[llvm] ADT: Add constructor from uint64_t array for Bitset (PR #162703)

[Matt Arsenault via llvm-commits]

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@@ -45,7 +45,18 @@ class Bitset {
   StorageType Bits{};
 
 protected:
-  constexpr Bitset(const StorageType &B) : Bits{B} {}
+  constexpr Bitset(const std::array<uint64_t, (NumBits + 63) / 64> &B) {
+    if (sizeof(BitWord) == sizeof(uint64_t)) {
+      for (size_t I = 0; I != B.size(); ++I)
+        Bits[I] = B[I];
+    } else {
+      for (size_t I = 0; I != B.size(); ++I) {
+        uint64_t Elt = B[I];
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arsenm wrote:

It's already static_asserted above, I guess I could move the assertion down 

https://github.com/llvm/llvm-project/pull/162703