[LLVMdev] Does the pass -postdomfrontier exist?

[Daniel Berlin]

On Fri, Jul 13, 2012 at 5:35 AM, Duncan Sands <baldrick at free.fr> wrote:
> Hi shadowkernel,
>
>> I searched the archives and found
>> http://llvm.1065342.n5.nabble.com/post-dominance-frontier-fix-td10221.html
>> http://llvm.1065342.n5.nabble.com/Is-there-a-control-dependence-graph-builder-td35919.html#a35921
>> http://llvm.1065342.n5.nabble.com/post-dominance-frontier-td6783.html
>>
>> It seems none of them are relevant.  Could you give me more hints about
>> this topic? Thanks!
>
> I'm not sure this is what I had in mind, but it does explain the issues with
> dominance frontiers in general:
>
> http://lists.cs.uiuc.edu/pipermail/llvmdev/2012-January/046638.html

Also, PostDominators is broken in various ways in a number of edge
cases (nick llewycky had emailed me some), so in all likelihood there
are edge cases where post dominance frontiers are broken as well.

In any case, as Duncan's quoted emails point out, computing
post-dominance frontiers for the entire function is expensive but not
really useful.