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by jlkjaoifnwlekfj 1659 days ago
> A first-year computer science student can tell you that the arguments get pushed onto the stack. In other words, a call to this 3GL function results in the following assembly pseudo code

Are people this ignorant when it comes to C/C++ or any systems language? ABI & calling conventions were introduced early in my C & C++ textbooks (age 13 btw, not even close to college years).
3 comments
jcranmer 1659 days ago
Well, if you believed as the author did that arguments are always pushed onto the stack, you are pretty ignorant--most major architectures these days don't use the stack for arguments, at least not for the first several arguments.

(Semi-random tangent: the hardest bug I ever had the pleasure of debugging was when I discovered that the PLT glue code to load an entry into the PLT was unexpectedly clobbering a register that the calling convention said needed to be preserved. By very, very careful using non-default calling conventions across shared object boundaries!)

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sumtechguy 1658 days ago
I think it would depend on which system you were introduced into. Also 99% sure in my classes in the mid 90s they taught stack push. Which made sense as registers were pretty valuable. It was not until RISC came along, and register renaming, that you could consider 'wasting' them on passing args in the general case. In the 'DOS'/'Win16' world calling conventions were all over the place. You could get into trouble real quick if you did not pay attention to those calling convention modifiers. Especially if you were using libs from different compilers. In the linux world where you can control the whole stack it is easier to say 'this way and if you stray away from it, good luck'.

Small sample of the remnants of that in the DOS world. https://docs.microsoft.com/en-us/cpp/cpp/argument-passing-an...

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mhh__ 1659 days ago
Ab initio first years probably just about know what registers are so I can believe that.

Decoupling the compilers optimizations and the ABI (particularly what constitutes a "move" of a struct) has derailed a few conversations I've been involved with - even from very smart devs (although mainly interpretation rather than basic misunderstandings like thinking what is actually due to the ABI is an optimization)

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