[Mlir-commits] [mlir] [MLIR][RemoveDeadValues] Fix affine.for induction variable incorrectly removed (PR #172612)

[Francisco Geiman Thiesen]

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@@ -327,6 +328,32 @@ RunLivenessAnalysis::RunLivenessAnalysis(Operation *op) {
   solver.load<LivenessAnalysis>(symbolTable);
   LDBG() << "Initializing and running solver";
   (void)solver.initializeAndRun(op);
+
+  // Mark block arguments of RegionBranchOpInterface ops that are NOT successor
+  // inputs as live. These include induction variables (IVs) like those in
+  // affine.for or scf.for. The fix in visitBranchOperand() only handles this
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FranciscoThiesen wrote:

I've updated the comment.

In a bit more detail, after the last commit:
  - visitBranchOperand() handles region-to-region transitions but is only called when non-forwarded operands exist
  - This fix handles parent-to-region transitions unconditionally
  - They are complementary: visitBranchOperand() is still relevant for ops that have non-forwarded operands, and it does other things beyond
  marking IVs (memory effect checks, result liveness propagation)
  - This fix ensures IVs are caught regardless of whether visitBranchOperand() runs

https://github.com/llvm/llvm-project/pull/172612