User Manual

Quick Start

The slang binary runs a full compilation of given SystemVerilog source files. Eventually it will produce a full simulation binary as output, but for now it serves as a checker of source code syntax, types, and various language rules.

Running it on one or more valid SystemVerilog files will note the top level modules found, and will return zero:

// test1.sv
module m;
    struct { logic a; } s;
    int i = s.a + 1;
    initial $display("%d", i);
endmodule

> slang test1.sv
Top level design units:
    m

Build succeeded: 0 errors, 0 warnings

> echo $?
0

Running it on a file with errors will produce nicely formatted diagnostic output:

// test2.sv
module m;
    struct { logic a; } s;
    int i = s + 1;
    initial $display("%d", i);
endmodule

Top level design units:
    m

../test2.sv:4:12: error: invalid operands to binary expression ('<unnamed unpacked struct>' and 'int')
        int i = s + 1;
                ~ ^ ~

Build failed: 1 error, 0 warnings

Compilation Units

By default slang treats all input files as separate SystemVerilog compilation units. This is the preferred method both because it keeps the code logically separate (it doesn't require a specific ordering of files on the command line in order to compile correctly) and because internally the tool can parse files in parallel if it knows they don't have to be parsed in a specific order.

If you have an older project where file ordering does matter, you can pass the --single-unit option to have all input files treated as a single compilation unit.

Built-in Macros

There are a handful of slang-specific predefined macros that you can reference in your code: