<table border="1" cellspacing="0" cellpadding="8">
    <tr>
        <th>Issue</th>
        <td>
            <a href=https://github.com/llvm/llvm-project/issues/163343>163343</a>
        </td>
    </tr>

    <tr>
        <th>Summary</th>
        <td>
            [mlir] null pointer UBSan alert in mlir/lib/IR/Diagnostics.cpp
        </td>
    </tr>

    <tr>
      <th>Labels</th>
      <td>
            mlir
      </td>
    </tr>

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

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

<pre>
    PoC:
```
 // expected-warning @unknown {{could not cast operand of type 'f16' to 'vector<4xf16>'}}
```

stderr:
```
/home/phpfuzz/WorkSpace/llvm-project/mlir/lib/IR/Diagnostics.cpp:599:71: runtime error: applying non-zero offset 55 to null pointer
    #0 0x5c8f982fe1e9 in mlir::detail::ExpectedDiag::emitError(llvm::raw_ostream&, llvm::SourceMgr&, llvm::Twine const&) /home/phpfuzz/WorkSpace/llvm-project/mlir/lib/IR/Diagnostics.cpp:599:71
 #1 0x5c8f982fabb3 in mlir::SourceMgrDiagnosticVerifierHandler::verify()::$_8::operator()(mlir::detail::ExpectedDiag&) const /home/phpfuzz/WorkSpace/llvm-project/mlir/lib/IR/Diagnostics.cpp:844:15
 #2 0x5c8f982fa4dd in mlir::SourceMgrDiagnosticVerifierHandler::verify() /home/phpfuzz/WorkSpace/llvm-project/mlir/lib/IR/Diagnostics.cpp:852:5
 #3 0x5c8f982fa08d in mlir::SourceMgrDiagnosticVerifierHandler::~SourceMgrDiagnosticVerifierHandler() /home/phpfuzz/WorkSpace/llvm-project/mlir/lib/IR/Diagnostics.cpp:833:9
 #4 0x5c8f854b74f9 in mlir::MlirOptMain(llvm::raw_ostream&, std::unique_ptr<llvm::MemoryBuffer, std::default_delete<llvm::MemoryBuffer> >, mlir::DialectRegistry&, mlir::MlirOptMainConfig const&) /home/phpfuzz/WorkSpace/llvm-project/mlir/lib/Tools/mlir-opt/MlirOptMain.cpp:746:1
 #5 0x5c8f854b7e6d in mlir::MlirOptMain(int, char**, llvm::StringRef, llvm::StringRef, mlir::DialectRegistry&) /home/phpfuzz/WorkSpace/llvm-project/mlir/lib/Tools/mlir-opt/MlirOptMain.cpp:784:14
 #6 0x5c8f854b85c2 in mlir::MlirOptMain(int, char**, llvm::StringRef, mlir::DialectRegistry&) /home/phpfuzz/WorkSpace/llvm-project/mlir/lib/Tools/mlir-opt/MlirOptMain.cpp:800:10
 #7 0x5c8f852d03ce in main /home/phpfuzz/WorkSpace/llvm-project/mlir/tools/mlir-opt/mlir-opt.cpp:343:33
 #8 0x781ff9447d8f in __libc_start_call_main csu/../sysdeps/nptl/libc_start_call_main.h:58:16
    #9 0x781ff9447e3f in __libc_start_main csu/../csu/libc-start.c:392:3
    #10 0x5c8f8520fb64 in _start (/home/phpfuzz/WorkSpace/llvm-mlir-build/bin/mlir-opt+0x8381b64) (BuildId: 8d3f598c321c686de3addc0e0905b4ae76916fb7)

SUMMARY: UndefinedBehaviorSanitizer: undefined-behavior /home/phpfuzz/WorkSpace/llvm-project/mlir/lib/IR/Diagnostics.cpp:599:71 in 
```
</pre>
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