[llvm-commits] [llvm][PATCH][Review Requested][Version 2!] Don't check liveness of unallocatable registers

[Jakob Stoklund Olesen]

On May 9, 2012, at 1:24 AM, Anton Korobeynikov <anton at korobeynikov.info> wrote:

> Hi Preston,
> 
> This looks like a hiding the real problem to me.
> 
>> This includes registers like EFLAGS and ST0-ST7. We don't check for
>> liveness issues in the verifier and scavenger because registers will
>> never be allocated from these classes.
> But still instructions can define / use EFLAGS and late codegen passes
> can insert such instructions. And if the liveness of EFLAGS is wrong
> then post-RA scheduler might interchange e.g. comparison and branch.
> So, instead the producers of broken code needs to be changed.
> 
> Though Jakob might have other opinion here..

No, I agree.

/jakob