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Asked: 2026-05-15T10:55:19+00:00

for a long time, I am thinking and studying output of C language compiler

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for a long time, I am thinking and studying output of C language compiler in assembler form, as well as CPU architecture. I know this may be silly to you, but it seems to me that something is very ineffective. Please, don´t be angry if I am wrong, and there is some reason I do not see for all these principles. I will be very glad if you tell me why is it designed this way. I actually truly believe I am wrong, I know the genius minds of people which get PCs together knew a reason to do so. What exactly, do you ask? I´ll tell you right away, I use C as a example:

1: Stack local scope memory allocation:

So, typical local memory allocation uses stack. Just copy esp to ebp and than allocate all the memory via ebp. OK, I would understand this if you explicitly need allocate RAM by default stack values, but if I do understand it correctly, modern OS use paging as a translation layer between application and physical RAM, when address you desire is further translated before reaching actual RAM byte. So why don´t just say 0x00000000 is int a,0x00000004 is int b and so? And access them just by mov 0x00000000,#10? Because you wont actually access memory blocks 0x00000000 and 0x00000004 but those your OS set the paging tables to. Actually, since memory allocation by ebp and esp use indirect addressing, “my” way would be even faster.

2: Variable allocation duplicity:

When you run application, Loader load its code into RAM. When you create variable, or string, compiler generates code that pushes these values on the top o stack when created in main. So there is actual instruction for do so, and that actual number in memory. So, there are 2 entries of the same value in RAM. One in form of instruction, second in form of actual bytes in the RAM. But why? Why not to just when declaring variable count at which memory block it would be, than when used, just insert this memory location?

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1 Answer

  1. Editorial Team

    1. Because C (and most other languages) support recursion, so a function can call itself, and each call of the function needs separate copies of any local variables. Also, on most current processors, your way would actually be slower — indirect addressing is so common that processors are optimized for it.

    2. You seem to want the behavior of C (or at least that C allows) for string literals. There are good and bad points to this, such as the fact that even though you’ve defined a “variable”, you can’t actually modify its contents (without affecting other variables that are pointing at the same location).

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