compressors 4:2, 7:2 gate count ?

[gstekboy]

From literature's I got below definition,

Compressors, in its several variants, are logic circuits which are capable of adding more than 3 bits at a time as opposed to a full adder and capable of performing this with a lesser gate count and higher speed in comparison with an equivalent full adder circuit.

But I know that it will reduce delay and increase speed.

what about gate count? From my manual calculation I found that gate count is increasing in compressors.
Can anyone share your views.

 

[artmalik]

Compressors are synthesizable cells which are used to implement multiplier circuits in RTL. The idea is to implement a custom cell which will be better in area/performance. Any multiplier implemented with full adders will perform worse than one which is done using compressor. This should be taken with a pinch of salt because the compressor has to be designed well and also the RTL code which synthesizes to compressor implementation.
There are rules in the design compiler for writing RTL in such a way that it uses the compressor cells. There are a couple of other cells needed along with compressor to implement a multiplier, they have to be in the library. But usage of compressor highly depends on the way the RTL is written.
Thanks
Art Malik