[Mlir-commits] [mlir] e6e0e2b - [mlir][DataFlow] Fix crash in TestLastModifiedPass for unreachable private functions (#186160)

[llvmlistbot at llvm.org]

Author: Mehdi Amini
Date: 2026-03-12T16:18:24Z
New Revision: e6e0e2b57ee8e9b3037f4ea56dce3d0df35bcc77

URL: https://github.com/llvm/llvm-project/commit/e6e0e2b57ee8e9b3037f4ea56dce3d0df35bcc77
DIFF: https://github.com/llvm/llvm-project/commit/e6e0e2b57ee8e9b3037f4ea56dce3d0df35bcc77.diff

LOG: [mlir][DataFlow] Fix crash in TestLastModifiedPass for unreachable private functions (#186160)

TestLastModifiedPass asserted that a dense lattice state is always
present after running the data flow solver. However, in interprocedural
analysis mode (the default), private functions that are never called
from any callee in the module are not analyzed, so no lattice state is
computed for their program points.

Replace the assertion with a null check that prints "<not computed>"
when the lattice state is absent. This matches the expected behavior:
unreachable code in interprocedural mode simply has no computed analysis
result.

Add a regression test for the case where a tagged op is inside an
unreachable private function.

Fixes #128333

Assisted-by: Claude Code

Added: 
    

Modified: 
    mlir/test/Analysis/DataFlow/test-last-modified.mlir
    mlir/test/lib/Analysis/DataFlow/TestDenseForwardDataFlowAnalysis.cpp

Removed: 
    


################################################################################
diff  --git a/mlir/test/Analysis/DataFlow/test-last-modified.mlir b/mlir/test/Analysis/DataFlow/test-last-modified.mlir
index 43326614d6793..da22fdbf56e84 100644
--- a/mlir/test/Analysis/DataFlow/test-last-modified.mlir
+++ b/mlir/test/Analysis/DataFlow/test-last-modified.mlir
@@ -348,3 +348,14 @@ func.func @store_with_a_loop_region_after_containing_a_store(%arg0: memref<f32>)
   memref.store %1, %arg0[] {tag_name = "post"} : memref<f32>
   return {tag = "return"} %arg0 : memref<f32>
 }
+
+// Regression test for https://github.com/llvm/llvm-project/issues/128333:
+// In interprocedural analysis mode, private functions that are never called
+// should not cause an assertion failure when querying the dense lattice.
+// Instead, the pass should gracefully report "<not computed>".
+// CHECK-LABEL: test_tag: tag_in_unreachable_private
+// CHECK-NEXT:   - <not computed>
+func.func private @unreachable_private(%arg0: i32) {
+  %cond = arith.index_cast %arg0 {tag = "tag_in_unreachable_private"} : i32 to index
+  return
+}

diff  --git a/mlir/test/lib/Analysis/DataFlow/TestDenseForwardDataFlowAnalysis.cpp b/mlir/test/lib/Analysis/DataFlow/TestDenseForwardDataFlowAnalysis.cpp
index a88ed7f8dea8b..9236e98168883 100644
--- a/mlir/test/lib/Analysis/DataFlow/TestDenseForwardDataFlowAnalysis.cpp
+++ b/mlir/test/lib/Analysis/DataFlow/TestDenseForwardDataFlowAnalysis.cpp
@@ -256,7 +256,13 @@ struct TestLastModifiedPass
       os << "test_tag: " << tag.getValue() << ":\n";
       const LastModification *lastMods =
           solver.lookupState<LastModification>(solver.getProgramPointAfter(op));
-      assert(lastMods && "expected a dense lattice");
+      if (!lastMods) {
+        // The lattice may not be computed for operations in unreachable code
+        // (e.g., private functions not called from anywhere in interprocedural
+        // analysis mode).
+        os << " - <not computed>\n";
+        return;
+      }
       for (auto [index, operand] : llvm::enumerate(op->getOperands())) {
         os << " operand #" << index << "\n";
         std::optional<Value> underlyingValue =