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ScopInfo: Split hasAffineMemoryAccesses() into multiple functions [NFC] 

This makes the overall code more readable.

llvm-svn: 253951
This commit is contained in:
Tobias Grosser 2015-11-24 05:00:36 +00:00
parent 919ce23566
commit d68ba42556
2 changed files with 187 additions and 115 deletions
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44
polly/include/polly/ScopDetection.h
View File

@ -222,6 +222,50 @@ private:
/// @returns True if the subregion can be over approximated, false otherwise.
bool addOverApproximatedRegion(Region *AR, DetectionContext &Context) const;
/// @brief Find for a given base pointer terms that hint towards dimension
/// sizes of a multi-dimensional array.
///
/// @param Context The current detection context.
/// @param BasePointer A base pointer indicating the virtual array we are
/// interested in.
SmallVector<const SCEV *, 4>
getDelinearizationTerms(DetectionContext &Context,
const SCEVUnknown *BasePointer) const;
/// @brief Check if the dimension size of a delinearized array is valid.
///
/// @param Context The current detection context.
/// @param Sizes The sizes of the different array dimensions.
/// @param BasePointer The base pointer we are interested in.
/// @returns True if one or more array sizes could be derived - meaning: we
/// see this array as multi-dimensional.
bool hasValidArraySizes(DetectionContext &Context,
SmallVectorImpl<const SCEV *> &Sizes,
const SCEVUnknown *BasePointer) const;
/// @brief Derive access functions for a given base pointer.
///
/// @param Context The current detection context.
/// @param Sizes The sizes of the different array dimensions.
/// @param BasePointer The base pointer of all the array for which to compute
/// access functions.
/// @param Shape The shape that describes the derived array sizes and
/// which should be filled with newly computed access
/// functions.
/// @returns True if a set of affine access functions could be derived.
bool computeAccessFunctions(DetectionContext &Context,
const SCEVUnknown *BasePointer,
std::shared_ptr<ArrayShape> Shape) const;
/// @brief Check if all accesses to a given BasePointer are affine.
///
/// @param Context The current detection context.
/// @param basepointer the base pointer we are interested in.
/// @param True if consistent (multi-dimensional) array accesses could be
/// derived for this array.
bool hasBaseAffineAccesses(DetectionContext &Context,
const SCEVUnknown *BasePointer) const;
// Delinearize all non affine memory accesses and return false when there
// exists a non affine memory access that cannot be delinearized. Return true
// when all array accesses are affine after delinearization.

80
polly/lib/Analysis/ScopDetection.cpp
View File

@ -487,15 +487,9 @@ bool ScopDetection::isInvariant(const Value &Val, const Region &Reg) const {
MapInsnToMemAcc InsnToMemAcc;
bool ScopDetection::hasAffineMemoryAccesses(DetectionContext &Context) const {
Region &CurRegion = Context.CurRegion;
for (const SCEVUnknown *BasePointer : Context.NonAffineAccesses) {
Value *BaseValue = BasePointer->getValue();
auto Shape = std::shared_ptr<ArrayShape>(new ArrayShape(BasePointer));
bool BasePtrHasNonAffine = false;
// First step: collect parametric terms in all array references.
SmallVector<const SCEV *, 4>
ScopDetection::getDelinearizationTerms(DetectionContext &Context,
const SCEVUnknown *BasePointer) const {
SmallVector<const SCEV *, 4> Terms;
for (const auto &Pair : Context.Accesses[BasePointer]) {
// In case the outermost expression is a plain add, we check if any of its
@ -534,14 +528,17 @@ bool ScopDetection::hasAffineMemoryAccesses(DetectionContext &Context) const {
if (Terms.empty())
SE->collectParametricTerms(Pair.second, Terms);
}
return Terms;
}
// Second step: find array shape.
SE->findArrayDimensions(Terms, Shape->DelinearizedSizes,
Context.ElementSize[BasePointer]);
for (const SCEV *DelinearizedSize : Shape->DelinearizedSizes) {
bool ScopDetection::hasValidArraySizes(DetectionContext &Context,
SmallVectorImpl<const SCEV *> &Sizes,
const SCEVUnknown *BasePointer) const {
Value *BaseValue = BasePointer->getValue();
Region &CurRegion = Context.CurRegion;
for (const SCEV *DelinearizedSize : Sizes) {
if (!isAffine(DelinearizedSize, Context, nullptr)) {
Shape->DelinearizedSizes.clear();
Sizes.clear();
break;
}
if (auto *Unknown = dyn_cast<SCEVUnknown>(DelinearizedSize)) {
@ -560,9 +557,9 @@ bool ScopDetection::hasAffineMemoryAccesses(DetectionContext &Context) const {
}
// No array shape derived.
if (Shape->DelinearizedSizes.empty()) {
if (Sizes.empty()) {
if (AllowNonAffine)
continue;
return true;
for (const auto &Pair : Context.Accesses[BasePointer]) {
const Instruction *Insn = Pair.first;
@ -575,17 +572,22 @@ bool ScopDetection::hasAffineMemoryAccesses(DetectionContext &Context) const {
return false;
}
}
continue;
return false;
}
return true;
}
// Third step: compute the access functions for each subscript.
//
// We first store the resulting memory accesses in TempMemoryAccesses. Only
// if the access functions for all memory accesses have been successfully
// delinearized we continue. Otherwise, we either report a failure or, if
// non-affine accesses are allowed, we drop the information. In case the
// information is dropped the memory accesses need to be overapproximated
// when translated to a polyhedral representation.
// We first store the resulting memory accesses in TempMemoryAccesses. Only
// if the access functions for all memory accesses have been successfully
// delinearized we continue. Otherwise, we either report a failure or, if
// non-affine accesses are allowed, we drop the information. In case the
// information is dropped the memory accesses need to be overapproximated
// when translated to a polyhedral representation.
bool ScopDetection::computeAccessFunctions(
DetectionContext &Context, const SCEVUnknown *BasePointer,
std::shared_ptr<ArrayShape> Shape) const {
Value *BaseValue = BasePointer->getValue();
bool BasePtrHasNonAffine = false;
MapInsnToMemAcc TempMemoryAccesses;
for (const auto &Pair : Context.Accesses[BasePointer]) {
const Instruction *Insn = Pair.first;
@ -622,6 +624,32 @@ bool ScopDetection::hasAffineMemoryAccesses(DetectionContext &Context) const {
if (!BasePtrHasNonAffine)
InsnToMemAcc.insert(TempMemoryAccesses.begin(), TempMemoryAccesses.end());
return true;
}
bool ScopDetection::hasBaseAffineAccesses(
DetectionContext &Context, const SCEVUnknown *BasePointer) const {
auto Shape = std::shared_ptr<ArrayShape>(new ArrayShape(BasePointer));
auto Terms = getDelinearizationTerms(Context, BasePointer);
SE->findArrayDimensions(Terms, Shape->DelinearizedSizes,
Context.ElementSize[BasePointer]);
if (!hasValidArraySizes(Context, Shape->DelinearizedSizes, BasePointer))
return false;
return computeAccessFunctions(Context, BasePointer, Shape);
}
bool ScopDetection::hasAffineMemoryAccesses(DetectionContext &Context) const {
for (const SCEVUnknown *BasePointer : Context.NonAffineAccesses)
if (!hasBaseAffineAccesses(Context, BasePointer)) {
if (KeepGoing)
continue;
else
return false;
}
return true;
}