[LLVMdev] visitBIT_CONVERT (previous Shouldn't DAGCombine insert legal nodes?)
Scott Michel
scottm at aero.org
Fri Mar 6 16:46:18 PST 2009
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
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