http://gcc.gnu.org/bugzilla/show_bug.cgi?id=57994
--- Comment #19 from Paolo Carlini <paolo.carlini at oracle dot com> ---
If I change fold_builtin_logarithm to pass a true as last argument to
do_mpfr_arg1 (thus 0 is accepted) and do_mpfr_ckconv to accept a folded result
which is infinity, things finally work. Patchlet below. Note however, that I
also need -O1 otherwise, at -O0, we don't try to propagate the constant num and
mpfr isn't used, we again have a library call which returns -nan.
Index: builtins.c
===================================================================
--- builtins.c (revision 204005)
+++ builtins.c (working copy)
@@ -8191,7 +8191,7 @@ fold_builtin_logarithm (location_t loc, tree fndec
const enum built_in_function fcode = builtin_mathfn_code (arg);
/* Calculate the result when the argument is a constant. */
- if ((res = do_mpfr_arg1 (arg, type, func, &dconst0, NULL, false)))
+ if ((res = do_mpfr_arg1 (arg, type, func, &dconst0, NULL, true)))
return res;
/* Special case, optimize logN(expN(x)) = x. */
@@ -13527,7 +13527,7 @@ do_mpfr_ckconv (mpfr_srcptr m, tree type, int inex
/* Proceed iff we get a normal number, i.e. not NaN or Inf and no
overflow/underflow occurred. If -frounding-math, proceed iff the
result of calling FUNC was exact. */
- if (mpfr_number_p (m) && !mpfr_overflow_p () && !mpfr_underflow_p ()
+ if (!mpfr_nan_p (m) && !mpfr_overflow_p () && !mpfr_underflow_p ()
&& (!flag_rounding_math || !inexact))
{
REAL_VALUE_TYPE rr;
@@ -13537,7 +13537,7 @@ do_mpfr_ckconv (mpfr_srcptr m, tree type, int inex
check for overflow/underflow. If the REAL_VALUE_TYPE is zero
but the mpft_t is not, then we underflowed in the
conversion. */
- if (real_isfinite (&rr)
+ if (!real_isnan (&rr)
&& (rr.cl == rvc_zero) == (mpfr_zero_p (m) != 0))
{
REAL_VALUE_TYPE rmode;
@@ -13623,7 +13623,7 @@ do_mpfr_arg1 (tree arg, tree type, int (*func)(mpf
{
const REAL_VALUE_TYPE *const ra = &TREE_REAL_CST (arg);
- if (real_isfinite (ra)
+ if (!real_isnan (ra)
&& (!min || real_compare (inclusive ? GE_EXPR: GT_EXPR , ra, min))
&& (!max || real_compare (inclusive ? LE_EXPR: LT_EXPR , ra, max)))
{
