VCS编译systemverilog和UVM的命令记录

正常应该看文档就可以了，但是在常看的 ug 和 VCSLCAFeatures真的找不到。估计是在其他的 文档里吧，所以就先记录在这。

1.-CFLAGS 和 -DVCS有什么用？

>> How to use the gcc compiler's option "-DVCS"?

-DVCS represents a macro defined for C source code. Please note that anything
followed by -D is treated as a macro by the gcc/g++ compiler. Along with
VCS compile-time options one should pass -DVCS with -CFLAGS so that
-DVCS gets passed to gcc/g++.

Example steps:
% vcs top.v test.c -CFLAGS -DVCS <rest_of_compile_options>

>> What's the compile environment that we need to use this option?

"-CFLAGS -DVCS" is usually required during UVM source compilation.
Therefore, if we are using an external UVM source then you must pass -DVCS. 
(If we are using -ntb_opts uvm then no need to pass this option because it is
internally passed with -ntb_opts uvm). Also, if we have any macros with
the name 'VCS' defined in any other C source then we need to pass
it with -CFLAGS