[LLVMdev] Dominance frontier & Postdominance frontier

[Sahoo, Swarup Kumar]

Hi,

    I found that LLVM 3.1 says Dominance frontier is deprecated. Can anyone please tell me, if there is any replacement for Dominance frontier & Postdominance frontier in LLVM? What are the options if we need to use them?

Thanks,
Swarup.

[John Criswell]

On 9/13/12 10:18 AM, Sahoo, Swarup Kumar wrote:

Hi,

    I found that LLVM 3.1 says Dominance frontier is deprecated. Can anyone please tell me, if there is any replacement for Dominance frontier & Postdominance frontier in LLVM? What are the options if we need to use them?

You may want to read this thread on llvmdev from August:

http://lists.cs.uiuc.edu/pipermail/llvmdev/2012-August/052682.html

Marco's reply mentions an alternative algorithm in Muchnick's compiler book.  I believe the algorithm in Section 7.3 of Allen and Kennedy uses the post dominator tree only.

-- John T.

Thanks,
Swarup.

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[Das, Dibyendu]

You can easily calculate the DF(x) of a node if you have the J-edges. Look at V Sreedhar's classic thesis on DJ graphs. Look at our work in TOPLAS 2005 for computing DF and phi using DJ graphs. Its pretty straightforward if u hv the dom tree and J-edges. J-edges are nothing else but CFG edges which are not present in the dominator tree.

Hope this helps. Post-dom-frontier is an analogous problem on the reverse cfg and pdom tree.

- Dibyendu