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When setting up a SimObject's Param structure, gem5 will autogenerate a header file which attempts to declare the SimObject's C++ type. It has had at least some level of sophistication there where it would pull off the namespaces ahead of the class name and handle them properly, but it didn't know how to handle templates. This change improves that handling in two ways. First, it adds a new magical SimObject attribute called 'cxx_template_params' which is used to specify what the template parameters are as a list. For instance, if your SimObject was a template which took an integer constant as its first parameter and a type as its second, this attribute could look like the following: cxx_template_params = [ 'int FOO', 'class Bar' ] Importantly, if there are any default values for these template parameters, they should *not* be included here, they should be specified where the class is later defined. The second new mechanism is to add an internal CxxClass in the SimObject.cxx_param_decl method. This class accepts the class signature in the cxx_class attribute and the cxx_template_params and does two things. First, it strips off namespaces like in the old implementation. Second, it extracts and processes any template arguments attached to the class. If these are constants (as determined by the contents of cxx_template_params), then they are stored verbatim. If they're types, then they're recursively expanded into a CxxClass and stored that way. Note that these are the *values* of the template arguments, where as cxx_template_params lists the *types* and *names* of those arguments. In our earlier example, if cxx_class was: cxx_class = 'CoolClasses::ClassName<12, Fruit::Apple>' Then CxxClass would extract the namespace 'CoolClasses', the class name 'ClassName', the argument '12', and the argument 'Fruit::Apple'. That second argument would be expanded into a CxxClass with the namespace 'Fruit' and the class name 'Apple'. Importantly here, because there were no default arguments given in cxx_template_params, all "hidden" arguments which would fall through to their defaults need to be fully specified in cxx_class. The CxxClass has a method called declare() which uses the information extracted earlier to output all of the "stuff" necessary for declaring the given class, including opening any containing namespaces and putting template<...> ahead of the actual class declaration with the template parameters specified. If any of the template arguments are themselves CxxClass instances, then they'll be recursively declared immediately before the current class is. An alternative solution to this problem might be to include the header file which actually defines the cxx_class type to avoid having to come up with a declaration. Unfortunately this doesn't work since it can set up include loops where the SimObject C++ header file includes the param header to get access to the Param type, but that includes the C++ header to get access to the SimObject type. This also makes it harder for SimObjects to refer to each other, since they rely on the declaration in the params header files when declaring a member pointer to that type in their own Param structures. Change-Id: I68cfc36ddff6d789eb4cdef5178c4619ac2cc8b1 Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/17228 Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com> Reviewed-by: Jason Lowe-Power <jason@lowepower.com> Maintainer: Gabe Black <gabeblack@google.com>
This is the gem5 simulator. The main website can be found at http://www.gem5.org A good starting point is http://www.gem5.org/Introduction, and for more information about building the simulator and getting started please see http://www.gem5.org/Documentation and http://www.gem5.org/Tutorials. To build gem5, you will need the following software: g++ or clang, Python (gem5 links in the Python interpreter), SCons, SWIG, zlib, m4, and lastly protobuf if you want trace capture and playback support. Please see http://www.gem5.org/Dependencies for more details concerning the minimum versions of the aforementioned tools. Once you have all dependencies resolved, type 'scons build/<ARCH>/gem5.opt' where ARCH is one of ALPHA, ARM, NULL, MIPS, POWER, SPARC, or X86. This will build an optimized version of the gem5 binary (gem5.opt) for the the specified architecture. See http://www.gem5.org/Build_System for more details and options. With the simulator built, have a look at http://www.gem5.org/Running_gem5 for more information on how to use gem5. The basic source release includes these subdirectories: - configs: example simulation configuration scripts - ext: less-common external packages needed to build gem5 - src: source code of the gem5 simulator - system: source for some optional system software for simulated systems - tests: regression tests - util: useful utility programs and files To run full-system simulations, you will need compiled system firmware (console and PALcode for Alpha), kernel binaries and one or more disk images. Please see the gem5 download page for these items at http://www.gem5.org/Download If you have questions, please send mail to gem5-users@gem5.org Enjoy using gem5 and please share your modifications and extensions.