[llvm-dev] [RFC] lld: Dropping TLS relaxations in favor of TLSDESC

Joerg Sonnenberger via llvm-dev llvm-dev at lists.llvm.org
Wed Nov 8 04:53:03 PST 2017

On Tue, Nov 07, 2017 at 06:27:37PM -0800, Rui Ueyama via llvm-dev wrote:
> tl;dr: TLSDESC have solved most problems in formerly inefficient TLS access
> models, so I think we can drop TLS relaxation support from lld.

I've skipped over the description and I have some difficulty sharing
this conlusion. I don't see how it makes any significant difference. I
also don't know if any system beyond glibc implements it.

Side note: position independent executables that are properly compiled
behave like non-position independent executables.

Side note 2: I strongly question the assertions about frequency of
dlopen vs direct linking from the TLSDESC paper. Quite a few hacks on
the dynamic linker side are a direct result of people wanting to dlopen
libGL from scripting languages like Python.


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