[avr-gcc-list] Code that fails to compile with any optimization enabled

[Dave Hylands]

Hi,

The following code snippet (as small as I could get it and still
reproduce the problem) fails to compile with the following command
line:

avr-gcc -c -mmcu=atmega168 ee-fail.c -Os

Dropping the -Os or using -O0 makes it work. Using -O1 -O2 -O3 or -Os
all cause the following errors:

606 >avr-gcc -c -mmcu=atmega168 ee-fail.c -O3
ee-fail.c: In function 'build_pwm_table':
c:/winavr/bin/../avr/include/avr/eeprom.h:208: error: can't find a
register in class 'BASE_POINTER_REGS' while reloading 'asm'
c:/winavr/bin/../avr/include/avr/eeprom.h:208: error: can't find a
register in class 'BASE_POINTER_REGS' while reloading 'asm'

Removing the second call to fill_pwm_table also allows things to work
with all optimization levels.

I figured I'd post to the list to discuss before filing a bug report.

#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);
}


--
Dave Hylands
Vancouver, BC, Canada
http://www.DaveHylands.com/