[PATCH] D43361: [ThinLTO] Enable AutoHide on symbols with local_unnamed_addr

[Rafael Avila de Espindola via Phabricator via llvm-commits]

espindola added a comment.

In https://reviews.llvm.org/D43361#1039665, @steven_wu wrote:

> > The solution is to use canBeOmittedFromSymbolTable from include/llvm/Object/IRSymtab.h.
> > 
> > The symbol table is computed earlier and so the above predicate still returns 1. Your examples work with lld and ThinLTO if you want to check the implementation details.
>
> It is easy to get 1 correct. This patch is to get 2 to be hidden using LTO.


Using the IRSymtab also solves 2.

> Sure, linker can consult the symbol table in IRSymtab but the problem is how much can it be trusted? LTO can already add/remove symbols from IRSymtab. Is changing symbol linkage/visibility legal during LTO?

It can be trusted. That is what lld and the gold plugin are using. The only theoretical change I can think of is a pass adding a use and dropping local_unnamed_addr, but the linker will see that in the .o file that LTO produces.


Repository:
  rL LLVM

https://reviews.llvm.org/D43361