[PATCH] D23559: [ADCE] Add control dependence computation

[David Callahan via llvm-commits]

david2050 added inline comments.

================
Comment at: lib/Transforms/Scalar/ADCE.cpp:459
@@ -395,2 +458,3 @@
   void getAnalysisUsage(AnalysisUsage &AU) const override {
-    AU.setPreservesCFG();
+    AU.addRequired<PostDominatorTreeWrapperPass>();
+    AU.setPreservesCFG(); // TODO -- will remove when we start removing branches
----------------
mehdi_amini wrote:
> How expensive is this?
In email, Daniel Berlin discusses this as well.

I measured ~400 cpp source files internally and impact is about ~0.6% (that is end to end starting with C++ source)


https://reviews.llvm.org/D23559