[PATCH] D41105: [ELF] Fix placement of a sentinel entry in the .ARM.exidx section.

[Rafael Avila de Espindola via llvm-commits]

Igor Kudrin via Phabricator <reviews at reviews.llvm.org> writes:

> +    // Find the last existing InputSectionDescription.
> +    // Add a new only if we cannot find one.
> +    // As a result, if we have a description for an output section like
> +    // .foo : { *(.foo) bar = . }
> +    // we will place the new section before the assignment so that it will
> +    // affect the value of 'bar', which is, probably, expected.
> +    // We also had a crash in the similar situation with an .ARM.exidx sentinel,
> +    // because 'ARMExidxSentinelSection::writeTo()' expected it to be placed
> +    // into a non-empty bucket.

I would actually find the result surprising in the general case.

I think we can just make the exidx code more resilient. Instead of
having a special handling in writeTo, could we push a relocation to the
Relocations vector of the sentinel entry?

Cheers,
Rafael