===============================================
HP-UX Flag Descriptions for CPU2000 - May 2001
===============================================
-----------------------------------------------
Flags for HP-UX C Compiler
-----------------------------------------------
-Bprotected[=symbol[,symbol...]*]
The named symbols, or all symbols if no symbols are
specified, are assigned the protected export class.
That means these symbols will not be preempted by
symbols from other load modules, so the compiler may
bypass the linkage table for both code and data
references and bind them to locally defined code and
data symbols.
When used with no symbol list, -Bprotected implies
-Wl,-aarchive_shared, causing the linker to prefer an
archive library over a shared library if one is
available. This can be overridden by following the
-Bprotected option with a subsequent -Wl,-a option.
-Bprotected_data
Marks only data symbols as having the protected export
class.
-Bprotected_def
Same as -Bprotected but only locally defined (non-
tentative) symbols are assigned the protected export
class.
+DSmodel Use the instruction scheduler tuned to the model
specified. The defined values for model are:
blended
Tune for best performance on a combination of
processors (i.e., Itanium or McKinley
processors).
itanium
Tune for best performance on an Itanium
processor. This is the only valid option for
HP-UX 11i v1.5.
mckinley
Tune for best performance on a McKinley
processor.
native
Tune for best performance on the processor on
which the compiler is running.
For this release of HP C, the default model is Itanium.
effmem.o Replacement for malloc/free that assumes ANSI compliance
and improves spatial locality and minimizes memory usage
by not maintaining a free list.
-exec Indicates that any object files created will be used to
create an executable file. Constants with a protected
or hidden export class are placed in the read-only data
section. This option also implies -Bprotected_def.
fastmem.o Replacement for malloc/free that assumes ANSI compliance.
+FP flags Specify how the run time environment for floating-point
operations should be initialized at program start up.
The default is that all trapping behaviors are
disabled. See ld(1) for specific values of flags. To
dynamically change these settings at run-time, refer to
fesetenv(3M).
D (d) Enable sudden underflow (flush to zero)
of denormalized values.
+I Instrument the application for profile-based
optimization. See ld(1), +P, and +pgm for more details.
The +I option is incompatible with the -G, +P, and -S
options. +I is equivalent to +Oprofile=collect. See
ld(1), +P, and +pgm for more details. The +I option is
incompatible with the -G, +P, and -S options. It is
incompatible with the -g option only during compile
time.
Kernel Tunables (Listed separately)
+Olevel Invoke optimizations selected by level. These can be
preceded by either +O or -O. Defined values for level
are:
0 Perform no optimizations.
1 Perform optimizations within basic blocks
only. This is the default.
2 Perform level 1 and global optimizations.
Same as -O and +O.
3 Perform level 2 as well as interprocedural
global optimizations.
4 Perform level 3 as well as doing link time
optimizations.
NOTE: +Oprocelim is the general default at all levels,
unless the users says +ild +ildrelink or -b. NOTE: +O4
is only supported with +P. Otherwise, attempts to
activate +O4 will cause the compiler to automatically
drop to +O3.
+Ofast Select a combination of compilation options for optimum
execution speed at build times. Currently: +O2,
+Olibcalls, +Onolimit, +Ofltacc=relaxed, +FPD,
+DSnative, and +Oshortdata. This option is a synonym
for -fast.
+Ofaster This option selects +Ofast, but with an increased
optimization level. If used with +P the optimization
level will be +O4. Otherwise it will be +O3.
+O[no]fltacc
Disable [enable] floating-point optimizations that can
result in numerical differences.
+Ofltacc is the same as +Ofltacc=strict.
+Onofltacc is the same as +Ofltacc=relaxed.
+Ofltacc=[strict|default|limited|relaxed]
Control the level of floating point optimizations that
the compiler may perform. The defined values for
optlevel are:
default
Allow contractions, such as fused multiply-
add ( FMA ), but disallows any other floating
point optimization that can result in
numerical differences.
limited
Like default, but also allows floating point
optimizations which may affect the generation
and propagation of infinities, NaNs, and the
sign of zero. Also implies +Ocxlimitedrange.
relaxed
In addition to the optimizations allowed by
limited, permits optimizations, such as
reordering of expressions, even if
parenthesized, that may affect a rounding
error. This is the same as +Onofltacc. Also
implies +Ocxlimitedrange.
strict
Disallow any floating point optimization that
can result in numerical differences. This is
the same as +Ofltacc.
The default is +Ofltacc=default.
+Oinlinebudget=n
Control the aggressiveness of inlining. n is an
integer in the range 1 - 1000000 that specifies the
level of aggressiveness as follows:
n Meaning
= 100 Default level on inlining.
> 100 More aggressive inlining.
2 - 99 Less aggressive inlining.
= 1 Only inline if it reduces code size.
This optimization can occur at optimization levels 3,
and 4. The default is +Oinlinebudget=100.
+O[no]libcalls
NOTE: This option is deprecated and may not be
supported on future releases. On IPF, including a
system header file will cause the functions declared
therein to be eligible for libcalls transformations,
regardless of the state of +O[no]libcalls.
+O[no]limit
Suppress [do not suppress] optimizations that significantly
increase compile-time or consume enormous amounts of memory.
+Olimit is the same as +Olimit=min.
+Onolimit is the same as +Olimit=none.
+O[no]ptrs_to_globals[=name1,name2,...,nameN]
Tell the optimizer whether global variables are
modified [are not modified] through pointers. This
optimization can occur at levels 2, 3, 4. The default
is +Optrs_to_globals.
+O[no]procelim
Enable [disable] the elimination of functions that
are not referenced by the application. Only
functions with the hidden export class may be
eliminated. The default is +Oprocelim.
+O[no]recovery
Generate [do not generate] recovery code for control
speculation. The +Orecovery option reduces the risk of
incorrect behavior for code that writes to uncacheable
memory and may not be properly identified as volatile.
Any program that uses signal handlers to catch signals
that are raised by accessing memory may not behave
correctly when +Onorecovery is used. The default is
+Onorecovery.
+Oshortdata[=size]
All objects of size size bytes or smaller will be
placed in the short data area, and references to such
data will assume it resides in the short data area.
Valid values of n are 0, or a decimal number between 8
and 4,194,304 (4MB). If no size is specified, all data
is placed in the short data area. If size is 0, no
data will be placed in the short data area, and all
data references will use long offsets. The default is
+Oshortdata=8.
+O[no]type_safety=[off|limited|ansi|strong]
Enable [disable] aliasing across types.
off The default. Specifies that aliasing can
occur freely across types.
limited
Code follows ANSI aliasing rules, and that
unnamed objects should be treated as if they
had an unknown type.
ansi Code follows ANSI aliasing rules, and unnamed
objects should be treated the same as named
objects.
strong
Code follows ANSI aliasing rules, except that
accesses through lvalues of a character type
are not permitted to touch objects of other
types. This assumes that field addresses are
not taken.
+P Optimize the application based on profile data found in
the database file flow.data, produced by compilation
with +I. +P is equivalent to +Oprofile=use or
+Oprofile=use:filename. See ld(1), +I, and +df, for
more details. The +P option is incompatible with the +I
and -S options. It is incompatible with the -g option
only during compile time.
-Wl,-aarchive_shared
(ld option -a search) Specifies library search order.
Archive_shared caused archive libraries to be
searched first, followed by shared libraries.
Specify whether shared or archive libraries are
searched with the -l option. The value of search
should be one of archive, shared, archive_shared,
shared_archive, or default. This option can
appear more than once, interspersed among -l
options, to control the searching for each
library. The default is to use the shared version
of a library if one is available, or the archive
version if not.
If either archive or shared is active, only the
specified library type is accepted.
If archive_shared is active, the archive form is
preferred, but the shared form is allowed.
If shared_archive is active, the shared form is
preferred but the archive form is allowed.
To create a statically-bound program, use the -
noshared option rather than -a archive .
-----------------------------------------------
Flags for HP-UX C++ Compiler
-----------------------------------------------
+FPflags Specify how the run time environment for floating-point
operations should be initialized at program start up.
The default is that all trapping behaviors are
disabled. See ld(1) for specific values of flags. To
dynamically change these settings at run time, refer to
fesetenv(3M).
D (d) Enable sudden underflow (flush to zero)
of denormalized values.
+inline_level [i]num
This option controls how C++ inlining hints influence
aCC. Specify num as 0, 1, 2, or 3.
num Meaning
0 No inlining is done (same effect as the +d
option).
1 Only small functions are inlined.
2 Only large functions are not inlined.
3 Inlining hints are respected in all cases,
except when the called function is recursive or
when it has a variable number of arguments.
The default level depends on +Olevel as shown in the
following table:
level num
0 1
1 1
2 2
3 2
4 2
If i is also specified, then implicit inlining is
invoked for "small" functions without the inline
keyword.
NOTE: This option controls functions declared with the
inline keyword or within the class declaration and is
effective at all optimization levels.
The options +Oinline and +Oinlinebudget control the
high level optimizer that recognizes other
opportunities in the same source file (+O3) or amongst
all source files (+O4).
-minshared Indicates that the result of the current compilation is
going into an executable file that will make minimal
use of shared libraries. Equivalent to -exec
-Bprotected.
+Ofast This option selects a combination of compilation
options for optimum execution speed and reasonable
build times. Currently: +O2, +Onolimit,
+Olibcalls, +Ofltacc=relaxed, +Onoinitcheck, +FPD
and +Oshortdata. This option is a synonym for
-fast.
+Olevel Invoke optimizations selected by level. Defined
values for level are:
0 Perform minimal optimizations.
1 Perform optimizations within basic
blocks only. This is the default.
2 Perform level 1 and global
optimizations. Same as -O.
3 Perform level 2 as well as
interprocedural global optimizations.
4 Perform level 3 as well as doing link
time optimizations. Requires concurrent
use of the +P option.
+Ofaster This option selects +Ofast, but with an increased
optimization level. If used with +P the optimization
level will be +O4. Otherwise it will be +O3.
+O[no]fltacc Disable [enable] floating-point optimizations that
can result in numerical differences.
+Ofltacc is the same as +Ofltacc=strict.
+Onofltacc is the same as +Ofltacc=relaxed.
+Ofltacc=level Controls the level of floating point optimizations
that the compiler may perform. The defined values
for level are:
default
Allows contractions, such as fused
multiply-add (FMA), but disallows any
other floating point optimization that
can result in numerical differences.
limited
Like default, but also allows floating
point optimizations which may affect the
generation and propagation of
infinities, NaNs, and the sign of zero.
relaxed
In addition to the optimizations allowed
by limited, permits optimizations, such
as reordering of expressions, even if
parenthesized, that may affect rounding
error. This is the same as +Onofltacc.
strict
Disallows any floating point
optimization that can result in
numerical differences. This is the same
as +Ofltacc.
The default is +Ofltacc=default.
+O[no]initcheck
Enable [disable] initialization to zero of any
local, scalar, non-static variable that is
uninitialized with respect to at least one path
leading to its use. This optimization can occur
at optimization levels 2, 3, and 4. The default
is to enable initialization if the variable is
uninitialized with respect to every path leading
to its use.
+O[no]libcalls NOTE: This option is deprecated and may not be
supported on future releases. On IPF, including a
system header file will cause the functions declared
therein to be eligible for libcalls transformations,
regardless of the state of +O[no]libcalls.
+O[no]limit Suppress [do not suppress] optimizations that
significantly increase compile-time or consume
enormous amounts of memory.
+Olimit is the same as +Olimit=min.
+Onolimit is the same as +Olimit=none.
+Oshortdata[=size]
All objects of size size bytes or smaller will be
placed in the short data area, and references to
such data will assume it resides in the short data
area. Valid values of n are 0, or a decimal
number between 8 and 4,194,304 (4MB). If no size
is specified, all data is placed in the short data
area. If size is 0, no data will be placed in the
short data area, all data references will use long
offsets, and thread-local storage will not be
supported. The default is +Oshortdata=8.
-----------------------------------------------
Flags for HP-UX F90 Compiler
-----------------------------------------------
+cat Concatenates all source files of the same source
form together, then compiles the concatenated
source all at once. This enables inlining at +O3
within the concatenated file.
+I/+P Optimize the application based on profile data
found in the database file flow.data , produced by
compilation with +I ld(1), +I, and +df, for more
details. The +P option is incompatible with the +I
and -S options. It is incompatible with the -g
option only during compile time. This option is
only valid on IPF.
+Ooptlevel Specify the level of optimization. Higher levels
include optimizations performed at lower levels.
Many other options beginning with +O enable
specific optimizations; see the OPTIMIZATION
section.
optlevel can be one of the following:
0 Minimal optimization, fastest compile
time, best debugging support. This is
the default.
1 Block-level optimizations, moderately
fast compile time, moderate improvement
in runtime performance.
2 Full optimization within each subprogram
in a file. Marked improvement in
runtime performance, noticeably longer
compile time, program transformations
more pronounced than at lower levels.
3 Full optimization across all subprograms
within the source file, including
subprogram cloning and inlining. This
level of optimization can greatly
improve the runtime performance of
programs that make frequent procedure
calls.
+Ofast Select a combination of compilation options for
optimum execution speed at build times.
Currently: +O2, +Olibcalls, +Onolimit,
+Ofltacc=relaxed, +FPD, +DSnative (on IPF), and
+Oshortdata.
+FPflags Specify how the run time environment for floating-point
operations should be initialized at program start up.
The default is that all trapping behaviors are
disabled. See ld(1) for specific values of flags. To
dynamically change these settings at run time, refer to
fesetenv(3M).
D (d) Enable sudden underflow (flush to zero)
of denormalized values.
+Ofltacc=[strict|default|limited|relaxed]
Control the level of floating point optimizations
that the compiler may perform. The defined values
for optlevel are:
default
Allow contractions, such as fused
multiply-add (FMA), but disallows any
other floating point optimization that
can result in numerical differences.
limited
Like default, but also allows floating
point optimizations which may affect the
generation and propagation of
infinities, NaNs, and the sign of zero.
Also implies +Ocxlimitedrange.
relaxed
In addition to the optimizations allowed
by limited, permits optimizations, such
as reordering of expressions, even if
parenthesized, that may affect a
rounding error. This is the same as
+Onofltacc. Also implies
+Ocxlimitedrange.
strict
Disallow any floating point optimization
that can result in numerical
differences. This is the same as
+Ofltacc.
The default is +Ofltacc=default.
+Oinline_budget=n
Perform more aggressive inlining, where n
specifies the degree of aggressiveness, as
follows:
100 Default level of inlining.
> 100 More aggressive inlining at the
expense of compilation time and code
size. The maximum for n is 1000000.
2 - 99 Less aggressive inlining. The
optimizer gives more weight to
compilation time and code size when
determining whether to inline.
1 Inline only if it reduces code size.
This option can be used at optimization level 3 or
higher.
+O[no]libcalls Use [do not use] low-call-overhead versions of
select library routines. This option can be used
at any level. At optimization level 0 or 1, the
default is +Onolibcalls; at optimization level 2
or higher, the default is +Olibcalls.
+O[no]limit Suppress [do not suppress] optimizations that
significantly increase compile-time or consume
large amounts of memory. This option can be used
at level 2 and higher. The default is +Olimit.
+O[no]loop_block
Enable [disable] loopblocking for data cache
optimizations. Available at optimization level 3
+O[no]ptrs_to_globals[=name1,name2,...,nameN]
Tell the optimizer whether global variables are
modified [are not modified] through pointers.
This optimization can occur at levels 2, 3, 4. The
default is +Optrs_to_globals
+Oshortdata[=size]
All objects of size size bytes or smaller will be
placed in the short data area, and references to
such data will assume it resides in the short data
area. Valid values of n are 0, or a decimal
number between 8 and 4,194,304 (4MB). If no size
is specified, all data is placed in the short data
area. If size is 0, no data will be placed in the
short data area, and all data references will use
long offsets. The default is +Oshortdata=8.
-----------------------------------------------
Descriptions of Kernel Tunables
-----------------------------------------------
dbc_max_pct Maximum dynamic buffer cache size as a percent of system memory
dbc_min_pct Minimum dynamic buffer cache size as a percent of system memory
maxdsiz Maximum data size
maxdsiz_64bit Maximum data size for 64 bit applications
maxssiz Maximum stack size
maxssiz_64bit Maximum stack size for 64 bit applications
vps_ceiling Maximum System-Selected Page Size (in Kbytes)
vps_pagesize Default user page size (in Kbytes)
swapmem_on Swap to memory flag.