Fix log1pl (LDBL_MAX) in FE_UPWARD mode (bug 16564).

Bug 16564 is spurious overflow of log1pl (LDBL_MAX) in FE_UPWARD mode,
resulting from log1pl adding 1 to its argument (for arguments not
close to 0), which overflows in that mode.  This patch fixes this by
avoiding adding 1 to large arguments (precisely what counts as large
depends on the floating-point format).

Tested x86_64 and x86, and spot-checked log1pl tests on mips64 and
powerpc64.

	[BZ #16564]
	* sysdeps/i386/fpu/s_log1pl.S (__log1pl): Do not add 1 to positive
	arguments with exponent 65 or above.
	* sysdeps/ieee754/ldbl-128/s_log1pl.c (__log1pl): Do not add 1 to
	arguments 0x1p113L or above.
	* sysdeps/ieee754/ldbl-128ibm/s_log1pl.c (__log1pl): Do not add 1
	to arguments 0x1p107L or above.
	* sysdeps/x86_64/fpu/s_log1pl.S (__log1pl): Do not add 1 to
	positive arguments with exponent 65 or above.
	* math/auto-libm-test-in: Add more tests of log1p.
	* math/auto-libm-test-out: Regenerated.

1 files changed, 8 insertions, 0 deletions

diff --git a/math/auto-libm-test-in b/math/auto-libm-test-in
index da93a302cc..6edad5ad7e 100644
--- a/math/auto-libm-test-in
+++ b/math/auto-libm-test-in
@@ -1421,6 +1421,14 @@ log1p min missing-underflow
 log1p min_subnorm missing-underflow
 log1p -min missing-underflow
 log1p -min_subnorm missing-underflow
+log1p 0x1p10
+log1p 0x1p20
+log1p 0x1p30
+log1p 0x1p50
+log1p 0x1p60
+log1p 0x1p100
+log1p 0x1p1000
+log1p max
 
 log2 1
 log2 e