llvm dev - Nov 2019 - Backend support for divisions > 128 bits

Hello,

Thanks you very much for LLVM! I'm very much enjoying working with it.

I'm currently experimenting with some frontend changes that eventually
generate IR with arbitrary big integer types like

define void @test(i129, i129, i129*)  {
    %4 = sdiv i129 %0, %1
    store i129 %4, i129* %2
    ret void
}

(or any bigger type). Unfortunately, this leads to "LLVM ERROR: Unsupported
library call operation!" from DAGTypeLegalizer::ExpandIntRes_SDIV on all
targets I tried (especially x86_64). It seems that most of the other
operations (e.g. mul, add, and, shift, bitreverse, ...) are supported on
those big integers.

What is the best way for me to make the divisions work?
Is there existing work I can build upon?

Thank you!
Matthias

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On Mon, Nov 11, 2019 at 11:45:12PM +0100, Matthias Gehre via llvm-dev
wrote:
> Hello,
> 
> Thanks you very much for LLVM! I'm very much enjoying working with it.
> 
> I'm currently experimenting with some frontend changes that eventually
> generate IR with arbitrary big integer types like
> 
> define void @test(i129, i129, i129*)  {
>     %4 = sdiv i129 %0, %1
>     store i129 %4, i129* %2
>     ret void
> }
> 
> (or any bigger type). Unfortunately, this leads to "LLVM ERROR:
Unsupported
> library call operation!" from DAGTypeLegalizer::ExpandIntRes_SDIV on
all
> targets I tried (especially x86_64). It seems that most of the other
> operations (e.g. mul, add, and, shift, bitreverse, ...) are supported on
> those big integers.
Most of the other operations are trivial to synthesize in a somewhat
reasonable way. Division is not. That's why there is no generic
expansion.

Joerg