On Fri, Nov 06, 2020 at 11:45:21PM -0500, Michael Meissner wrote: > On Mon, Nov 02, 2020 at 07:00:15PM -0600, Segher Boessenkool wrote: > > > + /* This test is written to test IBM extended double, which is a pair of > > > + doubles. If long double can hold a larger value than a double can, > > > such > > > + as when long double is IEEE 128-bit, just exit immediately. */ > > > > A double-double can hold bigger values than a double can, as well > > (if X is the biggest double, then X+Y is a valid double-double whenever > > you take Y small enough). > > > > > + if (LDBL_MAX_10_EXP > DBL_MAX_10_EXP) > > > + return 0; > > Yes a double-double can hold more mantissa bits than a double, but the > exponent > size is the same (which is what I'm testing).
But that is not what the comment says. My remark was about the comment. It is confusing as is. > > > +#if defined(_ARCH_PPC) && defined(__LONG_DOUBLE_IEEE128__) > > > +/* On PowerPC systems, long double uses either the IBM long double > > > format, or > > > + IEEE 128-bit format. The compiler switches the long double built-in > > > + function names and glibc switches the names when math.h is included. > > > + Because this test is run with -fno-builtin, include math.h so that the > > > + appropriate nextafter functions are called. */ > > > +#include <math.h> > > > +#endif > > > + > > > #include "nextafter-1.c" > > > > Please explain *what* mappings are made? And why is it okay to do this > > in the testsuite, when all "normal" code (that does not do this) will > > just fail? > > I can put in a better comment. However, this test fails because it explicitly > does not include math.h and it uses -fno-builtin. So the compiler can't > effectively map the nextafter math function. So either the compiler is wrong, or the test is? Or I do not grasp what you mean to say at all :-( Segher
