This was recently introduced in GNU linkers and it makes sense for
ld.lld to have the same support. This implementation omits checking if
the input string is valid json to reduce size bloat.
Differential Revision: https://reviews.llvm.org/D131439
D91426 makes .got possibly empty while needed. If .got and .data have the same
address, and .got's content is written after .data, the first word of .data will
be corrupted.
The bug is not testable without D131247.
Linux Standard Base Core Specification says that CIE/FDE is padded to an
addressing unit size boundary, but in practice GNU assembler/LLVM integrated
assembler pad FDE/CIE to 4 and the last FDE to 8 on 64-bit systems.
In addition, GNU ld doesn't pad to 8, so let's drop excess padding, too.
If the assembler provides aligned pieces, the output will be aligned.
Noticed .eh_frame size reduction for 3 executables: 0.3% (chrome), 4.7% (clang),
7.6% (an internal program).
This simplifies code, removes a read32 (for id==0 check), and makes it feasible
to combine some operations in EhInputSection::split and EhFrameSection::addRecords.
Mostly NFC, but fixes "Relocation not in any piece" assertion failure in an
erroneous case when a relocation offset precedes all CIE/FDE pices.
inputSections temporarily contains EhInputSection objects mainly for
combineEhSections. Place EhInputSection objects into a new vector
ehInputSections instead of inputSections.
llvm::sort is beneficial even when we use the iterator-based overload,
since it can optionally shuffle the elements (to detect
non-determinism). However llvm::sort is not usable everywhere, for
example, in compiler-rt.
Reviewed By: nhaehnle
Differential Revision: https://reviews.llvm.org/D130406
Patch created by running:
rg -l parallelForEachN | xargs sed -i '' -c 's/parallelForEachN/parallelFor/'
No behavior change.
Differential Revision: https://reviews.llvm.org/D128140
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
Linux kernel arch/arm64/kernel/vmlinux.lds.S discards .dynsym . D123985 triggers
a spurious assertion failure. Detect the case with
`!mainPart->dynSymTab->getParent()`.
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
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.
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
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
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
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
In many call sites we know uncompression cannot happen (non-SHF_ALLOC, or the
data (even if compressed) must have been uncompressed by a previous pass).
Prefer rawData in these cases. data() increases code size and prevents
optimization on rawData.
D118577: the 0.1~1.1% .strtab size reduction does not justify the 3~6%
link time increase. Just remove it even for -O2. release/14.x
has D118577 and the release note mentioned that this may be removed.
Fix https://github.com/ClangBuiltLinux/linux/issues/1578
caused by D118577 (empty string not in stringMap).
https://maskray.me/blog/2022-02-06-all-about-common-symbols#no-define-common
In GNU ld, -dc only affects -r links and causes COMMON symbols to be allocated.
--no-define-common is defined to make COMMON symbols undefined for -shared.
AIUI --no-define-common is a workaround around glibc 2.1 time and not really useful.
gold confuses --define-common with -d/FORCE_COMMON_ALLOCATION and implements
--define-common with -d semantics. Its --no-define-common is incompatible with
GNU ld.
In ld.lld, b2a23cf3c0 fixed the default -r
behavior for COMMON symbols but ported the incompatible gold
--[no-]define-common. To the best of my knowledge, no project uses -dp
--[no-]define-common. So just remove these options.
-d/-dc are used by the following projects:
* grub grub-core/genmod.sh.in uses -Wl,-r,-d (https://lists.gnu.org/archive/html/grub-devel/2022-02/msg00088.html)
* FreeBSD crunchgen uses -Wl,-dc (https://reviews.freebsd.org/D34215)
A no-op implementation works for them. Only when a program inspects relocatable
output by itself and does not recognize COMMON symbols, there may be a problem.
This is an extremely unlikely case.
Reviewed By: peter.smith
Differential Revision: https://reviews.llvm.org/D119108
The deduplication requires a DenseMap of the same size of the local part of
.strtab . I optimized it in e205445434 but it is
still quite slow.
For Release build of clang, deduplication makes .strtab 1.1% smaller and makes the link 3% slower.
For chrome, deduplication makes .strtab 0.1% smaller and makes the link 6% slower.
I suggest that we only perform the optimization with -O2 (default is -O1).
Not deduplicating local symbol names will simplify parallel symbol table write.
Reviewed By: peter.smith
Differential Revision: https://reviews.llvm.org/D118577
* `RelocationBaseSection::addReloc` increases `numRelativeRelocs`, which
duplicates the work done by RelocationSection<ELFT>::writeTo.
* --pack-dyn-relocs=android has inappropropriate DT_RELACOUNT.
AndroidPackedRelocationSection does not necessarily place relative relocations
in the front and DT_RELACOUNT might cause semantics error (though our
implementation doesn't and Android bionic doesn't use DT_RELACOUNT anyway.)
Move `llvm::partition` to a new function `partitionRels` and compute
`numRelativeRelocs` there. Now `RelocationBaseSection::addReloc` is trivial and
can be moved to the header to enable inlining.
The rest of DynamicReloc and `-z combreloc` handling is moved to the
non-template `RelocationBaseSection::computeRels` to decrease code size. My
x86-64 lld executable is 44+KiB smaller.
While here, rename `sort` to `combreloc`.
After the D33630 fallout was properly fixed by a4c5db30be.
Tested by D37462/D44986 tests, the new --no-rosegment test in build-id.s, and a few --rosegment/--no-rosegment programs.
Move all variables at file-scope or function-static-scope into a hosting structure (lld::CommonLinkerContext) that lives at lldMain()-scope. Drivers will inherit from this structure and add their own global state, in the same way as for the existing COFFLinkerContext.
See discussion in https://lists.llvm.org/pipermail/llvm-dev/2021-June/151184.html
Differential Revision: https://reviews.llvm.org/D108850
Sorting dynamic relocations is a bottleneck. Simplifying the comparator improves
performance. Linking clang is 4~5% faster with --threads=8.
This change may shuffle R_MIPS_REL32 for Mips and is a NFC for non-Mips.
db08df0570 does not work because part.relrDyn is
a unique_ptr and `reset` destroys the object which may still be referenced.
This commit uses the D114180 approach. Also improve the test to check that there
is no R_X86_64_RELATIVE.
We only support both TLSDESC and TLS GD for x86 so this is an x86-specific
problem. If both are used, only one R_X86_64_TLSDESC is produced and TLS GD
accesses will incorrectly reference R_X86_64_TLSDESC. Fix this by introducing
SymbolAux::tlsDescIdx.
Reviewed By: ikudrin
Differential Revision: https://reviews.llvm.org/D116900
Fangrui Song