[Mlir-commits] [mlir] [mlir] Make remove-dead-values remove block and successorOperands before delete ops (PR #166766)

[Mehdi Amini]

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@@ -742,7 +742,48 @@ static void processBranchOp(BranchOpInterface branchOp, RunLivenessAnalysis &la,
 static void cleanUpDeadVals(RDVFinalCleanupList &list) {
   LDBG() << "Starting cleanup of dead values...";
 
-  // 1. Operations
+  // 1. Blocks
+  LDBG() << "Cleaning up " << list.blocks.size() << " block argument lists";
+  for (auto &b : list.blocks) {
+    // blocks that are accessed via multiple codepaths processed once
+    if (b.b->getNumArguments() != b.nonLiveArgs.size())
+      continue;
+    LDBG() << "Erasing " << b.nonLiveArgs.count()
+           << " non-live arguments from block: " << b.b;
+    // it iterates backwards because erase invalidates all successor indexes
+    for (int i = b.nonLiveArgs.size() - 1; i >= 0; --i) {
+      if (!b.nonLiveArgs[i])
+        continue;
+      LDBG() << "  Erasing block argument " << i << ": " << b.b->getArgument(i);
+      b.b->getArgument(i).dropAllUses();
+      b.b->eraseArgument(i);
+    }
+  }
+
+  // 2. Successor Operands
+  LDBG() << "Cleaning up " << list.successorOperands.size()
+         << " successor operand lists";
+  for (auto &op : list.successorOperands) {
+    SuccessorOperands successorOperands =
+        op.branch.getSuccessorOperands(op.successorIndex);
+    // blocks that are accessed via multiple codepaths processed once
+    if (successorOperands.size() != op.nonLiveOperands.size())
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joker-eph wrote:

Note @matthias-springer : this is mostly code motion from existing code (see the left side of the diff)

https://github.com/llvm/llvm-project/pull/166766