Improve global placement performance

[oharboe]

Description

The example below was created with #1452 and make DESIGN_CONFIG=designs/asap7/mock-registerfile/config.mk global_place_issue

unzip https://drive.google.com/file/d/1FGZ6Q66ZlWVqFuJ6IQj0ovF5nN2RDDlz/view?usp=drive_link

and run global placement, takes 1200 seconds or so. Ideally it should be faster...

./run-me-mock-registerfile-asap7-base.sh

Suggested Solution

No response

Additional Context

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[rovinski]

I have asked around recently about implementing this paper which adds multithreading to GPL (albeit an older version from years ago). Haven't really gotten a clear reason why it hasn't been done - I think it may have had something to do with nondeterminism bugs. I or one of my students may start looking at that soon. There's some very low-hanging fruit in order to get decent speedups.

[maliberty]

abk mentioned the same recently. I don't see any sign that they made their code public. There is some student work on a GPU version of replace. I think all overlook the fact that calling grt/rsz/sta is a large fraction of the time that is not addressed.

[rovinski]

@maliberty https://github.com/gessfred/Parallel-RePlAce