[lld] [llvm] [DTLTO][ELF][COFF] Add archive support for DTLTO. (PR #157043)

[LLVM Continuous Integration via llvm-commits]

llvm-ci wrote:

LLVM Buildbot has detected a new failure on builder `polly-x86_64-linux-shared` running on `polly-x86_64-gce2` while building `cross-project-tests,lld,llvm` at step 5 "build".

Full details are available at: https://lab.llvm.org/buildbot/#/builders/97/builds/10219

<details>
<summary>Here is the relevant piece of the build log for the reference</summary>

```
Step 5 (build) failure: 'ninja' (failure)
...
[2066/4583] Linking CXX shared library lib/libLLVMCore.so.22.0git
[2067/4583] Linking CXX shared library lib/libLLVMDebugInfoDWARFLowLevel.so.22.0git
[2068/4583] Creating library symlink lib/libLLVMCore.so
[2069/4583] Creating library symlink lib/libLLVMDebugInfoDWARFLowLevel.so
[2070/4583] Linking CXX shared library lib/libLLVMFrontendHLSL.so.22.0git
[2071/4583] Linking CXX shared library lib/libLLVMBitReader.so.22.0git
[2072/4583] Creating library symlink lib/libLLVMFrontendHLSL.so
[2073/4583] Creating library symlink lib/libLLVMBitReader.so
[2074/4583] Linking CXX shared library lib/libLLVMCFGuard.so.22.0git
[2075/4583] Linking CXX shared library lib/libLLVMDTLTO.so.22.0git
FAILED: lib/libLLVMDTLTO.so.22.0git 
: && /usr/bin/c++ -fPIC -fPIC -fno-semantic-interposition -fvisibility-inlines-hidden -Werror=date-time -Wall -Wextra -Wno-unused-parameter -Wwrite-strings -Wcast-qual -Wno-missing-field-initializers -pedantic -Wno-long-long -Wimplicit-fallthrough -Wno-uninitialized -Wno-nonnull -Wno-class-memaccess -Wno-dangling-reference -Wno-redundant-move -Wno-pessimizing-move -Wno-array-bounds -Wno-stringop-overread -Wno-noexcept-type -Wdelete-non-virtual-dtor -Wsuggest-override -Wno-comment -Wno-misleading-indentation -Wctad-maybe-unsupported -fdiagnostics-color -ffunction-sections -fdata-sections -O3 -DNDEBUG  -Wl,-z,defs -Wl,-z,nodelete -fuse-ld=lld -Wl,--color-diagnostics   -Wl,--gc-sections -shared -Wl,-soname,libLLVMDTLTO.so.22.0git -o lib/libLLVMDTLTO.so.22.0git lib/DTLTO/CMakeFiles/LLVMDTLTO.dir/DTLTO.cpp.o  -Wl,-rpath,"\$ORIGIN/../lib:/home/worker/workers/polly-x86_64-gce2/polly-x86_64-linux-shared/llvm.obj/lib:"  lib/libLLVMCore.so.22.0git  lib/libLLVMSupport.so.22.0git  -Wl,-rpath-link,/home/worker/workers/polly-x86_64-gce2/polly-x86_64-linux-shared/llvm.obj/lib && :
ld.lld: error: undefined symbol: llvm::lto::InputFile::~InputFile()
>>> referenced by DTLTO.cpp
>>>               lib/DTLTO/CMakeFiles/LLVMDTLTO.dir/DTLTO.cpp.o:(std::_Sp_counted_ptr<llvm::lto::InputFile*, (__gnu_cxx::_Lock_policy)2>::_M_dispose())

ld.lld: error: undefined symbol: llvm::identify_magic(llvm::StringRef)
>>> referenced by DTLTO.cpp
>>>               lib/DTLTO/CMakeFiles/LLVMDTLTO.dir/DTLTO.cpp.o:(llvm::lto::DTLTO::isThinArchive(llvm::StringRef) (.localalias))

ld.lld: error: undefined symbol: llvm::lto::InputFile::getName() const
>>> referenced by DTLTO.cpp
>>>               lib/DTLTO/CMakeFiles/LLVMDTLTO.dir/DTLTO.cpp.o:(llvm::lto::DTLTO::removeTempFiles())
>>> referenced by DTLTO.cpp
>>>               lib/DTLTO/CMakeFiles/LLVMDTLTO.dir/DTLTO.cpp.o:(llvm::lto::DTLTO::~DTLTO())
>>> referenced by DTLTO.cpp
>>>               lib/DTLTO/CMakeFiles/LLVMDTLTO.dir/DTLTO.cpp.o:(llvm::lto::DTLTO::~DTLTO())
>>> referenced 2 more times

ld.lld: error: undefined symbol: llvm::lto::LTO::~LTO()
>>> referenced by DTLTO.cpp
>>>               lib/DTLTO/CMakeFiles/LLVMDTLTO.dir/DTLTO.cpp.o:(llvm::lto::DTLTO::~DTLTO())
>>> referenced by DTLTO.cpp
>>>               lib/DTLTO/CMakeFiles/LLVMDTLTO.dir/DTLTO.cpp.o:(llvm::lto::DTLTO::~DTLTO())

ld.lld: error: undefined symbol: llvm::lto::InputFile::getSingleBitcodeModule()
>>> referenced by DTLTO.cpp
>>>               lib/DTLTO/CMakeFiles/LLVMDTLTO.dir/DTLTO.cpp.o:(llvm::lto::DTLTO::addInput(std::unique_ptr<llvm::lto::InputFile, std::default_delete<llvm::lto::InputFile>>) (.localalias))
collect2: error: ld returned 1 exit status
[2076/4583] Creating library symlink lib/libLLVMCFGuard.so
ninja: build stopped: subcommand failed.
Cache directory:              /home/worker/.cache/ccache
Config file:                  /home/worker/.config/ccache/ccache.conf
System config file:           /etc/ccache.conf
Stats updated:                Wed Dec 31 09:02:27 2025
Cacheable calls:               1954 / 1955 (99.95%)
  Hits:                        1953 / 1954 (99.95%)
    Direct:                    1953 / 1953 (100.0%)
    Preprocessed:                 0 / 1953 ( 0.00%)

```

</details>

https://github.com/llvm/llvm-project/pull/157043