[PATCH] D41747: [libcxx] implement <experimental/simd> simd_mask<> and operators.

[Tim Shen via Phabricator via cfe-commits]

timshen created this revision.
timshen added reviewers: mclow.lists, EricWF.
Herald added a subscriber: sanjoy.

simd_mask<T, Abi> stores a simd<U, Abi>, where U has the same length of T, but is an unsigned integer. Then all functionality of simd_mask<T, Abi> can be implemented in terms of simd<U, Abi>.

For reference, Vc seems to store an int as a bitset. This results into inefficient code:

- https://godbolt.org/g/e4uDPM storing int is slow.
- https://godbolt.org/g/hT7SYT storing simd<U, Abi> has zero cost.


https://reviews.llvm.org/D41747

Files:
  libcxx/include/experimental/simd
  libcxx/test/std/experimental/simd/simd.elementwise/operators.pass.cpp
  libcxx/test/std/experimental/simd/simd.mask.access/a.out
  libcxx/test/std/experimental/simd/simd.mask.access/default.pass.cpp
  libcxx/test/std/experimental/simd/simd.mask.cons/broadcast.pass.cpp
  libcxx/test/std/experimental/simd/simd.mask.cons/default.pass.cpp
  libcxx/test/std/experimental/simd/simd.mask.cons/fixed_size_conversion.pass.cpp
  libcxx/test/std/experimental/simd/simd.mask.cons/load.pass.cpp
  libcxx/test/std/experimental/simd/simd.mask.elementwise/operators.pass.cpp
  libcxx/test/std/experimental/simd/simd.mask.mem/load.pass.cpp
  libcxx/test/std/experimental/simd/simd.mask.mem/store.pass.cpp

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