Armv7m compiler rt

[justinbalexander]

The builtin functions that are getting included for no reason will still require:

__aeabi_fdiv
__aeabi_ddiv
__aeabi_fcmpeq
__aeabi_dcmpeq
__aeabi_dcmpgt
__aeabi_dcmplt

[andrewrk]

Looks good to me. Thanks for this contribution @vegecode. Does it work for you now? Did you also try targeting thumb?

[andrewrk]

I opened an issue for the reason the tests are failing: #2154

As a workaround can you remove inline and add a comment linking to the issue?

[justinbalexander]

Hey Andrew, I have not tried targeting thumb yet. The MCU I'm targeting is a Cortex M4 and it doesn't have an Arm instruction state, only Thumb-2. I can try it and see what happens. I suspect the code will be identical.

I am running on the target currently. I can do release small for reasonable code, while release fast and release safe require me to make fake stubs for the missing compiler-rt functions I listed above in order to build. A release small and safe would be quite nice as the debug build is too big to be any use really on a microcontroller. I'll make an issue for it.

Also, the functions that are failing in the build log are in addXf3.zig. mulXf3 doesn't have them listed as inline.

[justinbalexander]

Also, sorry about the failing test. I'm stilling having issues with my build setup. I think I've got it figured out now.

[andrewrk]

Also, the functions that are failing in the build log are in addXf3.zig. mulXf3 doesn't have them listed as inline.

Right, I first ran into this issue when doing the mulXf3 functions and had to remove the inline for them. I didn't make the issue until now though.

[andrewrk]

Thanks for this @vegecode. I know you ran into a lot of frustrating things when working on it. Are there any more blockers for your project?

[justinbalexander]

No more blockers. There are more compiler-rt functions needed and the built-in functions not being excluded is irritating, but that's it. Anything else I just need to make an issue for.

Thanks for asking and for all your help.

I do need to actually come up with something to do with Zig now that it's running! Maybe I'll try writing a simple RTOS. I really just want to help get Zig out there. I think embedded is a critical area for its success. Rust doesn't seem to be making a dent at all, so there is definitely space for it.

[andrewrk]

I agree about the built in functions not being excluded is irritating. I opened #2062 for it. I could have sworn I addressed this already and solved it, but here we are. Maybe it is something simple. Anyway I'm confident it will be solved within a release cycle or two.

[shawnl]

I see that this comes straight from llvm's compiler-rt, but is this tested? because it clobbers r3

[shawnl]

You can test this with armv7 hardware. Just compile for armv6.

[shawnl]

nvm. I didn't realize there was a r0 register.