[PATCH] D159283: Add intrinsic to count trailing zero elements in a vector

[Craig Topper via Phabricator via llvm-commits]

craig.topper added a comment.

The RISC-V instruction that we'd want to use for this is vfirst.m that returns -1 if no bits in a mask are set and the bit position of the first set bit otherwise. Determining that no bits are set is simply checking if the result is less than 0. This the same instruction we use for reduce.or on mask vectors.


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  https://reviews.llvm.org/D159283/new/

https://reviews.llvm.org/D159283