Cloning of Replicated Modules

In the monolithic elaboration flow of Xcelium, the entire design hierarchy is elaborated. This leads to repetitive work for designs that have a high replication factor.

The cloning enhancement improves elaboration performance in designs where a module in the design hierarchy is instantiated many times. Cloning the replicated module ensures that only one instance of the replicated module is elaborated in the form of a snapshot, and the same snapshot is then cloned to fill in for other instances. Therefore, the tool avoids elaborating repetitive instances of the same module.

In mixed-signal designs, you can clone a replicated module using the following two command-line options:

-replicated_top <arg>: Allows you to specify the module that has to be cloned. You must specify the module name using the <arg> parameter.

You can also specify multiple modules that are anticipated to have high replication as shown below:
-REPLICATED_TOP mod_a \
-REPLICATED_TOP mod_b \
-REPLICATED_TOP mod_c \
…
Internally, Xcelium would skip elaborating repetitive instances of these specified modules and clone the first elaborated snapshot of each such module whenever further instantiations are encountered.
-autoreplicated_top: Specifies the tool to automatically clone a replicated module. Then, the tool elaborates the replicated module only once and re-uses the elaborated snapshot by cloning and stitching these clones towards the end of the elaboration process. If two or more modules are instantiated multiple times in a design, the tool chooses to clone the highest instantiated module.

Currently, the -autoreplicated_top option is supported only for module instances that are in the range, 2 to 64.

The following are some limitations with the cloning of modules:

Replication by an array of instances (AOI)
Designs that have enabled programmable coercion off/on
Instance-based ie card setting or cell setting that covers replicated top
SPICE and VAMS designs

Examples

The following is an example of a manual instance replication using the -autoreplicated_top option, where the module driver1 has been instantiated three times.

xrun top.sv -rnm_tech -autoreplicated_top module top;

import cds_rnm_pkg::*;
  wrealsum w;
  driver1 d1(w);
  driver1 d2(w);
  driver1 d3(w);
endmodule

// primary
module driver1 (dr_1);
import cds_rnm_pkg::*;
  inout dr_1;
  wire dr_1;
endmodule

The following is an example of a for-loop construct replication using the -autoreplicated_top option, where the module items have been instantiated multiple times.

xrun top.sv -rnm_tech -autoreplicated_top

import cds_rnm_pkg::*;
module top();
  wrealsum a;
  genvar i;
  for(i=0; i<31;i++)
    mid x1_0(a);
endmodule

module mid(inout clk);
  wire clk;
endmodule

Cloning of Replicated Modules

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