[En-Nut-Discussion] AVR-GCC 4.x compiler bug.

[Matthias Ringwald]

Hi
  although the GCC4.x signedness issues have been taken care of in  
Nut/OS, the build of BTnut fails as the switch
in the ioctl function of usart.c hits a compiler bug when using -Os  
(which is our default)

see:
http://sourceforge.net/tracker/index.php? 
func=detail&aid=1585230&group_id=34079&atid=410687

we played around with compiler flags -Os and/or -fno-jump-tables

usart.btnode3.o

with -Os (gcc 3.4.5)             2316
with -Os -fno-jump-tables:       3932
without  -Os:                    6184

a) -Os is important
b) jump-tables, too

with -Os -fno-jump-tables the code size increase by 2k

we tried to change the code to work-around this bug. one solution is  
to split the
single switch into two switches. This looks strange, but works.
I really don't like to change code to avoid a compiler bug. The  
latest avr-gcc 4.2
still fails to compile this switch.

is anyone who has some smart solution to this?
what can we do?

cheers
Matthias