[ELF] Drop unused original symbol after wrapping if not defined

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 t

[ELF] Drop unused original symbol after wrapping if not defined

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

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[ELF] Fix wrapping symbols produced during LTO codegen

We were previously not correctly wrapping symbols that were only
produced during LTO codegen and unreferenced before then, or symbols
only refe

[ELF] Fix wrapping symbols produced during LTO codegen

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

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[ELF] Move isUsedInRegularObj assignment from ctor to call sites. NFC

This removes the tricky
`isUsedInRegularObj(!file || file->kind() == InputFile::ObjKind)`
and the copy from `Symbol::mergeProper

[ELF] Move isUsedInRegularObj assignment from ctor to call sites. NFC

This removes the tricky
`isUsedInRegularObj(!file || file->kind() == InputFile::ObjKind)`
and the copy from `Symbol::mergeProperties`.

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[ELF] Don't rely on Symbols.h's transitive inclusion of InputFiles.h. NFC

[ELF] Move duplicate symbol check after input file parsing

https://discourse.llvm.org/t/parallel-input-file-parsing/60164

To decouple symbol initialization and section initialization, `Defined::sec

[ELF] Move duplicate symbol check after input file parsing

https://discourse.llvm.org/t/parallel-input-file-parsing/60164

To decouple symbol initialization and section initialization, `Defined::section`
assignment should be postponed after input file parsing. To avoid spurious
duplicate definition error due to two definitions in COMDAT groups of the same
signature, we should postpone the duplicate symbol check.

The function is called postScan instead of a more specific name like
checkDuplicateSymbols, because we may merge Symbol::mergeProperties into
postScan. It is placed after compileBitcodeFiles to apply to ET_REL files
produced by LTO. This causes minor diagnostic regression
for skipLinkedOutput configurations: ld.lld --thinlto-index-only a.bc b.o
(bitcode definition prevails) won't detect duplicate symbol error. I think this
is an acceptable compromise. The important cases where (a) both files are
bitcode or (b) --thinlto-index-only is unused are still detected.

Reviewed By: ikudrin

Differential Revision: https://reviews.llvm.org/D119908

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[ELF] Clean up headers. NFC

[ELF] Reorder Symbol members to improve access locality. NFC

* partition and isPreemptible are frequently used. Move it to the front
* move used beside isUsedInRegularObj. They are similar and acces

[ELF] Reorder Symbol members to improve access locality. NFC

* partition and isPreemptible are frequently used. Move it to the front
* move used beside isUsedInRegularObj. They are similar and accessed together in .symtab finalizing
* move auxIdx/dynsymIndex/verdefIndex to the end.

This decreases code size.

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[ELF] Merge canInline into scriptDefined

They perform similar tasks and are essentially the same after
d28c26bbdd9e6e55cc0a6156e9879f7e0ca36329.

[ELF] --wrap: don't copy exportDynamic

For -no-pie/-pie, when `__real_foo` is interposable in a shared object, `foo` is
exported. This rule does not match GNU ld and is unneeded because:

* the expo

[ELF] --wrap: don't copy exportDynamic

For -no-pie/-pie, when `__real_foo` is interposable in a shared object, `foo` is
exported. This rule does not match GNU ld and is unneeded because:

* the exported `foo` does not interpose `__real_foo` at run-time
* the similar `__wrap_foo` <-> `foo` relation does not have the rule

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[lld] Add support for other demanglers other than Itanium

LLVM core library supports demangling other mangled symbols other than itanium,
such as D and Rust. LLD should use those demanglers in order

[lld] Add support for other demanglers other than Itanium

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

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Revert "[lld] Add support for other demanglers other than Itanium"

This reverts commit e60d6dfd5acdc821d391ad5af2c706397bdfd36a.

clang-ppc64le-rhel buildbot failed (https://lab.llvm.org/buildbot#bu

Revert "[lld] Add support for other demanglers other than Itanium"

This reverts commit e60d6dfd5acdc821d391ad5af2c706397bdfd36a.

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&)'

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[lld] Add support for other demanglers other than Itanium

LLVM core library supports demangling other mangled symbols other than itanium,
such as D and Rust. LLD should use those demanglers in order

[lld] Add support for other demanglers other than Itanium

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

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[ELF] Add Symbol::hasVersionSuffix

"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()
== '@'`

[ELF] Add Symbol::hasVersionSuffix

"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.

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[ELF] scanVersionScript: remove unused variable

[ELF] Simplify SymbolTable::insert. NFC

[ELF] SymbolTable: change some vector<Symbol *> to SmallVector

The generated assembly for Symbol::insert is much shorter (std::vector resize is
inefficient) and enables some inlining.

[ELF] Change some global pointers to unique_ptr

Currently the singleton `config` is assigned by `config = make<Configuration>()`
and (if `canExitEarly` is false) destroyed by `lld::freeArena`.

`mak

[ELF] Change some global pointers to unique_ptr

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

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[ELF] Change Symbol::verdefIndex from uint32_t to uint16_t

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

[ELF] Change Symbol::verdefIndex from uint32_t to uint16_t

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.

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[ELF] SymbolTable::insert: keep @@ in the name

* Avoid the name truncation quirk in SymbolTable::insert: the truncated name will be replaced by @@ again.
* Allow foo and foo@@v1 in different files t

[ELF] SymbolTable::insert: keep @@ in the name

* 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

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[ELF] Remove dead code from SymbolTable::find

[ELF] Rename fetch to extract

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 wo

[ELF] Rename fetch to extract

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.

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[ELF] Update comments/diagnostics for some long options to use the canonical two-dash form

Rewrite some comments as appropriate.

[ELF] Apply version script patterns to non-default version symbols

Currently version script patterns are ignored for .symver produced
non-default version (single @) symbols. This makes such symbols

[ELF] Apply version script patterns to non-default version symbols

Currently version script patterns are ignored for .symver produced
non-default version (single @) symbols. This makes such symbols
not localizable by `local:`, e.g.

```
.symver foo3_v1,foo3@v1
.globl foo_v1
foo3_v1:

ld.lld --version-script=a.ver -shared a.o
```

This patch adds the support:

* Move `config->versionDefinitions[VER_NDX_LOCAL].patterns` to `config->versionDefinitions[versionId].localPatterns`
* Rename `config->versionDefinitions[versionId].patterns` to `config->versionDefinitions[versionId].nonLocalPatterns`
* Allow `findAllByVersion` to find non-default version symbols when `includeNonDefault` is true. (Note: `symtab` keys do not have `@@`)
* Make each pattern check both the unversioned `pat.name` and the versioned `${pat.name}@${v.name}`
* `localPatterns` can localize `${pat.name}@${v.name}`. `nonLocalPatterns` can prevent localization by assigning `verdefIndex` (before `parseSymbolVersion`).

---

If a user notices new `undefined symbol` errors with a version script containing
`local: *;`, the issue is likely due to a missing `global:` pattern.

Reviewed By: peter.smith

Differential Revision: https://reviews.llvm.org/D107234

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Revert "[ELF] Apply version script patterns to non-default version symbols"

This reverts commit 7ed22a6fa90cbdc70d6806c1121a0c50c1978dce.

buf is not cleared so the commit misses some cases.

[ELF] Apply version script patterns to non-default version symbols

Currently version script patterns are ignored for .symver produced
non-default version (single @) symbols. This makes such symbols

[ELF] Apply version script patterns to non-default version symbols

Currently version script patterns are ignored for .symver produced
non-default version (single @) symbols. This makes such symbols
not localizable by `local:`, e.g.

```
.symver foo3_v1,foo3@v1
.globl foo_v1
foo3_v1:

ld.lld --version-script=a.ver -shared a.o
# In a.out, foo3@v1 is incorrectly exported.
```

This patch adds the support:

* Move `config->versionDefinitions[VER_NDX_LOCAL].patterns` to `config->versionDefinitions[versionId].localPatterns`
* Rename `config->versionDefinitions[versionId].patterns` to `config->versionDefinitions[versionId].nonLocalPatterns`
* Allow `findAllByVersion` to find non-default version symbols when `includeNonDefault` is true. (Note: `symtab` keys do not have `@@`)
* Make each pattern check both the unversioned `pat.name` and the versioned `${pat.name}@${v.name}`
* `localPatterns` can localize `${pat.name}@${v.name}`. `nonLocalPatterns` can prevent localization by assigning `verdefIndex` (before `parseSymbolVersion`).

---

If a user notices new `undefined symbol` errors with a version script containing
`local: *;`, the issue is likely due to a missing `global:` pattern.

Reviewed By: peter.smith

Differential Revision: https://reviews.llvm.org/D107234

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