[llvm-dev] Moving the AVR backend out of experimental (original) (raw)

Dylan McKay via llvm-dev llvm-dev at lists.llvm.org
Mon Feb 17 23:44:53 PST 2020

Should we just make it a normal target?

My only remaining reservation here - the generic DebugInfo tests, which presumably due to an unimplemented 16-bit branch somewhere deep in the llvm-objdump callstack.

The AVR backend passes virtually all of the LLVM test suite but these when avr-unknown-unknown is set as the default target. It feels like the inclusion of ~80 XFAILs for these DebugInfo tests would be the only wart on the experimental->official code review. I've had a couple long attempts debugging this one, but have not yet found the source.

Fixing of the DebugInfo tests would make the AVR official backend pitch much more tenable.

My only concern with AVR is having active mantainers. It doesn't seem

to have had much development in the last 6 months.

This is a fair assessment; throughout the years, the amount of code I as the code owner directly write definitely follows something like a sine wave, with the last few months being one of the slower periods due to work and other personal projects. I value others' thoughts on this topic stronger than my own though, so I will reserve judgement.

Compared to say, the ARM backend, the AVR backend has much less corporate backing or resourcing, essentially developed by enthusiasts and those interested in electronics in their spare time. The arguments for and against making either backend official or not may or may not be different - I am not sure what the community thinks.

As of the two months or so, there's been quite a number of patches from both driveby and newly-active contributors. I suspect at least part of this will be due to the official deprecation of GCC's AVR backend[1] and impending removal from the tree. As far as I know, this will make LLVM the only open-source AVR C/C++ toolchain in active development, and perhaps more importantly, supporting of newer language standards.

In summary, if the DebugInfo tests were fixed, I think the AVR backend would be ready to be marked official. I am also interested in any other thoughts people have about the AVR backend.

Regards, Dylan

On Mon, Feb 17, 2020 at 9:57 PM Simon Moll via llvm-dev < llvm-dev at lists.llvm.org> wrote:

On 2/14/20 4:59 PM, Nico Weber via llvm-dev wrote:

Hi, There was a thread a few days ago about the expectations for experimental targets. At the moment, the only experimental target is AVR. It's been in the tree for a long time now, and generally seems well-behaved. FYI, the VE target is also experimental at this point. - Simon Should we just make it a normal target? Nico

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