User guide

13-8
SDF Backannotation
By default the +csdf+precompile option creates the precompiled
SDF file in the same directory as the ASCII text SDF file and
differentiates the precompiled version by appending "_c" to its
extension. For example, if the /u/design/sdf directory contains a
design1.sdf file, using the +csdf+precompile option creates the
precompiled version of the file named design1.sdf_c in the
/u/design/sdf directory.
After you have created the precompiled version of the SDF file you
no longer need to include the +csdf+precompile option on the vcs
command line unless there is a change in the SDF file. Continuing to
include it, however, such as in a script that you run every time you
compile your design, would have no effect when the precompiled
version is newer than the ASCII text SDF file, but would create a new
precompiled version of the SDF file whenever the ASCII text SDF file
changes. Therefore this option is intended to be used in scripts for
compiling your design.
When you recompile your design, VCS finds the precompiled SDF
file in the same directory as the SDF file specified in the
$sdf_annotate system task. You can also specify the precompiled
SDF file in the $sdf_annotate system task.
Specifying an Alternative Name and Location
You can use the +csdf+precomp+dir+directory option to
specify the directory path where you want VCS to write the
precompiled SDF file. When you do, make sure that you have already
created all directories in the path because VCS does not create
directories that are specified with this option.
You can use the +csdf+precomp+ext+ext option to specify an
alternative to the "_c" character string addition to the filename
extension of the precompiled SDF file.