llvm dev - Feb 2019 - Not to consolidate two structs with the same data types (but different names) in configure/make tool chain

> https://llvm.org/docs/LangRef.html#structure-types
I don't follow the above link. Could you help explain what it means?
> Fundamentally, llvm is not designed to preserve details about front end
language features.
If directly compile .c to .ll can preserve the original struct
information even they are essentially the same, why flto can not? It
seems to me that there must be a way to preserve such info if flto is
used.

-- 
Regards,
Peng

LTO has to merge the modules from different translation units. Those
modules very likely have duplicate types in them so LTO merges them to
avoid wasting memory on duplicates.

~Craig


On Wed, Feb 6, 2019 at 6:55 PM Peng Yu via llvm-dev <llvm-dev at
lists.llvm.org>
wrote:
> > https://llvm.org/docs/LangRef.html#structure-types
>
> I don't follow the above link. Could you help explain what it means?
>
> > Fundamentally, llvm is not designed to preserve details about front
end
> language features.
>
> If directly compile .c to .ll can preserve the original struct
> information even they are essentially the same, why flto can not? It
> seems to me that there must be a way to preserve such info if flto is
> used.
>
> --
> Regards,
> Peng
> _______________________________________________
> LLVM Developers mailing list
> llvm-dev at lists.llvm.org
> https://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
>
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> LTO has to merge the modules from different translation units. Those
modules very likely have duplicate types in them so LTO merges them to avoid
wasting memory on duplicates.
But I am checking the *.preopt.bc. Since it is before any
optimization, I'd expect such merging should not occur.

-- 
Regards,
Peng