[llvm-dev] EuroLLVM Numerics info

Venkataramanan Kumar via llvm-dev llvm-dev at lists.llvm.org
Wed Apr 3 22:46:52 PDT 2019

Hi Micheal,

Thanks for the blog post.  Just like to point out few things that I thought
is related to FP Numerics.
LLVM could do some additional transformation with "sqrt" and "division"
under fast math on X86 like 1/sqrt(x)* 1/sqrt(x) to 1/x.   These are long
latency instructions and could get benefit if enabled under unsafe math.

Also are we considering doing such FP transforms on vector floating point


On Mon, 1 Apr 2019 at 19:56, Cameron McInally via llvm-dev <
llvm-dev at lists.llvm.org> wrote:

> Hey Michael,
> Thank you for working on this!
> I'd like to touch on a topic mentioned in the blog post. The constrained
> intrinsics work is at a road block on how to proceed with the constrained
>  implementation in the backends, i.e. D55506. Reviews/ideas in this area
> would be greatly appreciated (attn: target code owners).
> Thanks,
> Cameron
> On Thu, Mar 28, 2019 at 5:54 PM Michael Berg via llvm-dev <
> llvm-dev at lists.llvm.org> wrote:
>> All:  There will be a BoF talk at the EuroLLVM conference regarding
>> Numerics (FMF and module flags which control fp behavior and optimization).
>> Even if you are not going to be in attendance, please reply to this
>> thread as we are collecting open issues and ideas for future direction in
>> all layers of LLVM for which optimizations are controlled by numerics flags.
>> Please read over the numerics blog if you like for reference material:
>> https://urldefense.proofpoint.com/v2/url?u=http-3A__blog.llvm.org_2019_03_llvm-2Dnumerics-2Dblog.html&d=DwIGaQ&c=slrrB7dE8n7gBJbeO0g-IQ&r=O_4M49EtSpZ_-BQYeigzGv0P4__noMcSu2RYEjS1vKs&m=CHHCGUAnxC91rtvrnhhoN0jXGXgXv8EQb8C4XiUEoxY&s=xzUyP83nqSY1h9GrDdHch4INrIFIU-Ycij4S4Tmxdko&e=
>> Regards,
>> Michael
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