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Re: "ld -r" on mixed IR/non-IR objects (
> On Mon, Dec 6, 2010 at 2:43 PM, Andi Kleen <andi@firstfloor.org> wrote:
>>> Hi,
>>>
>>> "ld -r" doesn't work with mixed IR/non-IR objects:
>>>
>>> http://www.sourceware.org/bugzilla/show_bug.cgi?id=12291
>>
>> There are various bugs for it in gcc bugzilla too.
>>
>>> Some compilers support it. Should it be supported?
>>
>> Yes. I've been working on it (slim lto was the first part needed for it,
>> without slim lto it's imho hopeless)
>
> Slim lto is a workaround, not a real solution.
Actually I consider fat lto as a workaround for toolchain deficiencies.
Generating everything twice and throwing one copy away is always
inefficient. IMHO slim lto is the natural way to do LTO.
The only problem is that you need to fix every piece in the toolchain
to not mess up LTO.
That's why I did the gcc-ar,nm etc. wrappers. There were other problems
too, like gcc's build system itself not handling LTO correctly (it normally
only works because fat saves the day)
> I think this support should
> be
> implemented in ld with help from GCC.
Without slim lto you never know if a duplicate symbol is a mistake
of the programmer or just the "fat lto" copy. Also ELF semantics
like weak are hard if you have multiple copies.
-Andi