[PATCH] D102090: [CMake][ELF] Link libLLVM.so and libclang-cpp.so with -Bsymbolic-functions

Fangrui Song via Phabricator via llvm-commits llvm-commits at lists.llvm.org
Thu May 13 17:05:47 PDT 2021


MaskRay added a comment.

In D102090#2758316 <https://reviews.llvm.org/D102090#2758316>, @xbolva00 wrote:

>>> I cannot figure out how to make -fno-semantic-interposition specific to llvm/ and clang/.
>
> Maybe @nikic knows? I think he is interested in this work, since the base (reverted) commit introduced 4% compile time improvement - really nice.

Thanks for showing interesting:) (At least let me know I am not wasting my energy.)
Posted D102453 <https://reviews.llvm.org/D102453> for the GCC optimization.

Personally I always build llvm-project with a stable Clang so D102453 <https://reviews.llvm.org/D102453> doesn't really make my life better.
D102453 <https://reviews.llvm.org/D102453> is for those distributions which build llvm-project with GCC...

When building Linux kernel, I don't see additional improvement by adding -fno-semantic-interposition,
but it does make libLLVM.so 2% smaller (notably, GCC -fPIC  -fno-semantic-interposition can optimize some
functions which call other non-inline functions so in various places the function body can be smaller.
Some vtable can be optimized out as well.)


Repository:
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https://reviews.llvm.org/D102090



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