[Mlir-commits] [mlir] [MLIR] Removing dead values for branches (PR #117501)

[Renat Idrisov]

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@@ -563,6 +575,48 @@ static void cleanRegionBranchOp(RegionBranchOpInterface regionBranchOp,
   dropUsesAndEraseResults(regionBranchOp.getOperation(), resultsToKeep.flip());
 }
 
+// 1. Iterate over each successor block of the given BranchOpInterface
+// operation.
+// 2. For each successor block:
+//    a. Retrieve the operands passed to the successor.
+//    b. Use the provided liveness analysis (`RunLivenessAnalysis`) to determine
+//    which
+//       operands are live in the successor block.
+//    c. Mark each operand as live or dead based on the analysis.
+// 3. Remove dead operands from the branch operation and arguments accordingly
+
+static void cleanBranchOp(BranchOpInterface branchOp, RunLivenessAnalysis &la) {
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parsifal-47 wrote:

I added such test, but after looking closely I realized that `walk` and `walk<WalkOrder::PostOrder>` does not help with BranchOp, probably because they do not have parent-child relation. Sorry, I was wrong, it does not reapply iteratively by itself. I am going to add a recursion in some form and let you know.

https://github.com/llvm/llvm-project/pull/117501