[llvm-dev] What is the status regarding min/max intrinsics?

Björn Pettersson A via llvm-dev llvm-dev at lists.llvm.org
Tue May 4 01:59:46 PDT 2021


The llvm.smin, llvm.smax, llvm.umin and llvm.umax intrinsics were
introduced quite some time ago.

As far as I known we still don't canonicalize IR to use those
intrinsics (but I suppose that is the end goal), nor do we
canonicalize by doing a reverse transform into a select.

Are there any known limitations in support for the min/max intrinsics
that prevents us from using them or trying to canonicalize IR into
using the intrinsics?
(and if so, shouldn't we canonicalize into a select-pattern if that
form still is "better")

Main reason for asking is that I'd like to know if it is safe
to simplify clang/opt to use the min/max intrinsics directly
instead of emitting a select-kind-of-pattern. Or is it a huge risk
that I end up with regressions due to optimizers not understanding
the min/max intrinsics yet?

Regards,
Björn




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