Bitcode writer does not flush buffer until the end by default. This is
fine to small bitcode files. When -flto,--plugin-opt=emit-llvm,-gmlt are
used, the final bitcode file is large, for example, >8G. Keeping all
data in memory consumes a lot of memory.
This change allows bitcode writer flush data to disk early when buffered
data size is above some threshold. This is only enabled when lld emits
LLVM bitcode.
One issue to address is backpatching bitcode: subblock length, function
body indexes, meta data indexes need to backfill. If buffer can be
flushed partially, we introduced raw_fd_stream that supports
read/seek/write, and enables backpatching bitcode flushed in disk.
Reviewed-by: tejohnson, MaskRay
Differential Revision: https://reviews.llvm.org/D86905
I have noticed that a 374MiB powerpc64le 'ld.lld' requires 11 passes to link.
There is a ThunkSection (whose parent OutputSection is ".text" of 169MiB) with 12867 thunks.
Optimize the filename glob pattern matching in
LinkerScript::computeInputSections() and LinkerScript::shouldKeep().
Add InputFile::getNameForScript() which gets and if required caches the
Inputfile's name used for linker script matching. This avoids the
overhead of name creation that was in getFilename() in LinkerScript.cpp.
Add InputSectionDescription::matchesFile() and
SectionPattern::excludesFile() which perform the glob pattern matching
for an InputFile and make use of a cache of the previous result. As both
computeInputSections() and shouldKeep() process sections in order and
the sections of the same InputFile are contiguous, these single entry
caches can significantly speed up performance for more complex glob
patterns.
These changes have been seen to reduce link time with --gc-sections by
up to ~40% with linker scripts that contain KEEP filename glob patterns
such as "*crtbegin*.o".
Differential Revision: https://reviews.llvm.org/D87469
Add Thread Local Storage Local Exec support to LLD. This is to support PC Relative addressing of Local Exec.
The patch teaches LLD to handle:
```
paddi r9, r13, x1@tprel
```
The relocation is:
```
R_PPC_TPREL34
```
Reviewed By: NeHuang, MaskRay
Differential Revision: https://reviews.llvm.org/D86608
With https://reviews.llvm.org/D87537 we made it an error
to import or export a mutable global with the +mutable-globals
feature present. However the scan was of the entire symbol
table rather than just the imports or exports and the filter
didn't match exaclyt meaning the `__stack_pointer` (a mutable
global) was always triggering with error when the `--export-all`
flag was used.
This also revealed that we didn't have any test coverage for
the `--export-all` flag.
This change fixes the current breakage on the emscripten-releases
roller.
Differential Revision: https://reviews.llvm.org/D87663
`ELFFile<ELFT>` has many methods that take pointers,
though they assume that arguments are never null and
hence could take references instead.
This patch performs such clean-up.
Differential revision: https://reviews.llvm.org/D87385
The motivation for this is ld.lld --help targeting MinGW which
currently prints help for the ELF backend unless -m i386pe{,p} is
added. This confuses build systems that grep through linker help to
find supported flags.
This matches LD from Binutils which always prints help for MinGW
when configured to target it.
After this change, the backend can still be overridden to any
supported ELF/MinGW target by using correct -m <arch>.
Differential Revision: https://reviews.llvm.org/D87418
Prefer `errorOrWarn` to `fatal` for recoverable errors and graceful degradation
when --noinhibit-exec is specified.
Mention the destination symbol, otherwise the diagnostic is not really actionable.
Two errors are not tested but the patch does not intend to add the coverage.
Reviewed By: grimar
Differential Revision: https://reviews.llvm.org/D87486
Also add the +mutable-globals features in clang when
building with `-fPIC` since the linker will generate mutable
globals imports and exports in that case.
Differential Revision: https://reviews.llvm.org/D87537
This adds and optional ", immutable" to the end of a `.globaltype`
declaration. I would have prefered to match the `.wat` syntax
where immutable is the default and `mut` is the signifier for
mutable globals. Sadly changing the default would break backwards
compat with existing assembly in the wild so I think its best
to stick with this approach.
Differential Revision: https://reviews.llvm.org/D87515
This matches the changes made to handling of zlib done in 10b1b4a
where we rely on find_package and the imported target rather than
manually appending the library and include paths. The use of
LLVM_LIBXML2_ENABLED has been replaced by LLVM_ENABLE_LIBXML2
thus reducing the number of variables.
Differential Revision: https://reviews.llvm.org/D84563
MarkLive::scanEhFrameSection is used to retain personality/LSDA
functions when --gc-sections is enabled.
Improve its performance by only iterating over the .eh_frame relocations
that need to be resolved for an EhSectionPiece. This optimization makes
the same assumption as elsewhere in LLD that the .eh_frame relocations
are sorted by r_offset.
This appears to be a performance regression introduced in commit
e6c24299d2 (https://reviews.llvm.org/D59800).
This change has been seen to reduce link time by up to ~50%.
Differential Revision: https://reviews.llvm.org/D87245
LLVM has bumped the minimum required CMake version to 3.13.4, so this has become dead code.
Reviewed By: #libc, ldionne
Differential Revision: https://reviews.llvm.org/D87189
Currently we treat SHT_RISCV_ATTRIBUTES like a normal section and
concatenate all such input sections, yielding invalid output unless only
a single attributes section is present in the input. Instead, pick the
first as with SHT_ARM_ATTRIBUTES. We do not currently need to condition
our behaviour on the contents, unlike Arm. In future, we should both do
stricter validation of the input and merge all sections together to
ensure we have, for example, the full arch string requirement, but this
rudimentary implementation is good enough for most common cases.
Reviewed By: MaskRay
Differential Revision: https://reviews.llvm.org/D86309
Following 97febb1, fix the out-of-memory error associated with buffering the output
in-memory by writing to an allocated file with the minimum offset and running it
on ppc system-linux only.
Peer reviewed by: nemanjai
Following 0becc27ebf, `ppc64-pcrel-long-branch-error.s` fails in some
environments with out-of-memory errors associated with buffering the
output in-memory. Since the alternative of writing to an allocated file
is also known to cause problems, we will disable the test
unconditionally (pending a mechanism to disable the test selectively).
In this patch, a pc-rel based long branch thunk is added for the local
call protocol that caller and callee does not use TOC.
Reviewed By: sfertile, nemanjai
Differential Revision: https://reviews.llvm.org/D86706
Found such a relocation while testing some real world programs.
Reviewed By: #lld-macho, smeenai
Differential Revision: https://reviews.llvm.org/D86642
We can have GOT_LOAD relocations that reference `__dso_handle`.
However, our binding opcode encoder doesn't support binding to the DSOHandle
symbol. Instead of adding support for that, I decided it would be cleaner to
implement GOT_LOAD relaxation since `__dso_handle`'s location is always
statically known.
Reviewed By: #lld-macho, smeenai
Differential Revision: https://reviews.llvm.org/D86641
These opcodes tell dyld to coalesce the overridden weak dysyms to this
particular symbol definition.
Reviewed By: #lld-macho, smeenai
Differential Revision: https://reviews.llvm.org/D86575
Since there is no "weak lazy" lookup, function calls to weak symbols are
always non-lazily bound. We emit both regular non-lazy bindings as well
as weak bindings, in order that the weak bindings may overwrite the
non-lazy bindings if an appropriate symbol is found at runtime. However,
the bound addresses will still be written (non-lazily) into the
LazyPointerSection.
Reviewed By: #lld-macho, smeenai
Differential Revision: https://reviews.llvm.org/D86573
It seems to be failing on some Google Buildbots.
This diff also includes a minor fix for the install name of one of
libSystem's re-exports. I don't think it's the cause of the test
failure, though. The wrong install name just meant that the symbol
lookup failure would still happen, but it would have been caused by the
re-export not being found, instead of the arch failing to match.
Differential Revision: https://reviews.llvm.org/D86728
Binutils generated sections seem to be padded to a multiple of 16 bytes,
but the aux section definition contains the original, unpadded section
length.
The size check used for IMAGE_COMDAT_SELECT_SAME_SIZE previously
only checked the size of the section itself. When checking the
currently processed object file against the previously chosen
comdat section, we easily have access to the aux section definition
of the currently processed section, but we have to iterate over the
symbols of the previously selected object file to find the section
definition of the previously picked section. (We don't want to
inflate SectionChunk to carry more data, for something that is only
needed in corner cases.) Only do this when the mingw flag is set.
This fixes statically linking clang-built C++ object files against
libstdc++ built with GCC, if the object files contain e.g. typeinfo.
Differential Revision: https://reviews.llvm.org/D86659
This matches lld-link's own default.
Add a new command line option --no-dynamicbase for disabling it.
(Unfortunately, GNU ld doesn't yet have a matching --no-dynamicbase
option, as that's the default there.)
Differential Revision: https://reviews.llvm.org/D86654
Whilst reviewing some internal testing, I noticed a couple of holes in
coverage of mergeable sections containing symbols. This patch addresses
these holes:
1) Show that mid-piece symbols have their values updated properly when
pieces are merged.
2) Show the behaviour of symbols in mergeable pieces when --gc-sections
is enabled.
Reviewed by: grimar, MaskRay
Differential Revision: https://reviews.llvm.org/D86543
Previously, we were only emitting regular bindings to weak
dynamic symbols; this diff adds support for the weak bindings too, which
can overwrite the regular bindings at runtime. We also treat weak
defined global symbols similarly -- since they can also be interposed at
runtime, they need to be treated as potentially dynamic symbols.
Note that weak bindings differ from regular bindings in that they do not
specify the dylib to do the lookup in (i.e. weak symbol lookup happens
in a flat namespace.)
Differential Revision: https://reviews.llvm.org/D86572
Previously, the BindingEntry struct could only store bindings to offsets
within InputSections. Since the GOTSection and TLVPointerSections are
OutputSections, I handled those in a separate code path. However, this
makes it awkward to support weak bindings properly without code
duplication. This diff allows BindingEntries to point directly to
OutputSections, simplifying the upcoming weak binding implementation.
Along the way, I also converted a bunch of functions taking references
to symbols to take pointers instead. Given how much casting we do for
Symbol (especially in the upcoming weak binding diffs), it's cleaner
this way.
Differential Revision: https://reviews.llvm.org/D86571
Jianzhou Zhao