When is the Caller Responsible for Stack Cleanup: cdecl vs. stdcall?

stdcall vs. cdecl: Understanding the Calling Conventions

In C/C , functions can be invoked using various calling conventions, two of the most common being stdcall and cdecl. These conventions determine how parameters are passed to functions and how the stack is managed during function calls.

1. Stack Cleanup in cdecl Functions

When a cdecl function is called, the caller is not responsible for freeing up the stack space reserved for function parameters. The function itself is responsible for cleaning up its stack space, as the stack pointer is adjusted upon function entry to accommodate its parameters. The caller does not need to know the calling convention of the called function as this information is handled by the compiler.

2. Calling Convention Mismatches

Mixing calling conventions is generally not recommended. If a stdcall function calls a cdecl function, the stdcall function will expect the cdecl function to clean up the stack, which it won't do, leading to memory leaks. The same issue arises when a cdecl function calls a stdcall function, as the cdecl function won't expect the stdcall function to have already cleaned up the stack.

3. Performance Comparison

In general, there is no significant performance difference between stdcall and cdecl calling conventions. However, some systems may optimize for one convention over the other. In the context of Windows programming, stdcall is the standard calling convention for WinAPI functions, while cdecl is used primarily for C and C language extensions.

The above is the detailed content of When is the Caller Responsible for Stack Cleanup: cdecl vs. stdcall?. For more information, please follow other related articles on the PHP Chinese website!