[PATCH] D49982: [TailCallElim] Preserve DT and PDT

[Jakub Kuderski via Phabricator via llvm-commits]

kuhar added inline comments.


================
Comment at: lib/Transforms/Scalar/TailRecursionElimination.cpp:596
     }
+    DTU.recalculate(*NewEntry->getParent());
   }
----------------
Can you add a comment explaining why we have to recalculate here?


================
Comment at: lib/Transforms/Scalar/TailRecursionElimination.cpp:826
+    auto *PDT = PDTWP ? &PDTWP->getPostDomTree() : nullptr;
+    DomTreeUpdater DTU(DT, PDT, DomTreeUpdater::UpdateStrategy::Eager);
+
----------------
Why is Eager better than Lazy here?


================
Comment at: lib/Transforms/Scalar/TailRecursionElimination.cpp:857
+  auto *PDT = AM.getCachedResult<PostDominatorTreeAnalysis>(F);
+  DomTreeUpdater DTU(DT, PDT, DomTreeUpdater::UpdateStrategy::Eager);
+  bool Changed = eliminateTailRecursion(F, &TTI, &AA, &ORE, DTU);
----------------
Same as above.


https://reviews.llvm.org/D49982