Previously by default, when not using `--ifc=`, lld would not
deduplicate string literals. This reveals reliance on undefined behavior
where string literal addresses are compared instead of using string
equality checks. While ideally you would be able to easily identify and
eliminate the reliance on this UB, this can be difficult, especially for
third party code, and increases the friction and risk of users migrating
to lld. This flips the default to deduplicate strings unless
`--no-deduplicate-strings` is passed, matching ld64's behavior.
Differential Revision: https://reviews.llvm.org/D140517
Previously unless ZERO_AR_DATE was set to any value, ld64.lld would
embed non-hermetic timestamps into the final binary. This flips that
default to zero those values unless ZERO_AR_DATE is set explicitly to 0.
As far as I know there isn't a downside to this, except that it differs
from ld64.
Differential Revision: https://reviews.llvm.org/D135529
Builds that error out on duplicate symbols can still succeed if the symbols
will be dead stripped. Currently, this is the current behavior in ld64.
https://github.com/apple-oss-distributions/ld64/blob/main/src/ld/Resolver.cpp#L2018.
In order to provide an easier to path for adoption, introduce a new flag that will
retain compatibility with ld64's behavior (similar to `--deduplicate-literals`). This is
turned off by default since we do not encourage this behavior in the linker.
Reviewed By: #lld-macho, thakis, int3
Differential Revision: https://reviews.llvm.org/D134794
This is similar to the `-alias` CLI option, but it gives finer-grained
control in that it allows the aliased symbols to be treated as private
externs.
While working on this, I realized that our `-alias` handling did not
cover the cases where the aliased symbol is a common or dylib symbol,
nor the case where we have an undefined that gets treated specially and
converted to a defined later on. My N_INDR handling neglects this too
for now; I've added checks and TODO messages for these.
`N_INDR` symbols cropped up as part of our attempt to link swift-stdlib.
Reviewed By: #lld-macho, thakis, thevinster
Differential Revision: https://reviews.llvm.org/D133825
This is similar to the `-alias` CLI option, but it gives finer-grained
control in that it allows the aliased symbols to be treated as private
externs.
While working on this, I realized that our `-alias` handling did not
cover the cases where the aliased symbol is a common or dylib symbol,
nor the case where we have an undefined that gets treated specially and
converted to a defined later on. My N_INDR handling neglects this too
for now; I've added checks and TODO messages for these.
`N_INDR` symbols cropped up as part of our attempt to link swift-stdlib.
Reviewed By: #lld-macho, thakis, thevinster
Differential Revision: https://reviews.llvm.org/D133825
1. Fixed rST hyperlink syntax
2. Renamed LD64 -> ld64
3. Moved up the `-no_deduplicate` section so it is right under the
section talking about how our default dedup behavior differs; IMO
it makes more sense to read them in that order
4. De-bullet-listed some other sections so we have less whitespace in
the rendered page
5. Since the Mach-O LLD Port page has only one sub-page, don't render an
entire toctree with just one item. Use a "See also" box instead.
6. Wrap lines at 80 chars.
Reviewed By: #lld-macho, thevinster
Differential Revision: https://reviews.llvm.org/D133717
I wasn't able to find any docs for Mach-O in `lld/docs`, so here's an attempt at adding basic docs. One of my goals here is to make it easy for users who are unfamiliar with linkers to successfully use lld.
Reviewed By: #lld-macho, int3
Differential Revision: https://reviews.llvm.org/D132893
