<table border="1" cellspacing="0" cellpadding="8">
    <tr>
        <th>Issue</th>
        <td>
            <a href=https://github.com/llvm/llvm-project/issues/64513>64513</a>
        </td>
    </tr>

    <tr>
        <th>Summary</th>
        <td>
            [LTO] [OpenMP] Linker for Win32 PE fails to find OpenMP threadprivate symbols if full LTO is enabled
        </td>
    </tr>

    <tr>
      <th>Labels</th>
      <td>
            new issue
      </td>
    </tr>

    <tr>
      <th>Assignees</th>
      <td>
      </td>
    </tr>

    <tr>
      <th>Reporter</th>
      <td>
          amyspark
      </td>
    </tr>
</table>

<pre>
    Hi all,

This is to report that if both `-flto` and `-fopenmp` are enabled for a target, and it makes use of a static library that contains a symbol exported by `#pragma openmp threadprivate(...)`, linking will fail with the following error:

```
FAILED: subprojects/pixman-0.42.2/test/region-test.exe
"cc"  -o subprojects/pixman-0.42.2/test/region-test.exe subprojects/pixman-0.42.2/test/region-test.exe.p/region-test.c.obj "-flto" "-Wl,--start-group" "subprojects\pixman-0.42.2\test\libtestutils.a" "subprojects\pixman-0.42.2\pixman\libpixman-1.a" "subprojects\pixman-0.42.2\pixman\libpixman-mmx.a" "subprojects\pixman-0.42.2\pixman\libpixman-sse2.a" "subprojects\pixman-0.42.2\pixman\libpixman-ssse3.a" "-pthread" "-fopenmp" "-fopenmp" "-lm" "D:/msys64/clang64/bin/../lib/libpng16.dll.a" "-Wl,--subsystem,console" "-lkernel32" "-luser32" "-lgdi32" "-lwinspool" "-lshell32" "-lole32" "-loleaut32" "-luuid" "-lcomdlg32" "-ladvapi32" "-Wl,--end-group"
ld.lld: error: undefined symbol: thread-local initialization routine for prng_state
>>> referenced by ../subprojects/pixman-0.42.2/test/region-test.c
>>> subprojects/pixman-0.42.2/test/region-test.exe.p/region-test.c.obj

ld.lld: error: undefined symbol: thread-local initialization routine for prng_state_data
>>> referenced by ../subprojects/pixman-0.42.2/test/region-test.c
>>> subprojects/pixman-0.42.2/test/region-test.exe.p/region-test.c.obj
cc: error: linker command failed with exit code 1 (use -v to see invocation)
ninja: build stopped: subcommand failed.
```

Linking with `-flto=thin`, as well as building with GCC + `-flto`, both result in a working build.

To reproduce, please download https://www.cairographics.org/releases/pixman-0.42.2.tar.gz, unpack it, and then perform:

```
cd pixman-0.42.2
meson setup build -Ddefault_library=static -Db_lto=true -Dbackend_max_links=1
meson compile -C build
```

clang version 16.0.5
Target: x86_64-w64-windows-gnu
Thread model: posix
InstalledDir: D:/msys64/clang64/bin
</pre>
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