[cfe-dev] ifunc resolver parameters

David Blaikie via cfe-dev cfe-dev at lists.llvm.org
Mon Oct 1 06:42:30 PDT 2018


(+echristo in case he has some thoughts here)

On Sun., 30 Sep. 2018, 6:57 am Dmitry Polukhin via cfe-dev, <
cfe-dev at lists.llvm.org> wrote:

> When I implemented ifunc I followed GCC documentation and was not aware of
> ifunc resolvers parameter. But if it is so much platform dependent and
> undocumented in GCC, I'm doubt if it should be supported in clang.
>
> On Sat, Sep 29, 2018 at 11:38 PM Ed Maste <emaste at freebsd.org> wrote:
>
>> When ifunc support was added to Clang with r265917
>> http://llvm.org/viewvc/llvm-project?rev=265917&view=rev it did not
>> allow resolvers to take parameters. It appears GCC documents ifunc
>> resolvers as taking no parameters, but GCC in fact allows it.
>>
>> In FreeBSD our rtld passes machine-dependent CPU ID information to
>> ifunc resolvers, and we had to remove the prohibition:
>> https://svnweb.freebsd.org/changeset/base/339019.
>>
>> In the glibc world, as far as I can tell it in fact passes dl_hwcap on
>> several architectures (but not on x86 or x86_64).
>>
>> I believe GCC's documentation is simply incorrect. Is there any reason
>> not to just remove this check and error case from Clang?
>>
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