[Patch][RFC] Verifying inputs to the Linker

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

Thanks for the ping!  I don't think it's possible to get the Verifier working when modules have been pre-linked.

llvm-link's -disable-debug-info-type-map option turns off the pre-linking.  We should continue to verify each input module when that option is set.  LGTM with that change.

> On 2016-Jun-29, at 11:05, Rafael Espíndola <rafael.espindola at gmail.com> wrote:
> 
> Duncan, are you OK with this or do you think it should be possible to
> get the Verifier to work on this case?
> 
> Cheers,
> Rafael
> 
> 
> On 24 June 2016 at 22:51, Davide Italiano <davide at freebsd.org> wrote:
>> On Fri, Jun 24, 2016 at 5:29 AM, Rafael Espíndola
>> <llvm-commits at lists.llvm.org> wrote:
>>> The attached patch is an attempt to fix pr28072.
>>> 
>>> The point as Duncan pointed out is that the file is already partially
>>> linked by just reading it.
>>> 
>>> Long term I think the solution is to make metadata owned by the module
>>> and then the linker will lazily read it and be in charge of all the
>>> linking. Running a verifier in each input will defeat the lazy
>>> loading, but will be legal.
>>> 
>>> Right now we are at the unfortunate position that to support odr
>>> merging we cannot verify the inputs, which mildly annoying (see test
>>> update).
>>> 
>> 
>> Meh, this is very annoying, but I don't see an alternative for now.
>> I'm fine with this, unfortunately :(
>> 
>> --
>> Davide
>> 
>> "There are no solved problems; there are only problems that are more
>> or less solved" -- Henri Poincare