[llvm-dev] Query target features?

[Chris Elrod via llvm-dev]

Hi everyone,

Is there a target equivalent to `getHostCPUFeatures`?
https://llvm.org/doxygen/namespacellvm_1_1sys.html#a768d54e5ada846d513f72d9e43e89ef6

Additionally, is it possible to query target vector widths, and the number
of vector registers (e.g. 16 for x86 with AVX, 32 with AVX512, but only 8
if in 32-bit mode)?

I have been using `getHostCPUFeatures` for features, and then on x86 I've
added some simple logic to pick vector width and number of registers. For
other architecutres, I'm using some generic values. LLVM has all this
information, so it'd be great if I could use it for other architectures
like ARM and POWER (and for x86 too), but I'm not sure how to access it
myself.

Background:
I'm the author of a somewhat experimental Julia library called
"LoopVectorization.jl" that autovectorizes loops.
The optimization decisions it makes are target specific, and the final
generated code itself is as well, and not always in a manner that backends
can handle if incorrect, e.g. it might use something like
`@llvm.x86.avx512.mask.pternlog.q.512`.
I've been making the assumption that the host is the target (and using
`getHostCPUFeatures`). This isn't always the case, which has resulted in
crashes before for some users.

Thanks everyone,
Chris
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.llvm.org/pipermail/llvm-dev/attachments/20200918/e81df88a/attachment.html>