<table border="1" cellspacing="0" cellpadding="8">
    <tr>
        <th>Issue</th>
        <td>
            <a href=https://github.com/llvm/llvm-project/issues/128333>128333</a>
        </td>
    </tr>

    <tr>
        <th>Summary</th>
        <td>
            [MLIR]`-test-last-modified` triggers Assertion Failure `lastMods && "expected a dense lattice"'
        </td>
    </tr>

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

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

    <tr>
      <th>Reporter</th>
      <td>
          xisang0
      </td>
    </tr>
</table>

<pre>
    Test on commit: https://github.com/llvm/llvm-project/commit/dca2ed31278c444f839e3e04fde0c21b62451d4a
steps to reproduce:
```
mlir-opt test.mlir -test-last-modified
```
test case:
```
module {
  func.func private @private2(%0 : i32) -> () {
 %cond = arith.index_cast %0 {tag = "in_private2"} : i32 to index
 return
  }
}
```
crash trace:
```
test_tag: in_private2:
mlir-opt: /home/workdir/llvm-project-19/mlir/test/lib/Analysis/DataFlow/TestDenseForwardDataFlowAnalysis.cpp:248: auto (anonymous namespace)::TestLastModifiedPass::runOnOperation()::(anonymous class)::operator()(Operation *) const: Assertion `lastMods && "expected a dense lattice"' failed.
PLEASE submit a bug report to https://github.com/llvm/llvm-project/issues/ and include the crash backtrace.
Stack dump:
0.      Program arguments: ./mlir-opt /home/workdir/test.mlir -test-last-modified
 #0 0x0000618e1a45a258 llvm::sys::PrintStackTrace(llvm::raw_ostream&, int) (./mlir-opt+0x10b5258)
 #1 0x0000618e1a457d7e llvm::sys::RunSignalHandlers() (./mlir-opt+0x10b2d7e)
 #2 0x0000618e1a45ac68 SignalHandler(int) Signals.cpp:0:0
 #3 0x00007893d57c2520 (/lib/x86_64-linux-gnu/libc.so.6+0x42520)
 #4 0x00007893d58169fc pthread_kill (/lib/x86_64-linux-gnu/libc.so.6+0x969fc)
 #5 0x00007893d57c2476 gsignal (/lib/x86_64-linux-gnu/libc.so.6+0x42476)
 #6 0x00007893d57a87f3 abort (/lib/x86_64-linux-gnu/libc.so.6+0x287f3)
 #7 0x00007893d57a871b (/lib/x86_64-linux-gnu/libc.so.6+0x2871b)
 #8 0x00007893d57b9e96 (/lib/x86_64-linux-gnu/libc.so.6+0x39e96)
 #9 0x0000618e1d3016cc void llvm::function_ref<void (mlir::Operation*)>::callback_fn<(anonymous namespace)::TestLastModifiedPass::runOnOperation()::'lambda'(mlir::Operation*)>(long, mlir::Operation*) TestDenseForwardDataFlowAnalysis.cpp:0:0
#10 0x0000618e1a56e04e void mlir::detail::walk<mlir::ForwardIterator>(mlir::Operation*, llvm::function_ref<void (mlir::Operation*)>, mlir::WalkOrder) (./mlir-opt+0x11c904e)
#11 0x0000618e1a56e04e void mlir::detail::walk<mlir::ForwardIterator>(mlir::Operation*, llvm::function_ref<void (mlir::Operation*)>, mlir::WalkOrder) (./mlir-opt+0x11c904e)
#12 0x0000618e1d2ff48a (anonymous namespace)::TestLastModifiedPass::runOnOperation() TestDenseForwardDataFlowAnalysis.cpp:0:0
#13 0x0000618e1d84fbcf mlir::detail::OpToOpPassAdaptor::run(mlir::Pass*, mlir::Operation*, mlir::AnalysisManager, bool, unsigned int) (./mlir-opt+0x44aabcf)
#14 0x0000618e1d850352 mlir::detail::OpToOpPassAdaptor::runPipeline(mlir::OpPassManager&, mlir::Operation*, mlir::AnalysisManager, bool, unsigned int, mlir::PassInstrumentor*, mlir::PassInstrumentation::PipelineParentInfo const*) (./mlir-opt+0x44ab352)
#15 0x0000618e1d852ade mlir::PassManager::run(mlir::Operation*) (./mlir-opt+0x44adade)
#16 0x0000618e1d84b62b performActions(llvm::raw_ostream&, std::shared_ptr<llvm::SourceMgr> const&, mlir::MLIRContext*, mlir::MlirOptMainConfig const&) MlirOptMain.cpp:0:0
#17 0x0000618e1d84b283 llvm::LogicalResult llvm::function_ref<llvm::LogicalResult (std::unique_ptr<llvm::MemoryBuffer, std::default_delete<llvm::MemoryBuffer>>, llvm::raw_ostream&)>::callback_fn<mlir::MlirOptMain(llvm::raw_ostream&, std::unique_ptr<llvm::MemoryBuffer, std::default_delete<llvm::MemoryBuffer>>, mlir::DialectRegistry&, mlir::MlirOptMainConfig const&)::$_0>(long, std::unique_ptr<llvm::MemoryBuffer, std::default_delete<llvm::MemoryBuffer>>, llvm::raw_ostream&) MlirOptMain.cpp:0:0
#18 0x0000618e1d8f49e5 mlir::splitAndProcessBuffer(std::unique_ptr<llvm::MemoryBuffer, std::default_delete<llvm::MemoryBuffer>>, llvm::function_ref<llvm::LogicalResult (std::unique_ptr<llvm::MemoryBuffer, std::default_delete<llvm::MemoryBuffer>>, llvm::raw_ostream&)>, llvm::raw_ostream&, llvm::StringRef, llvm::StringRef) (./mlir-opt+0x454f9e5)
#19 0x0000618e1d844ee2 mlir::MlirOptMain(llvm::raw_ostream&, std::unique_ptr<llvm::MemoryBuffer, std::default_delete<llvm::MemoryBuffer>>, mlir::DialectRegistry&, mlir::MlirOptMainConfig const&) (./mlir-opt+0x449fee2)
#20 0x0000618e1d845193 mlir::MlirOptMain(int, char**, llvm::StringRef, llvm::StringRef, mlir::DialectRegistry&) (./mlir-opt+0x44a0193)
#21 0x0000618e1d8453a2 mlir::MlirOptMain(int, char**, llvm::StringRef, mlir::DialectRegistry&) (./mlir-opt+0x44a03a2)
#22 0x0000618e1a439477 main (./mlir-opt+0x1094477)
#23 0x00007893d57a9d90 (/lib/x86_64-linux-gnu/libc.so.6+0x29d90)
#24 0x00007893d57a9e40 __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x29e40)
#25 0x0000618e1a438fe5 _start (./mlir-opt+0x1093fe5)
```
</pre>
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