[PATCH] D131309: [ELF] Add ability to get a symbol by name from the hash table section

Wed Aug 24 23:54:47 PDT 2022

MaskRay added a comment.

In D131309#3734346 <https://reviews.llvm.org/D131309#3734346>, @jhenderson wrote:

> Mostly just nits remaining from me, plus a couple of "normal behaviour" test cases I missed earlier.
>
> FWIW, I think implementing SHT_HASH support first, as this patch does, should definitely happen. This is because the SHT_HASH is the thing that is in the gABI, and not SHT_GNU_HASH, however widely the GNU version is supported. Last I checked my company's system didn't use GNU hash tables yet, for example. I wouldn't be opposed to follow-up work for the GNU hash table though.

OK, I did not know you have internal users with DT_HASH. https://maskray.me/blog/2022-08-21-glibc-and-dt-gnu-hash#what-is-dt_gnu_hash My investigation suggests that multiple major Linux distributions have switched to --hash-style=gnu before 2010...
Nowadays DT_HASH is unlikely to be used on non-mips Linux.
My mild objection is because such a feature would nearly assuredly benefit nobody, but I think I'll not hold a strong objection.

Note that the bloom filter in a GNU hash table is optional. @jhuber6 can just change the hash function, then the existing cost is almost a DT_GNU_HASH implementation.

> Presumably LLD has the GNU hash alogrithm in its source code, since it can generate such tables? Could that code be moved to libObject if needed?

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https://reviews.llvm.org/D131309