[LLVMdev] Def/Kill flags for subregisters

[Jakob Stoklund Olesen]

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?

/jakob