Fix strtold on 32-bit sparc (and probably others) (BZ #16965)

This patch fixes an issue observed running the tst-strtod-round test on
32 bit sparc. In some conditions, strtold calls round_and_return, which in
turn calls __mpn_rshift with cnt = 0, while stdlib/rshift.c explicitly says
that cnts should satisfy 0 < CNT < BITS_PER_MP_LIMB. In this case, the code
end up doing a logical shift right of the same amount than the register,
which is undefined in the C standard.

Due to this bug, 32-bit sparc does not correctly convert the value
"0x1p-16446", but it is likely that other architectures are also
affected for other input values.

1 files changed, 4 insertions, 0 deletions

diff --git a/ChangeLog b/ChangeLog
index 59464a6..e87fc22 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -11,6 +11,10 @@
 	* localedata/tst-langinfo.sh: Send output to stdout.
 	* localedata/tst-langinfo-static.c: New file.
 
+	[BZ #16965]
+	* stdlib/strtod_l.c (round_and_return): Add code to shift limbs
+	when the shift amount is modulo the limb size.
+
 2014-05-20  Richard Henderson  <rth@redhat.com>
 
 	[BZ #16967]