Details:
We often use wildcard symbols in the exported_symbols list, and sometimes they match autohide symbols, which triggers these "cannot export hidden symbols" warnings that can be a bit noisy.
It'd be more user-friendly if LLD could truncate these.
Differential Revision: https://reviews.llvm.org/D159095
D152495 makes clang warn on unused variables that are declared in conditions like `if (int var = init) {}`
This patch is an NFC fix to suppress the new warning in llvm,clang,lld builds to pass CI in the above patch.
Differential Revision: https://reviews.llvm.org/D158016
LLD resolves symbols regardless of LTO modes early when reading and parsing input files in order. The object files built from LTO passes are appended later.
Because LLD eagerly resolves the LC linker options while parsing a new object file (and its chain of dependent libraries), the prior decision on pending prevailing symbols (belonging to some bitcode files) can change to ones in those native libraries that are just loaded.
This patch delays processing LC linker options until all the native object files are added after LTO is done, similar to LD64. This way we preserve the decision on prevailing symbols LLD made, regardless of LTO modes.
- When parsing a new object file in `parseLinkerOptions()`, it just parses LC linker options in the header, and saves those contents to `unprocessedLCLinkerOptions`.
- After LTO is finished, `resolveLCLinkerOptions()` is called to recursively load dependent libraries, starting with initial linker options collected in `unprocessedLCLinkerOptions` (which also updates during recursions)
Reviewed By: #lld-macho, int3
Differential Revision: https://reviews.llvm.org/D157716
This reverts commit aa495214b39d475bab24b468de7a7c676ce9e366.
As discussed in https://github.com/llvm/llvm-project/issues/53475 this patch
allows for using LLD-as-a-lib. It also lets clients link only the drivers that
they want (see unit tests).
This also adds the unit test infra as in the other LLVM projects. Among the
test coverage, I've added the original issue from @krzysz00, see:
https://github.com/ROCmSoftwarePlatform/D108850-lld-bug-reproduction
Important note: this doesn't allow (yet) linking in parallel. This will come a
bit later hopefully, in subsequent patches, for COFF at least.
Differential revision: https://reviews.llvm.org/D119049
Enable support for CSPGO for lld MachO targets.
Since lld MachO does not support `-plugin-opt=`, we need to create the `--cs-profile-generate` and `--cs-profile-path=` options and propagate them in `Darwin.cpp`. These flags are not supported by ld64.
Also outline code into `getLastCSProfileGenerateArg()` to share between `CommonArgs.cpp` and `Darwin.cpp`.
CSPGO is already implemented for ELF (https://reviews.llvm.org/D56675) and COFF (https://reviews.llvm.org/D98763).
Reviewed By: MaskRay
Differential Revision: https://reviews.llvm.org/D151589
Add support for printing the passes run for LTO.
Both ELF and COFF have `--lto-debug-pass-manager` (`-ltodebugpassmanager`) to print the compiler passes run during LTO. This is useful to check that a certain compiler pass is run in a test, e.g., https://reviews.llvm.org/D151589
Reviewed By: #lld-macho, MaskRay, int3
Differential Revision: https://reviews.llvm.org/D151746
Apple deprecated bitcode in the deployment process in Xcode 14.0. Last
month Apple started requiring Xcode 14.1+ to submit apps to the App
Store. Since there isn't a use for bundling bitcode outside of
submitting to the App Store we should be safe to delete this handling
entirely from LLD.
Differential Revision: https://reviews.llvm.org/D150697
We never really supported 32-bit ARM arch entirely, and partial support was added for
very specific features. Regardless, it fails to even link the most basic applications that at
this point, it might be better to move this arch as unsupported. Given that Apple will be
moving towards arm64 long term, I don't see any reason for anyone to invest time in
supporting this either, and for those who still need it should use apple's ld64 linker.
Fixes#62691
Reviewed By: #lld-macho, int3
Differential Revision: https://reviews.llvm.org/D150544
As of Xcode 14.3 it passes -reproducible by default to ld64. It seems
this flag was added in ld64 with Xcode 14.0, but it is not documented.
Through my testing the only thing I have seen it do is the same as
ZERO_AR_DATE, but it's possible it does more, or will do more in the
future. Since we already default to this option, this is more about
handling the command line flag to maintain Xcode compatibility than
anything else.
Differential Revision: https://reviews.llvm.org/D147663
Currently, the --thinlto-prefix-replace="oldpath;newpath" option is used during
distributed ThinLTO thin links to specify the mapping of the input bitcode object
files' directory tree (oldpath) to the directory tree (newpath) used for both:
1) the output files of the thin link itself (the .thinlto.bc index files and the
optional .imports files)
2) the specified object file paths written to the response file given in the
--thinlto-index-only=${response} option, which is used by the final native
link and must match the paths of the native object files that will be
produced by ThinLTO backend compiles.
This patch expands the --thinlto-prefix-replace option to allow a separate directory
tree mapping to be specified for the object file paths written to the response file
(number 2 above). This is important to support builds and build systems where the
same output directory may not be written by multiple build actions (e.g. the thin link
and the ThinLTO backend compiles).
The new format is: --thinlto-prefix-replace="origpath;outpath[;objpath]"
This replaces the origpath directory tree of the thin link input files with
outpath when writing the thin link index and imports outputs (number 1
above). If objpath is specified it replaces origpath of the input files with
objpath when writing the response file (number 2 above), otherwise it
falls back to the old behavior of using outpath for this as well.
Reviewed By: tejohnson, MaskRay
Differential Revision: https://reviews.llvm.org/D144596
@oontvoo reports that the current implementation crashes on a bunch of
their builds. Let's leave it disabled by default for now.
Reviewed By: #lld-macho, oontvoo
Differential Revision: https://reviews.llvm.org/D147341
This implements ld64's checks for duplicate method names in categories &
classes.
In addition, this sets us up for implementing Obj-C category merging.
This diff handles the most of the parsing work; what's left is rewriting
those category / class structures.
Numbers for chromium_framework:
base diff difference (95% CI)
sys_time 2.182 ± 0.027 2.200 ± 0.047 [ -0.2% .. +1.8%]
user_time 6.451 ± 0.034 6.479 ± 0.062 [ -0.0% .. +0.9%]
wall_time 6.841 ± 0.048 6.885 ± 0.105 [ -0.1% .. +1.4%]
samples 33 22
Fixes https://github.com/llvm/llvm-project/issues/54912.
Issues seen with the previous land will be fixed in the next commit.
Reviewed By: #lld-macho, thevinster, oontvoo
Differential Revision: https://reviews.llvm.org/D142916
Specifically, we support this:
ld64.lld -dylib foo.o libbar.dylib -exported_symbol _bar -o libfoo.dylib
Where `_bar` is defined in libbar.dylib.
Reviewed By: #lld-macho, smeenai
Differential Revision: https://reviews.llvm.org/D144153
This implements ld64's checks for duplicate method names in categories &
classes.
In addition, this sets us up for implementing Obj-C category merging.
This diff handles the most of the parsing work; what's left is rewriting
those category / class structures.
Numbers for chromium_framework:
base diff difference (95% CI)
sys_time 2.182 ± 0.027 2.200 ± 0.047 [ -0.2% .. +1.8%]
user_time 6.451 ± 0.034 6.479 ± 0.062 [ -0.0% .. +0.9%]
wall_time 6.841 ± 0.048 6.885 ± 0.105 [ -0.1% .. +1.4%]
samples 33 22
Fixes https://github.com/llvm/llvm-project/issues/54912.
Reviewed By: #lld-macho, thevinster, oontvoo
Differential Revision: https://reviews.llvm.org/D142916
At some point PlatformInfo's Target changed types to a type that also
has minimum deployment target info. This caused ambiguity if you tried
to get the target triple from the Target, as the actual minimum version
info was being stored separately. This bulk of this change is changing
the parsing of these values to support this.
Differential Revision: https://reviews.llvm.org/D145263
Allow controlling the CodeGenOpt::Level independent of the LTO
optimization level in LLD via new options for the COFF, ELF, MachO, and
wasm frontends to lld. Most are spelled as --lto-CGO[0-3], but COFF is
spelled as -opt:lldltocgo=[0-3].
See D57422 for discussion surrounding the issue of how to set the CG opt
level. The ultimate goal is to let each function control its CG opt
level, but until then the current default means it is impossible to
specify a CG opt level lower than 2 while using LTO. This option gives
the user a means to control it for as long as it is not handled on a
per-function basis.
Reviewed By: MaskRay, #lld-macho, int3
Differential Revision: https://reviews.llvm.org/D141970
The forwarding header is left in place because of its use in
`polly/lib/External/isl/interface/extract_interface.cc`, but I have
added a GCC warning about the fact it is deprecated, because it is used
in `isl` from where it is included by Polly.
Adds support for the following flags:
* --thinlto-index-only, --thinlto-index-only=
* --thinlto-emit-imports-files
* --thinlto-emit-index-files
* --thinlto-object-suffix-replace=
* --thinlto-prefix-replace=
See https://blog.llvm.org/2016/06/thinlto-scalable-and-incremental-lto.html
for some words on --thinlto-index-only.
I don't really need the other flags, but they were in the vicinity
and _someone_ might need them, so I figured I'd add them too.
`-object_path_lto` now sets `c.AlwaysEmitRegularLTOObj` as in the other ports,
which means it can now only point to a filename for non-thin LTO.
I think that was the intent of D129705 anyways, so update
test/MachO/lto-object-path.ll to use a non-thin bitcode file for that test.
Differential Revision: https://reviews.llvm.org/D138451
By default ld64 ignores invalid LC_LINKER_OPTIONS unless the link fails,
in which case it prints a warning. Originally lld chose to be strict
about these, but it has uncovered that many of these exist in open
source projects today, since before developers never would have noticed
this issue. In order to make adoption of lld easier, this mirrors ld64's
behavior, while also adding a `--strict-auto-link-options` flag if
projects want to audit their libraries for these invalid options.
More discussion on https://reviews.llvm.org/D140225
Fixes https://github.com/llvm/llvm-project/issues/59627
Differential Revision: https://reviews.llvm.org/D140491
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
With newer versions of ld64 it generates an adhoc signature by default
for all arm64 simulator targets. This default is especially important
for unit test targets that rarely have custom codesigning requirements
but otherwise won't run on arm64 macs.
Differential Revision: https://reviews.llvm.org/D139672
I tried `-undefined suppress` without `-flat_namespace`.
lld printed `'-undefined suppress' only valid with '-flat_namespace'`
followed by many many screenfuls of error messages about undefined
symbols, making the original diag hard to see.
This is probably the common case when using `-undefined`, so let's
just abort the link immediately when there's an invalid `-undefined`
arg.
Differential Revision: https://reviews.llvm.org/D139559
ld64 rejects `-no_pie` when targeting arm64, this mirrors that behavior.
Newer versions of ld64 also reject it based on minimum OS versions, but
that logic isn't in an open source dump yet so it isn't implemented
here.
Fixes https://github.com/llvm/llvm-project/issues/59115
Differential Revision: https://reviews.llvm.org/D138884
Like D134013, but for COFF and Mach-O.
Also expand the ELF test a bit. I at first didn't realize that `getValue()` for
`-mllvm -foo=bar` would return `-foo=bar` instead of just `bar`, and so
I wrote the test to check if we indeed get this wrong. We don't, but
having the test for it seems nice, so I'm including it.
Differential Revision: https://reviews.llvm.org/D137971
We never noticed this before because the only time the size gets emitted is via
the linker map...
Reviewed By: #lld-macho, thakis
Differential Revision: https://reviews.llvm.org/D135884
This provides a workaround for a small difference in ld64 behavior where
ld64 ignores invalid LC_LINKER_OPTIONS unless the link fails. Instead of
fully adopting that behavior, this provides an escape hatch by allowing
users to specify `--ignore-auto-link-option` passing the invalid library
or framework name
Fixes https://github.com/llvm/llvm-project/issues/56939
Differential Revision: https://reviews.llvm.org/D135530
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
This commit adds support for chained fixups, which were introduced in
Apple's late 2020 OS releases. This format replaces the dyld opcodes
used for supplying rebase and binding information, and encodes most of
that data directly in the memory location that will have the fixup
applied.
This reduces binary size and is a requirement for page-in linking, which
will be available starting with macOS 13.
A high-level overview of the format and my implementation can be found
in SyntheticSections.h.
This feature is currently gated behind the `-fixup_chains` flag, and
will be enabled by default for supported targets in a later commit.
Like in ld64, lazy binding is disabled when chained fixups are in use,
and the `-init_offsets` transformation is performed by default.
Differential Revision: https://reviews.llvm.org/D132560
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 arg is undocumented but from looking at the code + experiment, it's used to add additional DYLD_ENVIRONMENT load commands to the output.
Differential Revision: https://reviews.llvm.org/D134058
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
This section stores 32-bit `__TEXT` segment offsets of initializer
functions, and is used instead of `__mod_init_func` when chained fixups
are enabled.
Storing the offsets lets us avoid emitting fixups for the initializers.
Differential Revision: https://reviews.llvm.org/D132947
Apple Clang in Xcode 14 introduced a new feature for reducing the
overhead of objc_msgSend calls by deduplicating the setup calls for each
individual selector. This works by clang adding undefined symbols for
each selector called in a translation unit, such as `_objc_msgSend$foo`
for calling the `foo` method on any `NSObject`. There are 2
different modes for this behavior, the default directly does the setup
for `_objc_msgSend` and calls it, and the smaller option does the
selector setup, and then calls the standard `_objc_msgSend` stub
function.
The general overview of how this works is:
- Undefined symbols with the given prefix are collected
- The suffix of each matching undefined symbol is added as a string to
`__objc_methname`
- A pointer is added for every method name in the `__objc_selrefs`
section
- A `got` entry is emitted for `_objc_msgSend`
- Stubs are emitting pointing to the synthesized locations
Notes:
- Both `__objc_methname` and `__objc_selrefs` can also exist from object
files, so their contents are merged with our synthesized contents
- The compiler emits method names for defined methods, but not for
undefined symbols you call, but stubs are used for both
- This only implements the default "fast" mode currently just to reduce
the diff, I also doubt many folks will care to swap modes
- This only implements this for arm64 and x86_64, we don't need to
implement this for 32 bit iOS archs, but we should implement it for
watchOS archs in a later diff
Differential Revision: https://reviews.llvm.org/D128108
