[LLVMdev] RFC: Are we ready to completely move away from the optionality of a DataLayout?

[Hal Finkel]

----- Original Message -----
> From: "Chandler Carruth" <chandlerc at gmail.com>
> To: "LLVM Developers Mailing List" <llvmdev at cs.uiuc.edu>, nicholas at mxc.ca, "Rafael Ávila de Espíndola"
> <rafael.espindola at gmail.com>
> Sent: Sunday, October 19, 2014 3:22:26 AM
> Subject: [LLVMdev] RFC: Are we ready to completely move away from the	optionality of a DataLayout?
> 
> I've just wasted a day chasing my tail because of subtleties
> introduced to handle the optionality of the DataLayout. I would like
> to never do this again. =]
> 

I agree; while I've heard of use cases, I don't personally feel that, at this stage, it is worth the maintenance burden. Realistically, we just don't have a good way to test the no-data-layout code paths (the great majority of our testing coverage comes from frontends that always add DataLayout). I also vote for making it mandatory.

 -Hal

> 
> We now have this attached to the Module with just a flimsy faked-up
> pass to keep APIs consistent. So, is there any problem with
> beginning down the path of:
> 
> 
> 1) Synthesizing a "default" boring DataLayout for all modules that
> don't specify one.
> 2) Changing the APIs to make it clear that this can never be missing
> and is always available.
> 3) Start ripping out all of the complexity in the compiler dealing
> with this.
> 
> 
> If there isn't, I'm willing to do some of the leg work here.
> -Chandler
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-- 
Hal Finkel
Assistant Computational Scientist
Leadership Computing Facility
Argonne National Laboratory