[llvm-commits] [PATCH 2/3] Remove workaround in PostDominators

[Dan Gohman]

On Jan 6, 2010, at 3:27 PM, Tobias Grosser wrote:

> 
> Remove a FIXME and unify code that was necessary to work around broken
> updateDFSNumbers().  Before updateDFSNumbers() did not work correctly for post
> dominators.

-  
-  // FIXME: This does not work on PostDomTrees.  It seems likely that this is
-  // due to an error in the algorithm for post-dominators.  This really should
-  // be investigated and fixed at some point.
-  // DT.updateDFSNumbers();
-
-  // Start out with the DFS numbers being invalid.  Let them be computed if
-  // demanded.
-  DT.DFSInfoValid = false;
+
+  DT.updateDFSNumbers();

Wouldn't it be better to do what the code was doing -- just set
DFSInfoValid to false and let the value be recomputed lazily,
instead of eagerly updating all the DFS numbers?

Dan