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

+Ointeger_overflow=moderate is the default for all optimization levels. This was

changed to enable a wider class of applications to be compiled with optimization and

run correctly.

The defined values of kind are:

conservative Directs the compiler to make fewer assumptions that integer arithmetic

expressions do not overflow.

moderate Allows the compiler to make a broad set of assumptions so that the

integer arithmetic expressions do not overflow, except that linear

function test replacement (LFTR) optimization is not performed.

+Olevel

+Olevel=name1[,name2,...,nameN]

The +Olevel option lowers optimization to the specified level for one or more named

functions.

level can be 0, 1, 2, 3, or 4.

The name parameters are names of functions in the module being compiled. Use this

option when one or more functions do not optimize well or properly. This option must

be used with a basic +Olevel or -O option. Note that currently only the C++ mangled

name of the function is allowed for name.

This option works like the OPT_LEVEL pragma. The option overrides the pragma for the

specified functions. As with the pragma, you can only lower the level of optimization;

you cannot raise it above the level specified by a basic +Olevel or -O option. To avoid

confusion, it is best to use either this option or the OPT_LEVEL pragma rather than both.

You can use this option at optimization levels 1, 2, 3, and 4. The default is to optimize

all functions at the level specified by the basic +Olevel or -O option.

Examples:

• The following command optimizes all functions at level 3, except for the functions

myfunc1 and myfunc2, which it optimizes at level 1.

aCC +O3 +O1=myfunc1,myfunc2 funcs.c main.c

• The following command optimizes all functions at level 2, except for the functions

myfunc1 and myfunc2, which it optimizes at level 0.

aCC -O +O0=myfunc1,myfunc2 funcs.c main.c

+O[no]loop_transform

This option transforms [does not transform] eligible loops for improved cache and other

performance. This option can be used at optimization levels 2, 3 and 4.

The default is +Oloop_transform.

Code Optimizing Options 73