Improve libm-test XFAILing for ibm128-libgcc.

This patch further improves XFAILing for ibm128-libgcc of tests in
auto-libm-test-*.

The bulk of the cases needing XFAILing are
xfail-rounding:ibm128-libgcc used for inputs where (possibly after
rounding the inputs to another floating-point type) the result
overflows (and the result in non-default rounding modes may be wildly
wrong with unpatched libgcc) or underflows near 0 (and the result in
non-default rounding modes may end up having the wrong sign).  This
patch makes gen-auto-libm-tests detect such cases and apply
xfail-rounding:ibm128-libgcc automatically to them, so most of the
manual XFAILs in auto-libm-test-in are no longer needed (some are
still needed if e.g. the result is very close to overflow, resulting
in an internal overflow in libgcc in some rounding modes).  A few
manual XFAILs are added for cases not covered by this
gen-auto-libm-tests change, and a few existing such XFAILs are left
in.

Tested for powerpc.

	* math/gen-auto-libm-tests.c (output_for_one_input_case): Apply
	xfail-rounding:ibm128-libgcc automatically to tests overflowing
	and those that can underflow to zero.
	* math/auto-libm-test-in: Remove most XFAILs for ibm128-libgcc and
	add others.
	* math/auto-libm-test-out: Regenerated.

1 files changed, 7 insertions, 0 deletions

diff --git a/ChangeLog b/ChangeLog
index 034cce97a2..983f0d7310 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,12 @@
 2017-01-09  Joseph Myers  <joseph@codesourcery.com>
 
+	* math/gen-auto-libm-tests.c (output_for_one_input_case): Apply
+	xfail-rounding:ibm128-libgcc automatically to tests overflowing
+	and those that can underflow to zero.
+	* math/auto-libm-test-in: Remove most XFAILs for ibm128-libgcc and
+	add others.
+	* math/auto-libm-test-out: Regenerated.
+
 	* math/test-fenv.c (fe_tests): Skip most tests when exceptions not
 	supported.
 	(feholdexcept_tests): Skip tests requiring exceptions or rounding