HP Pascal/HP-UX Release Notes Version A.10.08

28 Chapter 1
New and Changed Features
+DS Command-Line Option
Using +DS to Specify Instruction Scheduling
Instruction scheduling is different on different implementations of
PA-RISC architectures. You can improve performance on a particular
model or processor of the HP 9000 by requesting that the compiler 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.
By default, the compiler performs scheduling tuned for the system on
which you are compiling. Use the +DS option to change this default
behavior and to specify instruction scheduling tuned to a particular
implementation of PA-RISC. For example, to specify instruction
scheduling for the model 867, use +DS867. To specify instruction
scheduling for the PA-RISC 8000 processor, use +DSPA8000. See the file
/opt/langtools/lib/sched.models for model numbers and
processor names.
When you use the +DS option depends on your particular circumstances.
• If you plan to run your program on the same system where you are
compiling, you don't need to use the +DS option. The compiler
generates code tuned for your system.
• If you plan to run your program on one particular model of the HP
9000 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.
For example, if you are compiling on a system with a PA7100
processor and your program will run on a system with a PA7100LC
processor, you can use +DSPA7100LC. This will give you the best
performance on the PA7100LC system.