Similarly to how undefined symbol diagnostics were changed in D128184,
we now show where in the source file duplicate symbols are defined at:
ld64.lld: error: duplicate symbol: _foo
>> defined in bar.c:42
>> /path/to/bar.o
>> defined in baz.c:1
>> /path/to/libbaz.a(baz.o)
For objects that don't contain DWARF data, the format is unchanged.
A slight difference to undefined symbol diagnostics is that we don't
print the name of the symbol on the third line, as it's already
contained on the first line.
Differential Revision: https://reviews.llvm.org/D128425
According to ministat, this is a small but measurable speedup
(using the repro in PR56121):
N Min Max Median Avg Stddev
x 10 3.7439518 3.7783802 3.7730219 3.7655502 0.012375226
+ 10 3.6149218 3.692198 3.6519327 3.6502951 0.025905601
Difference at 95.0% confidence
-0.115255 +/- 0.0190746
-3.06078% +/- 0.506554%
(Student's t, pooled s = 0.0203008)
(Without 858e8b17f7, this change here to use parallelFor is an 18% speedup,
and doing 858e8b17f7 on top of this change is just a 2.55% +/- 0.58% win.
Doing both results in a total speedup of 20.85% +/- 0.44%.)
Differential Revision: https://reviews.llvm.org/D128298
The error used to look like this:
ld64.lld: error: undefined symbol: _foo
>>> referenced by /path/to/bar.o:(symbol _baz+0x4)
If DWARF line information is available, we now show where in the source
the references are coming from:
ld64.lld: error: unreferenced symbol: _foo
>>> referenced by: bar.cpp:42 (/path/to/bar.cpp:42)
>>> /path/to/bar.o:(symbol _baz+0x4)
The reland is identical to the first time this landed. The fix was in D128294.
This reverts commit 0cc7ad4175.
Differential Revision: https://reviews.llvm.org/D128184
If ld64.lld was supplied an object file that had a `__debug_abbrev` or
`__debug_str` section, but didn't have any compile unit DIEs in
`__debug_info`, it would dereference an iterator pointing to the empty
array of DIEs. This underlying issue started causing segmentation faults
when parsing for `__debug_info` was addded in D128184. That commit was
reverted, and this one fixes the invalid dereference to allow relanding
it.
This commit adds an assertion to `filter_iterator_base`'s dereference
operators to catch bugs like this one.
Ran check-llvm, check-clang and check-lld.
Differential Revision: https://reviews.llvm.org/D128294
It's in libSystem, so it doesn't bring in any new deps, and it's
currently much faster than LLVM's current SHA256 implementation.
Makes linking (arm64) Chromium Framework with ld64.lld 17% faster.
See also PR56121.
No behavior change.
Differential Revision: https://reviews.llvm.org/D128290
This reverts commit 9ffeaaa0ea.
This fixes debugging large executables with lldb and gdb.
When StringTableBuilder is used, the string offsets for any string
can point anywhere in the string table - while previously, all strings
were inserted in order (without deduplication and tail merging).
For symbols, there's no complications in encoding the string offset;
the offset is encoded as a raw 32 bit binary number in half of the
symbol name field.
For sections, the string table offset is written as
"/<decimaloffset>", but if the decimal offset would be larger than
7 digits, it's instead written as "//<base64offset>". Tools that
operate on object files can handle the base64 offset format, but
apparently neither lldb nor gdb expect that syntax when locating the
debug information section. Prior to the reverted commit, all long
section names were located at the start of the string table, so
their offset never exceeded the range for the decimal syntax.
Just reverting this change for now, as the actual benefit from it
was fairly modest.
Longer term, lld could write all long section names unoptimized
at the start of the string table, followed by all the strings for
symbol names, with deduplication and tail merging. And lldb and
gdb could be fixed to handle sections with the base64 offset syntax.
This fixes https://github.com/mstorsjo/llvm-mingw/issues/289.
Microsoft does not seem to document the flag. Ignoring it for now is probably
better than getting an unknown flag error.
Reviewed By: thakis
Differential Revision: https://reviews.llvm.org/D128231
The error used to look like this:
ld64.lld: error: undefined symbol: _foo
>>> referenced by /path/to/bar.o:(symbol _baz+0x4)
If DWARF line information is available, we now show where in the source
the references are coming from:
ld64.lld: error: unreferenced symbol: _foo
>>> referenced by: bar.cpp:42 (/path/to/bar.cpp:42)
>>> /path/to/bar.o:(symbol _baz+0x4)
Differential Revision: https://reviews.llvm.org/D128184
Patch created by running:
rg -l parallelForEachN | xargs sed -i '' -c 's/parallelForEachN/parallelFor/'
No behavior change.
Differential Revision: https://reviews.llvm.org/D128140
I realized we'd forgotten to cover this case (though our existing
behavior is indeed correct / matches ld64's).
Reviewed By: #lld-macho, thakis
Differential Revision: https://reviews.llvm.org/D128025
As an optimization for ld64 sometimes it can be useful to not export any
symbols for top level binaries that don't need any exports, to do this
you can pass `-exported_symbols_list /dev/null`, or new with Xcode 14
(ld64 816) there is a `-no_exported_symbols` flag for the same behavior.
This reproduces this behavior where previously an empty exported symbols
list file would have been ignored.
Differential Revision: https://reviews.llvm.org/D127562
It seems to be a bug in `LinkerDriver::findFile`, the file name is not converted
to lowercase when being inserted into `visitedLibs`. This is the only exception
in the file and all other places always convert file names to lowercase when
inserting them into `visitedLibs` (or `visitedFiles`).
Reviewed By: thieta, hans
Differential Revision: https://reviews.llvm.org/D127709
Since binutils 2.36, GNU ld defaults to emitting base relocations,
and that version added the new option --disable-reloc-section to
disable it.
Differential Revision: https://reviews.llvm.org/D127478
ld64.lld used to print the "undefined symbol" line for each reference to
an undefined symbol previously:
ld64.lld: error: undefined symbol: _foo
>>> referenced by /path/to/bar.o:(symbol _baz+0x0)
ld64.lld: error: undefined symbol: _foo
>>> referenced by /path/to/bar.o:(symbol _quux+0x1)
Now they are deduplicated:
ld64.lld: error: undefined symbol: _foo
>>> referenced by /path/to/bar.o:(symbol _baz+0x0)
>>> referenced by /path/to/bar.o:(symbol _quux+0x1)
As with the other lld ports, only the first 3 references are printed.
Differential Revision: https://reviews.llvm.org/D127753
The error used to look like this:
ld64.lld: error: undefined symbol: _foo
>>> referenced by /path/to/bar.o
Now it displays the name of the function that contains the undefined
reference as well:
ld64.lld: error: undefined symbol: _foo
>>> referenced by /path/to/bar.o:(symbol _baz+0x4)
Differential Revision: https://reviews.llvm.org/D127696
This commit fixes the issue that getLocation always printed the name of
the first symbol in the section.
For clarity, upper_bound is used instead of a linear search for finding
the closest symbol name. Note that this change does not affect
performance: this function is only called when printing errors and
`symbols` typically contains a single symbol because of
.subsections_via_symbols.
Differential Revision: https://reviews.llvm.org/D127670
This reverts commit 942f4e3a7c.
The additional change required to avoid the assertion errors seen
previously is:
--- a/lld/MachO/ICF.cpp
+++ b/lld/MachO/ICF.cpp
@@ -443,7 +443,9 @@ void macho::foldIdenticalSections() {
/*relocVA=*/0);
isec->data = copy;
}
- } else {
+ } else if (!isEhFrameSection(isec)) {
+ // EH frames are gathered as hashables from unwindEntry above; give a
+ // unique ID to everything else.
isec->icfEqClass[0] = ++icfUniqueID;
}
}
Differential Revision: https://reviews.llvm.org/D123435
Just matter of enabling the config option.
(Also changed the platform of the input test file to macOS, since that's
the default that we specify in the `%lld` substitution. The conflict was
causing errors when linking with LTO.)
Reviewed By: #lld-macho, thakis
Differential Revision: https://reviews.llvm.org/D127600
This flag suppresses warnings produced by the linker. In ld64 this has
an interesting interaction with -fatal_warnings, it silences the
warnings but the link still fails. Instead of doing that here we still
print the warning and eagerly fail the link in case both are passed,
this seems more reasonable so users can understand why the link fails.
Differential Revision: https://reviews.llvm.org/D127564
First of all, `LLVM_TOOLS_INSTALL_DIR` put there breaks our NixOS
builds, because `LLVM_TOOLS_INSTALL_DIR` defined the same as
`CMAKE_INSTALL_BINDIR` becomes an *absolute* path, and then when
downstream projects try to install there too this breaks because our
builds always install to fresh directories for isolation's sake.
Second of all, note that `LLVM_TOOLS_INSTALL_DIR` stands out against the
other specially crafted `LLVM_CONFIG_*` variables substituted in
`llvm/cmake/modules/LLVMConfig.cmake.in`.
@beanz added it in d0e1c2a550 to fix a
dangling reference in `AddLLVM`, but I am suspicious of how this
variable doesn't follow the pattern.
Those other ones are carefully made to be build-time vs install-time
variables depending on which `LLVMConfig.cmake` is being generated, are
carefully made relative as appropriate, etc. etc. For my NixOS use-case
they are also fine because they are never used as downstream install
variables, only for reading not writing.
To avoid the problems I face, and restore symmetry, I deleted the
exported and arranged to have many `${project}_TOOLS_INSTALL_DIR`s.
`AddLLVM` now instead expects each project to define its own, and they
do so based on `CMAKE_INSTALL_BINDIR`. `LLVMConfig` still exports
`LLVM_TOOLS_BINARY_DIR` which is the location for the tools defined in
the usual way, matching the other remaining exported variables.
For the `AddLLVM` changes, I tried to copy the existing pattern of
internal vs non-internal or for LLVM vs for downstream function/macro
names, but it would good to confirm I did that correctly.
Reviewed By: nikic
Differential Revision: https://reviews.llvm.org/D117977
This silences the following warning:
../tools/lld/ELF/SyntheticSections.cpp:1596:48: warning: suggest parentheses around ‘&&’ within ‘||’ [-Wparentheses]
1596 | assert((index != 0 || type != target->gotRel && type != target->pltRel ||
Differential Revision: https://reviews.llvm.org/D127395
For arm64, llvm-mc emits relocations for the target function
address like so:
ltmp:
<CIE start>
...
<CIE end>
... multiple FDEs ...
<FDE start>
<target function address - (ltmp + pcrel offset)>
...
If any of the FDEs in `multiple FDEs` get dead-stripped, then `FDE start`
will move to an earlier address, and `ltmp + pcrel offset` will no longer
reflect an accurate pcrel value. To avoid this problem, we "canonicalize"
our relocation by adding an `EH_Frame` symbol at `FDE start`, and updating
the reloc to be `target function address - (EH_Frame + new pcrel offset)`.
Reviewed By: #lld-macho, Roger
Differential Revision: https://reviews.llvm.org/D124561
== Background ==
`llvm-mc` generates unwind info in both compact unwind and DWARF
formats. LLD already handles the compact unwind format; this diff gets
us close to handling the DWARF format properly.
== Caveats ==
It's not quite done yet, but I figure it's worth getting this reviewed
and landed first as it's shaping up to be a fairly large code change.
**Known limitations of the current code:**
* Only works for x86_64, for which `llvm-mc` emits "abs-ified"
relocations as described in 618def651b.
`llvm-mc` emits regular relocations for ARM EH frames, which we do not
yet handle correctly.
Since the feature is not ready for real use yet, I've gated it behind a
flag that only gets toggled on during test suite runs. With most of the
new code disabled, we see just a hint of perf regression, so I don't
think it'd be remiss to land this as-is:
base diff difference (95% CI)
sys_time 1.926 ± 0.168 1.979 ± 0.117 [ -1.2% .. +6.6%]
user_time 3.590 ± 0.033 3.606 ± 0.028 [ +0.0% .. +0.9%]
wall_time 7.104 ± 0.184 7.179 ± 0.151 [ -0.2% .. +2.3%]
samples 30 31
== Design ==
Like compact unwind entries, EH frames are also represented as regular
ConcatInputSections that get pointed to via `Defined::unwindEntry`. This
allows them to be handled generically by e.g. the MarkLive and ICF
code. (But note that unlike compact unwind subsections, EH frame
subsections do end up in the final binary.)
In order to make EH frames "look like" a regular ConcatInputSection,
some processing is required. First, we need to split the `__eh_frame`
section along EH frame boundaries rather than along symbol boundaries.
We do this by decoding the length field of each EH frame. Second, the
abs-ified relocations need to be turned into regular Relocs.
== Next Steps ==
In order to support EH frames on ARM targets, we will either have to
teach LLD how to handle EH frames with explicit relocs, or we can try to
make `llvm-mc` emit abs-ified relocs for ARM as well. I'm hoping to do
the latter as I think it will make the LLD implementation both simpler
and faster to execute.
== Misc ==
The `obj-file-with-stabs.s` test had to be updated as the previous
version would trip assertion errors in the code. It appears that in our
attempt to produce a minimal YAML test input, we created a file with
invalid EH frame data. I've fixed this by re-generating the YAML and not
doing any hand-pruning of it.
Reviewed By: #lld-macho, Roger
Differential Revision: https://reviews.llvm.org/D123435
This reduces linking time by ~8% for my project (1.19s -> 0.53s for
writeSections()). writeTo is const, which bodes well for it being
parallelizable, and I've looked through the different overridden versions and
can't see any race conditions. It produces the same byte-for-byte output for my
project.
Differential Revision: https://reviews.llvm.org/D126800
This reverts commit dcf3368e33.
It breaks -DLLVM_ENABLE_ASSERTIONS=on builds. In addition, the description is
incorrect about ld.lld behavior. For wasm, there should be justification to add
the new mode.
As well as ELF linker does, retain all data segments named X referenced
through `__start_X` or `__stop_X`.
For example, `FOO_MD` should not be stripped in the below case, but it's currently mis-stripped
```llvm
@FOO_MD = global [4 x i8] c"bar\00", section "foo_md", align 1
@__start_foo_md = external constant i8*
@__stop_foo_md = external constant i8*
@llvm.used = appending global [1 x i8*] [i8* bitcast (i32 ()* @foo_md_size to i8*)], section "llvm.metadata"
define i32 @foo_md_size() {
entry:
ret i32 sub (
i32 ptrtoint (i8** @__stop_foo_md to i32),
i32 ptrtoint (i8** @__start_foo_md to i32)
)
}
```
This fixes https://github.com/llvm/llvm-project/issues/55839
Reviewed By: sbc100
Differential Revision: https://reviews.llvm.org/D126950
.zdebug is unlikely used any longer: gcc -gz switched from legacy
.zdebug to SHF_COMPRESSED with binutils 2.26 (2016), which has been
several years. clang 14 dropped -gz=zlib-gnu support. According to
Debian Code Search (`gz=zlib-gnu`), no project uses -gz=zlib-gnu.
Remove .zdebug support to (a) simplify code and (b) allow removal of llvm-mc's
--compress-debug-sections=zlib-gnu.
In case the old object file `a.o` uses .zdebug, run `objcopy --decompress-debug-sections a.o`
Reviewed By: peter.smith
Differential Revision: https://reviews.llvm.org/D126793
LTO code may end up mixing bitcode files from various sources varying in
their use of opaque pointer types. The current strategy to decide
between opaque / typed pointers upon the first bitcode file loaded does
not work here, since we could be loading a non-opaque bitcode file first
and would then be unable to load any files with opaque pointer types
later.
So for LTO this:
- Adds an `lto::Config::OpaquePointer` option and enforces an upfront
decision between the two modes.
- Adds `-opaque-pointers`/`-no-opaque-pointers` options to the gold
plugin; disabled by default.
- `--opaque-pointers`/`--no-opaque-pointers` options with
`-plugin-opt=-opaque-pointers`/`-plugin-opt=-no-opaque-pointers`
aliases to lld; disabled by default.
- Adds an `-lto-opaque-pointers` option to the `llvm-lto2` tool.
- Changes the clang driver to pass `-plugin-opt=-opaque-pointers` to
the linker in LTO modes when clang was configured with opaque
pointers enabled by default.
This fixes https://github.com/llvm/llvm-project/issues/55377
Differential Revision: https://reviews.llvm.org/D125847
This reduces the time emitStabs() takes by about 275ms, or 3% of overall
linking time for the project I'm on. Although the parent function is run in
parallel, it's one of the slowest tasks in that concurrent batch (I have
another optimization for another slow task as well).
Differential Revision: https://reviews.llvm.org/D126785
Symbols from LTO objects don't contain Wasm signatures, but we need a
signature when we create undefined/stub functions for missing weakly
undefined symbols.
Luckily, after LTO, we know that symbols that are not referenced by a
regular object file must not be needed in the final output so there
is no need to generate undefined/stub function for them.
Differential Revision: https://reviews.llvm.org/D126554
Currently there are 2 duplicate implementation, and I want to add
a use in a 3rd place. Combine them in lib/BinaryFormat so they can
be shared.
Also update toString for symbol and reloc types to use StringRef
Differential Revision: https://reviews.llvm.org/D126553
This matches the behaviour of the ELF backend (in fact this change
is mostly just copying directly from ELF/Options.td).
Differential Revision: https://reviews.llvm.org/D126500
I'm really not sure how this was overlooked when we first ported lld
to Wasm. The upstream code in the ELF backend has these two lines but
for some reason they never make it into the Wasm version.
Differential Revision: https://reviews.llvm.org/D126497
It turns out we were already allocating static address space for TLS
data along with the non-TLS static data, but this space was going
unused/ignored.
With this change, we include the TLS segment in `__wasm_init_memory`
(which does the work of loading the passive segments into memory when a
module is first loaded). We also set the `__tls_base` global to point
to the start of this segment.
This means that the runtime can use this static copy of the TLS data for
the first/primary thread if it chooses, rather than doing a runtime
allocation prior to calling `__wasm_init_tls`.
Practically speaking, this will allow emscripten to avoid dynamic
allocation of TLS region on the main thread.
Differential Revision: https://reviews.llvm.org/D126107
The <internal> symbol was tripping an assertion in getVA() because it
was not marked as used. Per the comment above that symbols creation,
dead stripping has already occurred so marking this symbol as used is
accurate.
Fixes https://github.com/llvm/llvm-project/issues/55565
Differential revision: https://reviews.llvm.org/D126072
This became empty when we removed the legacy macho lld. This results in
a warning when running `check-lld`. We can revert this in the future if
we want unit tests.
Differential Revision: https://reviews.llvm.org/D125436
Details:
The test was incorrectly expecting the error messages for the export symbols to have a particular order.
It shouldn't because the export symbol list is processed concurrently.
GNU ld does not allow `.foo : { (*foo) }`, but we may recognize it as three
input section descriptions: file "(" with any section name, file "*foo" with
any section name, file ")" with any section name. Disallow the error-prone usage.
Reviewed By: peter.smith
Differential Revision: https://reviews.llvm.org/D125523
We picked common-page-size to match GNU ld. Recently, the resolution to GNU ld
https://sourceware.org/bugzilla/show_bug.cgi?id=28824 (milestone: 2.39) switched
to max-page-size so that the last page can be protected by RELRO in case the
system page size is larger than common-page-size.
Thanks to our two RW PT_LOAD scheme (D58892), switching to max-page-size does
not change file size (while GNU ld's scheme may increase file size).
Reviewed By: peter.smith
Differential Revision: https://reviews.llvm.org/D125410
This flag is added by clang::driver::tools::addLTOOptions() and was causing
errors for me when building the llvm-test-suite repository with LTO and
-DTEST_SUITE_COLLECT_STATS=ON. This replaces the --stats-file= option
added in 1c04b52b25 since the flag is only
used for LTO and should therefore be in the -plugin-opt= namespace.
Additionally, this commit fixes the `REQUIRES: asserts` that was added in
948d05324a150a5a24e93bad07c9090d5b8bd129: the feature was never defined in
the lld test suite so it effectively disabled the test.
Reviewed By: MaskRay, MTC
Differential Revision: https://reviews.llvm.org/D124105
Placing a non-SHT_NOBITS input section in an output section specified with
(NOLOAD) is fishy but used by some projects. D118840 changed the output type to
SHT_PROGBITS, but using the specified type seems to make more sense and improve
GNU ld compatibility: `(NOLOAD)` seems to change the output section type
regardless of input.
I think we should keep the current type mismatch warning as it does indicate an
error-prone usage.
Reviewed By: peter.smith
Differential Revision: https://reviews.llvm.org/D125074
With -platform_version flags for two distinct platforms,
this writes a LC_BUILD_VERSION header for each.
The motivation is that this is needed for self-hosting with lld as linker
after D124059.
To create a zippered output at the clang driver level, pass
-target arm64-apple-macos -darwin-target-variant arm64-apple-ios-macabi
to create a zippered dylib.
(In Xcode's clang, `-darwin-target-variant` is spelled just `-target-variant`.)
(If you pass `-target arm64-apple-ios-macabi -target-variant arm64-apple-macos`
instead, ld64 crashes!)
This results in two -platform_version flags being passed to the linker.
ld64 also verifies that the iOS SDK version is at least 13.1. We don't do that
yet. But ld64 also does that for other platforms and we don't. So we need to
do that at some point, but not in this patch.
Only dylib and bundle outputs can be zippered.
I verified that a Catalyst app linked against a dylib created with
clang -shared foo.cc -o libfoo.dylib \
-target arm64-apple-macos \
-target-variant arm64-apple-ios-macabi \
-Wl,-install_name,@rpath/libfoo.dylib \
-fuse-ld=$PWD/out/gn/bin/ld64.lld
runs successfully. (The app calls a function `f()` in libfoo.dylib
that returns a const char* "foo", and NSLog(@"%s")s it.)
ld64 is a bit more permissive when writing zippered outputs,
see references to "unzippered twins". That's not implemented yet.
(If anybody wants to implement that, D124275 is a good start.)
Differential Revision: https://reviews.llvm.org/D124887
The arm64-apple-macos triple is only valid for versions >= 11.0. (If
one passes arm64-apple-macos10.15 to llvm-mc, the output's min version is still
11.0). In order to write tests easily for both target archs, let's up the
default min version in our tests.
Reviewed By: #lld-macho, thakis
Differential Revision: https://reviews.llvm.org/D124562
We currently hard code RELRO sections. When a custom section is between
DATA_SEGMENT_ALIGN and DATA_SEGMENT_RELRO_END, we may report a spurious
`error: section: ... is not contiguous with other relro sections`. GNU ld
makes such sections RELRO.
glibc recently switched to default --with-default-link=no. This configuration
places `__libc_atexit` and others between DATA_SEGMENT_ALIGN and
DATA_SEGMENT_RELRO_END. This patch allows such a ld.bfd --verbose
linker script to be fed into lld.
Reviewed By: peter.smith
Differential Revision: https://reviews.llvm.org/D124656
This change implements --icf=safe for MachO based on addrsig section that is implemented in D123751.
Reviewed By: int3, #lld-macho
Differential Revision: https://reviews.llvm.org/D123752
Similar to D117734. Take AArch64 as an example when the branch range is +-0x8000000.
getISDThunkSec returns `ts` when `src-0x8000000-r_addend <= tsBase < src-0x8000000`
and the new thunk will be placed in `ts` (`ts->addThunk(t)`). However, the new
thunk (at the end of ts) may be unreachable from src. In the next pass,
`normalizeExistingThunk` reverts the relocation back to the original target.
Then a new thunk is created and the same `ts` is picked as before. The `ts` is
still unreachable.
I have observed it in one test with a sufficiently large r_addend (47664): there
are initially 245 Thunk's, then in each pass 14 new Thunk's are created and get
appended to the unreachable ThunkSection. After 15 passes lld fails with
`thunk creation not converged`.
The new test aarch64-thunk-reuse2.s checks the case.
Without `- pcBias`, arm-thumb-thunk-empty-pass.s and arm-thunk-multipass-plt.s
will fail.
Reviewed By: peter.smith
Differential Revision: https://reviews.llvm.org/D124653
After 1af25a9860, we stop unconditionally
retaining wrapped symbols, which means that LTO's summary-based global
dead stripping can eliminate them even if they'll be referenced by a
linker script after the wrapping is performed. Mark symbols referenced
in linker scripts as `referenced` in addition to `isUsedInRegularObj`,
so that the wrapping logic correctly sets `referencedAfterWrap` for the
symbols which will be referenced after wrapping, which will prevent LTO
from eliminating them.
An alternative would have been to change the `referencedAfterWrap` logic
to look at `isUsedInRegularObj` in addition to `referenced`, but
`isUsedInRegularObj` is also set in other places (e.g. for the entry
symbol), and it's not clear that we want `referencedAfterWrap` to take
all those places into account, so it seemed better to keep that logic
as-is and instead set `referenced` for linker script-referenced symbols.
Reviewed By: MaskRay
Differential Revision: https://reviews.llvm.org/D124433
Before this,
clang empty.cc -target x86_64-apple-ios13.1-macabi \
-framework CoreServices -fuse-ld=lld
would error out with
ld64.lld: error: path/to/MacOSX.sdk/System/Library/Frameworks/
CoreServices.framework/Versions/A/Frameworks/CarbonCore.framework/
Versions/A/CarbonCore.tbd(
/System/Library/Frameworks/
CoreServices.framework/Versions/A/Frameworks/CarbonCore.framework/
Versions/A/CarbonCore) is incompatible with x86_64 (macCatalyst)
Now it works, like with ld64.
Differential Revision: https://reviews.llvm.org/D124336
It seems like we are overly asserting when running `-dead_strip` with
exported symbols. ld64 treats exported private extern symbols as a liveness
root. Loosen the assert to match ld64's behavior.
Reviewed By: #lld-macho, int3
Differential Revision: https://reviews.llvm.org/D124143
We were previously only omitting the original of a wrapped symbol if it
was not used by an object file and undefined. We can tighten the second
condition to drop any symbol that isn't defined instead, which lets us
drop a previous check (added in https://reviews.llvm.org/D118756) that
was only covering some such symbols.
Reviewed By: MaskRay
Differential Revision: https://reviews.llvm.org/D124065
We were previously not correctly wrapping symbols that were only
produced during LTO codegen and unreferenced before then, or symbols
only referenced from such symbols. The root cause was that we weren't
marking the wrapped symbol as used if we only saw the use after LTO
codegen, leading to the failed wrapping.
Fix this by explicitly tracking whether a symbol will become referenced
after wrapping is done. We can use this property to tell LTO to preserve
such symbols, instead of overload isUsedInRegularObj for this purpose.
Since we're no longer setting isUsedInRegularObj for all symbols which
will be wrapped, its value at the time of performing the wrapping in the
symbol table will accurately reflect whether the symbol was actually
used in an object (including in an LTO-generated object), and we can
propagate that value to the wrapped symbol and thereby ensure we wrap
correctly.
This incorrect wrapping was the only scenario I was aware of where we
produced an invalid PLT relocation, which D123985 started diagnosing,
and with it fixed, we lose the test for that diagnosis. I think it's
worth keeping the diagnosis though, in case we run into other issues in
the future which would be caught by it.
Fixes PR50675.
Reviewed By: MaskRay
Differential Revision: https://reviews.llvm.org/D124056
Otherwise they fires for every single file which includes the header,
which is very noisy when building.
Reviewed By: MaskRay, peter.smith
Differential Revision: https://reviews.llvm.org/D124041
Previously, when encountering a symbol reloc located in a literal section, we
would look up the contents of the literal at the `symbol value + addend` offset
within the literal section. However, it seems that this offset is not guaranteed
to be valid. Instead, we should use just the symbol value to retrieve the
literal's contents, and compare the addend values separately. ld64 seems to do
this.
Reviewed By: #lld-macho, thevinster
Differential Revision: https://reviews.llvm.org/D124223
Previously, we stored a pointer from the ObjFile to its compact unwind
section in order to avoid iterating over the file's sections a second
time. However, given the small number of sections (not subsections) per
file, this caching was really quite unnecessary. We will soon do lookups
for more sections (such as the `__eh_frame` section), so let's simplify
the code first.
Reviewed By: #lld-macho, Roger
Differential Revision: https://reviews.llvm.org/D123434
A "zippered" dylib contains several LC_BUILD_VERSION load commands, usually
one each for "normal" macOS and one for macCatalyst.
These are usually created by passing something like
-shared -target arm64-apple-macos -darwin-target-variant arm64-apple-ios13.1-macabi
to clang, which turns it into
-platform_version macos 12.0.0 12.3 -platform_version "mac catalyst" 14.0.0 15.4
for the linker.
ld64.lld can read these files fine, but it can't write them. Before this
change, it would just silently use the last -platform_version flag and ignore
the rest.
This change adds a warning that writing zippered dylibs isn't implemented yet
instead.
Sadly, parts of ld64.lld's test suite relied on the previous
"silently use last flag" semantics for its test suite: `%lld` always expanded
to `ld64.lld -platform_version macos 10.15 11.0` and tests that wanted a
different value passed a 2nd `-platform_version` flag later on. But this now
produces a warning if the platform passed to `-platform_version` is not `macos`.
There weren't very many cases of this, so move these to use `%no-arg-lld` and
manually pass `-arch`.
Differential Revision: https://reviews.llvm.org/D124106
Linux kernel arch/arm64/kernel/vmlinux.lds.S discards .dynsym . D123985 triggers
a spurious assertion failure. Detect the case with
`!mainPart->dynSymTab->getParent()`.
STB_HIPROC and STT_HIPROC are both 15, so we can fit the symbol binding
and type in 4 bits. This gives us an additional byte to use for Symbol
flags (without increasing the type's size), which I'll be making use of
in the next diff.
Reorder type and binding based on a suggestion from @MaskRay, to
optimize st_info computation on little-endian systems (see
https://godbolt.org/z/nMn8Yar43).
Reviewed By: MaskRay
Differential Revision: https://reviews.llvm.org/D124042
Because of https://llvm.org/PR50675, we can end up producing a PLT
relocation referencing a symbol that's dropped from the dynamic symbol
table, which in turn causes a crash at runtime. We ran into this again
recently, resulting in crashes for our users. A subsequent diff will fix
that issue, but add an assert to catch it if it happens again.
Reviewed By: MaskRay
Differential Revision: https://reviews.llvm.org/D123985
Otherwise, with recent versions of libstdc++, clang can't tell that the
atomic operations are properly aligned, and generates calls to
libatomic. (Actually, because of the use of reinterpret_cast, it wasn't
guaranteed to be aligned, but I think it ended up being aligned in
practice.)
Fixes https://github.com/llvm/llvm-project/issues/54790 , the part where
LLVM failed to build.
Differential Revision: https://reviews.llvm.org/D123872
Updated MipsInstPrinter to print absolute hex offsets for branch instructions.
It is necessary to make the llvm-objdump output close to the gnu objdump output.
This implementation is based on the implementation for RISC-V.
OS Laboratory. Huawei Russian Research Institute. Saint-Petersburg
Reviewed By: MaskRay
Differential Revision: https://reviews.llvm.org/D123764
Similar to D119787 for PPC64.
A hidden undefined weak may change its binding to local before some
`isUndefinedWeak` code, so some `isUndefinedWeak` code needs to be changed to
`isUndefined`. The undefined non-weak case has been errored, so just using
`isUndefined` is fine.
The Linux kernel recently has a usage that a branch from 0xffff800008491ee0
references a hidden undefined weak symbol `vfio_group_set_kvm`.
It relies on the behavior that a branch to undefined weak resolving to the next
instruction, otherwise it'd see spurious relocation out of range errors.
Fixes https://github.com/ClangBuiltLinux/linux/issues/1624
Differential Revision: https://reviews.llvm.org/D123750
Follow-on to {D123276}. Now that we work with an internal
representation of compact unwind entries, we no longer need to template
our UnwindInfoSectionImpl code based on the pointer size of the target
architecture.
I've still kept the split between `UnwindInfoSectionImpl` and
`UnwindInfoSection`. I'd introduced that split in order to do type
erasure, but I think it's still useful to have in order to keep
`UnwindInfoSection`'s definition in the header file clean.
Reviewed By: #lld-macho, oontvoo
Differential Revision: https://reviews.llvm.org/D123277
Mostly for compatibility reasons with link.exe this flag
makes sure we don't write a implib - not even when /implib
is also passed, that's how link.exe works.
Differential Revision: https://reviews.llvm.org/D123591
Mostly for compatibility reasons with link.exe this flag
makes sure we don't write a implib - not even when /implib
is also passed, that's how link.exe works.
Reviewed By: mstorsjo
Differential Revision: https://reviews.llvm.org/D123591
{D123302} got me looking deeper at `includeInSymtab`. I thought it was a
little odd that there were excluded (live) symbols for which
`includeInSymtab` was false; we shouldn't have so many different ways to
exclude a symbol. As such, this diff makes the `L`-prefixed-symbol
exclusion code use `includeInSymtab` too. (Note that as part of our
support for `__eh_frame`, we will also be excluding all `__eh_frame`
symbols from the symtab in a future diff.)
Another thing I noticed is that the `emitStabs` code never has to deal
with excluded symbols because `SymtabSection::finalize()` already
filters them out. As such, I've updated the comments and asserts from
{D123302} to reflect this.
Reviewed By: #lld-macho, thakis
Differential Revision: https://reviews.llvm.org/D123433
lib.exe by default exits successfully without writing an output
file when no inputs are passed. llvm-lib has the same behavior,
for compatibility.
This behavior interacts poorly with build systems: If a static
library target had no inputs, llvm-lib would not produce an output
file, causing ninja (or make, or a similar system) to successfully
run that step, but then re-run it on the next build.
After this patch, llvm-lib emits a warning in this case, that with
/WX can be turned into an error. That way, ninja (or make, or...)
will mark the initial build as failed.
People who don't like the warning can use /ignore:emptyoutput to
suppress it.
The warning also points out the existing flag /llvmlibempty which
forces creation of an empty .lib file (this is an extension to lib.exe).
Differential Revision: https://reviews.llvm.org/D123517
Details: The test previously expected a specific order of those symbols, which is not guaranteed (could change simply due to hashing changes, etc).
So we change it to explicitly sort the symbols before checking contents.
PR/53026
Differential Revision: https://reviews.llvm.org/D116813
The previous implementation of UnwindInfoSection materialized
all the compact unwind entries & applied their relocations, then parsed
the resulting data to generate the final unwind info. This design had
some unfortunate conseqeuences: since relocations can only be applied
after their referents have had addresses assigned, operations that need
to happen before address assignment must contort themselves. (See
{D113582} and observe how this diff greatly simplifies it.)
Moreover, it made synthesizing new compact unwind entries awkward.
Handling PR50956 will require us to do this synthesis, and is the main
motivation behind this diff.
Previously, instead of generating a new CompactUnwindEntry directly, we
would have had to generate a ConcatInputSection with a number of
`Reloc`s that would then get "flattened" into a CompactUnwindEntry.
This diff introduces an internal representation of `CompactUnwindEntry`
(the former `CompactUnwindEntry` has been renamed to
`CompactUnwindLayout`). The new CompactUnwindEntry stores references to
its personality symbol and LSDA section directly, without the use of
`Reloc` structs.
In addition to being easier to work with, this diff also allows us to
handle unwind info whose personality symbols are located in sections
placed after the `__unwind_info`.
Reviewed By: #lld-macho, oontvoo
Differential Revision: https://reviews.llvm.org/D123276
Fixes issue 47690. The reproduction steps produced a shared object
from clang directly, and then fed the shared object back into
lld. With no regular object files, this assert was hit. I'm not sure
if we need to or should be looking for equivalent fields in shared
objects.
Using a portable format specifier avoids a "format specifies type
'unsigned long long' but the argument has type 'uint64_t' (aka 'unsigned
long') [-Werror,-Wformat]" error depending on the exact definition of
`uint64_t`.
This fixes the issue when the current line offset is actually for next range.
Maintain a current code range with current line offset and cache next file/line
offset. Update file/line offset after finishing current range.
Differential Revision: https://reviews.llvm.org/D123151
This diff is motivated by my work to add proper DWARF unwind support. As
detailed in PR50956 functions that need DWARF unwind need to have
compact unwind entries synthesized for them. These CU entries encode an
offset within `__eh_frame` that points to the corresponding DWARF FDE.
In order to encode this offset during
`UnwindInfoSectionImpl::finalize()`, we need to first assign values to
`InputSection::outSecOff` for each `__eh_frame` subsection. But
`__eh_frame` is ordered after `__unwind_info` (according to ld64 at
least), which puts us in a bit of a bind: `outSecOff` gets assigned
during finalization, but `__eh_frame` is being finalized after
`__unwind_info`.
But it occurred to me that there's no real need for most
ConcatOutputSections to be finalized sequentially. It's only necessary
for text-containing ConcatOutputSections that may contain branch relocs
which may need thunks. ConcatOutputSections containing other types of
data can be finalized in any order.
This diff moves the finalization logic for non-text sections into a
separate `finalizeContents()` method. This method is called before
section address assignment & unwind info finalization takes place. In
theory we could call these `finalizeContents()` methods in parallel, but
in practice it seems to be faster to do it all on the main thread.
Reviewed By: #lld-macho, oontvoo
Differential Revision: https://reviews.llvm.org/D123279
This reverts commit 764cd491b1, which I
incorrectly assumed NFC partly because there were no test coverage for the
non-relocatable non-emit-relocs case before 9d6d936243fe343abe89323a27c7241b395af541.
The interaction of {,-r,--emit-relocs} {,--discard-locals} {,--gc-sections} is
complex but without -r/--emit-relocs, --gc-sections does need to discard .L
symbols like --no-gc-sections. The behavior matches GNU ld.
I was wondering if SymtabSection::emitStabs() should check
defined->includeInSymtab. Add asserts and comments explaining why that's not
necessary.
No behavior change.
Differential Revision: https://reviews.llvm.org/D123302
{D118797} means that we can now check the name/segname of a given
section directly, instead of having to look those properties up on one
of its subsections. This allows us to simplify our code.
Reviewed By: #lld-macho, oontvoo
Differential Revision: https://reviews.llvm.org/D123275
Our compact unwind handling code currently has some logic to locate a
symbol at a given offset in an InputSection. The EH frame code will need
to do something similar, so let's factor out the code.
Reviewed By: #lld-macho, thakis
Differential Revision: https://reviews.llvm.org/D123301
This matches ld64, and makes dsymutil work better with lld's output.
Fixes PR54783, see there for details.
Reduces time needed to run dsymutil on Chromium Framework from 8m30s
(which is already down from 26 min with D123218) to 6m30s and removes
many lines of "could not find object file symbol for symbol" from dsymutil output
(previously: several MB of those messages, now dsymutil is completely silent).
Differential Revision: https://reviews.llvm.org/D123252
This removes options for performing LTO with the legacy pass
manager in LLD. Options that explicitly enable the new pass manager
are retained as no-ops.
Differential Revision: https://reviews.llvm.org/D123219
Follow-up from 98bc304e9f - while that
commit fixed when you had two PDBs colliding on the same Guid it didn't
fix the case where you had more than two PDBs using the same Guid.
This commit fixes that and also tests much more carefully that all
the types are correct no matter the order.
Reviewed By: aganea, saudi
Differential Revision: https://reviews.llvm.org/D123185
Or rather, error out if it is set to something other than ON. This
removes the ability to enable the legacy pass manager by default,
but does not remove the ability to explicitly enable it through
various flags like -flegacy-pass-manager or -enable-new-pm=0.
I checked, and our test suite definitely doesn't pass with
LLVM_ENABLE_NEW_PASS_MANAGER=OFF anymore.
Differential Revision: https://reviews.llvm.org/D123126
Add void casts to mark the variables used, next to the places where
they are used in assert or `LLVM_DEBUG()` expressions.
Differential Revision: https://reviews.llvm.org/D123117
Returning `std::array<uint8_t, N>` is better ergonomics for the hashing functions usage, instead of a `StringRef`:
* When returning `StringRef`, client code is "jumping through hoops" to do string manipulations instead of dealing with fixed array of bytes directly, which is more natural
* Returning `std::array<uint8_t, N>` avoids the need for the hasher classes to keep a field just for the purpose of wrapping it and returning it as a `StringRef`
As part of this patch also:
* Introduce `TruncatedBLAKE3` which is useful for using BLAKE3 as the hasher type for `HashBuilder` with non-default hash sizes.
* Make `MD5Result` inherit from `std::array<uint8_t, 16>` which improves & simplifies its API.
Differential Revision: https://reviews.llvm.org/D123100
This ELF note is aarch64 and Android-specific. It specifies to the
dynamic loader that specific work should be scheduled to enable MTE
protection of stack and heap regions.
Current synthesis of the ".note.android.memtag" ELF note is done in the
Android build system. We'd like to move that to the compiler. This patch
adds the --memtag-stack, --memtag-heap, and --memtag-mode={async, sync,
none} flags to the linker, which synthesises the note for us.
Future changes will add -fsanitize=memtag* flags to clang which will
pass these through to lld.
Depends on D119381.
Differential Revision: https://reviews.llvm.org/D119384
Microsoft shipped a bunch of PDB files with broken/invalid GUIDs
which lead lld to use 0xFF as the key for these files in an internal
cache. When multiple files have this key it will lead to collisions
and confused symbol lookup.
Several approaches to fix this was considered. Including making the key
the path to the PDB file, but this requires some filesystem operations
in order to normalize the file path.
Since this only happens with malformatted PDB files and we haven't
seen this before they malformatted files where shipped with visual
studio we probably shouldn't optimize for this use-case.
Instead we now just don't insert files with Guid == 0xFF into the
cache map and warn if we get collisions so similar problems can be
found in the future instead of being silent.
Discussion about the root issue and the approach to this fix can be found on Github: https://github.com/llvm/llvm-project/issues/54487
Reviewed By: aganea
Differential Revision: https://reviews.llvm.org/D122372
When two local symbols (think: file-scope static functions, or functions in
unnamed namespaces) with the same name in two different translation units
both needed thunks, ld64.lld previously created external thunks for both
of them. These thunks ended up with the same name, leading to a duplicate
symbol error for the thunk symbols.
Instead, give thunks for local symbols local visibility.
(Hitting this requires a jump to a local symbol from over 128 MiB away.
It's unlikely that a single .o file is 128 MiB large, but with ICF
you can end up with a situation where the local symbol is ICF'd with
a symbol in a separate translation unit. And that can introduce a
large enough jump to require a thunk.)
Fixes PR54599.
Differential Revision: https://reviews.llvm.org/D122624
D86142 introduced --fortran-common and defaulted it to true (matching GNU ld
but deviates from gold/macOS ld64). The default state was motivated by transparently
supporting some FORTRAN 77 programs (Fortran 90 deprecated common blocks).
Now I think it again. I believe we made a mistake to change the default:
* this is a weird and legacy rule, though the breakage is very small
* --fortran-common introduced complexity to parallel symbol resolution and will slow down it
* --fortran-common more likely causes issues when users mix COMMON and
STB_GLOBAL definitions (see https://github.com/llvm/llvm-project/issues/48570 and
https://maskray.me/blog/2022-02-06-all-about-common-symbols).
I have seen several issues in our internal projects and Android.
On the other hand, --no-fortran-common is safer since
COMMON/STB_GLOBAL have the same semantics related to archive member extraction.
Therefore I think we should switch back, not punishing the common uage.
A platform wanting --fortran-common can implement ld.lld as a shell script
wrapper around `lld -flavor gnu --fortran-common "$@"`.
Reviewed By: ikudrin, sfertile
Differential Revision: https://reviews.llvm.org/D122450
Two code paths may reach the EHFrame case in SectionBase::getOffset:
* .eh_frame reference
* relocation copy for --emit-relocs
The first may be used by clang_rt.crtbegin.o and GCC crtbeginT.o to get the
start address of the output .eh_frame. The relocation has an offset of 0 or
(x86-64 PC-relative leaq for clang_rt.crtbegin.o) -4. The current code just
returns `offset`, which handles this case well.
The second is related to InputSection::copyRelocations on .eh_frame (used by
--emit-relocs). .eh_frame pieces may be dropped due to GC/ICF, so we should
convert the input offset to the output offset. Use the same way as
MergeInputSection with a special case handling outSecOff==-1 for an invalid
piece (see eh-frame-marker.s).
This exposes an issue in mips64-eh-abs-reloc.s that we don't reliably
handle anyway. Just add --no-check-dynamic-relocations to paper over it.
Differential Revision: https://reviews.llvm.org/D122459
addSectionSymbols suppresses the STT_SECTION symbol if the first input section
is non-SHF_MERGE synthetic. This is incorrect when the first input section is synthetic
while a non-synthetic input section exists:
* `.bss : { *(COMMON) *(.bss) }`
(abc388ed3c regressed the case because
COMMON symbols precede .bss in the absence of a linker script)
* Place a synthetic section in another section: `.data : { *(.got) *(.data) }`
For `%t/a1` in the new test emit-relocs-synthetic.s, ld.lld produces incorrect
relocations with symbol index 0.
```
0000000000000000 <_start>:
0: 8b 05 33 00 00 00 movl 51(%rip), %eax # 0x39 <bss>
0000000000000002: R_X86_64_PC32 *ABS*+0xd
6: 8b 05 1c 00 00 00 movl 28(%rip), %eax # 0x28 <common>
0000000000000008: R_X86_64_PC32 common-0x4
c: 8b 05 06 00 00 00 movl 6(%rip), %eax # 0x18
000000000000000e: R_X86_64_GOTPCRELX *ABS*+0x4
```
Fix the issue by checking every input section.
Reviewed By: ikudrin
Differential Revision: https://reviews.llvm.org/D122463
.eh_frame pieces may be dropped due to GC/ICF. When --emit-relocs adds
relocations against .eh_frame, the offsets need to be adjusted. Use the same
way as MergeInputSection with a special case handling outSecOff==-1 for an
invalid piece (see eh-frame-marker.s).
This exposes an issue in mips64-eh-abs-reloc.s that we don't reliably
handle anyway. Just add --no-check-dynamic-relocations to paper over it.
Original patch by Ayrton Muñoz
Differential Revision: https://reviews.llvm.org/D122459
CLANG_TOOLS_DIR holds the the current bin/ directory, maybe with a %(build_mode)
placeholder. It is used to add the just-built binaries to $PATH for lit tests.
In most cases it equals LLVM_TOOLS_DIR, which is used for the same purpose.
But for a standalone build of clang, CLANG_TOOLS_DIR points at the build tree
and LLVM_TOOLS_DIR points at the provided LLVM binaries.
Currently CLANG_TOOLS_DIR is set in clang/test/, clang-tools-extra/test/, and
other things always built with clang. This is a few cryptic lines of CMake in
each place. Meanwhile LLVM_TOOLS_DIR is provided by configure_site_lit_cfg().
This patch moves CLANG_TOOLS_DIR to configure_site_lit_cfg() and renames it:
- there's nothing clang-specific about the value
- it will also replace LLD_TOOLS_DIR, LLDB_TOOLS_DIR etc (not in this patch)
It also defines CURRENT_LIBS_DIR. While I removed the last usage of
CLANG_LIBS_DIR in e4cab4e24d, there are LLD_LIBS_DIR usages etc that
may be live, and I'd like to mechanically update them in a followup patch.
Differential Revision: https://reviews.llvm.org/D121763
--build-id was introduced as "approximation of true uniqueness across all
binaries that might be used by overlapping sets of people". It does not require
the some resistance mentioned below. In practice, people just use --build-id=md5
for 16-byte build ID and --build-id=sha1 for 20-byte build ID.
BLAKE3 has 256-bit key length, which provides 128-bit security against
(second-)preimage, collision, and differentiability attacks. Its portable
implementation is fast. It additionally provides Arm Neon/AVX2/AVX-512. Just
implement --build-id={md5,sha1} with truncated BLAKE3.
Linking clang 14 RelWithDebInfo with --threads=8 on a Skylake CPU:
* 1.13x as fast with --build-id=md5
* 1.15x as fast with --build-id=sha1
--threads=4 on Apple m1:
* 1.25x as fast with --build-id=md5
* 1.17x as fast with --build-id=sha1
Reviewed By: ikudrin
Differential Revision: https://reviews.llvm.org/D121531
This is the orignal patch + a check that LLVM_BUILD_EXAMPLES is enabled before
adding a dependency on the 'Bye' example pass.
Original summary:
Add cli options for new passmanager plugin support to lld.
Currently it is not possible to load dynamic NewPM plugins with lld. This is an
incremental update to D76866. While that patch only added cli options for
llvm-lto2, this adds them for lld as well. This is especially useful for running
dynamic plugins on the linux kernel with LTO.
Reviewed By: MaskRay
Differential Revision: https://reviews.llvm.org/D120490
Add cli options for new passmanager plugin support to lld.
Currently it is not possible to load dynamic NewPM plugins with lld. This is an
incremental update to D76866. While that patch only added cli options for
llvm-lto2, this adds them for lld as well. This is especially useful for running
dynamic plugins on the linux kernel with LTO.
Reviewed By: MaskRay
Differential Revision: https://reviews.llvm.org/D120490
`config->priorities` has been used to hold the intermediate state during the construction of the order in which sections should be laid out. This is not a good place to hold this state since the intermediate state is not a "configuration" for LLD. It should be encapsulated in a class for building a mapping from section to priority (which I created in this diff as the `PriorityBuilder` class).
The same thing is being done for `config->callGraphProfile`.
Reviewed By: #lld-macho, int3
Differential Revision: https://reviews.llvm.org/D122156
Code object version 5 will use the same EFlags as version 4, so we only need to add an additional case
Differential Revision: https://reviews.llvm.org/D122190
Update DataInCode's calculation of `endAddr` to use `getSize()` instead
of `getFileSize()` -- while in practice they're the same for
non-zerofill sections (which code sections are), we still should treat
address sizes / offsets as distinct from file sizes / offsets.
In programs that don't otherwise depend on `__tls_base` it won't
be marked as live. However this symbol is used internally in
a couple of places do we need to mark it as live explictily in
those places.
Fixes: #54386
Differential Revision: https://reviews.llvm.org/D121931
* Test the case where a symbol is sometimes linkonce_odr and sometimes weak_odr
* Test the visibility of the symbols at the IR level, after the internalize
stage of LTO is done. (Previously we only checked the visibility of
symbols in the final output binary.)
Reviewed By: modimo
Differential Revision: https://reviews.llvm.org/D121428
https://discourse.llvm.org/t/parallel-input-file-parsing/60164
initializeSymbols currently sets Defined::section and handles non-prevailing
COMDAT groups. Move the code to the parallel postParse to reduce work from the
single-threading code path and make parallel section initialization infeasible.
Postpone reporting duplicate symbol errors so that the messages have the
section information. (`Defined::section` is assigned in postParse and another
thread may not have the information).
* duplicated-synthetic-sym.s: BinaryFile duplicate definition (very rare) now
has no section information
* comdat-binding: `%t/w.o %t/g.o` leads to an undesired undefined symbol. This
is not ideal but we report a diagnostic to inform that this is unsupported.
(See release note)
* comdat-discarded-lazy.s: %tdef.o is unextracted. The new behavior (discarded
section error) makes more sense
* i386-comdat.s: switched to a better approach working around
.gnu.linkonce.t.__x86.get_pc_thunk.bx in glibc<2.32 for x86-32.
Drop the ancient no-longer-relevant workaround for __i686.get_pc_thunk.bx
Depends on D120640
Differential Revision: https://reviews.llvm.org/D120626
In particular we use these in two places:
1. When building PIC code we no longer need to combine output segments
into a single segment that can be initialized at `__memory_base`.
Instead each segment can encode its offset from `__memory_base` in
its initializer. e.g.
```
(i32.add (global.get __memory_base) (i32.const offset)
```
2. When building PIC code we no longer need to relocation internalized
global addresses. We can just initialize them with their correct
offsets.
Differential Revision: https://reviews.llvm.org/D121420
Since Mach-O has a two-level namespace (unlike ELF), we can usually set
this property to true.
(I believe this setting is only available in the new LTO backend, so I
can't really use ld64 / libLTO's behavior as a reference here... I'm
just doing what I think is correct.)
See {D119294} for the work done to calculate the `interposable` used in
this diff.
Reviewed By: MaskRay
Differential Revision: https://reviews.llvm.org/D119506
This is a new mode for handling unresolved symbols that allows all
symbols to be imported in the same that they would be in the case of
`-fpie` or `-shared`, but generting an otherwise fixed/non-relocatable
binary.
Code linked in this way should still be compiled with `-fPIC` so that
data symbols can be resolved via imports.
This essentially allows the building of static binaries that have
dynamic imports. See:
https://github.com/emscripten-core/emscripten/issues/12682
As with other uses of the experimental dynamic linking ABI, this
behaviour will produce a warning unless run with `--experimental-pic`.
Differential Revision: https://reviews.llvm.org/D91577
All references to interposable symbols can be redirected at runtime to
point to a different symbol definition (with the same name). For
example, if both dylib A and B define symbol _foo, and we load A before
B at runtime, then all references to _foo within dylib B will point to
the definition in dylib A.
ld64 makes all extern symbols interposable when linking with
`-flat_namespace`.
TODO 1: Support `-interposable` and `-interposable_list`, which should
just be a matter of parsing those CLI flags and setting the
`Defined::interposable` bit.
TODO 2: Set Reloc::FinalDefinitionInLinkageUnit correctly with this info
(we are currently not setting it at all, so we're erring on the
conservative side, but we should help the LTO backend generate more
optimal code.)
Reviewed By: modimo, MaskRay
Differential Revision: https://reviews.llvm.org/D119294
Previously, we only allowed this for DylibSymbols. However, in order to
properly support `-flat_namespace` as well as `-interposable`, we need
to allow this for Defined symbols too. Therefore we hoist the
`lazyBindOffset` and the `stubsHelperIndex` into the parent Symbol
class.
The actual change to support interposition under `-flat_namespace` is in
{D119294}; the NFC changes here have been split out for easier review.
Perf regression isn't stat sig on my 3.2 GHz 16-Core Intel Xeon W linking
chromium_framework:
base diff difference (95% CI)
sys_time 1.227 ± 0.021 1.234 ± 0.031 [ -0.3% .. +1.5%]
user_time 3.665 ± 0.036 3.674 ± 0.035 [ -0.2% .. +0.7%]
wall_time 4.596 ± 0.055 4.609 ± 0.064 [ -0.3% .. +0.9%]
samples 34 47
Max RSS regression is barely stat sig:
base diff difference (95% CI)
time 1003664356.324 ± 15404053.912 1010380403.613 ± 10578309.455 [ +0.0% .. +1.3%]
samples 37 31
Reviewed By: modimo
Differential Revision: https://reviews.llvm.org/D121351
This reverts commit e049a87f04.
That commit breaks the build with errors of the form:
/usr/local/google/home/saugustine/llvm/llvm-project/lld/MachO/ExportTrie.cpp:148:11: error: definition of implicitly declared destructor
TrieNode::~TrieNode() {
The code can be used in multi-threads and the allocator is not thread safe.
fixes PR/54378
Reviewed By: int3, #lld-macho
Differential Revision: https://reviews.llvm.org/D121638
https://discourse.llvm.org/t/parallel-input-file-parsing/60164
initializeSymbols currently sets Defined::section and handles non-prevailing
COMDAT groups. Move the code to the parallel postParse to reduce work from the
single-threading code path and make parallel section initialization infeasible.
Postpone reporting duplicate symbol errors so that the messages have the
section information. (`Defined::section` is assigned in postParse and another
thread may not have the information).
* duplicated-synthetic-sym.s: BinaryFile duplicate definition (very rare) now
has no section information
* comdat-binding: `%t/w.o %t/g.o` leads to an undesired undefined symbol. This
is not ideal but we report a diagnostic to inform that this is unsupported.
(See release note)
* comdat-discarded-lazy.s: %tdef.o is unextracted. The new behavior (discarded
section error) makes more sense
Depends on D120640
Reviewed By: peter.smith
Differential Revision: https://reviews.llvm.org/D120626
In GCC -fgnu-unique output, STB_GNU_UNIQUE symbols are always defined relative
to a section in a COMDAT group. Currently `other` cannot be STB_GNU_UNIQUE for
valid input, so this patch is NFC.
If we switch to the model that ignores COMDAT resolution when performing symbol
resolution (D120626), this will fix bogus `relocation refers to a symbol in a
discarded section` errors when mixing -fno-gnu-unique objects with -fgnu-unique
objects.
Differential Revision: https://reviews.llvm.org/D120640
This change continues to lay the ground work for supporting extended
const expressions in the linker.
The included test covers object file reading and writing and the YAML
representation.
Differential Revision: https://reviews.llvm.org/D121349
Previously, the test checked for a "undefined symbol" error
(instead of the "could not open std*.lib" which would happen without
the flag).
Instead, use /entry: so that the link succeeds.
No behavior change, but maybe makes the test a bit easier to understand.
Differential Revision: https://reviews.llvm.org/D121553
This clarifies that this is an LLVM specific variable and avoids
potential conflicts with other projects.
Differential Revision: https://reviews.llvm.org/D119918
GNU ld 2.38 added -z pack-relative-relocs which is similar to
--pack-dyn-relocs=relr but synthesizes the `GLIBC_ABI_DT_RELR` version
dependency if a shared object named `libc.so.*` has a `GLIBC_2.*` version
dependency.
This is used to implement the (as some glibc folks call) version lockout
mechanism. Add this option, because glibc does not want to support
--pack-dyn-relocs=relr which does not add `GLIBC_ABI_DT_RELR`.
See https://maskray.me/blog/2021-10-31-relative-relocations-and-relr for
detail.
Close https://github.com/llvm/llvm-project/issues/53775
Reviewed By: peter.smith
Differential Revision: https://reviews.llvm.org/D120701
Previously, we aligned every cstring to 16 bytes as a temporary hack to
deal with https://github.com/llvm/llvm-project/issues/50135. However, it
was highly wasteful in terms of binary size.
To recap, in contrast to ELF, which puts strings that need different
alignments into different sections, `clang`'s Mach-O backend puts them
all in one section. Strings that need to be aligned have the .p2align
directive emitted before them, which simply translates into zero padding
in the object file. In other words, we have to infer the alignment of
the cstrings from their addresses.
We differ slightly from ld64 in how we've chosen to align these
cstrings. Both LLD and ld64 preserve the number of trailing zeros in
each cstring's address in the input object files. When deduplicating
identical cstrings, both linkers pick the cstring whose address has more
trailing zeros, and preserve the alignment of that address in the final
binary. However, ld64 goes a step further and also preserves the offset
of the cstring from the last section-aligned address. I.e. if a cstring
is at offset 18 in the input, with a section alignment of 16, then both
LLD and ld64 will ensure the final address is 2-byte aligned (since
`18 == 16 + 2`). But ld64 will also ensure that the final address is of
the form 16 * k + 2 for some k (which implies 2-byte alignment).
Note that ld64's heuristic means that a dedup'ed cstring's final address is
dependent on the order of the input object files. E.g. if in addition to the
cstring at offset 18 above, we have a duplicate one in another file with a
`.cstring` section alignment of 2 and an offset of zero, then ld64 will pick
the cstring from the object file earlier on the command line (since both have
the same number of trailing zeros in their address). So the final cstring may
either be at some address `16 * k + 2` or at some address `2 * k`.
I've opted not to follow this behavior primarily for implementation
simplicity, and secondarily to save a few more bytes. It's not clear to me
that preserving the section alignment + offset is ever necessary, and there
are many cases that are clearly redundant. In particular, if an x86_64 object
file contains some strings that are accessed via SIMD instructions, then the
.cstring section in the object file will be 16-byte-aligned (since SIMD
requires its operand addresses to be 16-byte aligned). However, there will
typically also be other cstrings in the same file that aren't used via SIMD
and don't need this alignment. They will be emitted at some arbitrary address
`A`, but ld64 will treat them as being 16-byte aligned with an offset of
`16 % A`.
I have verified that the two repros in https://github.com/llvm/llvm-project/issues/50135
work well with the new alignment behavior.
Fixes https://github.com/llvm/llvm-project/issues/54036.
Reviewed By: #lld-macho, oontvoo
Differential Revision: https://reviews.llvm.org/D121342
Combined with the previous change, lld executable is ~2K smaller and some code
paths using InputSection::getParent are more efficient.
The fragmented headers lead to a design limitation that OutputSection has to be
incomplete, so we cannot use static_cast.
Add an OutputDesc class inheriting from SectionCommand. An OutputDesc wraps an
OutputSection. This change allows InputSection::getParent to be inlined.
Differential Revision: https://reviews.llvm.org/D120650
ld64 breaks down `__objc_classrefs` on a per-word level and deduplicates
them. This greatly reduces the number of bind entries emitted (and
therefore the amount of work `dyld` has to do at runtime). For
chromium_framework, this change to LLD cuts the number of (non-lazy)
binds from 912 to 190, getting us to parity with ld64 in this aspect.
Reviewed By: #lld-macho, thakis
Differential Revision: https://reviews.llvm.org/D121053
`__cfstring` has embedded addends that foil ICF's hashing / equality
checks. (We can ignore embedded addends when doing ICF because the same
information gets recorded in our Reloc structs.) Therefore, in order to
properly dedup CFStrings, we create a mutable copy of the CFString and
zero out the embedded addends before performing any hashing / equality
checks.
(We did in fact have a partial implementation of CFString deduplication
already. However, it only worked when the cstrings they point to are at
identical offsets in their object files.)
I anticipate this approach can be extended to other similar
statically-allocated struct sections in the future.
In addition, we previously treated all references with differing addends
as unequal. This is not true when the references are to literals:
different addends may point to the same literal in the output binary. In
particular, `__cfstring` has such references to `__cstring`. I've
adjusted ICF's `equalsConstant` logic accordingly, and I've added a few
more tests to make sure the addend-comparison code path is adequately
covered.
Fixes https://github.com/llvm/llvm-project/issues/51281.
Reviewed By: #lld-macho, Roger
Differential Revision: https://reviews.llvm.org/D120137
... from a `uint64_t` to a `uint32_t`. (LLD-ELF uses a `uint32_t` too.)
About a 1.7% reduction in peak RSS when linking chromium_framework on my
3.2 GHz 16-Core Intel Xeon W Mac Pro, and no stat sig change in wall
time.
</Users/jezng/test2.sh ["before"]> </Users/jezng/test2.sh ["after"]> difference (95% CI)
RSS 1003036672.000 ± 9891065.259 985539505.231 ± 10272748.749 [ -2.3% .. -1.2%]
samples 27 26
base diff difference (95% CI)
sys_time 1.277 ± 0.023 1.277 ± 0.024 [ -0.9% .. +0.9%]
user_time 6.682 ± 0.046 6.598 ± 0.043 [ -1.6% .. -0.9%]
wall_time 5.904 ± 0.062 5.895 ± 0.063 [ -0.7% .. +0.4%]
samples 46 28
No appreciable change (~0.01%) in number of `equals` comparisons either:
Before:
ld64.lld: ICF needed 8 iterations
ld64.lld: equalsConstant() called 701643 times
ld64.lld: equalsVariable() called 3438526 times
After:
ld64.lld: ICF needed 8 iterations
ld64.lld: equalsConstant() called 701729 times
ld64.lld: equalsVariable() called 3438526 times
Reviewed By: #lld-macho, MaskRay, thakis
Differential Revision: https://reviews.llvm.org/D121052
The existing hashing of stubsHelperIndex has mostly been a no-op* for
some time now (ever since we made ICF run before dylib symbols get their
stubs indices assigned). I guess we could consider hashing the name +
filename of the DylibSymbol instead, but I'm not sure the overhead's
worth it... moreover, LLD/ELF only hashes their Defined symbols as well.
*: Technically it does change the hash value since stubsHelperIndex is
initialized to `UINT32_MAX` by default. But since all stubsHelperIndex
values are the same at when ICF runs, they don't add any useful
information to the hash.
This is debug code that is disabled by default. It'll provide a easy way
to figure out the impact (if any) of tweaking ICF's hashing algorithm
(since a poor quality hash will result in many more `equals*` calls).
Reviewed By: #lld-macho, oontvoo
Differential Revision: https://reviews.llvm.org/D121051
ObjFile::parse combines symbol initialization and resolution. Many tasks
unrelated to symbol resolution can be postponed and parallelized. This patch
extracts local symbol initialization and parallelizes it.
Technically the new function initializeLocalSymbols can be merged into
ObjFile::postParse, but functions like getSrcMsg may access the
uninitialized (all nullptr) local part of InputFile::symbols.
Linking chrome: 1.02x as fast with glibc malloc, 1.04x as fast with mimalloc
Depends on f456c3ae3f and D119908
Reviewed By: ikudrin
Differential Revision: https://reviews.llvm.org/D119909
addWrappedSymbols may trigger archive extraction: split stack implementation
uses --wrap=pthread_create, which extracts libgcc.a(generic-morestack-thread.o).
This fixes the regression caused by 09602d3b47 by
making the invariant satisfied: no more non-compileBitcodeFiles object file is
produced at postParseObjectFile.
LLD (and ld64) emits uppercase hex addresses in the mapfile. The
map-file.s test passes right now because the addresses we emit happen
not to include any alphabets, but that can easily change.
I noticed this while dealing with
https://github.com/llvm/llvm-project/issues/54184.
Reviewed By: #lld-macho, thakis
Differential Revision: https://reviews.llvm.org/D120941
Now all the tests that cover symbol resolution / precedence have
"resolution" in their filename.
I also added a couple of extra comments.
Reviewed By: #lld-macho, thakis
Differential Revision: https://reviews.llvm.org/D120938
If we fix https://github.com/llvm/llvm-project/issues/54184, we will end
up including libSystem in every %lld invocation, which would break
tapi-link.s as it assumes that libSystem isn't directly linked (instead
it goes through libReexportSystem).
Let's remove this unnecessary coupling, as well as use `split-file`
instead of having a separate file under `Inputs`.
Reviewed By: #lld-macho, oontvoo
Differential Revision: https://reviews.llvm.org/D120939
Per discussion on
https://reviews.llvm.org/D59709#inline-1148734, this seems like the
right course of action. `canBeOmittedFromSymbolTable()` subsumes and
generalizes the previous logic. In addition to handling `linkonce_odr`
`unnamed_addr` globals, we now also internalize `linkonce_odr` +
`local_unnamed_addr` constants.
Reviewed By: tejohnson
Differential Revision: https://reviews.llvm.org/D120173
Previously, we were using a syslibroot that pointed to macos while
linking against arch arm64_32, which didn't really make sense. It isn't
currently an issue, but will be if we add the `-lSystem` as part of
dealing with https://github.com/llvm/llvm-project/issues/54184.
If we fix https://github.com/llvm/llvm-project/issues/54184, the
`dyld_stub_binder` symbol will get included in every output dylib. This
would cause the addresses of the other symbols to shift, breaking the
test as it currently stands. Let's make the test more flexible.
Reviewed By: lgrey
Differential Revision: https://reviews.llvm.org/D120940
So far, we sort all discardable sections at the end, with only some
extra logic to make sure that the .reloc section is at the start
of that group of sections. But if there are other discardable
sections, other than .reloc, they must also be ordered before
.debug_* sections, to avoid leaving gaps if the executable is
stripped.
(Stripping executables doesn't remove all discardable sections,
only the ones named .debug_*).
Rust binaries seem to include a .rmeta section, which is marked
discardable. This fixes stripping such binaries if built with
dwarf debug info included.
This fixes issues observed in MSYS2 in
https://github.com/msys2/MINGW-packages/pull/10555.
Differential Revision: https://reviews.llvm.org/D120805
Show the name of of the archive in the error message as well as the name
of the object within it.
Differential Revision: https://reviews.llvm.org/D120689
This does tail merging (and deduplication) of the strings.
On a statically linked clang.exe, this shrinks the ~17 MB string
table by around 0.5 MB. This adds ~160 ms to the linking time
which originally was around 950 ms.
For cases where `-debug:symtab` or `-debug:dwarf` isn't set, the
string table is only used for long section names, where this
shouldn't make any difference at all.
Differential Revision: https://reviews.llvm.org/D120677
The previous code used an unbounded sprintf, which in theory can
overflow, writing either the null terminator or the last digits
into the next struct member.
In practice, in LLD, all long section names are written sequentially
first at the start of the string table, followed by all the long
symbol names. Due to this, even if the total string table would
end up large, the long section names have fairly short offsets,
which is why this hasn't been an issue in practice.
I don't think it's worth trying to write a test that produces an
executable with enough long section names to make the section names
themselves exceed 10^6 bytes, which is currently necessary to trigger
faults with the previous form.
Differential Revision: https://reviews.llvm.org/D120676
https://github.com/ClangBuiltLinux/linux/issues/1606
When GNU_PROPERTY_X86_FEATURE_1_IBT is enabled, ld.lld will create .plt output
section even if there is no PLT entry. Fix this by implementing
IBTPltSection::isNeeded instead of using the default code path (which always
returns true).
Reviewed By: MaskRay
Differential Revision: https://reviews.llvm.org/D120600
Daniel Bertalan