[ScopBuilder] Move getNonHoistableCtx to ScopBuilder. NFC.

This review is based on review: https://reviews.llvm.org/D62925 . It is
part of moving hoistInvariantLoads function and all functions referenced
only by hoistInvariantLoads to ScopBuilder.

Moved getNonHoistableCtx and functions listed below to ScopBuilder:
isRequiredInvariantLoad
hasNonHoistableBasePtrInScop
isAccessRangeTooComplex

These functions were referenced only by getNonHoistableCtx.

MaxDimensionsInAccessRange and MaxDisjunctsInDomain constant is marked
as extern and it is added to polly namespace. It is used by Scop and
ScopBuilder classes.

MaxDimensionsInAccessRange constant moved to ScopBuilder. It is not used
outside ScopBuilder.

Patch by Dominik Adamski <adamski.dominik@gmail.com>

Differential Revision: https://reviews.llvm.org/D63066

llvm-svn: 363214

1 files changed, 1 insertions, 118 deletions

diff --git a/polly/lib/Analysis/ScopInfo.cpp b/polly/lib/Analysis/ScopInfo.cpp
index 00ede96ada3..b5f80bfc14a 100644
--- a/polly/lib/Analysis/ScopInfo.cpp
+++ b/polly/lib/Analysis/ScopInfo.cpp
@@ -110,22 +110,13 @@ STATISTIC(NumSingletonWrites, "Number of singleton writes after ScopInfo");
 STATISTIC(NumSingletonWritesInLoops,
           "Number of singleton writes nested in affine loops after ScopInfo");
 
-// The maximal number of basic sets we allow during domain construction to
-// be created. More complex scops will result in very high compile time and
-// are also unlikely to result in good code
-static int const MaxDisjunctsInDomain = 20;
+int const polly::MaxDisjunctsInDomain = 20;
 
 // The number of disjunct in the context after which we stop to add more
 // disjuncts. This parameter is there to avoid exponential growth in the
 // number of disjunct when adding non-convex sets to the context.
 static int const MaxDisjunctsInContext = 4;
 
-// The maximal number of dimensions we allow during invariant load construction.
-// More complex access ranges will result in very high compile time and are also
-// unlikely to result in good code. This value is very high and should only
-// trigger for corner cases (e.g., the "dct_luma" function in h264, SPEC2006).
-static int const MaxDimensionsInAccessRange = 9;
-
 static cl::opt<int>
     OptComputeOut("polly-analysis-computeout",
                   cl::desc("Bound the scop analysis by a maximal amount of "
@@ -2993,20 +2984,6 @@ MemoryAccess *Scop::lookupBasePtrAccess(MemoryAccess *MA) {
   return BasePtrStmt->getArrayAccessOrNULLFor(PointerBaseInst);
 }
 
-bool Scop::hasNonHoistableBasePtrInScop(MemoryAccess *MA,
-                                        isl::union_map Writes) {
-  if (auto *BasePtrMA = lookupBasePtrAccess(MA)) {
-    return getNonHoistableCtx(BasePtrMA, Writes).is_null();
-  }
-
-  Value *BaseAddr = MA->getOriginalBaseAddr();
-  if (auto *BasePtrInst = dyn_cast<Instruction>(BaseAddr))
-    if (!isa<LoadInst>(BasePtrInst))
-      return contains(BasePtrInst);
-
-  return false;
-}
-
 bool Scop::buildAliasChecks(AliasAnalysis &AA) {
   if (!PollyUseRuntimeAliasChecks)
     return true;
@@ -3684,100 +3661,6 @@ void Scop::addInvariantLoads(ScopStmt &Stmt, InvariantAccessesTy &InvMAs) {
   }
 }
 
-/// Check if an access range is too complex.
-///
-/// An access range is too complex, if it contains either many disjuncts or
-/// very complex expressions. As a simple heuristic, we assume if a set to
-/// be too complex if the sum of existentially quantified dimensions and
-/// set dimensions is larger than a threshold. This reliably detects both
-/// sets with many disjuncts as well as sets with many divisions as they
-/// arise in h264.
-///
-/// @param AccessRange The range to check for complexity.
-///
-/// @returns True if the access range is too complex.
-static bool isAccessRangeTooComplex(isl::set AccessRange) {
-  unsigned NumTotalDims = 0;
-
-  for (isl::basic_set BSet : AccessRange.get_basic_set_list()) {
-    NumTotalDims += BSet.dim(isl::dim::div);
-    NumTotalDims += BSet.dim(isl::dim::set);
-  }
-
-  if (NumTotalDims > MaxDimensionsInAccessRange)
-    return true;
-
-  return false;
-}
-
-isl::set Scop::getNonHoistableCtx(MemoryAccess *Access, isl::union_map Writes) {
-  // TODO: Loads that are not loop carried, hence are in a statement with
-  //       zero iterators, are by construction invariant, though we
-  //       currently "hoist" them anyway. This is necessary because we allow
-  //       them to be treated as parameters (e.g., in conditions) and our code
-  //       generation would otherwise use the old value.
-
-  auto &Stmt = *Access->getStatement();
-  BasicBlock *BB = Stmt.getEntryBlock();
-
-  if (Access->isScalarKind() || Access->isWrite() || !Access->isAffine() ||
-      Access->isMemoryIntrinsic())
-    return nullptr;
-
-  // Skip accesses that have an invariant base pointer which is defined but
-  // not loaded inside the SCoP. This can happened e.g., if a readnone call
-  // returns a pointer that is used as a base address. However, as we want
-  // to hoist indirect pointers, we allow the base pointer to be defined in
-  // the region if it is also a memory access. Each ScopArrayInfo object
-  // that has a base pointer origin has a base pointer that is loaded and
-  // that it is invariant, thus it will be hoisted too. However, if there is
-  // no base pointer origin we check that the base pointer is defined
-  // outside the region.
-  auto *LI = cast<LoadInst>(Access->getAccessInstruction());
-  if (hasNonHoistableBasePtrInScop(Access, Writes))
-    return nullptr;
-
-  isl::map AccessRelation = Access->getAccessRelation();
-  assert(!AccessRelation.is_empty());
-
-  if (AccessRelation.involves_dims(isl::dim::in, 0, Stmt.getNumIterators()))
-    return nullptr;
-
-  AccessRelation = AccessRelation.intersect_domain(Stmt.getDomain());
-  isl::set SafeToLoad;
-
-  auto &DL = getFunction().getParent()->getDataLayout();
-  if (isSafeToLoadUnconditionally(LI->getPointerOperand(), LI->getAlignment(),
-                                  DL)) {
-    SafeToLoad = isl::set::universe(AccessRelation.get_space().range());
-  } else if (BB != LI->getParent()) {
-    // Skip accesses in non-affine subregions as they might not be executed
-    // under the same condition as the entry of the non-affine subregion.
-    return nullptr;
-  } else {
-    SafeToLoad = AccessRelation.range();
-  }
-
-  if (isAccessRangeTooComplex(AccessRelation.range()))
-    return nullptr;
-
-  isl::union_map Written = Writes.intersect_range(SafeToLoad);
-  isl::set WrittenCtx = Written.params();
-  bool IsWritten = !WrittenCtx.is_empty();
-
-  if (!IsWritten)
-    return WrittenCtx;
-
-  WrittenCtx = WrittenCtx.remove_divs();
-  bool TooComplex = WrittenCtx.n_basic_set() >= MaxDisjunctsInDomain;
-  if (TooComplex || !isRequiredInvariantLoad(LI))
-    return nullptr;
-
-  addAssumption(INVARIANTLOAD, WrittenCtx, LI->getDebugLoc(), AS_RESTRICTION,
-                LI->getParent());
-  return WrittenCtx;
-}
-
 ScopArrayInfo *Scop::getOrCreateScopArrayInfo(Value *BasePtr, Type *ElementType,
                                               ArrayRef<const SCEV *> Sizes,
                                               MemoryKind Kind,