HP 3000 Manuals

HP C Programmer's Guide

Enabling Only Conservative Optimizations on HP-UX 

You can enable conservative optimizations at the second, third, or fourth
optimization levels by using the +Oconservative option, as follows:

     cc +O2 +Oconservative sourcefile.c 

or:

     cc +O3 +Oconservative sourcefile.c 

or:

     cc +O4 +Oconservative sourcefile.c 

Conservative optimizations are optimizations that do not change the
behavior of code, in most cases, even if the code does not conform to
standards.

Use the conservative optimizations provided with level 2, 3, and 4 when
your code is non-ANSI.

MPE/iX 5.0 Documentation