HP aC++/HP C Programmer's Guide (B3901-90036; A.06.26; September 2011)

Performance Options

The HP compiler provides a variety of options to help improve build and runtime

performance. These options are:

-fast

The -fast option selects a combination of optimization options for optimum execution

speed and reasonable build times. This option is equivalent to +Ofast. Currently chosen

options are:

• +O2

• +Ofltacc=relaxed

• +Onolimit

• +DSnative

• +FPD

You can override any of the options in -fast by specifying a subsequent option after

it.

Use this option when porting C++ and C applications compiled on other UNIX operating

systems to HP-UX.

NOTE: Do not use this option for programs that depend on IEEE standard floating-point

denormalized numbers. Otherwise, different numerical results may occur.

+Ofast

The +Ofast option selects a combination of optimization options for optimum execution

speed for reasonable build times. Currently chosen options are:

• +O2

• +Ofltacc=relaxed

• +Onolimit

• +DSnative

• +FPD

• -Wl,+pi,1M

• -Wl,+pd,1M

• -Wl,+mergeseg

This option is a synonym for -fast.

Performance Options 83