[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:826
+    auto *PDT = PDTWP ? &PDTWP->getPostDomTree() : nullptr;
+    DomTreeUpdater DTU(DT, PDT, DomTreeUpdater::UpdateStrategy::Eager);
+
----------------
NutshellySima wrote:
> kuhar wrote:
> > Why is Eager better than Lazy here?
> I ran `opt` using the newPM O3 pipeline using both strategies on three bitcode files (clang-preopt/clang-opt/SQLite), and observed a performance difference of approximately 0.1%, which can be considered as noise.
> 
> There is actually no strong preference of using either one because both work fine from my test. (After applying D50173).
> So I'd better left it not commented.
I'd rather you left a comment here saying there's no difference for the tests we ran and we can later switch to Lazy in the future, if that proves to be profitable.


https://reviews.llvm.org/D49982