[Bug c/37135] New: code size increase from gcc-4.2.4-3 to 4.3.1-9 for simple fct

[etienne_lorrain at yahoo dot fr]

file test.c:
----------------------
enum stdcolor_enum {
    black,    blue,         green,      cyan,
    red,      magenta,      brown,      lightgray,
    darkgray, lightblue,    lightgreen, lightcyan,
    lightred, lightmagenta, yellow,     white
    };

union mouse_color_union {
    struct mouse_color_str {
        unsigned deflt              : 4;
        unsigned leftbutton         : 4;
        unsigned rightbutton        : 4;
        unsigned middlebutton       : 4;
        unsigned topbutton          : 4;
        unsigned twobutton          : 4;
        unsigned invalid            : 4;
        unsigned infield            : 4;
        } colors;
    unsigned all;
    } conf;

const union mouse_color_union MOUSE_reset_colors = { .colors = {
    .deflt =            brown,
    .leftbutton =       red,
    .rightbutton =      green,
    .middlebutton =     lightcyan,
    .topbutton =        cyan,
    .twobutton =        magenta,
    .invalid =          black,
    .infield =          magenta,
    }};

void fct (void)
{
    conf = MOUSE_reset_colors;
}
----------------------
$ gcc-4.2 --version
gcc-4.2 (GCC) 4.2.4 (Debian 4.2.4-3)
Copyright (C) 2007 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

$ gcc-4.2 -Os -c test.c -o test.o-4.2
$ size test.o-4.2
   text    data     bss     dec     hex filename
     19       0       0      19      13 test.o-4.2
$ gcc-4.3 --version
gcc-4.3 (Debian 4.3.1-9) 4.3.1
Copyright (C) 2008 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

$ gcc-4.3 -Os -c test.c -o test.o-4.3
$ size test.o-4.3
   text    data     bss     dec     hex filename
     56       0       0      56      38 test.o-4.3

Basically, the assembler lines in gcc-4.2:
        movl    MOUSE_reset_colors, %eax
        movl    %eax, conf
becomes in 4.3:
        movl    $0, conf
        movb    conf+3, %al
        movb    $70, conf
        andl    $15, %eax
        orl     $80, %eax
        movb    $-78, conf+1
        movb    $83, conf+2
        movb    %al, conf+3
which looks like a regression.

Thanks, etienne.


-- 
           Summary: code size increase from gcc-4.2.4-3 to 4.3.1-9 for
                    simple fct
           Product: gcc
           Version: 4.3.1
            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: debian
  GCC host triplet: i386-linux-debian
GCC target triplet: i386-linux-debian


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37135