verilator/test_regress/t/t_dedupe_clk_gate.v
Varun Koyyalagunta e0edb596ea Add duplicate clock gate optimization, msg980.
Experimental and disabled unless -OD or -O3 used (for now),
Please try it as may get some significant speedups.

Signed-off-by: Wilson Snyder <wsnyder@wsnyder.org>
2013-02-20 20:14:15 -05:00

62 lines
1.4 KiB
Verilog

// DESCRIPTION: Verilator: Dedupe optimization test.
//
// This file ONLY is placed into the Public Domain, for any use,
// without warranty.
// Contributed 2012 by Varun Koyyalagunta, Centaur Technology.
module t(res,d,clk,en);
output res;
input d,en,clk;
wire q0,q1,q2,q3;
flop_gated_latch f0(q0,d,clk,en);
flop_gated_latch f1(q1,d,clk,en);
flop_gated_flop f2(q2,d,clk,en);
flop_gated_flop f3(q3,d,clk,en);
assign res = (q0 + q1) * (q2 - q3);
endmodule
module flop_gated_latch(q,d,clk,en);
input d, clk, en;
output q;
wire gated_clock;
clock_gate_latch clock_gate(gated_clock, clk, en);
always @(posedge gated_clock) begin
q <= d;
end
endmodule
module flop_gated_flop(q,d,clk,en);
input d, clk, en;
output q;
wire gated_clock;
clock_gate_flop clock_gate(gated_clock, clk, en);
always @(posedge gated_clock) begin
q <= d;
end
endmodule
module clock_gate_latch (gated_clk, clk, clken);
output gated_clk;
input clk, clken;
reg clken_latched /*verilator clock_enable*/;
assign gated_clk = clk & clken_latched ;
wire clkb = ~clk;
always @(clkb or clken)
if(clkb) clken_latched = clken;
endmodule
module clock_gate_flop (gated_clk, clk, clken);
output gated_clk;
input clk, clken;
reg clken_r /*verilator clock_enable*/;
assign gated_clk = clk & clken_r ;
always @(negedge clk)
clken_r <= clken;
endmodule