determine whether the compiler optimized

 

time-critical sections of your program. It

 

can be used at any level of optimization

 

but is most useful at level 3.

 

Currently, this option provides feedback

 

for the following optimizations:

 

• Cloning, the replacement of a call to

 

a routine by a call to a clone, which

 

is a copy of the routine with changes

 

specific to that call site.

 

• Inlining.

 

• Loop transformations to improve cache

 

performance.

 

• Vectorization

 

The default, +Onoinfo, disables the

 

display of informational messages about

 

optimization.

 

 

+O[no]initcheck

The initialization checking feature of the

 

optimizer has three possible states: on,

 

off, or unspecified. When this option is

 

specified in the on state (+Oinitcheck),

 

the optimizer initializes to zero any local,

 

nonarray, nonstatic variables that are

 

uninitialized with respect to at least one

 

path leading to a use of the variable.

 

When +Onoinitcheckis specified, the

 

optimizer issues warning messages when

 

it discovers definitely uninitialized

 

variables, but does not initialize them.

 

When this option is unspecified, the

 

optimizer initializes to zero any local,

 

scalar, nonstatic variables that are

 

definitely uninitialized with respect to all

 

paths leading to a use of the variable.

 

This option is only effective at optimization

 

level 2 or higher.

 

 

+O[no]inline

+Oinline makes all subprograms

 

eligible for inlining. This option is only

 

effective at optimization level 3 or higher.

 

The +Onoinline option disables inlining

 

for all subprograms in your program.

 

The default is +Oinline at optimization

 

level 3 and +Onoinline at the lower levels.

 

 

+O[no]inline:filename

The file indicated by filename contains a

 

list of function names, separated by

 

spaces or newlines. This option enables

 

[disables] optimizer inlining for the named

 

functions. This optimization can occur at

 

optimization levels 3 and 4.

 

The default is +Oinline.

 

 

+O[no]inline=function1[,function2...]

Enable [disable] optimizer inlining for the

 

named functions. This optimization can

 

occur at optimization levels 3 and 4.

 

The default is +Oinline.

 

 

+Oinline_budget=n

+Oinline_budget enables the

 

optimizer to perform more aggressive

 

 

44 Compiling and linking