Consistent placement of macro-blocks using floorplanning and standard-cell placement.

ABSTRACTWhile a number of recent works address large-scale standard-cellplacement, they typically assume that all macros are fixed.Floorplanning techniques are very good at handling macros, but donot scale to hundreds of thousands of placeable objects. Thereforewe combine floorplanning techniques with placement techniques in adesign flow that solves the more general placement problem. Ourwork shows how to place macros consistently with large numbers ofsmall standard cells. Our techniques can also be used to guidecircuit designers who prefer to place macros by hand.The proposed flow relies on an arbitrary black-box standard-cellplacer to obtain an initial placement and then removes possibleoverlaps using a fixed-outline floorplanner. This results in validplacements for macros, which are considered fixed. Remainingstandard cells are then placed by another call to the standard-cellplacer. Empirical evaluation on ibm benchmarks shows, in mostcases, wirelength improvements of 10%-50% compared to CadenceQPlace, as well as runtime improvements.