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

The +O[no]parminit option enables [disables] automatic initialization to non-NaT of

unspecified function parameters at call sites. This is useful in preventing NaT values in

parameter registers. The default is +Onoparminit.

+O[no]parmsoverlap

The +Onoparmsoverlap option optimizes with the assumption that on entry to a function

each of that function’s pointer-typed formals points to memory that is accessed only

through that formal or through copies of that formal made within the function. For example,

that memory must not be accessed through a different formal, and that formal must not

point to a global that is accessed by name within the function or any of its calls.

Use +Onoparmsoverlap if C/C++ programs have been literally translated from

FORTRAN programs.

The default is +Oparmsoverlap.

+O[no]procelim

The +O[no]procelim option enables [disables] the elimination of dead procedure

code and sometimes the unreferenced data.

Use this option when linking an executable file, to remove functions not referenced by

the application. You can also use this option when building a shared library to remove

functions not exported and not referenced from within the shared library. This may be

especially useful when functions have been inlined.

NOTE: Any function having symbolic debug information associated with it is not

removed.

The default is +Onoprocelim at optimization levels 0 and 1; at levels 2, 3 and 4, the

default is +Oprocelim.

+O[no]promote_indirect_calls

The +O[no]promote_indirect_calls option uses profile data from profile-based

optimization and other information to determine the most likely target of indirect calls

and promotes them to direct calls. Indirect calls occur with pointers to functions and

virtual calls.

In all cases the optimized code tests to make sure the direct call is being taken and if

not, executes the indirect call. If +Oinline is in effect, the optimizer may also inline the

promoted calls.

+Opromote_indirect_calls is only effective with profile-based optimization.

Code Optimizing Options 75