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Re: Do we create new insn in combine? Or can we rely on INSN_LUID checking the order of instuctions?


On Thu, Dec 11, 2014 at 03:13:50PM +0800, Bin.Cheng wrote:
> So I am wondering if I can rely on INSN_LUID checking orders of
> difference instruction.  If it can be done, I can easily differentiate
> live range shrink and extend.
> Further question is, if we don't insert new insns, can I use INSN_LUID
> safely for this purpose?

I0 is before I1 is before I2 is before I3; one of the first things
try_combine does is make sure this is true (by swapping the names
around if necessary).

The LUIDs are in strictly increasing order, and they stay that way:
combine never moves or inserts insns.


Segher


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