[Mlir-commits] [mlir] [mlir][CSE] fix use-after-free (PR #203849)

[Mehdi Amini]

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@@ -162,6 +162,11 @@ void CSEDriver::replaceUsesAndDelete(ScopedMapTy &knownValues, Operation *op,
   if (isa<UnknownLoc>(existing->getLoc()) && !isa<UnknownLoc>(op->getLoc()))
     existing->setLoc(op->getLoc());
 
+  // Deletion of the dead current op can only be done here, and not before,
+  // because the its location is still read above.
+  if (opIsDead)
+    eraseDeadOp(op);
+
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joker-eph wrote:

Instead of delaying the erasure, seem to me we can move the location assignment earlier instead? (and the `++numCSE;` as well.

Also adding early returns immediately after the erasure would make the control flow more clear.

I think we can just remove the `else` (no else after return) then.

https://github.com/llvm/llvm-project/pull/203849