[PATCH] D35279: [Dominators] Improve reachability verification

[Daniel Berlin via Phabricator via llvm-commits]

dberlin added inline comments.


================
Comment at: include/llvm/Support/GenericDomTreeConstruction.h:302
 
-      if (NodeToInfo.count(BB) == 0) {
+      // Virtual root doesn't have a corresponding CFG node.
+      if (DT.isVirtualRoot(TN)) continue;
----------------
It's more accurate to state that the virtual root *is* a cfg node. Or at least it was.
At least as used previously, the  virtual root was not really a dom tree root, it was really the thing that contained the edges to the blocks.

The virtual dom tree root was then the dom tree node that got built for the virtual cfg root.

I don't know if this is still the case.


================
Comment at: include/llvm/Support/GenericDomTreeConstruction.h:305
+
+      if (!BB || NodeToInfo.count(BB) == 0) {
         errs() << "DomTree node ";
----------------
When is it possible to have !BB but it's not a virtual root?
If it's really possible, please document this condition.


https://reviews.llvm.org/D35279