) {
+ const DataLayout &DL = Gep->getModule()->getDataLayout();
+ unsigned LastOperand = Gep->getNumOperands() - 1;
+ unsigned GEPAllocSize = DL.getTypeAllocSize(
+ cast<PointerType>(Gep->getType()->getScalarType())->getElementType());
+
+ // Walk backwards and try to peel off zeros.
+ while (LastOperand > 1 &&
+ match(Gep->getOperand(LastOperand), llvm::PatternMatch::m_Zero())) {
+ // Find the type we're currently indexing into.
+ gep_type_iterator GEPTI = gep_type_begin(Gep);
+ std::advance(GEPTI, LastOperand - 1);
+
+ // If it's a type with the same allocation size as the result of the GEP we
+ // can peel off the zero index.
+ if (DL.getTypeAllocSize(*GEPTI) != GEPAllocSize)
+ break;
+ --LastOperand;
+ }
+
+ return LastOperand;
+}
+
+/// \brief If the argument is a GEP, then returns the operand identified by
+/// getGEPInductionOperand. However, if there is some other non-loop-invariant
+/// operand, it returns that instead.
+llvm::Value *llvm::stripGetElementPtr(llvm::Value *Ptr, ScalarEvolution *SE,
+ Loop *Lp) {
+ GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(Ptr);
+ if (!GEP)
+ return Ptr;
+
+ unsigned InductionOperand = getGEPInductionOperand(GEP);
+
+ // Check that all of the gep indices are uniform except for our induction
+ // operand.
+ for (unsigned i = 0, e = GEP->getNumOperands(); i != e; ++i)
+ if (i != InductionOperand &&
+ !SE->isLoopInvariant(SE->getSCEV(GEP->getOperand(i)), Lp))
+ return Ptr;
+ return GEP->getOperand(InductionOperand);
+}
+
+/// \brief If a value has only one user that is a CastInst, return it.
+llvm::Value *llvm::getUniqueCastUse(llvm::Value *Ptr, Loop *Lp, Type *Ty) {
+ llvm::Value *UniqueCast = nullptr;
+ for (User *U : Ptr->users()) {
+ CastInst *CI = dyn_cast<CastInst>(U);
+ if (CI && CI->getType() == Ty) {
+ if (!UniqueCast)
+ UniqueCast = CI;
+ else
+ return nullptr;
+ }
+ }
+ return UniqueCast;
+}
+
+/// \brief Get the stride of a pointer access in a loop. Looks for symbolic
+/// strides "a[i*stride]". Returns the symbolic stride, or null otherwise.
+llvm::Value *llvm::getStrideFromPointer(llvm::Value *Ptr, ScalarEvolution *SE,
+ Loop *Lp) {
+ const PointerType *PtrTy = dyn_cast<PointerType>(Ptr->getType());
+ if (!PtrTy || PtrTy->isAggregateType())
+ return nullptr;
+
+ // Try to remove a gep instruction to make the pointer (actually index at this
+ // point) easier analyzable. If OrigPtr is equal to Ptr we are analzying the
+ // pointer, otherwise, we are analyzing the index.
+ llvm::Value *OrigPtr = Ptr;
+
+ // The size of the pointer access.
+ int64_t PtrAccessSize = 1;
+
+ Ptr = stripGetElementPtr(Ptr, SE, Lp);
+ const SCEV *V = SE->getSCEV(Ptr);
+
+ if (Ptr != OrigPtr)
+ // Strip off casts.
+ while (const SCEVCastExpr *C = dyn_cast<SCEVCastExpr>(V))
+ V = C->getOperand();
+
+ const SCEVAddRecExpr *S = dyn_cast<SCEVAddRecExpr>(V);
+ if (!S)
+ return nullptr;
+
+ V = S->getStepRecurrence(*SE);
+ if (!V)
+ return nullptr;
+
+ // Strip off the size of access multiplication if we are still analyzing the
+ // pointer.
+ if (OrigPtr == Ptr) {
+ const DataLayout &DL = Lp->getHeader()->getModule()->getDataLayout();
+ DL.getTypeAllocSize(PtrTy->getElementType());
+ if (const SCEVMulExpr *M = dyn_cast<SCEVMulExpr>(V)) {
+ if (M->getOperand(0)->getSCEVType() != scConstant)
+ return nullptr;
+
+ const APInt &APStepVal =
+ cast<SCEVConstant>(M->getOperand(0))->getValue()->getValue();
+
+ // Huge step value - give up.
+ if (APStepVal.getBitWidth() > 64)
+ return nullptr;
+
+ int64_t StepVal = APStepVal.getSExtValue();
+ if (PtrAccessSize != StepVal)
+ return nullptr;
+ V = M->getOperand(1);
+ }
+ }
+
+ // Strip off casts.
+ Type *StripedOffRecurrenceCast = nullptr;
+ if (const SCEVCastExpr *C = dyn_cast<SCEVCastExpr>(V)) {
+ StripedOffRecurrenceCast = C->getType();
+ V = C->getOperand();
+ }
+
+ // Look for the loop invariant symbolic value.
+ const SCEVUnknown *U = dyn_cast<SCEVUnknown>(V);
+ if (!U)
+ return nullptr;
+
+ llvm::Value *Stride = U->getValue();
+ if (!Lp->isLoopInvariant(Stride))
+ return nullptr;
+
+ // If we have stripped off the recurrence cast we have to make sure that we
+ // return the value that is used in this loop so that we can replace it later.
+ if (StripedOffRecurrenceCast)
+ Stride = getUniqueCastUse(Stride, Lp, StripedOffRecurrenceCast);
+
+ return Stride;
+}
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