Global routing revisited

Moffitt, Michael D.

doi:10.1145/1687399.1687549

Cited by 18 publications

(22 citation statements)

References 24 publications

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“…Although there exist no academic engines that presently respect layer directives, we have 6C-4 [17,3], which have slightly different layer capacities than those of earlier incarnations, and also include layer directives for individual nets. 3 We first report the amount of layer violation (along with other aspects of solution quality) observed when no encapsulation or modification is made to the routers themselves.…”

Section: Resultsmentioning

confidence: 99%

“…3 In accordance with [17], we target for solutions under the criteria -optimize [ overfl wireln ] -constrain { layers }. compliance while producing the least possible overflow for the given 2D projection.…”

Section: Resultsmentioning

confidence: 99%

“…Recall that the efficacy of layer assignment depends on the ability of the router to distribute wire segments arbitrarily among layers once two-dimensional routing has completed. With the introduction of layer directives, this assumption is no longer valid [17], and introduces a blindspot into the projection-based decomposition employed by all modern routers.…”

Section: B the Difficulties Of Directivesmentioning

confidence: 99%

“…The choice of strategy is made easier if the layer range of directives increases monotonically, as is often the case [14,17]. Nets with highest criticality are constrained to the topmost layers, with less critical nets receiving only a reduced lower bound.…”

Section: B Impact Of Class Orderingmentioning

confidence: 99%

“…Second, the popular projection-based layer assignment scheme fails to adequately anticipate the nonuniform wire distribution that results from these directives, forcing the router to either violate constraints or incur unexpected overflow. These shortcomings have led some to question the ability of academic formalisms to step up to the true class of routing problems faced by industrial design flows [17].…”

Section: Introductionmentioning

confidence: 99%

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Wire synthesizable global routing for timing closure

Moffitt¹,

Sze²

2011

16th Asia and South Pacific Design Automation Conference (ASP-DAC 2011)

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Despite remarkable progress in the area of global routing, the burdens imposed by modern physical synthesis flows are far greater than those expected or anticipated by available (academic) routing engines. As interconnects dominate the path delay, physical synthesis such as buffer insertion and gate sizing has to integrate with layer assignment. Layer directives -commonly generated during wire synthesis to meet tight frequency targets -play a critical role in reducing interconnect delay of smaller technology nodes. Unfortunately, they are not presently understood or honored by leading global routers, nor do existing techniques trivially extend toward their resolution. The shortcomings contribute to a dangerous blindspot in optimization and timing closure, leading to unroutable and/or underperforming designs. In this paper, we aim to resolve the layer compliance problem in routing congestion evaluation and global routing, which is very critical for timing closure with physical synthesis. We propose a method of progressive projection to account for wire tags and layer directives, in which classes of nets are successively applied and locked while performing partial aggregation. The method effectively models the resource contention of layer constraints by faithfully accumulating capacity of bounded layer ranges, enabling three-dimensional assignment to subsequently achieve complete directive compliance. The approach is general, and can piggyback on existing interfaces used to communicate with popular academic engines. Empirical results on the IC-CAD 2009 benchmarks demonstrate that our approach successfully routes many designs that are otherwise unroutable with existing techniques and naïve approaches.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: B the Difficulties Of Directivesmentioning

confidence: 99%

Section: B Impact Of Class Orderingmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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