[InstCombine][AVX-512] When turning intrinsics with masking into native IR, don't emit a select if the mask is known to be all ones.

This saves InstCombine the burden of having to optimize the select later.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@290774 91177308-0d34-0410-b5e6-96231b3b80d8
1 file changed