User:Kim Bruning/Compiler metaprogramming example

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Here is an example of how one can use a compiler to generate large amounts of assembly code. It has been linked from metaprogramming because of the length of the example.

The following programme to count from 1 to 1000 is written in C++ :

/* hello.cpp */
#include <iostream>

using std::cout;
using std::endl;

main() {
        for(int i=1 ; i <= 1000 ; i++) {
                std::cout << i << std::endl;
        }
}

Using the GNU GCC C++ compiler g++ to generate intel x86 assembler as follows:

 g++ hello.cpp -S

creates a new 221 line file hello.s as a result. The contents of this file is:

        .file   "hello.cpp"
        .local  _ZSt8__ioinit
        .comm   _ZSt8__ioinit,1,1
        .text
        .align 2
.globl main
        .type   main,@function
main:
.LFB1448:
        pushl   %ebp
.LCFI0:
        movl    %esp, %ebp
.LCFI1:
        subl    $24, %esp
.LCFI2:
        andl    $-16, %esp
        movl    $0, %eax
        subl    %eax, %esp
        movl    $1, -4(%ebp)
.L2:
        cmpl    $1000, -4(%ebp)
        jle     .L5
        jmp     .L3
.L5:
        movl    -4(%ebp), %eax
        movl    %eax, 4(%esp)
        movl    $_ZSt4cout, (%esp)
        call    _ZNSolsEi
        movl    $_ZSt4endlIcSt11char_traitsIcEERSt13basic_ostreamIT_T0_ES6_, 4(%esp)
        movl    %eax, (%esp)
        call    _ZNSolsEPFRSoS_E
        leal    -4(%ebp), %eax
        incl    (%eax)
        jmp     .L2
.L3:
        movl    $0, %eax
        leave
        ret
.LFE1448:
.Lfe1:
        .size   main,.Lfe1-main
        .align 2
        .type   _Z41__static_initialization_and_destruction_0ii,@function
_Z41__static_initialization_and_destruction_0ii:
.LFB1460:
        pushl   %ebp
.LCFI3:
        movl    %esp, %ebp
.LCFI4:
        subl    $24, %esp
.LCFI5:
        cmpl    $65535, 12(%ebp)
        jne     .L6
        cmpl    $1, 8(%ebp)
        jne     .L6
        movl    $_ZSt8__ioinit, (%esp)
        call    _ZNSt8ios_base4InitC1Ev
        movl    $__dso_handle, 8(%esp)
        movl    $0, 4(%esp)
        movl    $__tcf_0, (%esp)
        call    __cxa_atexit
.L6:
        leave
        ret
.LFE1460:
.Lfe2:
        .size   _Z41__static_initialization_and_destruction_0ii,.Lfe2-_Z41__static_initialization_and_destruction_0ii
        .align 2
        .type   __tcf_0,@function
__tcf_0:
.LFB1461:
        pushl   %ebp
.LCFI6:
        movl    %esp, %ebp
.LCFI7:
        subl    $8, %esp
.LCFI8:
        movl    $_ZSt8__ioinit, (%esp)
        call    _ZNSt8ios_base4InitD1Ev
        leave
        ret
.LFE1461:
.Lfe3:
        .size   __tcf_0,.Lfe3-__tcf_0
        .align 2
        .type   _GLOBAL__I_main,@function
_GLOBAL__I_main:
.LFB1463:
        pushl   %ebp
.LCFI9:
        movl    %esp, %ebp
.LCFI10:
        subl    $8, %esp
.LCFI11:
        movl    $65535, 4(%esp)
        movl    $1, (%esp)
        call    _Z41__static_initialization_and_destruction_0ii
        leave
        ret
.LFE1463:
.Lfe4:
        .size   _GLOBAL__I_main,.Lfe4-_GLOBAL__I_main
        .section        .ctors,"aw",@progbits
        .align 4
        .long   _GLOBAL__I_main
        .weak   pthread_mutex_unlock
        .weak   pthread_mutex_trylock
        .weak   pthread_mutex_lock
        .weak   pthread_create
        .weak   pthread_setspecific
        .weak   pthread_getspecific
        .weak   pthread_key_delete
        .weak   pthread_key_create
        .weak   pthread_once
        .section        .eh_frame,"a",@progbits
.Lframe1:
        .long   .LECIE1-.LSCIE1
.LSCIE1:
        .long   0x0
        .byte   0x1
        .string "zP"
        .uleb128 0x1
        .sleb128 -4
        .byte   0x8
        .uleb128 0x5
        .byte   0x0
        .long   __gxx_personality_v0
        .byte   0xc
        .uleb128 0x4
        .uleb128 0x4
        .byte   0x88
        .uleb128 0x1
        .align 4
.LECIE1:
.LSFDE1:
        .long   .LEFDE1-.LASFDE1
.LASFDE1:
        .long   .LASFDE1-.Lframe1
        .long   .LFB1448
        .long   .LFE1448-.LFB1448
        .uleb128 0x0
        .byte   0x4
        .long   .LCFI0-.LFB1448
        .byte   0xe
        .uleb128 0x8
        .byte   0x85
        .uleb128 0x2
        .byte   0x4
        .long   .LCFI1-.LCFI0
        .byte   0xd
        .uleb128 0x5
        .align 4
.LEFDE1:
.LSFDE3:
        .long   .LEFDE3-.LASFDE3
.LASFDE3:
        .long   .LASFDE3-.Lframe1
        .long   .LFB1460
        .long   .LFE1460-.LFB1460
        .uleb128 0x0
        .byte   0x4
        .long   .LCFI3-.LFB1460
        .byte   0xe
        .uleb128 0x8
        .byte   0x85
        .uleb128 0x2
        .byte   0x4
        .long   .LCFI4-.LCFI3
        .byte   0xd
        .uleb128 0x5
        .align 4
.LEFDE3:
.LSFDE5:
        .long   .LEFDE5-.LASFDE5
.LASFDE5:
        .long   .LASFDE5-.Lframe1
        .long   .LFB1461
        .long   .LFE1461-.LFB1461
        .uleb128 0x0
        .byte   0x4
        .long   .LCFI6-.LFB1461
        .byte   0xe
        .uleb128 0x8
        .byte   0x85
        .uleb128 0x2
        .byte   0x4
        .long   .LCFI7-.LCFI6
        .byte   0xd
        .uleb128 0x5
        .align 4
.LEFDE5:
.LSFDE7:
        .long   .LEFDE7-.LASFDE7
.LASFDE7:
        .long   .LASFDE7-.Lframe1
        .long   .LFB1463
        .long   .LFE1463-.LFB1463
        .uleb128 0x0
        .byte   0x4
        .long   .LCFI9-.LFB1463
        .byte   0xe
        .uleb128 0x8
        .byte   0x85
        .uleb128 0x2
        .byte   0x4
        .long   .LCFI10-.LCFI9
        .byte   0xd
        .uleb128 0x5
        .align 4
.LEFDE7:
        .ident  "GCC: (GNU) 3.2.3 20030422 (Gentoo Linux 1.4 3.2.3-r2, propolice)"