jroelofs added a comment.
> The Baremetal toolchain currently has a fixed behavior regardless of the
> -rtlib option's value. It is always linking against compiler-rt unless
> -nodefaultlibs is enabled.
>
> This proposal slightly changes the code in such a way that enabling
> -rtlib=libgcc implies linking against -libgcc.
>
> Something that I'm unsure about this patch is that we are not enforcing the
> existence of such libgcc. By reading other toolchains, I understood that is
> not always enforced. Do you think this policy is acceptable? If it is not,
> how would you think it should be addressed?
I think it's fine. You'll get linker errors if the library can't be found.
> Context:
>
> So far I manually set an -L path to a valid libgcc on my system when clang is
> invoked. In this particular case, I use arm-none-eabi-gcc -mthumb
> -mcpu=cortex-m4 -mfloat-abi=hard -mfpu=fpv4-sp-d16 -print-libgcc-file-name
> which retrieves the path I want.
>
> Assume the user forwards a gcc-toolchain installation through
> --gcc-toolchain. Would be a good idea to programmatically query
> arm-none-eabi-gcc for the libgcc as described above?
I don't think it's appropriate to bake this into clang's driver. Instead, this
should be done by the build script, and the resulting path should be fed in via
the -resource-dir flag.
> If that is the case, how would be the most "llvm way" to do it? I'm not very
> related to all abstractions and concepts from the framework.
>
> This is my very first contribution to LLVM so I'd really appreciate any
> feedback in order to improve this proposal :)
Sorry it took me a few days to get around to reviewing this. Been a bit busy
with a move.... thanks for the patch!
================
Comment at: clang/lib/Driver/ToolChains/BareMetal.cpp:164
+ Args.MakeArgString("-lclang_rt.builtins-" +
getTriple().getArchName()));
+ break;
+ case ToolChain::RLT_Libgcc:
----------------
If you make these `break`s into `return`s, and put an
`llvm_unreachable("unhandled RuntimeLibType");` after the switch, then whoever
adds a new entry to that enum will get a nice warning showing them that they
need to update this code.
Repository:
rG LLVM Github Monorepo
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D87164/new/
https://reviews.llvm.org/D87164
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