[LLVMdev] Still Another LiveInterval Question

David Greene dag at cray.com
Thu Jan 17 14:06:51 PST 2008

Ok, so I'm delving much more deeply into this stuff.  :)

On a target like x86, is it true to say that for virtual registers post 
phi-elimination, the only  time their live intervals should have more than one 
value number is if they participate in 2-address instructions where a copy had 
to be introduced to satisfy the read-write requirements of the instruction?  
And further, in that  case, LiveIntervals for virtual registers should only 
have at most two value numbers?

How about on targets without these reuiqrements?  Should LiveIntervals for 
virtual registers only ever have one value number?


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