diff --git a/clang/lib/Sema/SemaStmtAttr.cpp b/clang/lib/Sema/SemaStmtAttr.cpp
--- a/clang/lib/Sema/SemaStmtAttr.cpp
+++ b/clang/lib/Sema/SemaStmtAttr.cpp
@@ -306,21 +306,33 @@
   if (!DiagnoseMutualExclusions(S, Attrs))
     return;
 
-  // There are 6 categories of loop hints attributes: vectorize, interleave,
-  // unroll, unroll_and_jam, pipeline and distribute. Except for distribute they
-  // come in two variants: a state form and a numeric form.  The state form
-  // selectively defaults/enables/disables the transformation for the loop
-  // (for unroll, default indicates full unrolling rather than enabling the
-  // transformation). The numeric form provides an integer hint (for
-  // example, unroll count) to the transformer. The following array accumulates
-  // the hints encountered while iterating through the attributes to check for
-  // compatibility.
+  enum CategoryType {
+    // For the following categories, they come in two variants: a state form and
+    // a numeric form. The state form may be one of default, enable, and
+    // disable. The numeric form provides an integer hint (for example, unroll
+    // count) to the transformer.
+    Vectorize,
+    Interleave,
+    UnrollAndJam,
+    Pipeline,
+    // For unroll, default indicates full unrolling rather than enabling the
+    // transformation.
+    Unroll,
+    // The loop distribution transformation only has a state form that is
+    // exposed by #pragma clang loop distribute (enable | disable).
+    Distribute,
+    // The vector predication only has a state form that is exposed by
+    // #pragma clang loop vectorize_predicate (enable | disable).
+    VectorizePredicate,
+    // This serves as a indicator to how many category are listed in this enum.
+    NumberOfCategories
+  };
+  // The following array accumulates the hints encountered while iterating
+  // through the attributes to check for compatibility.
   struct {
     const LoopHintAttr *StateAttr;
     const LoopHintAttr *NumericAttr;
-  } HintAttrs[] = {{nullptr, nullptr}, {nullptr, nullptr}, {nullptr, nullptr},
-                   {nullptr, nullptr}, {nullptr, nullptr}, {nullptr, nullptr},
-                   {nullptr, nullptr}};
+  } HintAttrs[CategoryType::NumberOfCategories] = {};
 
   for (const auto *I : Attrs) {
     const LoopHintAttr *LH = dyn_cast<LoopHintAttr>(I);
@@ -329,16 +341,8 @@
     if (!LH)
       continue;
 
+    CategoryType Category = CategoryType::NumberOfCategories;
     LoopHintAttr::OptionType Option = LH->getOption();
-    enum {
-      Vectorize,
-      Interleave,
-      Unroll,
-      UnrollAndJam,
-      Distribute,
-      Pipeline,
-      VectorizePredicate
-    } Category;
     switch (Option) {
     case LoopHintAttr::Vectorize:
     case LoopHintAttr::VectorizeWidth:
@@ -369,7 +373,7 @@
       break;
     };
 
-    assert(Category < sizeof(HintAttrs) / sizeof(HintAttrs[0]));
+    assert(Category != NumberOfCategories && "Unhandled loop hint option");
     auto &CategoryState = HintAttrs[Category];
     const LoopHintAttr *PrevAttr;
     if (Option == LoopHintAttr::Vectorize ||