MaskRay added a comment.
> [...] all functions with that attribute end up in a single section, defeating
> the linker GC.
This can be made preciser.
Say we have
__attribute__((section("foo"))) void f(i) {}
__attribute__((section("foo"))) void g() {}
`f` and `g` don't use COMDAT, therefore they are in the same section `foo` in
Clang and GCC (coarse-grained). This `foo` section is retained or discarded as
a unit. Considering the whole link, a `foo` section in a translation unit can
be discarded.
I suspect that some people may find the new behavior surprising, so an option
is probably needed. Ideally inform GCC about this new toggle as well.
I think ThinLTO's `comdat nodeduplicate` handling is great. In D108879
<https://reviews.llvm.org/D108879> I noted an interesting issue related to
regular LTO. I haven't tested more scenarios about regular LTO. If you want to
use it at scale, consider more testing.
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D143745/new/
https://reviews.llvm.org/D143745
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