[ADT] Add bit_ceil_constexpr (#164115)

This patch adds llvm::bit_ceil_constexpr, a constexpr version of
llvm::bit_ceil.

The new function is intended to serve as a marker.  When we switch to
C++20, we will most likely go through functions in llvm/ADT/bit.h and
replace them with their counterparts from <bit>.  With
llvm::bit_ceil_constexpr, we can easily replace its use with
std::bit_ceil.

This patch replaces RoundUpToPowerOfTwo in SmallPtrSet.h the new
function.

0 files changed, 0 insertions, 0 deletions