Hi Jason. The instruction definitions in gem5 can be quite complex, and it's unlikely you'll find a lot of information about specific details like this through Google. Probably a good place to start is to try to understand how the ISA description files work in general, since that will give you more context on how they're being used in this particular case. You can find some info about its basic structure here:
https://www.gem5.org/documentation/general_docs/architecture_support/isa_parser/ And you might want to take a look at one of the simpler ISAs like MIPS or SPARC to see these in use without as much complexity getting in the way and obscuring what's really going on. For some of these variables like wbDecl and pcDecl, I think they are just shuttling information around in the python code which is part of the ISA description. For some others like use_wb and use_pc, these are used in the instruction templates which are basically (but not just) format strings which tell the ISA parser how to generate the C++ which implements a given instruction. Gabe On Tue, Nov 30, 2021 at 12:45 PM Jason Z via gem5-users <gem5-users@gem5.org> wrote: > Hello everyone, I hope you are all doing well! > > I apologize for this question if it seems simple, but I am still fairly > new to gem5 and still trying to finalize my understanding, so any help > would be greatly appreciated > > I am working on changing some instructions in the ISA files (i.e., > src/arch/arm/isa/insts/str64.isa), and I am coming across a few variables > that I am not entirely certain of their meaning, and it's causing some > confusion with what I am trying to implement and I haven't been able to > find anything about them through searching the gem5 code base, the gem5 > discussion pages, or even just a general Google search > > So I was wondering if there was perhaps a listing of these variables > somewhere or if anyone had any more insight into them > > Specifically, I wondering about the following variables and their > interpretation/meaning: > > - wbDecl > - pcDecl > - use_wb > - use_pc > - rasPop > > I am assuming the following: > > - wbDecl --> writeback Declare > - pcDecl --> program counter Declare > - use_wb --> use writeback > - use_pc --> use program counter > - rasPop --> return address stack pop > > But I am only assuming that this might be what these variables are > referencing and I am still not certain of their use in the bigger context > of creating instructions in the ISA files, so if anyone has any more > insight, it would be greatly appreciated, thank you for your time! > > Respectfully, > > Jason Z > _______________________________________________ > gem5-users mailing list -- gem5-users@gem5.org > To unsubscribe send an email to gem5-users-le...@gem5.org > %(web_page_url)slistinfo%(cgiext)s/%(_internal_name)s >
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