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

14 Chapter 1
New and Changed Features
Optimization Parameters
Table 1-2 General Optimization Options
General Option Optimization Performed
+O[no]aggressive
Levels 2, 3, 4
+Oaggressive enables optimizations that can result in
significant performance improvement, but can change a
program's behavior. These optimizations include newly released
optimizations and the optimizations invoked by the following
advanced optimization parameters (see Table 1-3):
• +Oentrysched
• +Onofltacc
• +Olibcalls
• +Onoinitcheck
• +Oregionsched
The default is +Onoaggressive.
+O[no]all
Level 4
+Oall performs maximum optimization, including aggressive
optimizations and optimizations that can significantly increase
compile time and memory usage.
The default is +Onoall.
+O[no]conservative
Levels 2, 3, 4
+Oconservative causes the optimizer to make conservative
assumptions about the code when optimizing. Use
+Oconservative when conservative assumptions are
necessary due to the coding style, as with non-standard
programs.
The default is +Onoconservative.
+O[no]dataprefetch
Levels 2, 3, 4
When +Odataprefetch is enabled, the optimizer will insert
instructions within innermost loops to explicitly prefetch data
from memory into the data cache. Data prefetch instructions
will be inserted only for data structures referenced within
innermost loops using simple loop varying addresses (that is, in
a simple arithmetic progression). It is only available for
PA-RISC 2.0 targets.
Use this option for applications that have high data cache miss
overhead.
The default is +Onodataprefetch.