[llvm-commits] [PATCH] Make SimplifyCFGPass preserve the dominator tree

[Peter Cooper]

On Jun 8, 2012, at 2:55 PM, John Criswell wrote:

> On 6/8/12 12:47 PM, Peter Cooper wrote:
>> 
>> Hi all
>> 
>> Attached is a pass to make the SimplifyCFGPass preserve the dominator tree.  Currently we see lots of               recalculations of the dom tree right after simplify cfg runs, regardless of whether simplify cfg actually did               anything.
> 
> Does SimplifyCFGPass return false from its run method when it doesn't change anything?  If so, does the PassManager just invalidate DomTree anyway because SimplifyCFGPass does not claim to preserve it?
It does return false in this case, yeah, but the pass manager actually invalidates it anyway.  I don't think it trusts the return value because some passes (like simplify lib calls) actually return false even if they did something.

Pete
> 
> -- John T.
> 
>> 
>> Thanks,
>> Pete
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> 

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