<table border="1" cellspacing="0" cellpadding="8">
    <tr>
        <th>Issue</th>
        <td>
            <a href=https://github.com/llvm/llvm-project/issues/75507>75507</a>
        </td>
    </tr>

    <tr>
        <th>Summary</th>
        <td>
            [X86] UNREACHABLE executed at llvm\lib\Target\X86\X86FlagsCopyLowering.cpp
        </td>
    </tr>

    <tr>
      <th>Labels</th>
      <td>
            backend:X86
      </td>
    </tr>

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

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

<pre>
    Reduced from https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=64822
```ll
define fastcc void @func() {
entry:
  br label %bb5

bb5: ; preds = %entry
  %C33 = fcmp true float 0x36A0000000000000, 0x36A0000000000000
  %B43 = or i1 %C33, true
  br i1 %B43, label %overflow, label %bb7

bb7: ; preds = %bb5
  br label %bb8

bb8: ; preds = %bb8, %bb7
  %L7 = load i128, ptr null, align 4
  %C19 = icmp sgt i128 %L7, 18446744073709551616
  %G21 = getelementptr i128, ptr null, i1 %C19
  store ptr %G21, ptr undef, align 8
  br i1 %C19, label %bb8, label %BB2

BB2: ; preds = %bb8
  unreachable

overflow: ; preds = %bb5
  ret void
}
```
llc -mtriple=x86_64-- fuzz.ll -o -
```asm
 .text
        .file   "fuzz.ll"
Unlowered EFLAGS copy!
UNREACHABLE executed at E:\llvm\llvm-project\llvm\lib\Target\X86\X86FlagsCopyLowering.cpp:706!
PLEASE submit a bug report to https://github.com/llvm/llvm-project/issues/ and include the crash backtrace.
Stack dump:
0.      Program arguments: ninja\\bin\\llc -mtriple=x86_64-- fuzz.ll -o -
1.      Running pass 'Function Pass Manager' on module 'fuzz.ll'.
2.      Running pass 'X86 EFLAGS copy lowering' on function '@func'
Exception Code: 0x80000003
 #0 0x00007ff6f1cad7d5 HandleAbort E:\llvm\llvm-project\llvm\lib\Support\Windows\Signals.inc:424:0
 #1 0x00007ff862e51881 (C:\Windows\System32\ucrtbase.dll+0x71881)
 #2 0x00007ff862e52851 (C:\Windows\System32\ucrtbase.dll+0x72851)
 #3 0x00007ff6f1bcc087 llvm::llvm_unreachable_internal(char const *, char const *, unsigned int) E:\llvm\llvm-project\llvm\lib\Support\ErrorHandling.cpp:212:0
 #4 0x00007ff6f011cb72 `anonymous namespace'::X86FlagsCopyLoweringPass::runOnMachineFunction E:\llvm\llvm-project\llvm\lib\Target\X86\X86FlagsCopyLowering.cpp:706:0
```
</pre>
<img width="1px" height="1px" alt="" src="http://email.email.llvm.org/o/eJy0Vltv2zoS_jX0yyCGROrmBz_ItxbYdLdIdrF9KyhqJLOlSIGkWqe__oCS4kua4BQBjmHY4pDzzcw35Cdy52SrEdck3ZB0t-CDPxq7fvjXo-yMXlSmflo_YD0IrKGxpoOj970jrCT0QOihGlq3FEdrOjl0S2NbQg89oQfj3F0z_PpF6EE6N6Aj9FCj51IRdpA1YbssKSgl0Y5EJcmi6avUZKixkRqh4c4LAT-MrIEkUTNoQWhB6ApIvplWovb2KWQzjgAqC4pXqIDQtKrSGX_8DUNWAmEb6C3WDgjbhWUTxOxPaLplbJxqRNeDtwNCowz3EJ1YVkbXH0K3r1kvUJtkgjIWZDxjB6eAepXxNLdJxrlz-uYH2kaZnzfGqspva8pfrelc-ktGilvv4g3vIgS9DjeWc5-PK5ThNciYjot6b0EPSoVnrmSrIbnmMl6NLjJw6Vo_uk1QwSEukiTLkyTKWR6t0jTO4uzK-wONR-8WPSrsUPsQ7bXIM7vx6tnbeWNxXDLhPDsMusbmkmvxWxcCxi3hxc14s6HXFIbhWxTO0IO2yMWRVwqvPc_t_Zv-WfTjCZh9892LMzMNlRJw13kre4WE7U5F9jVL7u4gnMGlUnBn4O6FI3fdHGPp8eSf402fZSMVQugCnSHI82n9n1bmJ1qsYX-4Lz88gjD9E6HxPPvvh325_Vhu7veAJxSDxxq4h304pOlWqR_d_HfXW_MNhb-yyoqk2_9y22Kwfimy6fegeOu2pn-6D4Glbpei7wkr8yg7x_18vy8f9-CGqpMeOFRDCxZ7Yz1480K0WumPQ7UUpiP0MMae_s4ZXYkWcF2D1EINNYI_IgjL3REqLr57ywUup_CPnovvUA9dfxajaDlR-dma1vIOuG2HsIdDHqCl_sZJuiXptpJ6evjzHsYz9MOgtdQt9Nw5IDQ_DFp4aTR8DoZPXPMWLaE5GA2dqQeFYdW5ofmcPH0D7kuRXfcY1Ez_jNg8RyM0P8vzrBf7k8B-nNyaGkPF0amY9JHNO41QFkF0Cqa8abImFrzO6xQ-cl0rLKvQuj_fNY9DH5pN0u3_pa7NTxdsstVcuaXUgrAyoQlhZXSJHl-iFxnFNC6KIAHFdgp6hfPkPHaMknQ7COsr7nBZBwI30SkPXoSuLrD0BSwt0nfABq8bWHbDVSVEVOQwUsBKwsrw9PVKar5K7dFqrggtxJFbEEY7D4SWQc5-twx6vAeEve7DG_Y9zO-tNXZs3-WM0pjesp5c1xHFsahyCkGOtNFPnRkcaN6h67nAsJvG4l7TgLDFp1k76P_oT1wcpcbzCfin9OZcy1lHF_Wa1Su24gtcx3lE0zxb5cXiuI7zVRzX1YoXjDJRJatUMGSYoRAxj6p0Idc0oiymcRIXEU2LZcUF5RSblWANQ1yRJMKOS7UMCYfb1WLUpXWeplG-GN9Jbry4URoECXU9kRW0Ot0t7HqsO9zRSBIp6by7IHnp1XjrG8vewVvC_R6uFoNV6_dr7ljeXwEAAP__vFoXOg">