[avr-gcc-list] avr-gcc bug

[Francisco T. A. Silva]

Hi all,

I´ve come upon the following bug.

The code:

int main(void)
{
    unsigned int i;
    for(i = 31533; i > 0; i--);
}

The compiled code:

    .file "bug.c"
    .arch avr2
__SREG__ = 0x3f
__SP_H__ = 0x3e
__SP_L__ = 0x3d
__tmp_reg__ = 0
__zero_reg__ = 1
_PC_ = 2
 ; GNU C version 3.1 20010228 (experimental) (avr)
 ; compiled by GNU C version egcs-2.91.66 19990314/Linux (egcs-1.
1.2 release).
 ; options passed: -lang-c -D__GNUC__=3 -D__GNUC_MINOR__=1
 ; -D__GNUC_PATCHLEVEL__=0 -DAVR -D__AVR__ -D__AVR -D__OPTIMIZE_SIZE__
 ; -D__OPTIMIZE__ -D__STDC_HOSTED__=1 -D__AVR_ARCH__=2
 ; -D__SIZE_TYPE__=unsigned int -D__PTRDIFF_TYPE__=int -D__INT_MAX__=32767
 ; -Os -fverbose-asm
 ; options enabled: -fdefer-pop -fomit-frame-pointer
 ; -foptimize-sibling-calls -fcse-follow-jumps -fcse-skip-blocks
 ; -fexpensive-optimizations -fthread-jumps -fstrength-reduce -fpeephole
 ; -fforce-mem -ffunction-cse -finline -fkeep-static-consts -fcaller-
saves
 ; -freg-struct-return -fgcse -frerun-cse-after-loop -frerun-loop-opt
 ; -fdelete-null-pointer-checks -fsched-interblock -fsched-spec
 ; -fbranch-count-reg -fnew-exceptions -fsjlj-exceptions -freorder-
blocks
 ; -fcommon -fverbose-asm -fgnu-linker -fregmove -foptimize-register-
move
 ; -fargument-alias -fstrict-aliasing -fident -fpeephole2
 ; -fguess-branch-probability -fmath-errno -minit-stack=__stack 
-mmcu=avr2

gcc2_compiled.:
    .text
.global main
    .type main,@function
main:
/* prologue: frame size=0 */
    ldi r28,lo8(__stack - 0)
    ldi r29,hi8(__stack - 0)
    out __SP_H__,r29
    out __SP_L__,r28
/* prologue end (size=4) */
    ldi r24,lo8(31524) <<<<<<<<<<<<<<<<< wrong value (should be 31533)
    ldi r25,hi8(31524)
.L5:
    sbiw r24,12 <<<<<<<<<<<<<<<<< wrong (should be sbiw r24,1)
    brne .L5
/* epilogue: frame size=0 */
__stop_progIi__:
    rjmp __stop_progIi__
/* epilogue end (size=1) */
/* function main size 10 (5) */
.Lfe1:
    .size main,.Lfe1-main
/* File bug.c: code 10 = 0x000a ( 5), prologues 4, epilogues 
1 */


This bug apears with -Os, -O2, -O3. It seems from now on I´m restricted
to -O :(.

Regards,
--
Francisco