The following code snippet fails to compile with -Os -O1 -O2 or -O3. It
compiles fine using -O0
I tested both the Win32 and linux versions of the compiler and they both fail
the same way.
The exact command line used was:
avr-gcc -c -mmcu=atmega168 -Os ee-fail.c
Removing the second call to fill_pwm_table also allows the code to compile.
The error message received from the compiler are as follows:
ee-fail.c: In function 'build_pwm_table':
/home/dhylands/avr-4.1.1/lib/gcc/avr/4.1.1/../../../../avr/include/avr/eeprom.h:208:
error: can't find a register in class 'BASE_POINTER_REGS' while reloading 'asm'
/home/dhylands/avr-4.1.1/lib/gcc/avr/4.1.1/../../../../avr/include/avr/eeprom.h:208:
error: can't find a register in class 'BASE_POINTER_REGS' while reloading 'asm'
avr-gcc -v on my linux box reports:
Using built-in specs.
Target: avr
Configured with: ../../source/gcc-4.1.1/configure -v --target=avr --disable-nls
--prefix=/home/dhylands/avr-4.1.1 --with-gnu-ld --with-gnu-as
--enable-languages=c,c++ --quiet --disable-libssp --with-dwarf2
Thread model: single
gcc version 4.1.1
#include <avr/eeprom.h>
uint8_t pwm_tab_1 [126];
static uint16_t ee_chan_1_min EEMEM = 140,
ee_chan_1_cent EEMEM = 188,
ee_chan_1_max EEMEM = 240,
ee_chan_1_forw_min EEMEM = 20,
ee_chan_1_forw_max EEMEM = 90,
ee_chan_1_back_max EEMEM = 80;
void fill_pwm_table (int8_t chan_num, uint8_t pwm [], int16_t forward_max,
int16_t center, int16_t reverse_min, int16_t forward_high,
int16_t forward_low, int16_t reverse_high );
void build_pwm_table (void)
{
int16_t center_1,
forward_max_1,
reverse_min_1,
forward_high_1,
forward_low_1,
reverse_high_1;
center_1 = eeprom_read_word (&ee_chan_1_cent);
forward_max_1 = eeprom_read_word (&ee_chan_1_max);
reverse_min_1 = eeprom_read_word (&ee_chan_1_min);
forward_high_1 = eeprom_read_word (&ee_chan_1_forw_max);
forward_low_1 = eeprom_read_word (&ee_chan_1_forw_min);
reverse_high_1 = eeprom_read_word (&ee_chan_1_back_max);
fill_pwm_table (1, pwm_tab_1, forward_max_1, center_1, reverse_min_1,
forward_high_1, forward_low_1, reverse_high_1);
fill_pwm_table (1, pwm_tab_1, forward_max_1, center_1, reverse_min_1,
forward_high_1, forward_low_1, reverse_high_1);
}
--
Summary: Code snippet that fails to compile with optimization
enabled
Product: gcc
Version: 4.1.1
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c
AssignedTo: unassigned at gcc dot gnu dot org
ReportedBy: dhylands at gmail dot com
GCC host triplet: i686-pc-linux-gnu
GCC target triplet: avr
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=31644
