They are LLD-specific and by convention we enforce the double-dash form to avoid
collision with short options (e.g. weird `-c olor-diagnostics` interpretation in
GNU ld). They are rarely used and to the best of my investigation the undesired
single-dash forms are not used in the wild.
The last use of `REQUIRES: debug` was removed in 2013 in 72c5d3d7c in favor of
`REQUIRES: asserts`.
The last use of `REQUIRES: asserts` was removed in 2015 in 251b0e268 when the
old COFF linker was removed.
lld's test suite currently has no behavior difference with respect to
assertions or debug builds (and hasn't had it for 6 years). Let's keep it that
way :)
Differential Revision: https://reviews.llvm.org/D115941
This complements D111365.
D111365 did not demote isUsedInRegularObj lazy symbols just to work around
a --symbol-ordering-file diagnostic quirk.
The quirk was dropped by 00dd2d15a4,
so we can demote all lazy symbols now, not just the isUsedInRegularObj ones.
This reverts commit 640beb38e7.
That commit caused performance degradtion in Quicksilver test QS:sGPU and a functional test failure in (rocPRIM rocprim.device_segmented_radix_sort).
Reverting until we have a better solution to s_cselect_b64 codegen cleanup
Change-Id: Ibf8e397df94001f248fba609f072088a46abae08
Reviewed By: kzhuravl
Differential Revision: https://reviews.llvm.org/D115960
Change-Id: Id169459ce4dfffa857d5645a0af50b0063ce1105
lld-link used to consistently print all /verbose output to stdout, and that was
an intentional decision: https://reviews.llvm.org/rG4bce7bcc88f3https://reviews.llvm.org/rGe6e206d4b4814 added message() and log(),
and back then `log()` morally was just `if (verbose) message(...)`
and message() wrote to stdout.
So that change moved most /verbose-induced writes to outs() to
log(). Except for the one in printDiscardedMessage(), since
the check for `verbose` for that one is in the caller, in
Writer::createSections():
if (config->verbose)
sc->printDiscardedMessage();
Later, https://reviews.llvm.org/D41033 changed log() to write to
stderr. That moved lld-link from writing all its /verbose output
to stdout to writing almost all of its /verbose output to stderr --
except for printDiscardedMessage() output.
This change moves printDiscardedMessage() to call log() as well,
so that all /verbose output once again consistently goes to the same
stream.
Differential Revision: https://reviews.llvm.org/D116667
The diagnostic is emitted for an unextracted lazy symbol but suppressed for an
undefined symbol. Suppressing the diagnostic for unextracted lazy symbol
probably makes more sense because (a) an unextracted lazy symbol is quite
similar to an undefined symbol and (b) an unextracted lazy symbol is different
from "no such symbol".
In https://reviews.llvm.org/D86905, we introduce an optimization, when lld emits LLVM bitcode,
we allow bitcode writer flush data to disk early when buffered data size is above some threshold.
But when `--plugin-opt=emit-llvm` and `-o /dev/null` are used,
lld will trigger assertion `BytesRead >= 0 && static_cast<size_t>(BytesRead) == BytesFromDisk`.
When we write output to /dev/null, BytesRead is zero, but at this program point BytesFromDisk is always non-zero.
Reviewed By: stephan.yichao.zhao, MaskRay
Differential Revision: https://reviews.llvm.org/D112297
LLVM core library supports demangling other mangled symbols other than itanium,
such as D and Rust. LLD should use those demanglers in order to output pretty
demangled symbols on error messages.
Reviewed By: MaskRay, #lld-macho
Differential Revision: https://reviews.llvm.org/D116279
Similar to ELF 3a5fb57393.
* previously when a LazyObjFile was extracted, a new ObjFile/BitcodeFile was created; now the file is reused, just with `lazy` cleared
* avoid the confusing transfer of `symbols` from LazyObjFile to the new file
* simpler code, smaller executable (5200+ bytes smaller on x86-64)
* make eager parsing feasible (for parallel section/symbol table initialization)
Reviewed By: aganea, rnk
Differential Revision: https://reviews.llvm.org/D116434
In the post commit discussion of https://reviews.llvm.org/D116484 it was concluded that `--no-as-needed` should not be ignored. `--as-needed` stays ignored as it is already the default behaviour on COFF, which cannot be changed.
It’s still possible to build parts of the main llvm build (lld, clang etc) by symlinking them into llvm/tools.
Reviewed By: Ericson2314
Differential Revision: https://reviews.llvm.org/D116472
Extracted from D99484. My new plan is to start from the outside and work
inward.
Reviewed By: stephenneuendorffer
Differential Revision: https://reviews.llvm.org/D115568
Similar to D62188: a BitcodeFile's symbol table may be iterated twice, once in
--start-lib (lazy) state, and once in the non-lazy state. This patch
makes `parseLazy` save `symbols[i]` so that the non-lazy state does not need to
re-insert to the global symbol table. Avoiding a redundant `saver.save` may save
memory.
`Maximum resident set size (kbytes)` for a large --thinlto-index-only link:
* without the patch: 10164000
* with the patch: 10095716 (0.6% decrease)
Note: we can remove `saver.save` if `BitcodeCompiler::add` does not transfer the ownership
of `f.obj` in `checkError(ltoObj->add(std::move(f.obj), resols));`.
Reviewed By: tejohnson
Differential Revision: https://reviews.llvm.org/D116390
@tejohnson noticed that freeing MemoryBuffer instances right before
`lto->compile` can save RSS, likely because the memory can be reused by
LTO indexing (e.g. ThinLTO import/export lists).).
For ELFFileBase instances, symbol and section names are backed by MemoryBuffer,
so destroying MemoryBuffer would make some infrequent passes (parseSymbolVersion,
reportBackrefs) crash and make debugging difficult.
For a BitcodeFile, its content is completely unused, but destroying its
MemoryBuffer makes the buffer identifier inaccessible and may introduce
constraints for future changes.
This patch leverages madvise(MADV_DONTNEED) which achieves the major gain
without the latent issues.
`Maximum resident set size (kbytes): ` for a large --thinlto-index-only link:
* current behavior: 10146104KiB
* destroy MemoryBuffer instances: 8555240KiB
* madvise(MADV_DONTNEED) just bitcodeFiles and lazyBitcodeFiles: 8737372KiB
* madvise(MADV_DONTNEED) all MemoryBuffers: 8739796KiB (16% decrease)
Depends on D116366
Reviewed By: tejohnson
Differential Revision: https://reviews.llvm.org/D116367
This reverts commit e60d6dfd5a.
clang-ppc64le-rhel buildbot failed (https://lab.llvm.org/buildbot#builders/57/builds/13424):
tools/lld/MachO/CMakeFiles/lldMachO.dir/Symbols.cpp.o: In function `lld::demangle(llvm::StringRef, bool)':
Symbols.cpp:(.text._ZN3lld8demangleEN4llvm9StringRefEb[_ZN3lld8demangleEN4llvm9StringRefEb]+0x90): undefined reference to `llvm::demangle(std::string const&)'
LLVM core library supports demangling other mangled symbols other than itanium,
such as D and Rust. LLD should use those demanglers in order to output pretty
demangled symbols on error messages.
Reviewed By: MaskRay
Differential Revision: https://reviews.llvm.org/D116279
References from thread-local variable sections are treated as offsets
relative to the start of the thread-local data memory area, which is
initialized via copying all the TLV data sections (which are all
contiguous). If later data sections require a greater alignment than
earlier ones, the offsets of data within those sections won't be
guaranteed to aligned unless we normalize alignments. We therefore use
the largest alignment for all TLV data sections.
Reviewed By: #lld-macho, int3
Differential Revision: https://reviews.llvm.org/D116263
and remove associated make<XXX> calls.
gnuHash and sysvHash are unchanged, otherwise LinkerScript::discard would
destroy the objects which may be referenced by input section descriptions.
My x86-64 lld executable is 121+KiB smaller.
New deleteFallThruJmpInsn calls `make<JumpInstrMod>` which cannot be called
concurrently. Losing parallelism is unfortunate but we can think of a better
approach if parallelism here justifies itself.
Placeholders (-y and redirectSymbols removed versioned symbols) are very rare and
the check just makes symbol table iteration slower. Most iterations filter out
placeholders anyway, so this change just drops the filter behavior.
For "Add symbols to symtabs", we need to ensure that redirectSymbols sets
isUsedInRegularObj to false when making a symbol placeholder, to avoid an
assertion failure in SymbolTableSection<ELFT>::writeTo.
My .text is 2KiB smaller. The speed-up linking chrome is 0.x%.
"Process symbol versions" may take 2+% time.
"Redirect symbols" may take 0.6% time.
This change speeds up the two passes and makes `*sym.getVersionSuffix()
== '@'` in the `undefined reference` diagnostic cleaner.
Linking chrome (no debug info) and another large program is 1.5% faster.
For empty-ver2.s: the behavior now matches GNU ld, though I'd consider the input
invalid and the exact behavior does not matter.
This temporarily increases sizeof(SymbolUnion), but allows us to mov GOT/PLT/etc
index members outside Symbol in the future.
Then, we can make TLSDESC and TLSGD use different indexes and support mixed
TLSDESC and TLSGD (tested by x86-64-tlsdesc-gd-mixed.s).
Note: needsTlsGd and needsTlsGdToIe may optionally be combined.
Test updates are due to reordered GOT entries.
It is fairly easy to forget SectionBase::repl after ICF.
Let ICF rewrite a Defined symbol's `section` field to avoid references to
SectionBase::repl in subsequent passes. This slightly improves the --icf=none
performance due to less indirection (maybe for --icf={safe,all} as well if most
symbols are Defined).
With this change, there is only one reference to `repl` (--gdb-index D89751).
We can undo f4fb5fd752 (`Move Repl to SectionBase.`)
but move `repl` to `InputSection` instead.
Reviewed By: ikudrin
Differential Revision: https://reviews.llvm.org/D116093
Try to revert D113741 once again.
This also reverts 0ac75e82ff (D114705)
as it causes LLDB's lldb-api.lang/cpp/nsimport.TestCppNsImport.py test
failure w/o D113741.
This reverts commit f9607d45f3.
Differential Revision: https://reviews.llvm.org/D116225
I added `PPC32Got2Section` D62464 to support .got2 but did not implement .got2
in another output section.
PR52799 has a linker script placing .got2 in .rodata, which causes a null
pointer dereference because a MergeSyntheticSection's file is nullptr.
Add the support.
The new `lazy` state is the inverse of the previous `LazyObjFile::extracted`.
There are many advantages:
* previously when a LazyObjFile was extracted, a new ObjFile/BitcodeFile was created; now the file is reused, just with `lazy` cleared
* avoid the confusing transfer of `symbols` from LazyObjFile to the new file
* the `incompatible file:` diagnostic is unified with `is incompatible with`
* simpler code, smaller executable (6200+ bytes smaller on x86-64)
* make eager parsing feasible (for parallel section/symbol table initialization)
Currently the singleton `config` is assigned by `config = make<Configuration>()`
and (if `canExitEarly` is false) destroyed by `lld::freeArena`.
`make<Configuration>` allocates a stab with `malloc(4096)`. This both wastes
memory and bloats the executable (every type instantiates `BumpPtrAllocator`
which costs more than 1KiB code on x86-64).
(No need to worry about `clang::no_destroy`. Regular invocations (`canExitEarly`
is true) call `_Exit` via llvm::sys::Process::ExitNoCleanup.)
Reviewed By: lichray
Differential Revision: https://reviews.llvm.org/D116143
Older Go cmd/link used SHT_PROGBITS for .init_array .
Work around the lack of https://golang.org/cl/373734 for a while.
It does not generate .fini_array or .preinit_array
When linking a 1.2G output (nearly no debug info, 2846621 dynamic relocations) using `--threads=8`, I measured
```
9.131462 Total ExecuteLinker
1.449913 Total Write output file
1.445784 Total Write sections
0.657152 Write sections {"detail":".rela.dyn"}
```
This change decreases the .rela.dyn time to 0.25, leading to 4% speed up in the total time.
* The parallelSort is slow because of expensive r_sym/r_offset computation. Cache the values.
* The iteration is slow. Move r_sym/r_addend computation ahead of time and parallelize it.
With the change, the new encodeDynamicReloc is cheap (0.05s). So no need to parallelize it.
Reviewed By: ikudrin
Differential Revision: https://reviews.llvm.org/D115993
Summary: When disassembling, symbolize a branch target operand
to print a label instead of a real address.
Reviewed By: shchenz
Differential Revision: https://reviews.llvm.org/D114492
In 20a895c4be, we introduce `finalizeOptimizationRemarks()` to make sure we flush the diagnostic remarks file in case the linker doesn't call the global destructors before exiting.
In https://reviews.llvm.org/D73597, we add optimization remarks for removed functions for debugging or for detecting dead code.
But there is a case, if PreOptModuleHook or PostInternalizeModuleHook is defined (e.g. `--plugin-opt=emit-llvm` is passed to linker), we do not call `finalizeOptimizationRemarks()`, therefore we will get an incomplete optimization remarks file.
This patch make sure we flush the diagnostic remarks file when PreOptModuleHook or PostInternalizeModuleHook is defined.
Reviewed By: tejohnson, MaskRay
Differential Revision: https://reviews.llvm.org/D115417
writeSections is typically a bottleneck.
This was used to track down the following bottlenecks:
* Output section .rela.dyn (9115d75117)
* Output section .debug_str (3aae04c744)
* posix_fallocate is slow for Linux tmpfs: D115957
Reviewed By: ikudrin
Differential Revision: https://reviews.llvm.org/D115984
GCC's powerpc32 port predefines `PPC` as a macro in GNU C++ mode in some configurations (Linux,
FreeBSD, and some others. See `builtin_define_std ("PPC"); ` in gcc/config/rs6000).
```
% powerpc-linux-gnu-g++ -E -dM -xc++ /dev/null -o - | grep -w PPC
#define PPC 1
```
Fixes https://bugs.gentoo.org/829599
Reviewed By: thesamesam
Differential Revision: https://reviews.llvm.org/D116017
This decreases struct sizes and usually decreases the lld executable
size (39KiB for my x86-64 executable) (unless in some cases smaller
SmallVector leads to more inlining, e.g. StringTableBuilder).
For --gdb-index, there may be memory usage saving.
Fixes#52778.
Probably fixes Chromium crashing on startup on macOS 10.15 (and older) systems
when building with LTO, but I haven't verified that yet.
Differential Revision: https://reviews.llvm.org/D115949
Matches llvm's and clang's /test/CMakeLists.txt, makes it easier to
see in diffs which deps get added, and makes it easier to see if
a given dependency is present or not.
No behavior change.
Only called once. Moving to OutputSections.cpp can make it inlined.
finalizeInputSections can be very hot, especially in -O1 links with much debug info.
Everyone uses -l -L instead of the long option counterparts.
Make help messages attach to -L -l and (--reproduce) use them for response.txt
command line options.
Calling `Allocate` with 0 size (when .symtab is absent, e.g.
`invalid/mips-invalid-options-descriptor.test`) may return a nullptr, which will
crash with -fsanitize=null (the underlying `Allocate` function is
LLVM_ATTRIBUTE_RETURNS_NONNULL).
The SHT_GNU_version index is 16-bit, so the 32-bit value is a waste.
Technically non-default version index 0x7fff uses version index 0xffff,
but it is impossible in practice.
This change decreases sizeof(SymbolUnion) from 80 to 72 on ELF64 platforms.
Memory usage decreases by 1% when linking a large executable.
For large applications that write to map files, writing map files can take quite
a bit of time. Sorting the biggest contributors to link times, writing map files
ranks in at 2nd place, with load input files being the biggest contributor of
link times. Avoiding writing map files on the critical path (and having its own
thread) saves ~2-3 seconds when linking chromium framework on a 16-Core
Intel Xeon W.
```
base diff difference (95% CI)
sys_time 1.617 ± 0.034 1.657 ± 0.026 [ +1.5% .. +3.5%]
user_time 28.536 ± 0.245 28.609 ± 0.180 [ -0.1% .. +0.7%]
wall_time 23.833 ± 0.271 21.684 ± 0.194 [ -9.5% .. -8.5%]
samples 31 24
```
Reviewed By: #lld-macho, oontvoo, int3
Differential Revision: https://reviews.llvm.org/D115416
* Avoid the name truncation quirk in SymbolTable::insert: the truncated name will be replaced by @@ again.
* Allow foo and foo@@v1 in different files to be diagnosed as duplicate definition error (GNU ld behavior)
* Avoid potential redundant strlen on symbol name due to StringRefZ in ObjFile<ELFT>::initializeSymbols
Sorting the prefixes by decreasing frequency can improve performance.
.gcc_except_table is relatively frequent, so move it ahead.
.ctors and .dtors mostly disappear and should be the last.
SHT_GNU_verdef is typically small, so it's unnecessary to reserve the vector.
While here, fix a hypothetical issue when SHT_GNU_verdef has non-increasing
version indexes, which don't happen with GNU ld, gold, ld.lld's output.
My x86-64 lld executable is 256 bytes smaller.
sizeof(ObjFile<ELF64LE>) is decreased from 344 to 272 on an ELF64 system.
In a large link with 30000 ObjFiles, this may be 2+MiB saving.
Change std::vector members to SmallVector, and std::string members to
SmallString<0> (these members typically don't benefit from small string optimization).
On Linux x86-64 the lld executable is ~6k smaller.
(Fixed an issue about GOT on a copy relocated alias.)
(Fixed an issue about not creating r_addend=0 IRELATIVE for unreferenced non-preemptible ifunc.)
The idea is to make scanRelocations mark some actions are needed (GOT/PLT/etc)
and postpone the real work to postScanRelocations. It gives some flexibility:
* Make it feasible to support .plt.got (PR32938): we need to know whether GLOB_DAT and JUMP_SLOT are both needed.
* Make non-preemptible IFUNC handling slightly cleaner: avoid setting/clearing sym.gotInIgot
* -z nocopyrel: report all copy relocation places for one symbol
* Make GOT deduplication feasible
* Make parallel relocation scanning feasible (if we can avoid all stateful operations and make Symbol attributes atomic), but parallelism may not be the appealing choice
Since this patch moves a large chunk of code out of ELFT templates. My x86-64
executable is actually a few hundred bytes smaller.
For ppc32-ifunc-nonpreemptible-pic.s: I remove absolute relocation references to non-preemptible ifunc
because absolute relocation references are incorrect in -fpie mode.
Reviewed By: peter.smith, ikudrin
Differential Revision: https://reviews.llvm.org/D114783
Add missing coverage exposed by D114783.
There should be no associated IRELATIVE, otherwise (a) glibc ld.so may
crash (b) it wastes space (c) unused IPLT causes confusion.
If a copy related symbol (say `copy`) is referenced in two .o
files, this change removes a duplicated line from the -Map output:
```
202470 202470 1 1 .bss.rel.ro
202470 202470 1 1 <internal>:(.bss.rel.ro)
202470 202470 1 1 copy
removed 202470 202470 1 1 copy
```
Differential Revision: https://reviews.llvm.org/D115697
needsPltAddr is equivalent to `needsCopy && isFunc`. In many places, it is
equivalent to `needsCopy` because the non-STT_FUNC cases are ruled out.
Reviewed By: ikudrin, peter.smith
Differential Revision: https://reviews.llvm.org/D115603
(Fixed an issue about GOT on a copy relocated alias.)
The idea is to make scanRelocations mark some actions are needed (GOT/PLT/etc)
and postpone the real work to postScanRelocations. It gives some flexibility:
* Make it feasible to support .plt.got (PR32938): we need to know whether GLOB_DAT and JUMP_SLOT are both needed.
* Make non-preemptible IFUNC handling slightly cleaner: avoid setting/clearing sym.gotInIgot
* -z nocopyrel: report all copy relocation places for one symbol
* Make GOT deduplication feasible
* Make parallel relocation scanning feasible (if we can avoid all stateful operations and make Symbol attributes atomic), but parallelism may not be the appealing choice
Since this patch moves a large chunk of code out of ELFT templates. My x86-64
executable is actually a few hundred bytes smaller.
For ppc32-ifunc-nonpreemptible-pic.s: I remove absolute relocation references to non-preemptible ifunc
because absolute relocation references are incorrect in -fpie mode.
Reviewed By: peter.smith, ikudrin
Differential Revision: https://reviews.llvm.org/D114783
This reverts commit fc33861d48.
`replaceWithDefined` should copy needsGot, otherwise an alias for a copy
relocated symbol may not have GOT entry if its needsGot was originally true.
lld only needs DIContext.h which it gets through Symbolize.h -> SymbolizableModule.h -> DIContext.h. This replaces it with a direct include of DIContext.h to avoid any confusion and pulling in unnecessary headers.
Reviewed By: phosek
Differential Revision: https://reviews.llvm.org/D115659
The idea is to make scanRelocations mark some actions are needed (GOT/PLT/etc)
and postpone the real work to postScanRelocations. It gives some flexibility:
* Make it feasible to support .plt.got (PR32938): we need to know whether GLOB_DAT and JUMP_SLOT are both needed.
* Make non-preemptible IFUNC handling slightly cleaner: avoid setting/clearing sym.gotInIgot
* -z nocopyrel: report all copy relocation places for one symbol
* Make parallel relocation scanning possible (if we can avoid all stateful operations and make Symbol attributes atomic), but parallelism may not be the appealing choice
* Make GOT deduplication feasible
Since this patch moves a large chunk of code out of ELFT templates. My x86-64
executable is actually a few hundred bytes smaller.
For ppc32-ifunc-nonpreemptible-pic.s: I remove absolute relocation references to non-preemptible ifunc
because absolute relocation references are incorrect in -fpie mode.
Reviewed By: peter.smith, ikudrin
Differential Revision: https://reviews.llvm.org/D114783
An unstable sort suffices. In a large link (11.06s), this decreases .rela.dyn
writeTo time from 1.52s to 0.81s, resulting in 6% total time speedup (the
benefit will greatly dilute if --pack-dyn-relocs=relr becomes prevailing).
Encoding the dynamic relocations then sorting raw Elf_Rel/Elf_Rela doesn't seem
to improve much (doing that would require code duplicate because of
Elf_Rel/Elf_Rela plus unfortunate mips64le), so don't do that.
1. After D113241, we have the section address easily accessible and no
longer need to iterate across the LC_SEGMENT commands to emit
LC_DATA_IN_CODE.
2. There's no need to store a pointer to the data in code entries during
the parse step; we can just look it up as part of the output step.
Reviewed By: #lld-macho, thakis
Differential Revision: https://reviews.llvm.org/D115556
... only whether they have more than zero. This simplifies the code slightly.
I've also moved the field into the ConcatInputSection subclass since it doesn't
actually get used by the other InputSections.
Reviewed By: #lld-macho, oontvoo
Differential Revision: https://reviews.llvm.org/D115539
This fixes an issue introduced in D101996.
A weak reference in a shared library could be incorrectly reported if
there is another library that has a strong reference to the same symbol.
Differential Revision: https://reviews.llvm.org/D115041
Enable the pdbpagesize flag to allow linking of PDB files > 4GB.
Also includes a couple small fixes to change to uint64_t to support the
larger file sizes. I updated the max file size check in MSFBuilder.cpp
to take into account the page size.
Differential Revision: https://reviews.llvm.org/D115051
We were fetching archive symbols too eagerly, bloating binary size as well as
just screwing up binaries that expected to look up certain symbols only at
runtime.
Reviewed By: #lld-macho, oontvoo
Differential Revision: https://reviews.llvm.org/D115092
This patch proposes to move emission of global variables, types,
imported entities, etc from DwarfDebug::beginModule() to DwarfDebug::endModule().
Effectively, this changes nothing but the order of debug entities which
will be as follows:
* subprograms (including related context, local variables/labels,
local imported entities; related types can be created as a part of
the emission of local entities of an abstract subprogram);
* global variables (including related context and types);
* retained types and enums;
* non-local-scoped imported entities;
* basic types;
* other types left (as a part of local variables attributes emission).
Note that the order of emitted compile units may also be changed as now we emit
units that contain subprograms first and then all other non-empty units.
The motivation behind this change is the following:
(1) DwarfDebug::beginModule() is run at the very beginning of backend's pipeline,
from this time IR can be significantly changed by target-specific passes.
If it happens for debug metadata of global entities, those changes will not
be reflected in the emitted DWARF.
(2) imported subprogram names should refer to an abstract subprogram if it exists,
but it isn't known in DwarfDebug::beginModule() (it's possible to make some
guesses based on location info, but it's not quite reliable);
(3) aforementioned entities if they are scoped within a bracketed block
(subject of D113741) couldn't be emitted in DwarfDebug::beginModule()
(they need parent emitted first). Another problem is if to try to gather
some information about local entities and defer their emission
(till subprogram's processing or DwarfDebug::endModule()) all the gathered
details might be irrelevant / invalid by the time the entities are being
emitted (because of (1)).
Reviewed By: dblaikie
Differential Revision: https://reviews.llvm.org/D114705
Mach-O LLD uses the buffer identifier of the memory buffer backing an object
file to generate stabs which are used by `dsymutil` to find the object file for
dSYM generation.
When using thinLTO, these buffers are provided by the cache which initially
saves them to disk as temporary files beginning with "Thin-" but renames them
to persistent files beginning with "llvmcache-" before the buffer is provided
to the cache user.
However, the buffer is created before the file is renamed and is given the temp
file's name as an identifier. This causes the generated stabs to point to
nonexistent files.
This change names the buffer with the eventual persistent filename. I think
this is safe because failing to rename the temp file is a fatal error.
Differential Revision: https://reviews.llvm.org/D115055
This patch proposes to move emission of global variables, types,
imported entities, etc from DwarfDebug::beginModule() to DwarfDebug::endModule().
Effectively, this changes nothing but the order of debug entities which
will be as follows:
* subprograms (including related context, local variables/labels,
local imported entities; related types can be created as a part of
the emission of local entities of an abstract subprogram);
* global variables (including related context and types);
* retained types and enums;
* non-local-scoped imported entities;
* basic types;
* other types left (as a part of local variables attributes emission).
Note that the order of emitted compile units may also be changed as now we emit
units that contain subprograms first and then all other non-empty units.
The motivation behind this change is the following:
(1) DwarfDebug::beginModule() is run at the very beginning of backend's pipeline,
from this time IR can be significantly changed by target-specific passes.
If it happens for debug metadata of global entities, those changes will not
be reflected in the emitted DWARF.
(2) imported subprogram names should refer to an abstract subprogram if it exists,
but it isn't known in DwarfDebug::beginModule() (it's possible to make some
guesses based on location info, but it's not quite reliable);
(3) aforementioned entities if they are scoped within a bracketed block
(subject of D113741) couldn't be emitted in DwarfDebug::beginModule()
(they need parent emitted first). Another problem is if to try to gather
some information about local entities and defer their emission
(till subprogram's processing or DwarfDebug::endModule()) all the gathered
details might be irrelevant / invalid by the time the entities are being
emitted (because of (1)).
Reviewed By: dblaikie
Differential Revision: https://reviews.llvm.org/D114705
PLT usage needs the first 12 bytes of the .got section. We need to keep .got and
DT_GOT_PPC even if .got/_GLOBAL_OFFSET_TABLE_ are not referenced (large PIC code
may only reference .got2), which is the case in OpenBSD's ld.so, leading
to a misleading error, "unsupported insecure BSS PLT object".
Fix this by adding R_PPC32_PLTREL to the list of hasGotOffRel.
Reviewed By: MaskRay
Differential Revision: https://reviews.llvm.org/D114982
During the llvm round table it was generally agreed that the newer macho
lld implementation is feature complete enough to replace the old
implementation entirely. This will reduce confusion for new users who
aren't aware of the history.
Differential Revision: https://reviews.llvm.org/D114842
This is very similar to https://reviews.llvm.org/D103557 but applies to
symbols which are undefined at link time rather than compile time.
We already have code that handles symbols which were defined at link
time but dead stripped by `--gc-sections` (See
`test/wasm/debug-removed-fn.ll`). In that case the symbols are not live
(!isLive()). However, we can also have live symbols (which are
references by the program) but which are undefined at link time and are
imported by the linker.
In the test case here the symbol `undef` is used but is not defined
in the program but is imported by the linker due to the
`--import-undefined` flag.
Fixes: https://github.com/emscripten-core/emscripten/issues/15528
Differential Revision: https://reviews.llvm.org/D114921
When a comdat symbol is defined in both bitcode and regular object
files, which are contained in the same archive, the linker could lose
the flag that the symbol is used in the regular object file and allow
LTO to internalize it, which led to "error: undefined symbol".
The issue was introduced in D79300.
Differential Revision: https://reviews.llvm.org/D114801
This reverts the PPC64PCRelLongBranchThunk part from D86706.
PPC64PCRelLongBranchThunk is the same as PPC64R12SetupStub.
Use `__gep_setup_` instead of `__long_branch_pcrel_` for the stub symbol name
as it more closely indicates the operation.
(Note: GNU ld uses `*.long_branch.*` and `*.plt_branch.*`).
Reviewed By: NeHuang, nemanjai
Differential Revision: https://reviews.llvm.org/D114656
There is a trend of having more optional options (usually security
hardening related) like -z cet-report=, -z bti-report=, -z force-bti.
If ld.lld 14.0.0 uses a warning, in 15/16/17/... timeframe when people
add new options to software, they can worry less about linker errors on ld.lld 14.0.0.
In some cases `-z foo` does essential work where a silent ignore can be
problematic, but the user has received a warning. From my observation, the
doing-essential-work `-z foo` is much fewer than the converse. In addition,
the user who cares can use `--fatal-warnings` (Note: GNU ld doesn't upgrade warnings to errors).
It is unclear whether we need something like `clang -Wunknown-warning-option`.
If we ever run into unfortunate transition like `-z start-stop-gc`, the
affected software (e.g. ldc is a compiler which passes linker options to the underlying ld)
can blindly add the `-z` option, without worrying it may cause a linker error to LLD 14.0.0.
Reviewed By: jrtc27, peter.smith
Differential Revision: https://reviews.llvm.org/D114748
Make one change: when the OutputSection is nullptr (due to /DISCARD/ or garbage
collected BssSection (replaceCommonSymbols)), discard the SyntheticSection as well.
I attempted to remove it 1 or 2 year ago but kept it just to have a good
diagnostic in case the output section is nullptr (should be impossible).
It is long enough that we haven't seen such a case.
Fix r285764: there is no guarantee that Out::first is placed before other
static data members of `struct Out`. After `bufferStart` was introduced, this
out-of-bounds write is destined in many compilers. It is likely benign, though.
And move `Out::elfHeader->size` assignment beside `Out::elfHeader->sectionIndex`
For -z separate-code and -z separate-loadable-segments:
When RW is present, the RX to RW transition is aligned with max-page-size.
When RW is absent, the RX to non-SHF_ALLOC transition should use max-page-size as well.
Currently, LLD does not support the complete set of ARM group relocations.
Given that I intend to start using these in the Linux kernel [0], let's add
support for these.
This implements the group processing as documented in the ELF psABI. Notably,
this means support is dropped for very far symbol references that also carry a
small component, where the immediate is rotated in such a way that only part of
it wraps to the other end of the 32-bit word. To me, it seems unlikely that
this is something anyone could be relying on, but of course I could be wrong.
[0] https://lore.kernel.org/r/20211122092816.2865873-8-ardb@kernel.org/
Reviewed By: peter.smith, MaskRay
Differential Revision: https://reviews.llvm.org/D114172
This allows --power10-stubs= and --[no-]power10-stubs to override each other
(they are position dependent in GNU ld).
Also improve --help messages and the manpage.
Note: GNU ld's default "auto" mode uses heuristics to decide whether Power10
instructions are used. Arguably it is a design mistake of R_PPC64_REL24_NOTOC
(acked by the relevant folks on a libc-alpha discussion). We don't implement
"auto", so the default --power10-stubs is the same as "yes".
The canonical term is "extract" (GNU ld documentation, Solaris's `-z *extract`
options). Avoid inventing a term and match --why-extract. (ld64 prefers "load"
but the word is overloaded too much)
Mostly MFC, except for --help messages and the header row in
--print-archive-stats output.
BaseCommand was picked when PHDRS/INSERT/etc were not implemented. Rename it to
SectionCommand to match `sectionCommands` and make it clear that the commands
are used in SECTIONS (except a special case for SymbolAssignment).
Also, improve naming of some BaseCommand variables (base -> cmd).
This partially reverts r315409: the description applies to LinkerScript, but not
to OutputSection.
The name "sectionCommands" is used in both LinkerScript::sectionCommands and
OutputSection::sectionCommands, which may lead to confusion.
"commands" in OutputSection has no ambiguity because there are no other types
of commands.
The attribute 'r' allows (or disallows for the negative case) read-only
sections, i.e. ones without the SHF_WRITE flag, to be assigned to the
memory region. Before the patch, lld could put a section in the wrong
region or fail with "error: no memory region specified for section".
Differential Revision: https://reviews.llvm.org/D113771
Fangrui Song