<table border="1" cellspacing="0" cellpadding="8">
    <tr>
        <th>Issue</th>
        <td>
            <a href=https://github.com/llvm/llvm-project/issues/152883>152883</a>
        </td>
    </tr>

    <tr>
        <th>Summary</th>
        <td>
            [LLD] Crash in Machine Block Frequency Analysis when linking AMD GPU drivers with LTO
        </td>
    </tr>

    <tr>
      <th>Labels</th>
      <td>
            lld
      </td>
    </tr>

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

    <tr>
      <th>Reporter</th>
      <td>
          svan71
      </td>
    </tr>
</table>

<pre>
    ## Bug Description
LLD crashes with segfault when linking Linux kernel with LTO enabled, specifically when processing AMD GPU driver code.

## Environment
- **LLVM Version:** [run `ld.lld --version`]
- **Target:** x86_64-unknown-linux-gnu  
- **Kernel Version:** 6.16
- **GPU:** AMD RX 6950 XT (Navi 21)
- **Distribution:** CachyOS

## Crash Details

Stack dump:
0. Program arguments: ld.lld -m elf_x86_64 -mllvm -import-instr-limit=5 -z noexecstack -r -o drivers/gpu/drm/amd/amdgpu/amdgpu.o @drivers/gpu/drm/amd/amdgpu/amdgpu.mod

Running pass 'Function Pass Manager' on module 'ld-temp.o'.
Running pass 'Machine Block Frequency Analysis' on function '@gfx_v9_0_update_coarse_grain_clock_gating' #0 0x00007fe1734ea01d llvm::sys::PrintStackTrace(llvm::raw_ostream&, int) (/usr/lib/libLLVM.so.20.1+0x8ea01d) #1 0x00007fe1734e7647 (/usr/lib/libLLVM.so.20.1+0x8e7647) #2 0x00007fe17243e540 (/usr/lib/libc.so.6+0x3e540) #3 0x00007ffc5a2b6110 make[6]: *** [scripts/Makefile.build:502: drivers/gpu/drm/amd/amdgpu/amdgpu.o] Error 139## Reproduction Steps
1. Clone CachyOS kernel: `git clone https://github.com/CachyOS/linux-cachyos.git`
2. Enable LTO in PKGBUILD: `_use_llvm_lto=full` or `_use_llvm_lto=thin`
3. Run `makepkg` to build kernel
4. Crash occurs during AMD GPU driver linking

## Workaround
Using GNU linker (`export LLVM=0`) instead of LLD avoids the crash.

## Additional Info
- Crash is deterministic and always occurs at same function
- Only affects builds with LTO enabled
- AMD GPU drivers load successfully in current running kernel


</pre>
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