Calling Conventions

Program
=======

int __attribute__((cdecl / stdcall / fastcall)) foo(int a, int b) {
    return (a < b) ? a : b;
}

int main() {
    int i = foo(88, 99);
    return i;
}

--------------------------------------------------------------------------------------------
Command
=======

gcc -S -m32 main.c && cat main.s

--------------------------------------------------------------------------------------------
// cdecl
// =====

    .file   "main.c"
    .text
    .globl  foo
    .type   foo, @function
foo:
    pushl   %ebp
    movl    %esp, %ebp
    movl    8(%ebp), %eax
    cmpl    %eax, 12(%ebp)
    cmovle  12(%ebp), %eax
    popl    %ebp
        ret
    .size   foo, .-foo
    .globl  main
    .type   main, @function
main:
    pushl   %ebp
    movl    %esp, %ebp
    subl    $16, %esp
    pushl   $99
    pushl   $88
    call    foo
    addl    $8, %esp
    movl    %eax, -4(%ebp)
    movl    -4(%ebp), %eax
    leave
    ret
    .size   main, .-main
    .ident  "GCC: (Ubuntu 5.4.0-6ubuntu1~16.04.2) 5.4.0 20160609"
    .section    .note.GNU-stack,"",@progbits
--------------------------------------------------------------------------------------------
// stdcall
// =======

    .file   "main.c"
    .text
    .globl  foo
    .type   foo, @function
foo:
    pushl   %ebp
    movl    %esp, %ebp
    movl    8(%ebp), %eax
    cmpl    %eax, 12(%ebp)
    cmovle  12(%ebp), %eax
    popl    %ebp
        ret     $8
    .size   foo, .-foo
    .globl  main
    .type   main, @function
main:
    pushl   %ebp
    movl    %esp, %ebp
    subl    $16, %esp
    pushl   $99
    pushl   $88
    call    foo
    movl    %eax, -4(%ebp)
    movl    -4(%ebp), %eax
    leave
    ret
    .size   main, .-main
    .ident  "GCC: (Ubuntu 5.4.0-6ubuntu1~16.04.2) 5.4.0 20160609"
    .section    .note.GNU-stack,"",@progbits
--------------------------------------------------------------------------------------------
// fastcall
// ========

    .file   "main.c"
    .text
    .globl  foo
    .type   foo, @function
foo:
    pushl   %ebp
    movl    %esp, %ebp
    subl    $8, %esp
    movl    %ecx, -4(%ebp)
    movl    %edx, -8(%ebp)
    movl    -4(%ebp), %eax
    cmpl    %eax, -8(%ebp)
    cmovle  -8(%ebp), %eax
    leave
    ret
    .size   foo, .-foo
    .globl  main
    .type   main, @function
main:
    pushl   %ebp
    movl    %esp, %ebp
    subl    $16, %esp
    movl    $99, %edx
    movl    $88, %ecx
    call    foo
    movl    %eax, -4(%ebp)
    movl    -4(%ebp), %eax
    leave
    ret
    .size   main, .-main
    .ident  "GCC: (Ubuntu 5.4.0-6ubuntu1~16.04.2) 5.4.0 20160609"
    .section    .note.GNU-stack,"",@progbits