| Message ID | 52861ACD.5050000@linux.vnet.ibm.com |
|---|---|
| State | New |
| Headers | show |
diff --git a/libgcc/config/rs6000/ibm-ldouble.c b/libgcc/config/rs6000/ibm-ldouble.c index 28e02e9..7ca900c 100644 --- a/libgcc/config/rs6000/ibm-ldouble.c +++ b/libgcc/config/rs6000/ibm-ldouble.c @@ -104,6 +104,8 @@ __gcc_qadd (double a, double aa, double c, double cc) if (nonfinite (z)) { + if (fabs (z) != inf()) + return z; z = cc + aa + c + a; if (nonfinite (z)) return z;
Hi all, For IBM long double, adding a normal number to a qNaN raises an inexact exception. Adding any number to qNaN should not raise any exception. The following testcase triggers the issue (the testcase is meant to run a gnu compatible libc): -------------------------------------------------------------- $ cat gcc_testcase.c #include <math.h> #include <fenv.h> #include <stdio.h> double sum (double x, long double y) { return x + y; } int main () { feenableexcept (FE_INEXACT); double x = __builtin_nan (""); long double y = 1.1L; printf ("%e\n", sum (x, y)); return 0; } $ gcc -O3 -m64 -fno-inline gcc_testcase.c -o gcc_testcase -lm $ ./gcc_testcase Floating point exception (core dumped) -------------------------------------------------------------- The issue is in __gcc_qadd implementation at libgcc/config/rs6000/ibm-ldouble.c, if the number if non finite, there is not check if it a NaN before actually summing all the components. A possible solution would be to add an extra test and return the first sum if the number if not infinity. This also fixes two GLIBC math issues I'm seeing: TEST_ff_f (nexttoward, qnan_value, 1.1L, qnan_value, NO_INEXACT_EXCEPTION), TEST_ff_f (nexttoward, 1.1L, qnan_value, qnan_value, NO_INEXACT_EXCEPTION), Fix tested on PPC32 and PPC64. --- 2013-11-15 Adhemerval Zanella <azanella@linux.vnet.ibm.com> * libgcc/config/rs6000/ibm-ldouble.c (__gcc_qadd): Fix add of normal number and sNaN to not raise an inexact exception. ---