The algorithm used is called "iterated register coalescing", an
advanced form of graph colouting and was designed by Andrew W. Appel.
He describes in detail in his book "Modern Compiler Implementation in C".
Thanks, I think i'll grab a copy from the uni library tomorrow.
Basically the registers are put into "worklists"
How does it decice which worklist to put a register in? do registers
move between the worklists?
, and then 4 procedures:
* simplify -> takes registers out of the graph that can safely be
coloured
* coalesce -> tries to coalesce registers together to reduce pressure
* freeze -> selects registers that have a chance to be coalesced and
should therefore not be spilled yet
* spill -> selects a register that should move to memory.
These procedures are called iteratively until the worklists are empty.
Then the graph is coloured.
Is this process run seperately for each type of register (int/float/mm)?
P.S. I tried putting debug writelns in the code that generates spills
and it doesn't seem to be being called for my current testcase :/ (this
wasn't the only testcase that failed but I feel it's best to approach
them one at a time).
_______________________________________________
fpc-devel maillist - fpc-devel@lists.freepascal.org
http://lists.freepascal.org/mailman/listinfo/fpc-devel
