|managing register spills? email@example.com (1997-06-10)|
|Re: managing register spills? firstname.lastname@example.org (Cliff Click) (1997-06-13)|
|Re: managing register spills? email@example.com (1997-06-13)|
|Re: managing register spills? firstname.lastname@example.org (David L Moore) (1997-06-13)|
|From:||email@example.com (George C. Lindauer)|
|Date:||10 Jun 1997 23:58:34 -0400|
|Organization:||University of Louisville|
|Keywords:||registers, code, optimize|
It seems easy enough, but suppose I have two register banks, register
bank A and register bank B. All the registers in both banks are
overused and have spilled. Now I want to move a value from bank A to
bank B, allocating a new register in bank B and freeing the old one
from bank A. Clearly, the free will cause an unspill, and the
allocate will cause a spill. But if I free the bank a register BEFORE
the move I've lost the value I want to move. And if I free it AFTER
the move this is invalid because I've spilled from bank B and since I
am using a stack to manage the spills the bank A unspill value is no
longer available. An exchange instruction would be nice about
now... unfortunately I don't have one.
What do I do?
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