[LLVMdev] [llvmdev] Whole function SelectionDAG

Zhongxing Xu xuzhongxing at gmail.com
Fri Jun 11 18:53:54 PDT 2010


On Sat, Jun 12, 2010 at 12:35 AM, Dan Gohman <gohman at apple.com> wrote:

>
>
> On Jun 11, 2010, at 12:48 AM, Zhongxing Xu <xuzhongxing at gmail.com> wrote:
>
>  I have another idea: let the BasicBlockSDNode points to the last node in
>> its predecessor blocks. But this will introduce cycles into the selection
>> DAG, making it not a DAG anymore.
>>
>> So what's the impact of a non-DAG on the existing DAG legalizers and
>> combiner?
>>
>
> Lots of stuff would break, for example anything that uses the topological
> sort facility.
>
> But I guess non-DAG is inevitable since there is loop in the code and I
want to represent control relationships in the graph.
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