[lld] [llvm] [lld][DebugInfo/BTF] Add BTF section merging and deduplication (PR #183915)

[via llvm-commits]

github-actions[bot] wrote:

<!--PREMERGE ADVISOR COMMENT: Linux-->
# :penguin: Linux x64 Test Results

* 99157 tests passed
* 1963 tests skipped

All executed tests passed, but another part of the build **failed**. Click on a failure below to see the details.

<details>
<summary>unittests/DebugInfo/BTF/CMakeFiles/DebugInfoBTFTests.dir/BTFDedupTest.cpp.o</summary>

```
FAILED: unittests/DebugInfo/BTF/CMakeFiles/DebugInfoBTFTests.dir/BTFDedupTest.cpp.o
sccache /opt/llvm/bin/clang++ -DLLVM_BUILD_STATIC -D_DEBUG -D_GLIBCXX_ASSERTIONS -D_GLIBCXX_USE_CXX11_ABI=1 -D_GNU_SOURCE -D_LIBCPP_HARDENING_MODE=_LIBCPP_HARDENING_MODE_EXTENSIVE -D__STDC_CONSTANT_MACROS -D__STDC_FORMAT_MACROS -D__STDC_LIMIT_MACROS -I/home/gha/actions-runner/_work/llvm-project/llvm-project/build/unittests/DebugInfo/BTF -I/home/gha/actions-runner/_work/llvm-project/llvm-project/llvm/unittests/DebugInfo/BTF -I/home/gha/actions-runner/_work/llvm-project/llvm-project/build/include -I/home/gha/actions-runner/_work/llvm-project/llvm-project/llvm/include -I/home/gha/actions-runner/_work/llvm-project/llvm-project/third-party/unittest/googletest/include -I/home/gha/actions-runner/_work/llvm-project/llvm-project/third-party/unittest/googlemock/include -gmlt -fPIC -fno-semantic-interposition -fvisibility-inlines-hidden -Werror -Werror=date-time -Werror=unguarded-availability-new -Wall -Wextra -Wno-unused-parameter -Wwrite-strings -Wcast-qual -Wmissing-field-initializers -pedantic -Wno-long-long -Wc++98-compat-extra-semi -Wimplicit-fallthrough -Wcovered-switch-default -Wno-noexcept-type -Wnon-virtual-dtor -Wdelete-non-virtual-dtor -Wsuggest-override -Wstring-conversion -Wno-pass-failed -Wmisleading-indentation -Wctad-maybe-unsupported -fdiagnostics-color -ffunction-sections -fdata-sections -O3 -DNDEBUG -std=c++17 -UNDEBUG -Wno-variadic-macros -Wno-gnu-zero-variadic-macro-arguments -fno-exceptions -funwind-tables -fno-rtti -Wno-suggest-override -MD -MT unittests/DebugInfo/BTF/CMakeFiles/DebugInfoBTFTests.dir/BTFDedupTest.cpp.o -MF unittests/DebugInfo/BTF/CMakeFiles/DebugInfoBTFTests.dir/BTFDedupTest.cpp.o.d -o unittests/DebugInfo/BTF/CMakeFiles/DebugInfoBTFTests.dir/BTFDedupTest.cpp.o -c /home/gha/actions-runner/_work/llvm-project/llvm-project/llvm/unittests/DebugInfo/BTF/BTFDedupTest.cpp
/home/gha/actions-runner/_work/llvm-project/llvm-project/llvm/unittests/DebugInfo/BTF/BTFDedupTest.cpp:755:12: error: unused variable 'BS' [-Werror,-Wunused-variable]
755 |   uint32_t BS = B.addString("b");
|            ^~
1 error generated.
```
</details>

If these failures are unrelated to your changes (for example tests are broken or flaky at HEAD), please open an issue at https://github.com/llvm/llvm-project/issues and add the `infrastructure` label.

https://github.com/llvm/llvm-project/pull/183915