3 ms·

You ask a compiler, since it knows the max stack requirements of every function it compiled, if it's fixed. If it's not fixed it may give you at least the minim

by megous 5y ago

You ask a compiler, since it knows the max stack requirements of every function it compiled, if it's fixed. If it's not fixed it may give you at least the minimum. For total depth, keeping you program simple and predictable helps. People certainly manage to do it even for large programs like Linux itself, where stack size is like 16KiB or so. https://elixir.bootlin.com/linux/v5.2/source/arch/x86/include/asm/page_64_types.h#L16 https://elixir.bootlin.com/linux/v5.2/source/arch/x86/includ... and less on other archs. 8 KiB on arm https://elixir.bootlin.com/linux/v5.13-rc7/source/arch/arm/include/asm/thread_info.h#L25 https://elixir.bootlin.com/linux/v5.13-rc7/source/arch/arm/i...

chrisseaton 5y ago
But the compiler may not compile simple 'functions' as the user understands them - it may compile loop bodies, functions with other functions compiled in them, individual branches of functions, multiple versions of functions based on where they're called from... If I tell you as a compiler writer that this loop body from this function, but with this branch and this branch outlined, but only when called from this context, takes n bytes... I don't get what most working programmers are going to usefully do with that information.
- megous 5y ago
  Where's the problem? Compiler will tell you what amount of stack a function will use, if it's inlined it may not tell you for that function, but it will tell you for the function the function was inlined to, which is what matters. If the language is complicated and has generics or whatever, the programmer will have to do more work to understand it. It's not a huge issue in C.
  - chrisseaton 5y ago
    > Compiler will tell you what amount of stack a function will use If you ask a compiler how much stack a function will use the answer for a non-trivial compiler for a complicated language is always going to be 'it depends...'
    - MaxBarraclough 5y ago
      As I mentioned in my other comment, AdaCore's GNATstack tool appears to be capable of reporting this information conservatively but with enough accuracy to be useful. https://www.adacore.com/gnatpro/toolsuite/gnatstack https://www.adacore.com/gnatpro/toolsuite/gnatstack
      - user5994461 5y ago
        The tool will simply freak out when there is any recursion or indirect call. It's not helpful since it happens everywhere in standard libraries and non trivial programs (forget about sorting, any regex, parsing source code, linting, etc...). The only use case is for real-time embedded code -typically in aerospace- where the coding guidelines prohibits you from using any recursion at all and you have to prove the highest stack usage fits into the chosen microcontroller.
        MaxBarraclough 5y ago
        I mentioned such restrictions in my other comment, [0] I should have mentioned them here too. [0] https://news.ycombinator.com/item?id=27642406 https://news.ycombinator.com/item?id=27642406
    - megous 5y ago
      Original article is about C compiled programs, not about arbitrary languages. It's not a huge problem in C.

by megous 5y ago

chrisseaton 5y ago

But the compiler may not compile simple 'functions' as the user understands them - it may compile loop bodies, functions with other functions compiled in them, individual branches of functions, multiple versions of functions based on where they're called from... If I tell you as a compiler writer that this loop body from this function, but with this branch and this branch outlined, but only when called from this context, takes n bytes... I don't get what most working programmers are going to usefully do with that information.

megous 5y ago
Where's the problem? Compiler will tell you what amount of stack a function will use, if it's inlined it may not tell you for that function, but it will tell you for the function the function was inlined to, which is what matters. If the language is complicated and has generics or whatever, the programmer will have to do more work to understand it. It's not a huge issue in C.
- chrisseaton 5y ago
  > Compiler will tell you what amount of stack a function will use If you ask a compiler how much stack a function will use the answer for a non-trivial compiler for a complicated language is always going to be 'it depends...'
  - MaxBarraclough 5y ago
    As I mentioned in my other comment, AdaCore's GNATstack tool appears to be capable of reporting this information conservatively but with enough accuracy to be useful. https://www.adacore.com/gnatpro/toolsuite/gnatstack https://www.adacore.com/gnatpro/toolsuite/gnatstack
    - user5994461 5y ago
      The tool will simply freak out when there is any recursion or indirect call. It's not helpful since it happens everywhere in standard libraries and non trivial programs (forget about sorting, any regex, parsing source code, linting, etc...). The only use case is for real-time embedded code -typically in aerospace- where the coding guidelines prohibits you from using any recursion at all and you have to prove the highest stack usage fits into the chosen microcontroller.
      - MaxBarraclough 5y ago
        I mentioned such restrictions in my other comment, [0] I should have mentioned them here too. [0] https://news.ycombinator.com/item?id=27642406 https://news.ycombinator.com/item?id=27642406
  - megous 5y ago
    Original article is about C compiled programs, not about arbitrary languages. It's not a huge problem in C.