[llvm-commits] [PATCH] Scavenging callee-saved registers

[Evan Cheng]

On Aug 2, 2009, at 10:34 PM, Chris Lattner wrote:

>
> On Aug 2, 2009, at 1:00 PM, Evan Cheng wrote:
>
>>>
>>> I noticed that ARM tries to predict this situation so an extra CSR
>>> can be spilled. That probably means that ARM will never meet this
>>> situation. Unless it guesses wrong for some reason. Blackfin is not
>>> so advanced yet. It cannot predict scavenger use.
>>
>> Looks good. Please commit.
>>
>> I have a plan to completely revamp the use of register scavenger.
>> Basically I want PEI to introduce virtual registers instead of
>> scavenging. At the end of PEI it will do another round register
>> allocation using the scavenger.
>
> ... with the constraint that the new vregs have are defined by one
> instruction and killed by the next, right?

Yes, with the exception of use-def by a series  of two-address  
instructions.

Evan

>
> -Chris
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