yosys/tests/techmap/constmap.ys

read_verilog << EOT

module test();
  wire [31:0] in;
  wire [31:0] out;
  assign out = in + 16;
endmodule

EOT

constmap -cell const_cell O value
select -assert-count 1 t:const_cell r:value=16 %i

design -reset

read_verilog -lib << EOT
module const_cell(O);
parameter value=0;
output O;
endmodule
EOT

read_verilog << EOT

module test();
  wire [31:0] in;
  wire [31:0] out1;
  wire [31:0] out2;
  assign out1 = in + 16;
  assign out2 = in + 32;
endmodule

EOT

constmap -cell const_cell O value

select -assert-count 2 t:const_cell
select -assert-count 1 r:value=16
select -assert-count 1 r:value=32
select -assert-count 1 test/out1 %ci* r:value=16 %i
select -assert-count 1 test/out2 %ci* r:value=32 %i
select -assert-count 1 t:const_cell r:value=16 %i
select -assert-count 1 t:const_cell r:value=32 %i