[llvm] [OpenMP] Implement EnumSet container (PR #211323)

[Tom Eccles via llvm-commits]

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@@ -17,11 +17,118 @@
 #include "llvm/Support/Compiler.h"
 
 #include "llvm/ADT/ArrayRef.h"
+#include "llvm/ADT/Bitset.h"
 #include "llvm/ADT/Sequence.h"
 #include "llvm/ADT/SmallVector.h"
 #include "llvm/ADT/StringRef.h"
 
 namespace llvm::omp {
+template <typename Enum, size_t Size> struct EnumSet;
+
+namespace detail {
+template <size_t Size>
+static constexpr inline size_t findFirstSet(size_t Begin, size_t End,
+                                            const llvm::Bitset<Size> &Set) {
+  unsigned FirstWord = Begin / 64;
+  unsigned LastWord = End / 64;
+
+  for (unsigned I = FirstWord; I <= LastWord; ++I) {
+    uint64_t Word = Set.getWord64(I);
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tblah wrote:

For EnumSet<E, 64>, findFirstSet will be called with End == 64 and so LastWord == 1 and it will fetch Set.getWord64(1). But `llvm::Bitset<64>` only has word 0.

I think either LastWord should be (end - 1)/64, or this should only iterate to `I < LastWord`.

https://github.com/llvm/llvm-project/pull/211323