// //
//===----------------------------------------------------------------------===//
-#define DEBUG_TYPE "da"
-
#include "llvm/Analysis/DependenceAnalysis.h"
#include "llvm/ADT/Statistic.h"
#include "llvm/Analysis/AliasAnalysis.h"
using namespace llvm;
+#define DEBUG_TYPE "da"
+
//===----------------------------------------------------------------------===//
// statistics
DstI != DstE; ++DstI) {
if (isa<StoreInst>(*DstI) || isa<LoadInst>(*DstI)) {
OS << "da analyze - ";
- if (Dependence *D = DA->depends(&*SrcI, &*DstI, true)) {
+ if (auto D = DA->depends(&*SrcI, &*DstI, true)) {
D->dump(OS);
for (unsigned Level = 1; Level <= D->getLevels(); Level++) {
if (D->isSplitable(Level)) {
OS << "da analyze - split level = " << Level;
- OS << ", iteration = " << *DA->getSplitIteration(D, Level);
+ OS << ", iteration = " << *DA->getSplitIteration(*D, Level);
OS << "!\n";
}
}
- delete D;
}
else
OS << "none!\n";
}
}
+void DependenceAnalysis::unifySubscriptType(Subscript *Pair) {
+ const SCEV *Src = Pair->Src;
+ const SCEV *Dst = Pair->Dst;
+ IntegerType *SrcTy = dyn_cast<IntegerType>(Src->getType());
+ IntegerType *DstTy = dyn_cast<IntegerType>(Dst->getType());
+ if (SrcTy == nullptr || DstTy == nullptr) {
+ assert(SrcTy == DstTy && "This function only unify integer types and "
+ "expect Src and Dst share the same type "
+ "otherwise.");
+ return;
+ }
+ if (SrcTy->getBitWidth() > DstTy->getBitWidth()) {
+ // Sign-extend Dst to typeof(Src) if typeof(Src) is wider than typeof(Dst).
+ Pair->Dst = SE->getSignExtendExpr(Dst, SrcTy);
+ } else if (SrcTy->getBitWidth() < DstTy->getBitWidth()) {
+ // Sign-extend Src to typeof(Dst) if typeof(Dst) is wider than typeof(Src).
+ Pair->Src = SE->getSignExtendExpr(Src, DstTy);
+ }
+}
// removeMatchingExtensions - Examines a subscript pair.
// If the source and destination are identically sign (or zero)
(isa<SCEVSignExtendExpr>(Src) && isa<SCEVSignExtendExpr>(Dst))) {
const SCEVCastExpr *SrcCast = cast<SCEVCastExpr>(Src);
const SCEVCastExpr *DstCast = cast<SCEVCastExpr>(Dst);
- if (SrcCast->getType() == DstCast->getType()) {
- Pair->Src = SrcCast->getOperand();
- Pair->Dst = DstCast->getOperand();
+ const SCEV *SrcCastOp = SrcCast->getOperand();
+ const SCEV *DstCastOp = DstCast->getOperand();
+ if (SrcCastOp->getType() == DstCastOp->getType()) {
+ Pair->Src = SrcCastOp;
+ Pair->Dst = DstCastOp;
}
}
}
AddRec->getNoWrapFlags());
}
if (SE->isLoopInvariant(AddRec, TargetLoop))
- return SE->getAddRecExpr(AddRec,
- Value,
- TargetLoop,
- SCEV::FlagAnyWrap);
- return SE->getAddRecExpr(addToCoefficient(AddRec->getStart(),
- TargetLoop, Value),
- AddRec->getStepRecurrence(*SE),
- AddRec->getLoop(),
- AddRec->getNoWrapFlags());
+ return SE->getAddRecExpr(AddRec, Value, TargetLoop, SCEV::FlagAnyWrap);
+ return SE->getAddRecExpr(
+ addToCoefficient(AddRec->getStart(), TargetLoop, Value),
+ AddRec->getStepRecurrence(*SE), AddRec->getLoop(),
+ AddRec->getNoWrapFlags());
}
/// source and destination array references are recurrences on a nested loop,
/// this function flattens the nested recurrences into separate recurrences
/// for each loop level.
-bool
-DependenceAnalysis::tryDelinearize(const SCEV *SrcSCEV, const SCEV *DstSCEV,
- SmallVectorImpl<Subscript> &Pair) const {
+bool DependenceAnalysis::tryDelinearize(const SCEV *SrcSCEV,
+ const SCEV *DstSCEV,
+ SmallVectorImpl<Subscript> &Pair,
+ const SCEV *ElementSize) {
+ const SCEVUnknown *SrcBase =
+ dyn_cast<SCEVUnknown>(SE->getPointerBase(SrcSCEV));
+ const SCEVUnknown *DstBase =
+ dyn_cast<SCEVUnknown>(SE->getPointerBase(DstSCEV));
+
+ if (!SrcBase || !DstBase || SrcBase != DstBase)
+ return false;
+
+ SrcSCEV = SE->getMinusSCEV(SrcSCEV, SrcBase);
+ DstSCEV = SE->getMinusSCEV(DstSCEV, DstBase);
+
const SCEVAddRecExpr *SrcAR = dyn_cast<SCEVAddRecExpr>(SrcSCEV);
const SCEVAddRecExpr *DstAR = dyn_cast<SCEVAddRecExpr>(DstSCEV);
if (!SrcAR || !DstAR || !SrcAR->isAffine() || !DstAR->isAffine())
return false;
- SmallVector<const SCEV *, 4> SrcSubscripts, DstSubscripts, SrcSizes, DstSizes;
- const SCEV *RemainderS = SrcAR->delinearize(*SE, SrcSubscripts, SrcSizes);
- const SCEV *RemainderD = DstAR->delinearize(*SE, DstSubscripts, DstSizes);
-
- int size = SrcSubscripts.size();
- // Fail when there is only a subscript: that's a linearized access function.
- if (size < 2)
- return false;
+ // First step: collect parametric terms in both array references.
+ SmallVector<const SCEV *, 4> Terms;
+ SrcAR->collectParametricTerms(*SE, Terms);
+ DstAR->collectParametricTerms(*SE, Terms);
- int dstSize = DstSubscripts.size();
- // Fail when the number of subscripts in Src and Dst differ.
- if (size != dstSize)
- return false;
+ // Second step: find subscript sizes.
+ SmallVector<const SCEV *, 4> Sizes;
+ SE->findArrayDimensions(Terms, Sizes, ElementSize);
- // Fail when the size of any of the subscripts in Src and Dst differs: the
- // dependence analysis assumes that elements in the same array have same size.
- // SCEV delinearization does not have a context based on which it would decide
- // globally the size of subscripts that would best fit all the array accesses.
- for (int i = 0; i < size; ++i)
- if (SrcSizes[i] != DstSizes[i])
- return false;
+ // Third step: compute the access functions for each subscript.
+ SmallVector<const SCEV *, 4> SrcSubscripts, DstSubscripts;
+ SrcAR->computeAccessFunctions(*SE, SrcSubscripts, Sizes);
+ DstAR->computeAccessFunctions(*SE, DstSubscripts, Sizes);
- // When the difference in remainders is different than a constant it might be
- // that the base address of the arrays is not the same.
- const SCEV *DiffRemainders = SE->getMinusSCEV(RemainderS, RemainderD);
- if (!isa<SCEVConstant>(DiffRemainders))
+ // Fail when there is only a subscript: that's a linearized access function.
+ if (SrcSubscripts.size() < 2 || DstSubscripts.size() < 2 ||
+ SrcSubscripts.size() != DstSubscripts.size())
return false;
- // Normalize the last dimension: integrate the size of the "scalar dimension"
- // and the remainder of the delinearization.
- DstSubscripts[size-1] = SE->getMulExpr(DstSubscripts[size-1],
- DstSizes[size-1]);
- SrcSubscripts[size-1] = SE->getMulExpr(SrcSubscripts[size-1],
- SrcSizes[size-1]);
- SrcSubscripts[size-1] = SE->getAddExpr(SrcSubscripts[size-1], RemainderS);
- DstSubscripts[size-1] = SE->getAddExpr(DstSubscripts[size-1], RemainderD);
+ int size = SrcSubscripts.size();
-#ifndef NDEBUG
- DEBUG(errs() << "\nSrcSubscripts: ");
- for (int i = 0; i < size; i++)
- DEBUG(errs() << *SrcSubscripts[i]);
- DEBUG(errs() << "\nDstSubscripts: ");
- for (int i = 0; i < size; i++)
- DEBUG(errs() << *DstSubscripts[i]);
-#endif
+ DEBUG({
+ dbgs() << "\nSrcSubscripts: ";
+ for (int i = 0; i < size; i++)
+ dbgs() << *SrcSubscripts[i];
+ dbgs() << "\nDstSubscripts: ";
+ for (int i = 0; i < size; i++)
+ dbgs() << *DstSubscripts[i];
+ });
// The delinearization transforms a single-subscript MIV dependence test into
// a multi-subscript SIV dependence test that is easier to compute. So we
for (int i = 0; i < size; ++i) {
Pair[i].Src = SrcSubscripts[i];
Pair[i].Dst = DstSubscripts[i];
+ unifySubscriptType(&Pair[i]);
// FIXME: we should record the bounds SrcSizes[i] and DstSizes[i] that the
// delinearization has found, and add these constraints to the dependence
//
// Care is required to keep the routine below, getSplitIteration(),
// up to date with respect to this routine.
-Dependence *DependenceAnalysis::depends(Instruction *Src,
- Instruction *Dst,
- bool PossiblyLoopIndependent) {
+std::unique_ptr<Dependence>
+DependenceAnalysis::depends(Instruction *Src, Instruction *Dst,
+ bool PossiblyLoopIndependent) {
if (Src == Dst)
PossiblyLoopIndependent = false;
if (!isLoadOrStore(Src) || !isLoadOrStore(Dst)) {
// can only analyze simple loads and stores, i.e., no calls, invokes, etc.
DEBUG(dbgs() << "can only handle simple loads and stores\n");
- return new Dependence(Src, Dst);
+ return make_unique<Dependence>(Src, Dst);
}
Value *SrcPtr = getPointerOperand(Src);
case AliasAnalysis::PartialAlias:
// cannot analyse objects if we don't understand their aliasing.
DEBUG(dbgs() << "can't analyze may or partial alias\n");
- return new Dependence(Src, Dst);
+ return make_unique<Dependence>(Src, Dst);
case AliasAnalysis::NoAlias:
// If the objects noalias, they are distinct, accesses are independent.
DEBUG(dbgs() << "no alias\n");
++SrcIdx, ++DstIdx, ++P) {
Pair[P].Src = SE->getSCEV(*SrcIdx);
Pair[P].Dst = SE->getSCEV(*DstIdx);
+ unifySubscriptType(&Pair[P]);
}
}
else {
}
if (Delinearize && Pairs == 1 && CommonLevels > 1 &&
- tryDelinearize(Pair[0].Src, Pair[0].Dst, Pair)) {
+ tryDelinearize(Pair[0].Src, Pair[0].Dst, Pair, SE->getElementSize(Src))) {
DEBUG(dbgs() << " delinerized GEP\n");
Pairs = Pair.size();
}
return nullptr;
}
- FullDependence *Final = new FullDependence(Result);
+ auto Final = make_unique<FullDependence>(Result);
Result.DV = nullptr;
- return Final;
+ return std::move(Final);
}
//
// breaks the dependence and allows us to vectorize/parallelize
// both loops.
-const SCEV *DependenceAnalysis::getSplitIteration(const Dependence *Dep,
+const SCEV *DependenceAnalysis::getSplitIteration(const Dependence &Dep,
unsigned SplitLevel) {
- assert(Dep && "expected a pointer to a Dependence");
- assert(Dep->isSplitable(SplitLevel) &&
+ assert(Dep.isSplitable(SplitLevel) &&
"Dep should be splitable at SplitLevel");
- Instruction *Src = Dep->getSrc();
- Instruction *Dst = Dep->getDst();
+ Instruction *Src = Dep.getSrc();
+ Instruction *Dst = Dep.getDst();
assert(Src->mayReadFromMemory() || Src->mayWriteToMemory());
assert(Dst->mayReadFromMemory() || Dst->mayWriteToMemory());
assert(isLoadOrStore(Src));
}
if (Delinearize && Pairs == 1 && CommonLevels > 1 &&
- tryDelinearize(Pair[0].Src, Pair[0].Dst, Pair)) {
+ tryDelinearize(Pair[0].Src, Pair[0].Dst, Pair, SE->getElementSize(Src))) {
DEBUG(dbgs() << " delinerized GEP\n");
Pairs = Pair.size();
}
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