HP aC++/HP C A.06.28 Programmer's Guide Integrity servers (769150-001, March 2014)

dynamic This is a less efficient mode in which thread local data outside the program startup

set can be accessed as well. This is the default.

Translation units compiled with different settings of this option may be freely mixed, even within

the same load module.

+wlock

The +wlock option enables compile-time diagnostic messages for potential errors in using

lock/unlock calls in programs that use pthread-library-based lock/unlock functions. Warnings are

emitted for acquiring an already acquired lock, releasing an already released lock, and

unconditionally releasing a lock that has been conditionally acquired.

This diagnostic checking is based on cross-module analysis performed by the compiler. Therefore,

the +wlockoption implicitly enables a limited form of cross-module analysis, even if -ipo or+O4

options are not specified. This can lead to a significant increase in the compile time compared to

a build without the +wlock option. Using this option could result in the compiler invoking

optimizations other than those that are part of the user-specified optimization level. If +wlock is

used in addition to -ipo or +O4, the generated code is not affected, and the compile time does

not increase much.

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

68 Command-Line Options