[ELF] Reorder SectionBase/InputSectionBase members

Move `sectionKind` outside the bitfield and move bss/keepUnique to
InputSectionBase.

* sizeof(InputSection) decreases from 160 to 152 on 64-bit sy

[ELF] Reorder SectionBase/InputSectionBase members

Move `sectionKind` outside the bitfield and move bss/keepUnique to
InputSectionBase.

* sizeof(InputSection) decreases from 160 to 152 on 64-bit systems.
* The numerous `sectionKind` accesses are faster.

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[ELF] Replace contex-less toString(x) with toStr(ctx, x)

so that we can remove the global `ctx` from toString implementations.
Rename lld::toString (to lld::elf::toStr) to simplify name lookup (we
h

[ELF] Replace contex-less toString(x) with toStr(ctx, x)

so that we can remove the global `ctx` from toString implementations.
Rename lld::toString (to lld::elf::toStr) to simplify name lookup (we
have many llvm::toString and another lld::toString(const llvm::opt::Arg
&)).

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[ELF] Replace error(...) with ErrAlways or Err

Most are migrated to ErrAlways mechanically.
In the future we should change most to Err.

[ELF] Pass Ctx &

[ELF] Pass Ctx & to Symbol::getVA

[ELF] Pass Ctx &

[ELF] Pass Ctx & to MapFile

[ELF] Replace config-> with ctx.arg.

[ELF] Move script into Ctx. NFC

Ctx was introduced in March 2022 as a more suitable place for such
singletons.

We now use default-initialization for `LinkerScript` and should pay
attention to non-c

[ELF] Move script into Ctx. NFC

Ctx was introduced in March 2022 as a more suitable place for such
singletons.

We now use default-initialization for `LinkerScript` and should pay
attention to non-class types (e.g. `dot` is initialized by commit
503907dc505db1e439e7061113bf84dd105f2e35).

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[LLD] Add CLASS syntax to SECTIONS (#95323)

This allows the input section matching algorithm to be separated from
output section descriptions. This allows a group of sections to be
assigned to mul

[LLD] Add CLASS syntax to SECTIONS (#95323)

This allows the input section matching algorithm to be separated from
output section descriptions. This allows a group of sections to be
assigned to multiple output sections, providing an explicit version of
--enable-non-contiguous-regions's spilling that doesn't require altering
global linker script matching behavior with a flag. It also makes the
linker script language more expressive even if spilling is not intended,
since input section matching can be done in a different order than
sections are placed in an output section.

The implementation reuses the backend mechanism provided by
--enable-non-contiguous-regions, so it has roughly similar semantics and
limitations. In particular, sections cannot be spilled into or out of
INSERT, OVERWRITE_SECTIONS, or /DISCARD/. The former two aren't
intrinsic, so it may be possible to relax those restrictions later.

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[LLD][ELF] Silence warning when building with Clang ToT

This fixes:
```
[5839/7452] Building CXX object tools\lld\ELF\CMakeFiles\lldELF.dir\MapFile.cpp.obj
C:\git\llvm-project\lld\ELF\MapFile.cpp(12

[LLD][ELF] Silence warning when building with Clang ToT

This fixes:
```
[5839/7452] Building CXX object tools\lld\ELF\CMakeFiles\lldELF.dir\MapFile.cpp.obj
C:\git\llvm-project\lld\ELF\MapFile.cpp(124,38): warning: comparison of integers of different signs: 'uint32_t' (aka 'unsigned int') and 'const ssize_t' (aka 'const int') [-Wsign-compare]
124 | last.outputOff + last.size == p.outputOff) {
| ~~~~~~~~~~~~~~~~~~~~~~~~~~ ^ ~~~~~~~~~~~
1 warning generated.
```

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[ELF] Demote symbols in /DISCARD/ discarded sections to Undefined (#69295)

When an input section is matched by /DISCARD/ in a linker script, GNU ld
reports errors for relocations referencing symbols

[ELF] Demote symbols in /DISCARD/ discarded sections to Undefined (#69295)

When an input section is matched by /DISCARD/ in a linker script, GNU ld
reports errors for relocations referencing symbols defined in the section:

`.aaa' referenced in section `.bbb' of a.o: defined in discarded section `.aaa' of a.o

Implement the error by demoting eligible symbols to `Undefined` and changing
STB_WEAK to STB_GLOBAL. As a side benefit, in relocatable links, relocations
referencing symbols defined relative to /DISCARD/ discarded sections no longer
set symbol/type to zeros.

It's arguable whether a weak reference to a discarded symbol should lead to
errors. GNU ld reports an error and our demoting approach reports an error as
well.

Close #58891

Co-authored-by: Bevin Hansson <bevin.hansson@ericsson.com>

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[ELF] Make subsequent opens to auxiliary files append

Previously, the same file could be used across diagnostic options but
the file would be silently overwritten by the whichever option gets
handle

[ELF] Make subsequent opens to auxiliary files append

Previously, the same file could be used across diagnostic options but
the file would be silently overwritten by the whichever option gets
handled last.

Differential Revision: https://reviews.llvm.org/D153873

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[NFC] Optimize vector usage in lld

By using emplace_back, as well as converting some loops to for-each, we can do more efficient vectorization.

Make copy constructor for TemporaryFile noexcept.

Re

[NFC] Optimize vector usage in lld

By using emplace_back, as well as converting some loops to for-each, we can do more efficient vectorization.

Make copy constructor for TemporaryFile noexcept.

Reviewed By: #lld-macho, int3

Differential Revision: https://reviews.llvm.org/D139552

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[lld][NFC] rename ELF alignment into addralign

[ELF] Remove ctx indirection. NFC

Add LLVM_LIBRARY_VISIBILITY to remove unneeded GOT and unique_ptr
indirection. We can move other global variables into ctx without
indirection concern. In the long

[ELF] Remove ctx indirection. NFC

Add LLVM_LIBRARY_VISIBILITY to remove unneeded GOT and unique_ptr
indirection. We can move other global variables into ctx without
indirection concern. In the long term we may consider passing Ctx
as a parameter to various functions and eliminate global state as
much as possible and then remove `Ctx::reset`.

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[ELF] Merge Symbol::needs* into uint16_t flags. NFC

Split off from D133003 ([ELF] Parallelize relocation scanning) to make its diff smaller.

[ELF] Move InputFiles global variables (memoryBuffers, objectFiles, etc) into Ctx. NFC

Rename parallelForEachN to just parallelFor

Patch created by running:

rg -l parallelForEachN | xargs sed -i '' -c 's/parallelForEachN/parallelFor/'

No behavior change.

Differential Revision: ht

Rename parallelForEachN to just parallelFor

Patch created by running:

rg -l parallelForEachN | xargs sed -i '' -c 's/parallelForEachN/parallelFor/'

No behavior change.

Differential Revision: https://reviews.llvm.org/D128140

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[ELF] Don't use multiple inheritance for OutputSection. NFC

Add an OutputDesc class inheriting from SectionCommand. An OutputDesc wraps an
OutputSection. This change allows InputSection::getParent t

[ELF] Don't use multiple inheritance for OutputSection. NFC

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

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[ELF] Move --print-archive-stats= and --why-extract= beside --warn-backrefs report

So that early errors don't suppress their output.

[ELF] Parse archives as --start-lib object files

https://maskray.me/blog/2022-01-16-archives-and-start-lib

For every definition in an extracted archive member, we intern the symbol twice,
once for

[ELF] Parse archives as --start-lib object files

https://maskray.me/blog/2022-01-16-archives-and-start-lib

For every definition in an extracted archive member, we intern the symbol twice,
once for the archive index entry, once for the .o symbol table after extraction.
This is inefficient.

Symbols in a --start-lib ObjFile/BitcodeFile are only interned once because the
result is cached in symbols[i].

Just handle an archive using the --start-lib code path. We can therefore remove
ArchiveFile and LazyArchive. For many projects, archive member extraction ratio
is high and it is a net performance win. Linking a Release build of clang is
1.01x as fast.

Note: --start-lib scans symbols in the same order that llvm-ar adds them to the
index, so in the common case the semantics should be identical. If the archive
symbol table was created in a different order, or is incomplete, this strategy
may have different semantics. Such cases are considered user error.

The `is neither ET_REL nor LLVM bitcode` error is changed to a warning.
Previously an archive may have such members without a diagnostic. Using a
warning prevents breakage.

* For some tests, the diagnostics get improved where we did not consider
the archive member name: `b.a:` => `b.a(b.o):`.
* `no-obj.s`: the link is now allowed, matching GNU ld
* `archive-no-index.s`: the `is neither ET_REL nor LLVM bitcode` diagnostic is
demoted to a warning.
* `incompatible.s`: even when an archive is unextracted, we may report an
"incompatible with" error.

---

I recently decreased sizeof(SymbolUnion) by 8 and decreased memory usage quite a
bit, so retaining `symbols` for un-extracted archive members should not cause a
memory usage problem.

Reviewed By: peter.smith

Differential Revision: https://reviews.llvm.org/D119074

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[ELF] Clean up headers. NFC

[ELF] Optimize two vector. NFC

[ELF] Optimize -Map. NFC

getVA is slow. Avoid calling it in the llvm::sort comparator.