[llvm-dev] LLVM gold plugin do not add llvm instrinsics symbols to the linker symbol table

[Duncan P. N. Exon Smith via llvm-dev]

> On Mar 26, 2018, at 00:41, Bakhvalov, Denis via llvm-dev <llvm-dev at lists.llvm.org> wrote:
> 
> >  <>I'm trying to understand how the non-LTO case is supposed to work
> non-LTO case works because when linker starts it’s job all the llvm intrinsics are already lowered.

Yup, this has been a long-time problem for LTO.  The right answer is for LTO to determine a fairly tight superset of the symbols that will be used after lowering, and request them from the linker (i.e., add them to the reported symbol table as undefined).  This isn't particularly easy to do and there are workarounds, so no one has prioritized it.

> 
> > Right, which is why I am suggesting that it might be appropriate to build with -fno-builtin (or -fno-builtin-exp) here –
> > this solves the LTO issue as there will no longer be an llvm intrinsic in the bitcode
> Yes, I just tested it and -fno-builtin helps in this case. I added definition of __exp_finite to libexp.a and now it was resolved from libexp.a (because no llvm intrinsics).
>  
> Best regards,
> Denis Bakhvalov.
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