<table border="1" cellspacing="0" cellpadding="8">
    <tr>
        <th>Issue</th>
        <td>
            <a href=https://github.com/llvm/llvm-project/issues/61030>61030</a>
        </td>
    </tr>

    <tr>
        <th>Summary</th>
        <td>
            llvm-mc on rv64 gets confused by -mcpu=not-a-processor
        </td>
    </tr>

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

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

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

<pre>
    Simply run `llvm-mc --arch=riscv64 -mcpu=not-a-processor /dev/null`, and you'll get a stack trace.
```
'not-a-processor' is not a recognized processor for this target (ignoring processor)
'not-a-processor' is not a recognized processor for this target (ignoring processor)
LLVM ERROR: RV64 target requires an RV64 CPU
PLEASE submit a bug report to https://github.com/llvm/llvm-project/issues/ and include the crash backtrace.
Stack dump:
0.      Program arguments: /opt/compiler-explorer/clang-15.0.0/bin/llvm-mc -filetype=obj -o example.o --arch=riscv64 -mcpu=not-a-processor <source>
 #0 0x000055b6be85d354 PrintStackTraceSignalHandler(void*) Signals.cpp:0:0
 #1 0x000055b6be85b034 SignalHandler(int) Signals.cpp:0:0
 #2 0x00007f837b712420 __restore_rt (/lib/x86_64-linux-gnu/libpthread.so.0+0x14420)
 #3 0x00007f837b1e500b raise (/lib/x86_64-linux-gnu/libc.so.6+0x4300b)
 #4 0x00007f837b1c4859 abort (/lib/x86_64-linux-gnu/libc.so.6+0x22859)
 #5 0x000055b6be1bb801 (/opt/compiler-explorer/clang-15.0.0/bin/llvm-mc+0x485801)
 #6 0x000055b6be80c86e (/opt/compiler-explorer/clang-15.0.0/bin/llvm-mc+0xad686e)
 #7 0x000055b6be53065a (/opt/compiler-explorer/clang-15.0.0/bin/llvm-mc+0x7fa65a)
 #8 0x000055b6be53c10f llvm::createRISCVAsmBackend(llvm::Target const&, llvm::MCSubtargetInfo const&, llvm::MCRegisterInfo const&, llvm::MCTargetOptions const&) (/opt/compiler-explorer/clang-15.0.0/bin/llvm-mc+0x80610f)
 #9 0x000055b6be1c0d36 main (/opt/compiler-explorer/clang-15.0.0/bin/llvm-mc+0x48ad36)
#10 0x00007f837b1c6083 __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x24083)
#11 0x000055b6be1f8d0e _start (/opt/compiler-explorer/clang-15.0.0/bin/llvm-mc+0x4c2d0e)
```
https://godbolt.org/z/1fWz9v4hh

Looks like that processor isn't ignored after all. I think it tries constructing a fallback processor, but said fallback is accidentally 32bit.

Arguably a garbage in garbage out, but it's also a PLEASE, so I might as well report it.
</pre>
<img width="1px" height="1px" alt="" src="http://email.email.llvm.org/o/eJy8Vl1v2zoS_TX0y8AGReqDfvCDm8TYAC0aJN3uo0FSY5kNRXpJKk366xeUksYK0L29bXEBG7Y45DnzpTmUMZrOIW5I9Y5Ulws5pKMPm63VMviF8u3T5s70J_sEYXBAamrtQ7_sNSyXMugj4ZfBRP1Ql7Ds9Wkg_NL5tJTLU_AaY_QBCNu1-EDYzg3WkpoSdgHStfDkB8Iaa6HDBBJikvoeUpAaV4ReErrNe6fP9MiaN9CENWAiOJ_PB9S-c-YbtvDKffAB0tFESDJkGsKE6ZwPxnVwBrP-pxjev__8Aa5ubz_eEr6F2891-XIu4H8HEzCCdNP6xc2_pzM376-2d1cQB9Wb7IYaOgh48iFB8nBM6RQJ3xK2I2zXmXQc1Er7nrBdrtTzT47oC-pE2M7EOGAkbDcWwThthxYhHRF0kPEISur78yrcjXVph_6UWcYluiJ0fRN8F2QPMnRDjy5lJ3Kt_SmzaN-fjMWwxMeT9QFDXrPSdcuiWtEVJWynjHvxLrfTwVhMTyck_NKrL7D0gI-yP1lc-b_Ra_wi-iFoJPxq8hUI4xToI6WUVpWqFYqq5VUJN8G4NAb3KUd7Zzon7b-ka212Vjx40xK2JWwNkymu9CmngI7f79jFG2xFeQlvwYxLfwnEnoGag-CNagpWMgr7fcCYfMB9GFsrJ8wownaPot7X5dIaNzwuOzdMhlM6BpTtKvqc4Xf0sShLRr93X6bhM5oCK0oVBGki_gS-zsj1iFxyStUMuZwj61JUa5DK_5TnZ8iMiWo9Q65mOS6UErR4xvy1bpsiEJWgxYyonheTalHj7xPJthY1zoiaGVHFaV3J3ydqDrKu5IxIvCHSBT3AOBj4lvCtDigT3l7fXXzexv6d1PfoWsLE645P03jS3sVEWJ2H96vxw8XdoKYBdu0O_oe7brEzMWH4v5smpo-nZLyLZ7vWv58YQeuCHmaJWc97StOW19BL4_5EY8mW12eqwgv65t2oqeCw3-fG38ckQ9qfUf_se1JSwWcs81lUHERLESb8PxCVZi197eI34vxGhnyrvE0rHzrCdt8I2xWH_3xbP5TH4_PpSQ29v49gzX3WH5nOVNVER1iTYJRSbEEeEgaQ1q7gOsutuweTIAWDz50SBp2y5Eo4SGuzhp2r7wWoIUGUpn01mwhSa9OiS9LaJ-BMmbQ6d28bukEq-wQSOhmU7BCM-_7XD-kF2CTCmgjSRg8SJr3OtujhGnrTHRPICF_R2hfhNmm1aDe8XfO1XOCmqJumYpwKsThuhKZCi5a2dZ7NbaVKVdNG61qLsjyscWE2jDJOGWsKwQUVKxRYlFUphKJr3kgkJcVeGrvK9ctFWIyiv6kLyunCSoU2jvc9xhx-hdFIGMvXv7AZa66GLpKSWhNTfEVJJlncvCi2dxCyFneYxiIchogtqKcfifNiCHbz69eV0fn_BQAA__-Xw0nZ">