/* ** Public domain. ** ** This program demonstrates a bug in the -ffast-math option of the gcc ** armel compiler : gcc version 4.3.2 (Debian 4.3.2-1.1) ** ** This works as expected: ** ** > gcc -Wall -O3 gcc-test.c -o gcc-test && ./gcc-test ** min : 0.0000 max : 0.0000 ** ** Compile with -ffast-math and things goes screwy. ** ** > gcc -Wall -O3 -ffast-math gcc-test.c -o gcc-test && ./gcc-test ** min : 99999.0000 max : 0.0000 ** ** Thanks to Erik de Castro Lopo for this. ** Minimal optimization flags to spring the bug are: ** gcc -O -ffinite-math-only ** on arm-*-linux-gnueabi-gcc 4.1.2, 4.2.4, 4.3.3, 4.4.0 ** Martin Guy March 2009. */ #include #define COUNT 10 #define test_max(x,y) ((x) < (y) ? (y) : (x)) #define test_min(x,y) ((x) > (y) ? (y) : (x)) int main (void) { /* C Standard says static data gets initialized to zero. */ static float data [COUNT] ; float max = -99999.0, min = 99999.0 ; int k ; for (k = 0 ; k < COUNT ; k++) { max = test_max (max, data [k]) ; min = test_min (min, data [k]) ; } ; printf ("min : %12.4f max : %12.4f\n", min, max) ; return 0 ; }