[Loads] Move generic code out of vectorizer into a location it might be reused [NFC]
llvm-svn: 371558
diff --git a/llvm/lib/Analysis/Loads.cpp b/llvm/lib/Analysis/Loads.cpp
index e74df9c..ea98ca9 100644
--- a/llvm/lib/Analysis/Loads.cpp
+++ b/llvm/lib/Analysis/Loads.cpp
@@ -12,6 +12,9 @@
#include "llvm/Analysis/Loads.h"
#include "llvm/Analysis/AliasAnalysis.h"
+#include "llvm/Analysis/LoopInfo.h"
+#include "llvm/Analysis/ScalarEvolution.h"
+#include "llvm/Analysis/ScalarEvolutionExpressions.h"
#include "llvm/Analysis/ValueTracking.h"
#include "llvm/IR/DataLayout.h"
#include "llvm/IR/GlobalAlias.h"
@@ -190,6 +193,53 @@
return false;
}
+bool llvm::isDereferenceableAndAlignedInLoop(LoadInst *LI, Loop *L,
+ ScalarEvolution &SE,
+ DominatorTree &DT) {
+ auto &DL = LI->getModule()->getDataLayout();
+ Value *Ptr = LI->getPointerOperand();
+ auto *AddRec = dyn_cast<SCEVAddRecExpr>(SE.getSCEV(Ptr));
+ if (!AddRec || AddRec->getLoop() != L || !AddRec->isAffine())
+ return false;
+ auto* Step = dyn_cast<SCEVConstant>(AddRec->getStepRecurrence(SE));
+ if (!Step)
+ return false;
+ APInt StepC = Step->getAPInt();
+ APInt EltSize(DL.getIndexTypeSizeInBits(Ptr->getType()),
+ DL.getTypeStoreSize(LI->getType()));
+ // TODO: generalize to access patterns which have gaps
+ // TODO: handle uniform addresses (if not already handled by LICM)
+ if (StepC != EltSize)
+ return false;
+
+ // TODO: If the symbolic trip count has a small bound (max count), we might
+ // be able to prove safety.
+ auto TC = SE.getSmallConstantTripCount(L);
+ if (!TC)
+ return false;
+
+ const APInt AccessSize = TC * EltSize;
+
+ auto *StartS = dyn_cast<SCEVUnknown>(AddRec->getStart());
+ if (!StartS)
+ return false;
+ assert(SE.isLoopInvariant(StartS, L) && "implied by addrec definition");
+ Value *Base = StartS->getValue();
+
+ Instruction *HeaderFirstNonPHI = L->getHeader()->getFirstNonPHI();
+
+ unsigned Align = LI->getAlignment();
+ if (Align == 0)
+ Align = DL.getABITypeAlignment(LI->getType());
+ // For the moment, restrict ourselves to the case where the access size is a
+ // multiple of the requested alignment and the base is aligned.
+ // TODO: generalize if a case found which warrants
+ if (EltSize.urem(Align) != 0)
+ return false;
+ return isDereferenceableAndAlignedPointer(Base, Align, AccessSize,
+ DL, HeaderFirstNonPHI, &DT);
+}
+
/// Check if executing a load of this pointer value cannot trap.
///
/// If DT and ScanFrom are specified this method performs context-sensitive