[LLVMdev] Increasing TargetRegisterInfo::FirstVirtualRegister?

[Dale Johannesen]

We might want to make physical registers negative and virtuals positive, or vice versa.   Then FirstVirtualRegister is 0 or 1, and we could get rid of those annoying subtractions of FirstVirtualRegister all over the virtual-register-handling passes.  Since 0 is used all over the place as "invalid register" it is probably best to leave this alone, let FirstVirtualRegister be 1, and simply ignore (i.e. treat as erroneous) the 0th element of anything keyed off FirstVirtualRegister.

On Jan 7, 2011, at 11:08 AMPST, Andrew Clinton wrote:

> On 01/07/2011 02:07 AM, Chris Lattner wrote:
>> 
>> Unless your goal is to merge this work onto LLVM mainline, the best thing to do is a local hack in your tree.
>> 
>> -Chris
> 
> Yes, I will create a patch for my tree to increase 
> FirstVirtualRegister.  Would this be a good change to include in 2.9?
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