Revert "[OpenMP] Avoid VLAs for some reductions on array sections"

This breaks at least two buildbots:
http://lab.llvm.org:8011/builders/clang-cmake-x86_64-avx2-linux/builds/1175
http://lab.llvm.org:8011/builders/clang-atom-d525-fedora-rel/builds/10478

This reverts commit r316229 during local investigation.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@316235 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 1 insertions, 82 deletions

diff --git a/lib/Sema/SemaOpenMP.cpp b/lib/Sema/SemaOpenMP.cpp
index bf89eb0b2f..a024888fbf 100644
--- a/lib/Sema/SemaOpenMP.cpp
+++ b/lib/Sema/SemaOpenMP.cpp
@@ -9330,68 +9330,6 @@ struct ReductionData {
 };
 } // namespace
 
-static bool CheckOMPArraySectionConstantForReduction(
-    ASTContext &Context, const OMPArraySectionExpr *OASE, bool &SingleElement,
-    SmallVectorImpl<llvm::APSInt> &ArraySizes) {
-  const Expr *Length = OASE->getLength();
-  if (Length == nullptr) {
-    // For array sections of the form [1:] or [:], we would need to analyze
-    // the lower bound...
-    if (OASE->getColonLoc().isValid())
-      return false;
-
-    // This is an array subscript which has implicit length 1!
-    SingleElement = true;
-    ArraySizes.push_back(llvm::APSInt::get(1));
-  } else {
-    llvm::APSInt ConstantLengthValue;
-    if (!Length->EvaluateAsInt(ConstantLengthValue, Context))
-      return false;
-
-    SingleElement = (ConstantLengthValue.getSExtValue() == 1);
-    ArraySizes.push_back(ConstantLengthValue);
-  }
-
-  // Get the base of this array section and walk up from there.
-  const Expr *Base = OASE->getBase()->IgnoreParenImpCasts();
-
-  // We require length = 1 for all array sections except the right-most to
-  // guarantee that the memory region is contiguous and has no holes in it.
-  while (const auto *TempOASE = dyn_cast<OMPArraySectionExpr>(Base)) {
-    Length = TempOASE->getLength();
-    if (Length == nullptr) {
-      // For array sections of the form [1:] or [:], we would need to analyze
-      // the lower bound...
-      if (OASE->getColonLoc().isValid())
-        return false;
-
-      // This is an array subscript which has implicit length 1!
-      ArraySizes.push_back(llvm::APSInt::get(1));
-    } else {
-      llvm::APSInt ConstantLengthValue;
-      if (!Length->EvaluateAsInt(ConstantLengthValue, Context) ||
-          ConstantLengthValue.getSExtValue() != 1)
-        return false;
-
-      ArraySizes.push_back(ConstantLengthValue);
-    }
-    Base = TempOASE->getBase()->IgnoreParenImpCasts();
-  }
-
-  // If we have a single element, we don't need to add the implicit lengths.
-  if (!SingleElement) {
-    while (const auto *TempASE = dyn_cast<ArraySubscriptExpr>(Base)) {
-      // Has implicit length 1!
-      ArraySizes.push_back(llvm::APSInt::get(1));
-      Base = TempASE->getBase()->IgnoreParenImpCasts();
-    }
-  }
-
-  // This array section can be privatized as a single value or as a constant
-  // sized array.
-  return true;
-}
-
 static bool ActOnOMPReductionKindClause(
     Sema &S, DSAStackTy *Stack, OpenMPClauseKind ClauseKind,
     ArrayRef<Expr *> VarList, SourceLocation StartLoc, SourceLocation LParenLoc,
@@ -9690,26 +9628,7 @@ static bool ActOnOMPReductionKindClause(
     auto *RHSVD = buildVarDecl(S, ELoc, Type, D->getName(),
                                D->hasAttrs() ? &D->getAttrs() : nullptr);
     auto PrivateTy = Type;
-
-    // Try if we can determine constant lengths for all array sections and avoid
-    // the VLA.
-    bool ConstantLengthOASE = false;
-    if (OASE) {
-      bool SingleElement;
-      llvm::SmallVector<llvm::APSInt, 4> ArraySizes;
-      ConstantLengthOASE = CheckOMPArraySectionConstantForReduction(
-          Context, OASE, SingleElement, ArraySizes);
-
-      // If we don't have a single element, we must emit a constant array type.
-      if (ConstantLengthOASE && !SingleElement) {
-        for (auto &Size : ArraySizes) {
-          PrivateTy = Context.getConstantArrayType(
-              PrivateTy, Size, ArrayType::Normal, /*IndexTypeQuals=*/0);
-        }
-      }
-    }
-
-    if ((OASE && !ConstantLengthOASE) ||
+    if (OASE ||
         (!ASE &&
          D->getType().getNonReferenceType()->isVariablyModifiedType())) {
       // For arrays/array sections only: