[llvm-dev] [RFC] Lanai backend

Chris Lattner via llvm-dev llvm-dev at lists.llvm.org
Tue Feb 9 22:30:46 PST 2016

> On Feb 9, 2016, at 10:24 PM, Chandler Carruth via llvm-dev <llvm-dev at lists.llvm.org> wrote:
> You've raised an important point here Pete, and while I disagree pretty strongly with it (regardless of whether Lanai makes sense or not), I'm glad that you've surfaced it where we can clearly look at the issue.
> The idea of "it really should have users outside of just the people who have access to the HW" I think is deeply problematic for the project as a whole. Where does it stop?
> While I may have the theoretical ability to get access to an AVR, Hexagon, MSP430, SystemZ, or XCore processor... It is a practical impossibility. There is no way that I, or I suspect 95% of LLVM contributors, will be able to run code for all these platforms. And for some of them, I suspect it is already the case that their only users have access to specialized, quite hard to acquire hardware (both Hexagon[1] and SystemZ come to mind).

Yes, I think this is a reasonable point.  The cheapest SystemZ system is somewhere around $75K, so widespread availability isn’t really a relevant criteria for accepting that.

Given that, I personally have no objection to accepting the port as an experimental backend.  For it to be a non-experiemental backend, I think it needs to have a buildbot running execution tests for the target.  This can either be a simulator or google could host a buildbot on the hardware they presumably have and make the results public.


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