Sun Studio 12: C User's Guide

B.2.75 –xcg[89|92]

(SPARC) Obsolete. You should not use this option. Current Solaris operating systems no longer support SPARC V7 architecture. Compiling with this option generates code that runs slower on current SPARC platforms. Use -O instead and take advantage of compiler defaults for -xarch, -xchip, and -xcache.