When compiling your design using Synopsys FPGA compiler, you may get an warning that "compile_fix_multiple_port_nets has been obsoleted."
Here is a quote on the Compile_fix_multiple_port_nets command from the Synopsys Synthesis release notes version 1998.02:
Multiple Port Net Fixing
In previous releases, multiple port net fixing was done late in the optimization; this could sometimes increase delay. In this release (1998.02), multiple port net fixing is done before delay optimization so Design Compiler can not recover any performance loss. Optimization is performed on the buffers inserted to meet delay or area constraints.
A new command, set_fix_multiple_port_nets, provides you more independent control of the different faccets of multiple port net fixing: multiple outputs, feedthroughs, and constant-driven outputs. This command replaces the old compile_fix_multiple_port_nets variable.
Please, refer to Synopsys on-line doc for more information on the usage of this command and attributes.