[LLVMdev] Def/Kill flags for subregisters

Jakob Stoklund Olesen stoklund at 2pi.dk
Wed Apr 22 09:25:55 PDT 2009

Evan, thanks for clarifying.

On 22/04/2009, at 17.45, Evan Cheng wrote:

> I think you have probably run into a bug in one of the passes. It's
> probably the coalescer. It's tricky to get the sub-register liveness
> right.

I think you are right. The bad kill seems to be introduced by the  
coalescer. I will take a look at it.

I have written a machine code verifier pass that checks the def/kill  
rules, see PR408. Currently it finds a lot of multiply defined  
registers in targets using subregisters (X86 and Blackfin).

I would like to fix this in LiveVariables / LiveIntervals. Are there  
any major roadblocks I should be aware of?


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