Tests: Add a test to improve code coverage of V3Const.cpp (#2878)

test_regress/t/t_const_opt.pl

@@ -0,0 +1,22 @@
+#!/usr/bin/env perl
+if (!$::Driver) { use FindBin; exec("$FindBin::Bin/bootstrap.pl", @ARGV, $0); die; }
+# DESCRIPTION: Verilator: Verilog Test driver/expect definition
+#
+# Copyright 2003 by Wilson Snyder. This program is free software; you
+# can redistribute it and/or modify it under the terms of either the GNU
+# Lesser General Public License Version 3 or the Perl Artistic License
+# Version 2.0.
+# SPDX-License-Identifier: LGPL-3.0-only OR Artistic-2.0
+
+scenarios(simulator => 1);
+
+compile(
+    verilator_flags2=>["-Wno-UNOPTTHREADS", "--stats"],
+    );
+
+execute(
+    check_finished => 1,
+    );
+
+ok(1);
+1;

test_regress/t/t_const_opt.v

@@ -0,0 +1,105 @@
+// DESCRIPTION: Verilator: Verilog Test module
+//
+// This file ONLY is placed under the Creative Commons Public Domain, for
+// any use, without warranty, 2021 Yutetsu TAKATSUKASA.
+// SPDX-License-Identifier: CC0-1.0
+
+module t(/*AUTOARG*/
+   // Inputs
+   clk
+   );
+   input clk;
+
+   integer cyc=0;
+   reg [63:0] crc;
+   reg [63:0] sum;
+
+   // Take CRC data and apply to testblock inputs
+   wire [31:0] in = crc[31:0];
+
+   /*AUTOWIRE*/
+   // Beginning of automatic wires (for undeclared instantiated-module outputs)
+   logic                o;                     // From test of Test.v
+   // End of automatics
+
+   wire [31:0]          i = crc[31:0];
+
+   Test test(/*AUTOINST*/
+             // Outputs
+             .o                         (o),
+             // Inputs
+             .clk                       (clk),
+             .i                         (i[31:0]));
+
+   // Aggregate outputs into a single result vector
+   wire [63:0] result = {63'b0, o};
+
+   // Test loop
+   always @ (posedge clk) begin
+`ifdef TEST_VERBOSE
+      $write("[%0t] cyc==%0d crc=%x result=%x\n",$time, cyc, crc, result);
+      $display("o %b", o);
+`endif
+      cyc <= cyc + 1;
+      crc <= {crc[62:0], crc[63]^crc[2]^crc[0]};
+      sum <= result ^ {sum[62:0],sum[63]^sum[2]^sum[0]};
+      if (cyc == 0) begin
+         // Setup
+         crc <= 64'h5aef0c8d_d70a4497;
+         sum <= '0;
+      end
+      else if (cyc < 10) begin
+         sum <= '0;
+      end
+      else if (cyc < 99) begin
+      end
+      else begin
+         $write("[%0t] cyc==%0d crc=%x sum=%x\n",$time, cyc, crc, sum);
+         if (crc !== 64'hc77bb9b3784ea091) $stop;
+         // What checksum will we end up with (above print should match)
+`define EXPECTED_SUM 64'hfab547b426149442
+         if (sum !== `EXPECTED_SUM) $stop;
+         $write("*-* All Finished *-*\n");
+         $finish;
+      end
+   end
+
+endmodule
+
+module Test(/*AUTOARG*/
+   // Outputs
+   o,
+   // Inputs
+   clk, i
+   );
+
+   input clk;
+   input [31:0] i;
+   logic [31:0] d;
+   logic d0, d1, d2, d3, d4, d5, d6, d7;
+
+   output logic o;
+
+   logic [3:0] tmp;
+   assign o = ^tmp;
+
+   always_ff @(posedge clk) begin
+      d <= i;
+      d0 <= i[0];
+      d1 <= i[1];
+      d2 <= i[2];
+      d3 <= i[3];
+      d4 <= i[4];
+      d5 <= i[5];
+      d6 <= i[6];
+      d7 <= i[7];
+   end
+   always_ff @(posedge clk) begin
+      // Cover more lines in V3Const.cpp
+      tmp[0] <= (d0 || (!d0 && d1)) ^ ((!d2 && d3) || d2); // maatchOrAndNot()
+      tmp[1] <= ((32'd2 ** i) & 32'h10) == 32'b0;  // replacePowShift
+      tmp[2] <= ((d0 & d1) | (d0 & d2))^ ((d3 & d4) | (d5 & d4));  // replaceAndOr()
+      tmp[3] <= d0 <-> d1; // replaceLogEq()
+   end
+
+endmodule