verilator/test_regress/t/t_dfg_constpool_unused.v

45 lines
1.2 KiB
Systemverilog

// DESCRIPTION: Verilator: Verilog Test module
//
// This file ONLY is placed under the Creative Commons Public Domain.
// SPDX-FileCopyrightText: 2026 Wilson Snyder
// SPDX-License-Identifier: CC0-1.0
// verilog_format: off
`define stop $stop
`define checkh(gotv,expv) do if ((gotv) !== (expv)) begin $write("%%Error: %s:%0d: got=%0x exp=%0x (%s !== %s)\n", `__FILE__,`__LINE__, (gotv), (expv), `"gotv`", `"expv`"); `stop; end while(0);
// verilog_format: on
module t;
logic clk = 1'b0;
always #5 clk = ~clk;
logic [31:0] cyc = 0;
// Converted to case table in const pool, but proven unused by Dfg
logic [15:0] out;
always_comb begin
case (cyc[3:0])
4'd0: out = 16'h1111;
4'd1: out = 16'h2222;
4'd2: out = 16'h4444;
4'd3: out = 16'h8888;
default: out = 16'h0f0f;
endcase
end
// Complicated way to write constant 0 that only Dfg can decipher
wire [63:0] convoluted_zero = (({64{cyc[0]}} & ~{64{cyc[0]}}));
wire logic [15:0] zero = &convoluted_zero ? out : 16'd0;
// Test driver/checker
always @(posedge clk) begin
`checkh(zero, 16'd0);
cyc <= cyc + 32'd1;
if (cyc == 32'd32) begin
$write("*-* All Finished *-*\n");
$finish;
end
end
endmodule