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RTL Compiler's New "Spatial Technology"

Comments(2)Filed under: Logic Design, Physical Prediction, RTL Compiler 9.1, PLE, Spatial, Jeff FliederBy Jeff Flieder
Sr. Solutions Manager

Over the last few years, RTL Compiler has added a significant number of features targeted toward users that require more physical awareness in their synthesis flow. We first introduced the PLE (Physical Layout Estimation) flow that allows a very low impact way to accurately model 80-90% of the wires in a design in order to take the most advantage of RC's advance global optimization algorithms in a physical context.

We then introduced RC-Physical (RCP), which provides the ability to run silicon virtual prototyping within RC in order to accurately model all the wires and perform both logical and physical optimization based on detailed physical information. This includes the ability to natively measure and optimize for congestion. In addition, RCP allows the user to write out a full placed DEF as a starting seed for physical design, ensuring that the physical design team will see things exactly how the logic design team saw them at handoff.

RTL Compiler spatial technology is the latest advance of physically aware synthesis in the RTL Compiler toolbox. This methodology fits in between a PLE based flow and an RCP flow in terms of how much physical modeling is performed. In addition to the initial synthesis with PLE, RC-Spatial runs a fast placement on the design in order to better predict the remaining 10% to 20% of nets that are difficult to predict with PLE alone. Since RC-Spatial is running a fast placement with a production placement engine, all of the information in the floorplan is used in order to achieve the most accurate results. These include things like die box, core box, aspect ratio, preplaced instances, pin locations, blockages, rows, power routing and pre-routes.

RC-Spatial will result in better prediction of the pre-CTS results and would be expected to have some positive effect on QoS due to more accurate wire modeling. It will also work without a floorplan, although having a floorplan is highly recommended and will improve the quality of prediction. It is important to note that the QoR measured in the synthesis environment may in fact "look" worse than PLE alone, as the PLE estimates for longer nets are by definition optimistic.

The RC-Spatial flow is expected to greatly improve physical prediction, providing better guidance to logic optimizations, and RC-Spatial will also apply some basic optimization techniques for congestion alleviation. For heavily congested or over-utilized designs, you'll want to use the full capabilities of the RC-Physical solution. RC-Spatial is available in all packages of RC. As with any new technology, make sure you're using the latest update release of RC when you try this.


By Henry Wang on September 2, 2009
What is the major difference between RCP and RC-Spatial?

By Jack Erickson on November 4, 2009
There are a bunch of differences, the first being that RC-Physical employs legal placement under the hood. And this includes its incremental placement, which is crucial as you do optimizations in synthesis based on the placement. And the incremental legal placement also enables you to hand off the placement at the end of synthesis, seeding the back-end flow with exactly the view of the design that you saw out of synthesis.
The other major difference is that RC-Physical has full capabilities for congestion analysis, fixing, and prevention. For more information on that, check out the archived webinar we recently did:

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