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

montecito
Tune for the Montecito® processor.
native Tune for the processor on which the compiler is running.
The default is blended. Object code with scheduling tuned for a particular model will
execute on other HP-UX systems, although possibly less efficiently.
Using +DS to Specify Instruction Scheduling
Instruction scheduling is different on different implementations of Itanium®-based
architectures. You can improve performance on a particular model or processor of the
HP-UX system by requesting the compiler to use instruction scheduling tuned to that
particular model or processor. Using scheduling for one model or processor does not
prevent your program from executing on another model or processor.
If you plan to run your program on the same system where you are compiling, you do
not need to use the +DS option. The compiler generates code tuned for your system.
If you plan to run your program on a particular model of the HP-UX system, and that
model is different from the one where you compile your program, use +DSmodel with
either the model number of the target system or the processor name of the target system.
Compiling in Networked Environments
When compiles are performed using diskless workstations or NFS-mounted file systems,
it is important that the default code generation and scheduling are based on the local
host processor. The system model numbers of the hosts where the source or object files
reside do not affect the default code generation and scheduling.
-S
The -S option compiles a program and logs the assembly language output in a
corresponding file with a .s suffix. The -S option is only for displaying the assembler
code. The generated code is not intended to be used as input to the assembler (as).
Example:
The following command compiles prog.C to assembly code rather than to object code,
and puts the assembly code in the file prog.s.
aCC -S prog.C
Data Alignment and Storage
This section describes default data storage allocation and alignment for HP compiler
data types.
Data storage refers to the size of data types, such as bool, short, int, float, and
char*. Data alignment refers to the way the HP compiler aligns data structures in memory.
Data type alignment and storage differences can cause problems when moving data
between systems that have different alignment and storage schemes. These differences
become apparent when a structure is exchanged between systems using files or
Data Alignment and Storage 37