HP C Programmer's Guide (92434-90009)

Chapter 4 67
Optimizing HP C Programs
Summary of Optimization Parameters
Summary of Optimization Parameters
The HP C optimization parameters are summarized in Table on page 67.
Table 4-3. HP C Optimization Parameters
Option What It Does Level of Opt
+O[no]aggressive The +O[no]aggressive option enables optimizations
that can result in significant performance improvement,
but that can change a program's behavior. These
optimizations include newly released optimizations and
the optimizations invoked by the following advanced
optimization options:
a
• +Osignedpointers
• +Oregionsched
• +Oentrysched
• +Onofltacc
• +Olibcalls
• +Onoinitcheck
• +Ovectorize
The default is +Onoaggressive.
2, 3, 4
+O[no]all The +Oall option performs maximum optimization,
including aggressive optimizations and optimizations
that can significantly increase compile time and memory
usage. The default is +Onoall.
4
+O[no]conservative The +O[no]conservative option causes the optimizer to
make conservative assumptions about the code when
optimizing it. Use +Oconservative when conservative
assumptions are necessary due to the coding style, as
with non-standard conforming programs. The
+Oconservative option relaxes the optimizer's
assumptions about the target program. The default is
+Onoconservative.
2, 3, 4
+O[no]info +Oinfo displays informational messages about the
optimization process. This option supports the core
optimization levels, and therefore, can be used at levels
0-4. The default is +Onoinfo.
0, 1, 2, 3, 4
+O[no]limit The +Olimit option suppresses optimizations that
significantly increase compile-time or that can consume a
lot of memory. The +Onolimit option allows
optimizations to be performed regardless of their effect
on compile-time or memory usage. The default is
+Olimit.
2, 3, 4