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The options.tcl file contains platform-agnostic settings that are stored in the Oc_Option database. Some of these settings affect the build process, while others control post-build runtime behavior. All are set using the Oc_Option command, which takes name + value pairs. The cflags and optlevel settings control compiler options. The default setting for cflags is
Oc_Option Add * Platform cflags {-def NDEBUG}
which causes the C macro “NDEBUG” to be defined. If this is
not set then various run-time checks such as assert statements and
some array index checks are activated. These checks slow execution but
may be helpful in diagnosing errors. Other cflag options include
-warn, which enables compiler warning messages, and -debug,
which tells the compiler to generate debugging symbols. A good
cflags setting for debugging is
Oc_Option Add * Platform cflags {-warn 1 -debug 1}
There is also an lflags option, similar to cflags, that
controls options to the linker. The default is an empty string (no
options), and you generally don't need to change this.
The optlevel option sets the compiler optimization level, with an integer value between 0 and 3. The default value is 2, which selects for a high but reliable level of optimizations. Some optimizations may reorder and combine source code statements, making it harder to debug code, so you may want to use
Oc_Option Add * Platform optlevel 0to disable all optimizations.
The config/platforms/<platform>.tcl files set default platform and compiler specific options. For example, config/platforms/windows-x86_64.tcl is the base platform file for 64-bit Windows. There are separate sections inside this file for the various supported compilers. You can make local changes to the default settings by creating a subdirectory of config/platforms/ named local/, and creating there an initially empty file with the same name as the base platform file. Inside the base platform file is a code block labeled LOCAL CONFIGURATION, which lists all the available local modifications. You can copy some or all of this Tcl code block to your new config/platforms/local/ file, and then uncomment and modify options as desired. For example, if you are using the Visual C++ compiler on Windows, you may want to include the /RTCus compiler flag to enable some run-time error checks. You can do that with these lines in your local/windows-x86_64.tcl file:
$config SetValue program_compiler_c++_remove_flags {/O2}
$config SetValue program_compiler_c++_remove_valuesafeflags {/O2}
$config SetValue program_compiler_c++_add_flags {/RTCus}
$config SetValue program_compiler_c++_add_valuesafeflags {/RTCus}
The *_valuesafeflags options are for code with sensitive
floating-point operations that must be evaluated exactly as
specified. This pertains primarily to the double-double routines in
pkg/xp/. The *_flags options are for everything else. The
*_remove_* controls remove options from the default compile
command. This can be a (Tcl) list, with each element matching as a
regular expression. (Refer to the
Tcl documentation
on the regexp command for details.) The *_add_* controls
append options. OOMMF sets /O2 optimization by default, but
/O2 is incompatible with /RTCus, so in this example /O2
is removed to allow /RTCus to be added. (Setting optlevel 0 in
the config/local/options.tcl file, as explained above, replaces
/O2 with /Od. So strictly speaking it is not necessary to
remove /O2 in that case, but it doesn't hurt either.)
You can run the command “oommf.tcl +platform +v” to see the effects of your current options.tcl and <platform>.tcl settings. For example,
To see the exact, full platform-specific compile and link commands, you can delete and rebuild individual executables in the OOMMF package. Two examples, one using the standard build options (pkg/oc/<platform>/varinfo) and one using the value-safe options (pkg/xp/<platform>/build_port) are presented below. (The response lines have been edited for clarity.)
You can also use this method to manually compile and/or link individual files: (1) Change to the relevant build directory (always one level below either pkg or app), (2) delete the file you want to rebuild from the <platform> directory, (3) run pimake as above to build the file, (4) copy and paste the compile/link command to the shell prompt, edit as desired, and rerun.
The varinfo and build_port executables are used to construct the platform-specific header files pkg/oc/<platform>/ocport.h and pkg/xp/<platform>/xpport.h. These files contain C++ macro definitions, typedefs, and function wrappers, and are an important adjunct when reading the OOMMF source code.
For in-depth investigations Tcl can be used to directly query and debug OOMMF initialization scripts. Start a Tcl shell, and from inside the shell append the OOMMF pkg/oc directory to the Tcl global auto_path variable. Next run package require Oc to load the Tcl-only portion of the OOMMF Oc library into the shell. Then you can check any and all Oc_Option values from config/options.tcl, platform configuration settings from config/platforms/<platform>.tcl, and perform various other types of introspection from the Tcl shell. See Fig. 5.1 for a sample session.