[PATCH] D79100: [LV][TTI] Emit new IR intrinsic llvm.get.active.mask for tail-folded loops

[Eli Friedman via Phabricator via llvm-commits]

efriedma added a comment.

I think all Simon is asking for is that the first argument of the intrinsic should be a scalar, equal to the first lane of the vector induction variable.  How much work would that be?



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Comment at: llvm/lib/Transforms/Vectorize/LoopVectorize.cpp:6812
     // Introduce the early-exit compare IV <= BTC to form header block mask.
     // This is used instead of IV < TC because TC may wrap, unlike BTC.
     // Start by constructing the desired canonical IV.
----------------
It would be nice to explicitly note here that we're assuming the vector factor is a power of two (so the induction variable can't wrap).


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  https://reviews.llvm.org/D79100/new/

https://reviews.llvm.org/D79100