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Moving two instances together during placement

zamzam

Hi,

I have a placement question.

1) Is there a command/constraint that can be set for moving an instance and a desired unconnected spare cell together during placement?

2) Is there a command/constraint that can be set for moving an instance and a desired unconnected spare module (containing multiple spare cells) together during placement?

I have a workaround where I add some padding to the first instance and then move the desired spare modules/cells in that padding region after the initial placement. But it would make my life  alot easier if I can somehow use some constraints that allow them to move together as the design is placed.

Thanks,

Zaman.

Parents

  • ZamZam:

    Input tie-hi / tie-lo connected spare cells are by definition "floating", Placement efficiency demands spare cells migrate to the least offensive routing location, and ultimately the most useless ECO corner locations. If you are truly anticipating an ECO connect your first guesstimate spare inputs to the  real logic. that way it is already local and the extra ip pin cap is just noise.

    setPlaceMode -moduleAwareSpare might work with user created groups

    OR let the far more useful  placeSpareModule  evenly distribute spares.

    OR better still backfill with programmable gate-array-ish  DeCap cells.

    Shawn; Spare cells? Spare cells ? Who needs stinking Spare cells : )

Reply

  • ZamZam:

    Input tie-hi / tie-lo connected spare cells are by definition "floating", Placement efficiency demands spare cells migrate to the least offensive routing location, and ultimately the most useless ECO corner locations. If you are truly anticipating an ECO connect your first guesstimate spare inputs to the  real logic. that way it is already local and the extra ip pin cap is just noise.

    setPlaceMode -moduleAwareSpare might work with user created groups

    OR let the far more useful  placeSpareModule  evenly distribute spares.

    OR better still backfill with programmable gate-array-ish  DeCap cells.

    Shawn; Spare cells? Spare cells ? Who needs stinking Spare cells : )

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