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
Fangrui Song