HP C Programmer's Guide (92434-90009)

Chapter 4 71
Optimizing HP C Programs
Controlling Specific Optimizer Features
scheduling, note that instruction scheduling occurs at link time. Therefore, the system
on which you link, rather than compile, determines the implementation of instruction
scheduling.
For more information on profile-based optimization, see the
HP-UX Linker and
Libraries Online User Guide
.
Controlling Specific Optimizer Features
Most of the time, specifying optimization level 1, 2, 3, or 4 should provide you with the
control over the optimizer that you need. Additional parameters are provided when you
require a finer level of control.
At each level, you can turn on and off specific optimizations using the
+O[no]
optimization option. The optimization parameter is the name of a specific
optimization technique described below. The optional prefix [no] disables the specified
optimization.
The following section describes the optimizations that can be turned on or off, their
defaults, and the optimization levels at which they may be used. The options listed in
<Undefined Cross-Reference> are described below.
Table 4-4. HP C Advanced Optimization Options
Option Option
+O[no]dataprefetch +O[no]entrysched
+O[no]fail_safe +O[no]fastaccess
+O[no]fltacc +O[no]global_ptrs_unique
+O[no]initcheck +O[no]inline
+Oinline_budget +O[no]libcalls
+O[no]loop_transform +O[no]loop_unroll
+O[no]moveflops +O[no]parallel
+O[no]parallel_env +O[no]parmsoverlap
+O[no]pipeline +O[no]procelim
+O[no]ptrs_ansi +O[no]ptrs_strongly_type
d
+O[no]ptrs_to_globals +O[no]regionsched
+O[no]regreassoc +O[no]sideeffects
+O[no]signedpointers +O[no]static_prediction
+O[no]vectorize +O[no]volatile