[Bug c/27357] New: 20 % increase code size in 4.1 vs 3.4.5, tail return optimisation

[Bug c/27357] New: 20 % increase code size in 4.1 vs 3.4.5, tail return optimisation

[etienne_lorrain at yahoo dot fr]

Here is a 20 % increase code size, because the compiler tries too much to
 jump to UI_plotHline() instead of just calling the function and then doing
 a standard return at the end of drawbutton()...


[etienne@localhost projet]$ cat tmp.c
typedef struct {
    unsigned short x, y;        /* x should be the easyest to read */
    } __attribute__ ((packed)) coord;

extern inline void
UI_plotHline (coord xy, unsigned short xend, unsigned color) {
    extern UI_function_plotHline (coord xy, unsigned xend, unsigned color);
    UI_function_plotHline (xy, xend, color);
    }

extern inline void
UI_setpixel (coord xy, unsigned color) {
    extern UI_function_setpixel (coord xy, unsigned color);
    UI_function_setpixel (xy, color);
    }

extern inline void bound_stack (void)
  {
/*
 * limit included - but add 2 to high limit for reg16, and 4 for reg32
 * if not in bound, exception #BR generated (INT5).
 * iret from INT5 will retry the bound instruction.
 */
  extern unsigned STATE_stack_limit;
  asm volatile (" bound %%esp,%0 " : : "m" (STATE_stack_limit) );
  }

void
drawbutton (coord    upperleft, coord  lowerright,
            unsigned upperleftcolor, unsigned lowerrightrcolor,
            unsigned fillcolor, unsigned drawbackground)
  {bound_stack();{
  /* Enlarge the button by few pixels: */
  upperleft.x -= 2;
  lowerright.x += 2;
  lowerright.y -= 1; /* do not overlap two consecutive lines */

  UI_plotHline (upperleft, lowerright.x, upperleftcolor);       /* top line */
  /* do not change VESA1 banks too often, process horizontally,
     left to right, line per line */
  for (;;) {
      upperleft.y += 1;
      if (upperleft.y >= lowerright.y)
          break;
      UI_setpixel (upperleft, upperleftcolor);
      if (drawbackground)
          UI_plotHline (((coord) { .x = upperleft.x + 1, .y = upperleft.y }),
                        lowerright.x - 1, fillcolor);
      UI_setpixel (((coord) { .x = lowerright.x - 1, .y = upperleft.y }),
                        lowerrightrcolor);
      }

  UI_plotHline (upperleft, lowerright.x, lowerrightrcolor);     /* bottom line
*/
  }}

[etienne@localhost projet]$ gcc -v
Using built-in specs.
Target: i386-redhat-linux
Configured with: ../configure --prefix=/usr --mandir=/usr/share/man
--infodir=/usr/share/info --enable-shared --enable-threads=posix
--enable-checking=release --with-system-zlib --enable-__cxa_atexit
--disable-libunwind-exceptions --enable-libgcj-multifile
--enable-languages=c,c++,objc,obj-c++,java,fortran,ada --enable-java-awt=gtk
--disable-dssi --with-java-home=/usr/lib/jvm/java-1.4.2-gcj-1.4.2.0/jre
--with-cpu=generic --host=i386-redhat-linux
Thread model: posix
gcc version 4.1.0 20060304 (Red Hat 4.1.0-3)
[etienne@localhost projet]$ gcc -Os -c tmp.c && size *.o
   text    data     bss     dec     hex filename
    276       0       0     276     114 tmp.o
[etienne@localhost projet]$ toolchain-3.4.5/bin/gcc -v
Reading specs from
/home/etienne/projet/toolchain-3.4.5/bin/../lib/gcc/i686-pc-linux-gnu/3.4.5/specs
Configured with: ../configure --prefix=/home/etienne/projet/toolchain
--enable-languages=c
Thread model: posix
gcc version 3.4.5
[etienne@localhost projet]$ toolchain-3.4.5/bin/gcc -Os -c tmp.c && size *.o
   text    data     bss     dec     hex filename
    227       0       0     227      e3 tmp.o
[etienne@localhost projet]$


-- 
           Summary: 20 % increase code size in 4.1 vs 3.4.5, tail return
                    optimisation
           Product: gcc
           Version: 4.1.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: etienne_lorrain at yahoo dot fr
 GCC build triplet: i386-redhat-linux
  GCC host triplet: i386-redhat-linux
GCC target triplet: i386-redhat-linux


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=27357

[Bug rtl-optimization/27357] 20 % increase code size in 4.1 vs 3.4.5

[pinskia at gcc dot gnu dot org]

------- Comment #1 from pinskia at gcc dot gnu dot org  2006-05-02 07:43 -------
This has nothing to do with tail return optimization as 3.4.0 also did it.


-- 

pinskia at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
            Summary|20 % increase code size in  |20 % increase code size in
                   |4.1 vs 3.4.5, tail return   |4.1 vs 3.4.5
                   |optimisation                |


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=27357

[Bug rtl-optimization/27357] 20 % increase code size in 4.1 vs 3.4.5

[etienne_lorrain at yahoo dot fr]

------- Comment #2 from etienne_lorrain at yahoo dot fr  2006-05-24 13:22 -------
etienne@cygne:~/projet/gujin$ /home/etienne/projet/toolchain/bin/gcc -v
Using built-in specs.
Target: i686-pc-linux-gnu
Configured with: ../configure --prefix=/home/etienne/projet/toolchain
--enable-languages=c
Thread model: posix
gcc version 4.1.1 20060517 (prerelease)
etienne@cygne:~/projet/gujin$ /home/etienne/projet/toolchain/bin/gcc tmp1.c -Os
-c -o tmp.o && size tmp.o
   text    data     bss     dec     hex filename
    279       0       0     279     117 tmp.o
etienne@cygne:~/projet/gujin$ /home/etienne/projet/toolchain/bin/gcc tmp1.c -Os
-c -o tmp.o -fno-optimize-sibling-calls && size tmp.o
   text    data     bss     dec     hex filename
    251       0       0     251      fb tmp.o

  So "tail return optimization" disabled by -fno-optimize-sibling-calls has at
least something to do with the size increase.

 Note that this new GCC-4.1.1 prerelease also produce such code:
        addl    $12, %esp
        leal    -12(%ebp), %esp
        pop     allregs
        ret


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=27357

[Bug rtl-optimization/27357] 20 % increase code size in 4.1 vs 3.4.5

[rguenth at gcc dot gnu dot org]

------- Comment #3 from rguenth at gcc dot gnu dot org  2010-02-16 10:30 -------
rguenther@murzim:/tmp> gcc-3.3 -Os -c t.i -m32
rguenther@murzim:/tmp> size t.o
   text    data     bss     dec     hex filename
    222       0       0     222      de t.o
rguenther@murzim:/tmp> gcc-4.1 -Os -c t.i -m32
rguenther@murzim:/tmp> size t.o
   text    data     bss     dec     hex filename
    280       0       0     280     118 t.o
rguenther@murzim:/tmp> gcc-4.3 -Os -c t.i -m32
rguenther@murzim:/tmp> size t.o
   text    data     bss     dec     hex filename
    269       0       0     269     10d t.o
rguenther@murzim:/tmp> gcc-4.4 -Os -c t.i -m32
rguenther@murzim:/tmp> size t.o
   text    data     bss     dec     hex filename
    290       0       0     290     122 t.o
rguenther@murzim:/tmp> gcc-4.5 -Os -c t.i -m32
rguenther@murzim:/tmp> size t.o
   text    data     bss     dec     hex filename
    237       0       0     237      ed t.o


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=27357

[Bug rtl-optimization/27357] 20 % increase code size in 4.1 vs 3.4.5

[rguenth at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=27357

Richard Guenther <rguenth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2011.03.24 16:33:55
                 CC|                            |rguenth at gcc dot gnu.org
      Known to work|                            |3.4.5, 4.6.0
     Ever Confirmed|0                           |1

--- Comment #5 from Richard Guenther <rguenth at gcc dot gnu.org> 2011-03-24 16:33:55 UTC ---
Seems to be fixed for 4.6.  Now on to a way to add object-size testcases ...

[Bug rtl-optimization/27357] 20 % increase code size in 4.1 vs 3.4.5

[hubicka at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=27357

Jan Hubicka <hubicka at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |hubicka at gcc dot gnu.org

--- Comment #4 from Jan Hubicka <hubicka at gcc dot gnu.org> 2010-11-11 00:05:13 UTC ---
With current mainline
h@gcc17:~/trunk/build/gcc$ size pa.o
   text    data     bss     dec     hex filename
    211       0       0     211      d3 pa.o
I get gcc-4.1 also producing 480 bytes.
I however need -fno-asynchornous-unwind-tables.
Otherwise I get:
jh@gcc17:~/trunk/build/gcc$ size pa.o
   text    data     bss     dec     hex filename
    347       0       0     347     15b pa.o
jh@gcc17:~/trunk/build/gcc$ objdump -h pa.o

pa.o:     file format elf32-i386

Sections:
Idx Name          Size      VMA       LMA       File off  Algn
  0 .text         000000d3  00000000  00000000  00000034  2**2
                  CONTENTS, ALLOC, LOAD, RELOC, READONLY, CODE
  1 .data         00000000  00000000  00000000  00000108  2**2
                  CONTENTS, ALLOC, LOAD, DATA
  2 .bss          00000000  00000000  00000000  00000108  2**2
                  ALLOC
  3 .eh_frame     00000088  00000000  00000000  00000108  2**2
                  CONTENTS, ALLOC, LOAD, RELOC, READONLY, DATA
  4 .comment      0000002a  00000000  00000000  00000190  2**0
                  CONTENTS, READONLY
  5 .note.GNU-stack 00000000  00000000  00000000  000001ba  2**0
                  CONTENTS, READONLY

why .eh_frame is counted as text?