[llvm-dev] Doubts

Pedro Lopes via llvm-dev llvm-dev at lists.llvm.org
Sun Jun 5 14:05:05 PDT 2016

Sorry, glad I'm in the right place.
Before I start, I want to state that I'm a beginer and I'm trying to
develop a backend by adapting an existent target to my platform.

My first doubt is about the SelectionDAG and the TargetLowering class.
When I use, for example:
setOperationAction(ISD::ADD, MVT::i1, Promote);

Is it correct to say that I'm promoting any operand used by the ISD::ADD
node to a larger type? If so, what would that value type be?

If I use the same function with the expand as the third argument like below:
setOperationAction(ISD::FSIN, MVT::f32, Expand);
What will the expansion look like, since I don´t provide any custom
implementation of the node? Also, what is the meaning of the MVT::f32 in
this case?


2016-06-05 19:16 GMT+01:00 Pierre Gagelin <Pierre.Gagelin at myport.ac.uk>:

> Hi Patosga,
> You are on the right place to ask your questions and get help!
> Try to be more specific with your problem. We need some details to help
> you =)
> Pierre
> On 5 June 2016 at 18:12, via llvm-dev <llvm-dev at lists.llvm.org> wrote:
>> Hello sir,
>> I'm having some problems understading how llvm works. I'm following a
>> concrete example and visualizing the DAG and the .s output and some stuff
>> doesn´t seem to match.
>> I sorry to bother you but I don´t know where I can expose my doubts and I
>> wonder if you could redirect me to some discussion place where someone
>> might help me.
>> Thanks,
>> Patosga
>> _____________________________________
>> Sent from http://llvm.1065342.n5.nabble.com
>> _______________________________________________
>> LLVM Developers mailing list
>> llvm-dev at lists.llvm.org
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