rang@cpsin3.cps.msu.edu (Anton Rang) (12/01/88)
On a Sun-3/280 (SunOS 3.4, GCC 1.31) the following program can
generate bad assembly code. A warning message is produced
(x.c:7: warning: floating point number exceeds range of `double') but
the generated code is wrong with optimization on.
#include <math.h>
main()
{
float f;
f = HUGE; /* Defined by Sun to be 99.e999 */
printf("%f\n", f);
}
Without optimization, the constant is stored in memory as:
.long 0x7f800000
which is (correctly) IEEE "infinity". With optimization, this is
integrated into an "fmoves" instruction; apparently, a printf() or
similar call is used to format it, and the result is:
fmoves #0rInfinity,fp0
which the assembler rejects.
+---------------------------+------------------------+----------------------+
| Anton Rang (grad student) | "VMS Forever!" | "Do worry...be SAD!" |
| Michigan State University | rang@cpswh.cps.msu.edu | |
+---------------------------+------------------------+----------------------+