Fix scalb spurious "invalid" exceptions (bug 16770).

This patch fixes bug 16770, spurious "invalid" exceptions from scalb
when testing whether the second argument is an integer, by inserting
appropriate range checks to determine whether a cast to int is safe.
(Note that invalid_fn is a function that handles both nonintegers and
large integers, distinguishing them reliably using functions such as
__rint; note also that there are no issues with scalb needing to avoid
spurious "inexact" exceptions - it's an old-POSIX XSI function, not a
standard C function bound to an IEEE 754 operation - although the
return value is still fully determined.)

Tested x86_64 and x86.

	[BZ #16770]
	* math/e_scalb.c (__ieee754_scalb): Check second argument is not
	too large before casting to int.
	* math/e_scalbf.c (__ieee754_scalbf): Likewise.
	* math/e_scalbl.c (__ieee754_scalbl): Likewise.
	* math/libm-test.inc (scalb_test_data): Add more tests.

1 files changed, 9 insertions, 0 deletions

diff --git a/ChangeLog b/ChangeLog
index 081bf0b6d6..5bb69dc0b2 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,12 @@
+2014-03-29  Joseph Myers  <joseph@codesourcery.com>
+
+	[BZ #16770]
+	* math/e_scalb.c (__ieee754_scalb): Check second argument is not
+	too large before casting to int.
+	* math/e_scalbf.c (__ieee754_scalbf): Likewise.
+	* math/e_scalbl.c (__ieee754_scalbl): Likewise.
+	* math/libm-test.inc (scalb_test_data): Add more tests.
+
 2014-03-29  Siddhesh Poyarekar  <siddhesh@redhat.com>
 
 	* benchtests/Makefile (DETAILED_OPT): New make option.