From mboxrd@z Thu Jan 1 00:00:00 1970 From: Fernando Nasser To: Jim Blandy Cc: gdb-patches@sources.redhat.com, Michael Snyder Subject: Re: RFA: don't try to compare IEEE NaN's Date: Wed, 06 Jun 2001 06:45:00 -0000 Message-id: <3B1E3359.2F286246@redhat.com> References: <20010606034145.7D5065E9CB@zwingli.cygnus.com> X-SW-Source: 2001-06/msg00057.html Approved. Jim Blandy wrote: > > 2001-06-05 Jim Blandy > > * gdb.base/return2.exp (main): Use values to test float and double > returns that are not NaN's, to avoid being confused by IEEE > comparison rules. > > Index: gdb/testsuite/gdb.base/return2.c > =================================================================== > RCS file: /cvs/cvsfiles/devo/gdb/testsuite/gdb.base/return2.c,v > retrieving revision 1.2 > diff -c -r1.2 return2.c > *** gdb/testsuite/gdb.base/return2.c 2000/12/20 14:34:27 1.2 > --- gdb/testsuite/gdb.base/return2.c 2001/06/06 03:39:25 > *************** > *** 84,91 **** > int_resultval = int_func (); /* short_checkpoint */ > long_resultval = long_func (); /* int_checkpoint */ > long_long_resultval = long_long_func (); /* long_checkpoint */ > ! float_resultval = float_func (); /* long_long_checkpoint */ > ! double_resultval = double_func (); /* float_checkpoint */ > main_test = 1; /* double_checkpoint */ > return 0; > } > --- 84,110 ---- > int_resultval = int_func (); /* short_checkpoint */ > long_resultval = long_func (); /* int_checkpoint */ > long_long_resultval = long_long_func (); /* long_checkpoint */ > ! > ! /* On machines using IEEE floating point, the test pattern of all > ! 1-bits established above turns out to be a floating-point NaN > ! ("Not a Number"). According to the IEEE rules, NaN's aren't even > ! equal to themselves. This can lead to stupid conversations with > ! GDB like: > ! > ! (gdb) p testval.float_testval == testval.float_testval > ! $7 = 0 > ! (gdb) > ! > ! This is the correct answer, but it's not the sort of thing > ! return2.exp wants to see. So to make things work the way they > ! ought, we'll set aside the `union' cleverness and initialize the > ! test values explicitly here. These values have interesting bits > ! throughout the value, so we'll still detect truncated values. */ > ! > ! testval.float_testval = 2.7182818284590452354;/* long_long_checkpoint */ > ! float_resultval = float_func (); > ! testval.double_testval = 3.14159265358979323846; /* float_checkpoint */ > ! double_resultval = double_func (); > main_test = 1; /* double_checkpoint */ > return 0; > } -- Fernando Nasser Red Hat Canada Ltd. E-Mail: fnasser@redhat.com 2323 Yonge Street, Suite #300 Toronto, Ontario M4P 2C9