[Libreoffice] message construction bloat ...

So,

        While the discussion on logging goes on; I knocked up a little test to
compare the difference between a couple of styles of string creation,
orthogonally for eg. exception message construction.

        One of LibreOffice's -big- problems is size: we're too big. There are
lots of reasons for that, but little bits of bloat everywhere would be a
major cause of that.

        The attached test contrasts:

        fprintf (stderr, "P is %s and b is %d\n", p, b);
vs.
        std::cout << "P is " << p << " and b is " << b << "\n";

        Discarding the extra symbols + plt entries, ioinit & destruction, extra
string termination overhead from fragmented strings etc. and just
looking at the size of complete compiled 'main' .text

        I get 61 bytes vs. 102 bytes in favour of fprintf.

        Given that the real per-site difference is larger. Add to this the
issue that there are real translation problems with the 2nd approach
(that it cannot be appropriately re-ordered), and IMHO the argument here
is overwhelmingly against 'cute' operator-overloading approaches - where
each 'little' operator turns into a chunky function call at compile
time. Clearly if we introduce operators / allocations that can throw -
we also end up with some chunky eh_frame / exception unwind tables too.

        If we can choose a way of constructing message, IMHO it should not be
one that has this problem; concatenation by '+' operator shares this of
course.

        I know C++ doesn't like var-args, and I know var-args is type-unsafe,
and thus per-se 'evil' :-) but it also happens to be really easy to use
& read, better to translate, very familiar to most developers, and ...

        Anyhow - just to throw some data at the problem.

        ATB,

                Michael.

-- 
michael.meeks@suse.com  <><, Pseudo Engineer, itinerant idiot

/* to compile:
g++ -DSTDARG -Os -S -o stdarg.s ~/a.cxx
g++ -Os -S -o iostream.s ~/a.cxx
*/

#ifdef STDARG
#  include <stdio.h>
#else
#  include <iostream>
#  include <fstream>
#endif

int main (int argc, char **argv)
{
  volatile const char *p = "foo";
  volatile int b = 42;
#ifdef STDARG
  fprintf (stderr, "P is %s and b is %d\n", p, b);
#else
  std::cout << "P is " << p << " and b is " << b << "\n";
#endif
  return 1;
}

        .file   "a.cxx"
        .section        .rodata.str1.1,"aMS",@progbits,1
.LC0:
        .string "foo"
.LC1:
        .string "P is %s and b is %d\n"
        .text
.globl main
        .type   main, @function
main:
.LFB0:
        .cfi_startproc
        leal    4(%esp), %ecx
        .cfi_def_cfa 1, 0
        andl    $-16, %esp
        pushl   -4(%ecx)
        pushl   %ebp
        movl    %esp, %ebp
        .cfi_escape 0x10,0x5,0x2,0x75,0x0
        pushl   %ecx
        .cfi_escape 0xf,0x3,0x75,0x7c,0x6
        subl    $20, %esp
        movl    $42, -12(%ebp)
        movl    -12(%ebp), %eax
        pushl   %eax
        pushl   $.LC0
        pushl   $.LC1
        pushl   stderr
        .cfi_escape 0x2e,0x10
        call    fprintf
        movl    -4(%ebp), %ecx
        .cfi_def_cfa 1, 0
        movl    $1, %eax
        leave
        leal    -4(%ecx), %esp
        .cfi_def_cfa 4, 4
        ret
        .cfi_endproc
.LFE0:
        .size   main, .-main
        .ident  "GCC: (SUSE Linux) 4.5.1 20101208 [gcc-4_5-branch revision 167585]"
        .section        .comment.SUSE.OPTs,"MS",@progbits,1
        .string "OSpwg"
        .section        .note.GNU-stack,"",@progbits

        .file   "a.cxx"
        .section        .rodata.str1.1,"aMS",@progbits,1
.LC0:
        .string "P is "
.LC1:
        .string " and b is "
.LC2:
        .string "\n"
        .text
.globl main
        .type   main, @function
main:
.LFB1026:
        .cfi_startproc
        leal    4(%esp), %ecx
        .cfi_def_cfa 1, 0
        andl    $-16, %esp
        pushl   -4(%ecx)
        pushl   %ebp
        movl    %esp, %ebp
        .cfi_escape 0x10,0x5,0x2,0x75,0x0
        pushl   %ebx
        pushl   %ecx
        .cfi_escape 0xf,0x3,0x75,0x78,0x6
        subl    $24, %esp
        pushl   $.LC0
        pushl   $_ZSt4cout
        movl    $42, -12(%ebp)
        movl    -12(%ebp), %ebx
        .cfi_escape 0x10,0x3,0x2,0x75,0x7c
        .cfi_escape 0x2e,0x10
        call    _ZStlsISt11char_traitsIcEERSt13basic_ostreamIcT_ES5_PKc
        popl    %edx
        popl    %ecx
        pushl   $1
        pushl   %eax
        call    _ZNSo9_M_insertIbEERSoT_
        popl    %edx
        popl    %ecx
        pushl   $.LC1
        pushl   %eax
        call    _ZStlsISt11char_traitsIcEERSt13basic_ostreamIcT_ES5_PKc
        popl    %edx
        popl    %ecx
        pushl   %ebx
        pushl   %eax
        call    _ZNSolsEi
        popl    %edx
        popl    %ecx
        pushl   $.LC2
        pushl   %eax
        call    _ZStlsISt11char_traitsIcEERSt13basic_ostreamIcT_ES5_PKc
        leal    -8(%ebp), %esp
        movl    $1, %eax
        popl    %ecx
        .cfi_def_cfa 1, 0
        popl    %ebx
        .cfi_restore 3
        popl    %ebp
        .cfi_restore 5
        leal    -4(%ecx), %esp
        .cfi_def_cfa 4, 4
        ret
        .cfi_def_cfa 4, -4
        .cfi_endproc
.LFE1026:
        .size   main, .-main
        .type   _GLOBAL__I_main, @function
_GLOBAL__I_main:
.LFB1032:
        .cfi_startproc
        pushl   %ebp
        .cfi_def_cfa_offset 8
        movl    %esp, %ebp
        .cfi_offset 5, -8
        .cfi_def_cfa_register 5
        subl    $20, %esp
        pushl   $_ZStL8__ioinit
        .cfi_escape 0x2e,0x10
        call    _ZNSt8ios_base4InitC1Ev
        addl    $12, %esp
        pushl   $__dso_handle
        pushl   $_ZStL8__ioinit
        pushl   $_ZNSt8ios_base4InitD1Ev
        call    __cxa_atexit
        addl    $16, %esp
        leave
        .cfi_restore 5
        .cfi_def_cfa 4, 4
        ret
        .cfi_def_cfa_offset -8
        .cfi_endproc
.LFE1032:
        .size   _GLOBAL__I_main, .-_GLOBAL__I_main
        .section        .ctors,"aw",@progbits
        .align 4
        .long   _GLOBAL__I_main
        .local  _ZStL8__ioinit
        .comm   _ZStL8__ioinit,1,1
        .weakref        _ZL20__gthrw_pthread_oncePiPFvvE,pthread_once
        .weakref        _ZL27__gthrw_pthread_getspecificj,pthread_getspecific
        .weakref        _ZL27__gthrw_pthread_setspecificjPKv,pthread_setspecific
        .weakref        _ZL22__gthrw_pthread_createPmPK14pthread_attr_tPFPvS3_ES3_,pthread_create
        .weakref        _ZL20__gthrw_pthread_joinmPPv,pthread_join
        .weakref        _ZL21__gthrw_pthread_equalmm,pthread_equal
        .weakref        _ZL20__gthrw_pthread_selfv,pthread_self
        .weakref        _ZL22__gthrw_pthread_detachm,pthread_detach
        .weakref        _ZL22__gthrw_pthread_cancelm,pthread_cancel
        .weakref        _ZL19__gthrw_sched_yieldv,sched_yield
        .weakref        _ZL26__gthrw_pthread_mutex_lockP15pthread_mutex_t,pthread_mutex_lock
        .weakref        _ZL29__gthrw_pthread_mutex_trylockP15pthread_mutex_t,pthread_mutex_trylock
        .weakref        
_ZL31__gthrw_pthread_mutex_timedlockP15pthread_mutex_tPK8timespec,pthread_mutex_timedlock
        .weakref        _ZL28__gthrw_pthread_mutex_unlockP15pthread_mutex_t,pthread_mutex_unlock
        .weakref        
_ZL26__gthrw_pthread_mutex_initP15pthread_mutex_tPK19pthread_mutexattr_t,pthread_mutex_init
        .weakref        _ZL29__gthrw_pthread_mutex_destroyP15pthread_mutex_t,pthread_mutex_destroy
        .weakref        _ZL30__gthrw_pthread_cond_broadcastP14pthread_cond_t,pthread_cond_broadcast
        .weakref        _ZL27__gthrw_pthread_cond_signalP14pthread_cond_t,pthread_cond_signal
        .weakref        
_ZL25__gthrw_pthread_cond_waitP14pthread_cond_tP15pthread_mutex_t,pthread_cond_wait
        .weakref        
_ZL30__gthrw_pthread_cond_timedwaitP14pthread_cond_tP15pthread_mutex_tPK8timespec,pthread_cond_timedwait
        .weakref        _ZL28__gthrw_pthread_cond_destroyP14pthread_cond_t,pthread_cond_destroy
        .weakref        _ZL26__gthrw_pthread_key_createPjPFvPvE,pthread_key_create
        .weakref        _ZL26__gthrw_pthread_key_deletej,pthread_key_delete
        .weakref        
_ZL30__gthrw_pthread_mutexattr_initP19pthread_mutexattr_t,pthread_mutexattr_init
        .weakref        
_ZL33__gthrw_pthread_mutexattr_settypeP19pthread_mutexattr_ti,pthread_mutexattr_settype
        .weakref        
_ZL33__gthrw_pthread_mutexattr_destroyP19pthread_mutexattr_t,pthread_mutexattr_destroy
        .ident  "GCC: (SUSE Linux) 4.5.1 20101208 [gcc-4_5-branch revision 167585]"
        .section        .comment.SUSE.OPTs,"MS",@progbits,1
        .string "OSpwg"
        .section        .note.GNU-stack,"",@progbits