Might not be a bug even, but I haven't had much luck in finding a definitive
answer. I get different output depending on whether I compile the following
testcase as 32-bit vs 64-bit on linux-ppc64 (gcc-3.4 and gcc-4).
include <stdio.h>
#include <fenv.h>
int main()
{
int x=1023, y=1023;
double z;
fesetround(FE_DOWNWARD);
z = (double)(x-y);
printf ("z = %e\n", z);
return 0;
}
If I compile this as '-O0 -m32' I get a result of:
z = -0.000000e+00
But compiling for 64-bit, '-O0 -m64' I get result of:
z = 0.000000e+00
This was noticed by someone testing linux-ppc glibc::logb(1) after having set
the rounding mode to FE_DOWNWARD and getting a -0.0 result (glibc has similar
code as testcase above).
GCC bug vs GLIBC bug vs User Error?
--
Summary: FE_DOWNWARD testcase results differ in -m32 and -m64. OK
or bug?
Product: gcc
Version: 3.4.3
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: target
AssignedTo: unassigned at gcc dot gnu dot org
ReportedBy: jgrimm2 at us dot ibm dot com
CC: gcc-bugs at gcc dot gnu dot org
GCC target triplet: ppc64-unknown-linux
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=20776
