declaration of static function corrupts main function

[Tom Fields]

Binary package hint: gcc-avr

Hi,

gcc-Version 4.3.5 (GCC), AMD64 default Maverick package.

The attached source file (see also the preprocessed input) yields corrupted machine code:

The short example "control_unit.c" contains a single for(i=0; i<6; i++)-loop that is supposed to run exactly six times.
Instead, the compiler produces a loop with undetermined behaviour that runs tens of times at least.

I compiled with the following command line for target ATTiny26:
avr-gcc -v -save-temps -c -std=c99 -g -Os -Wall -Wstrict-prototypes -Wextra -Wa,-ahlms=control_unit.lst -mmcu=attiny26 control_unit.c

I've also attached the messages displayed during the above compile run in the file "stdout-compile-messages.txt"

That file also contains the GCC options with which GCC for the AVR target was configured.

Regards,
Ulrich

[Tom Fields (udzelem)]

Amendment 1: If the source file is modified as in this attachement, the error is gone, and the compiled result works as expected.

What was changed: the function "owioReceiveWord()" is /not/ declared static in this case.

Attachement: control_unit.WORKS.c

[Tom Fields (udzelem)]

Current /official/ GCC release version 4.5.1 does NOT produce the erroneous result.