[LLVMdev] visitBIT_CONVERT (previous Shouldn't DAGCombine insert legal nodes?)

[Scott Michel]

On Mar 5, 2009, at 12:15 PM, Duncan Sands wrote:
>> 2) Is there any bug report generated after the discussion below?
>
> I don't know, sorry.

Gabriele, Duncan, et. al.:

No, I never created a bug report. I did post some thoughts in a post  
entitled "DAGCombiner rants", expressing my frustration. Your best  
bet is to make your backend lower 64-bit constants during instruction  
selection (the ISelDAGtoDAG.cpp source) rather than fight  
DAGCombiner. Fighting DAGCombiner is a losing battle.

I would definitely concur that the whole concept of Legal vs. Custom  
vs. Promote vs. Expand needs a rethink and refactoring. It seems to  
me that the functionality is now badly overloaded, now that they mean  
different things during different DAG to instruction selection phases.


-scooter