Re: [avr-gcc-list] Avr-gcc Produces Incorrect Code with -Os

[Thomas D. Dean]

I changed the variables to volatile and that fixed things.

The compiler does not seem to move things around the
sin/cos/tan/asin/acos/atan functions, only the atan2.

I put the code segment below.  I was looking into size/time for these
functions.  I saw what I expected around all the functions except
atan2().  Is this because of two arguments???

BTW, I use standard includes and the code does use PORTA and _BV(),
just the comment was in lower case.

tomdean

double rad;
double sin_rad, cos_rad;
double atan_rad;

while (1) {
        TRACE_ON(TRACE0);
        start = timer_current();
        rad = M_PI/4.0;
        TRACE_ON(TRACE1);
        sin_rad = sin(rad);   // 214 usec
        TRACE_OFF(TRACE1);
        TRACE_ON(TRACE2);
        dtostrf(rad,6,3,&line3[4]);  // 85 usec
        TRACE_OFF(TRACE2);
        line3[10]=')';
        dtostrf(sin_rad,6,3,&line3[14]);
        TRACE_ON(TRACE3);
        cos_rad = atan(sin_rad);    // 220 usec
        TRACE_OFF(TRACE3);
        dtostrf(rad,6,3,&line4[4]);
        line4[10]=')';
        dtostrf(cos_rad,6,3,&line4[14]);
        line3[20] = ' ';
        line4[20] = ' ';
        TRACE_ON(TRACE4);  // porta |= _bv(04)
        atan_rad = atan2(cos_rad,sin_rad);  
        TRACE_OFF(TRACE4);  // porta &= ~_bv(04)
        dtostrf(atan_rad,6,3,&line4[26]);       
        lcd_print(1,&line1[0]);  // 1.6 msec
        lcd_print(2,&line2[0]);  // 1.6 msec
        lcd_print(3,&line3[0]);  // 1.6 msec
        lcd_print(4,&line4[0]);  // 1.6 msec
        TRACE_OFF(TRACE0);
}