[Bug c/23782] New: -Os +22%: gcc-3.4.4 does it in 230 bytes, gcc-4.0.2-pre in 281 bytes

[etienne_lorrain at yahoo dot fr]

etienne@cygne:~/projet/gujin$ gcc -v
Using built-in specs.
Target: i486-linux-gnu
Configured with: ../src/configure -v --enable-
languages=c,c++,java,f95,objc,ada,treelang --prefix=/usr --enable-shared --
with-system-zlib --libexecdir=/usr/lib --enable-nls --without-included-
gettext --enable-threads=posix --program-suffix=-4.0 --enable-__cxa_atexit --
enable-libstdcxx-allocator=mt --enable-clocale=gnu --enable-libstdcxx-debug --
enable-java-gc=boehm --enable-java-awt=gtk --enable-gtk-cairo --with-java-
home=/usr/lib/jvm/java-1.4.2-gcj-4.0-1.4.2.0/jre --enable-mpfr --disable-
werror --enable-checking=release i486-linux-gnu
Thread model: posix
gcc version 4.0.2 20050821 (prerelease) (Debian 4.0.1-6)
etienne@cygne:~/projet/gujin$ gcc -Os -c -o tmp.o tmp.c && size tmp.o
   text    data     bss     dec     hex filename
    281       0       0     281     119 tmp.o
etienne@cygne:~/projet/gujin$ ../toolchain-3.4.4-2.16/bin/gcc -v
Reading specs from /home/etienne/projet/toolchain-3.4.4-
2.16/bin/../lib/gcc/i686-pc-linux-gnu/3.4.4/specs
Configured with: ../configure --prefix=/home/etienne/projet/toolchain --enable-
languages=c
Thread model: posix
gcc version 3.4.4
etienne@cygne:~/projet/gujin$ ../toolchain-3.4.4-2.16/bin/gcc -Os -c -o tmp.o 
tmp.c && size tmp.o
   text    data     bss     dec     hex filename
    230       0       0     230      e6 tmp.o
etienne@cygne:~/projet/gujin$ cat tmp.c
typedef struct {
    unsigned short x, y;        /* x should be the easyest to read */
    } __attribute__ ((packed)) coord;

#define FASTCALL        __attribute__ (( fastcall ))

struct user_interface_fct_str {
     void     (*setpixel) (coord xy, unsigned color) FASTCALL;
     void     (*plotHline) (coord xy, unsigned short xend, unsigned color);
     } function;

extern inline void
UI_plotHline (coord xy, unsigned short xend, unsigned color) {
  function.plotHline (xy, xend, color);
  }
extern inline void
UI_setpixel (coord xy, unsigned color) {
  function.setpixel (xy, color);
  }

extern unsigned stack_limit;

extern inline void bound_stack (void)
  {
  asm volatile (" bound %%esp,%0 " : : "m" (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@cygne:~/projet/gujin$ 

  Doing the commands:
../toolchain-3.4.4-2.16/bin/gcc -Os -S -o tmp.a tmp.c
gcc -Os -S -o tmp.b tmp.c
diff -y tmp.a tmp.b
  does not give me a clear idea of the reason...

-- 
           Summary: -Os +22%: gcc-3.4.4 does it in 230 bytes, gcc-4.0.2-pre
                    in 281 bytes
           Product: gcc
           Version: 4.0.2
            Status: UNCONFIRMED
          Severity: normal
          Priority: P2
         Component: c
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: etienne_lorrain at yahoo dot fr
                CC: gcc-bugs at gcc dot gnu dot org
 GCC build triplet: i486-linux-gnu
  GCC host triplet: i486-linux-gnu
GCC target triplet: i486-linux-gnu


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=23782