fanhy2114 / hw-cbmc

The HW-CBMC and EBMC Model Checkers for Verilog

About

EBMC is a bounded model checker for the Verilog language (and other HW specification languages). The verification is performed by synthesizing a transition system from the Verilog, unwinding the loops (up to a certain bound), and then producing a SAT formula. The formula encodes the circuit and the negation of the property under verification. Hence if satisfiable, the tool produces a counterexample demonstrating violation of the property. EBMC employs CBMC for the last two steps of the above described verification chain, i.e. SAT encoding and satisfiability checking.

For full information see cprover.org

Compiling

• initialize and update the CBMC submodule: $> git submodule init; git submodule update
• build EBMC: $> cd src; make (this also build CBMC internally)
• optionally: $> export PATH=/full/path/hw-cbmc/src/ebmc:${PATH} to get EBMC on the path

Usage

Let us assume we have the following Verilog code in main.v

module main(input clk, x, y);

  reg [1:0] cnt1;
  reg z;

  initial cnt1=0;
  initial z=0;

  always @(posedge clk) cnt1=cnt1+1;

  always @(posedge clk)
    casex (cnt1)
      2'b00:;
      2'b01:;
      2'b1?: z=1;
    endcase

  always assert p1: z==0;

endmodule

Then we can run the EBMC verification as

$> ebmc main.v --module main --bound 3

setting the unrolling bound to 3 and running the verification of the module main.

For more information see EBMC Manual