BoxRouter: A New Global Router Based on Box Expansion and Progressive ILP
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BoxRouter: A New Global Router Based on Box Expansion and Progressive ILP Minsik Cho and David Z. Pan ECE Dept. Univ. of Texas at Austin DAC 2006, July 24-28. Global Routing – plans approximate route of each net to reduce complexity of detailed router

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BoxRouter: A New Global Router Based on Box Expansion and Progressive ILPMinsik Cho and David Z. PanECE Dept. Univ. of Texas at AustinDAC 2006, July 24-28


Introduction

Global Routing – plans approximate route of each net to reduce complexity of detailed router

Goal: Optimize wire density during global routing

Improve manufacturability

Potential to feedback interconnect information

Introduction


Steps

PreRouting captures congested areas reduce complexity of detailed router

BoxRouting starts in most congested area and expands box to cover entire chip

Progressive integer linear programming (ILP) technique to route wires in box

Maze routing algorithm for rest of wires

PostRouting reroutes wires without rip-up

Parameter controls trade-off between length and routability

Steps


Boxrouter

Route as many wires inside box as possible with ILP reduce complexity of detailed router

Maze routing algorithm if ILP fails

BoxRouter


Algorithm
Algorithm reduce complexity of detailed router


Steps1
Steps reduce complexity of detailed router

2) Box around congested area

3) ILP routing between G-cells

1) PreRouting – Identify congested area

6) Repeat

4) Maze routing

5) Expand box


Postrouting

Start from congested area reduce complexity of detailed router

Reroute wires to reduce length (if possible)

Reroute surrounding wires

Repeat

Parameter controls cost function

Wirelength vs. routability

PostRouting


Experimental results

Larger box expansion can improve results at a cost of runtime

Compared to Labyrinth

Reduce wirelength by 14.3%

Reduce overflow by 91.7%

Compared to Fengshui

Reduce overflow by 79%

Compared to multicommodity flow-based router

15.7x faster

4.2% shorter wirelength

Experimental Results


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