------- Comment #3 from rob1weld at aol dot com 2007-06-03 15:15 -------
Here is simple test for the "float-store" issue:
main() {
double v = 1E308;
double x = (v * v) / v;
printf("Try compiling with and without -ffloat-store\n");
printf("(1E308 * 1E308) / 1E308\n");
printf("Correct output is 'inf 0' - Incorrect output is '1e+308 1'.\n");
printf("%g %d\n", x, x==v);
}
Reading the info file for cpp I notice in the node "Common Predefined Macros"
that we define various macros for many things but nothing for "-ffloat-store".
We have __NO_INLINE__ for -fno-inline
We have __USER_LABEL_PREFIX__ for -f(no-)underscores
We have __EXCEPTIONS for -fno-exceptions
We have __NEXT_RUNTIME__ for -fnext-runtime
We have __SSP__ for -fstack-protector
We have __SSP_ALL__ for -fstack-protector-all
On the basis that using "-ffloat-store" alters the resulting output of gcc I
propose we use cpp_define() in gcc-4_3-trunk/gcc/c-cppbuiltin.c to add
"__FLOAT_STORE__" for -ffloat-store.
We should also fix the code so the math is as accurate as the standard provides
for; regardless of use of -ffloat-store or -ffast-math, -msoft-float,
-mfpmath=xyz, -msse*, -minline-float-*, -minline-sqrt-*, or anything else.
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=32180
