ldbl-128ibm-compat: Add printf_size

Since the addition of the _Float128 API, strfromf128 and printf_size use
__printf_fp to print _Float128 values.  This is achieved by setting the
'is_binary128' member of the 'printf_info' structure to one.  Now that
the format of long double on powerpc64le is getting a third option, this
mechanism is reused for long double values that have binary128 format
(i.e.: when -mabi=ieeelongdouble).

This patch adds __printf_sizeieee128 as an exported symbol, but doesn't
provide redirections from printf_size, yet.  All redirections will be
installed in a future commit, once all other functions that print or
read long double values with binary128 format are ready.  In
__printf_fp, when 'is_binary128' is one, the floating-point argument is
treated as if it was of _Float128 type, regardless of the value of
'is_long_double', thus __printf_sizeieee128 sets 'is_binary128' to the
same value of 'is_long_double'.  Otherwise, double values would not be
printed correctly.

Tested for powerpc64le.

1 files changed, 38 insertions, 0 deletions

diff --git a/stdio-common/tst-printfsz-islongdouble.sh b/stdio-common/tst-printfsz-islongdouble.sh
new file mode 100644
index 0000000000..6eda634844
--- /dev/null
+++ b/stdio-common/tst-printfsz-islongdouble.sh
@@ -0,0 +1,38 @@
+#!/bin/sh
+# Test for the behaviour of 'is_binary128' in printf_size.
+# Copyright (C) 2018 Free Software Foundation, Inc.
+# This file is part of the GNU C Library.
+
+# The GNU C Library is free software; you can redistribute it and/or
+# modify it under the terms of the GNU Lesser General Public
+# License as published by the Free Software Foundation; either
+# version 2.1 of the License, or (at your option) any later version.
+
+# The GNU C Library is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+# Lesser General Public License for more details.
+
+# You should have received a copy of the GNU Lesser General Public
+# License along with the GNU C Library; if not, see
+# <http://www.gnu.org/licenses/>.
+
+set -e
+
+test_program=$1; shift
+test_program_prefix=$1; shift
+test_program_output=$1; shift
+
+status=0
+
+${test_program_prefix} \
+  ${test_program} \
+  > ${test_program_output} || status=1
+
+echo -n "2k4k" | cmp - ${test_program_output} > /dev/null 2>&1 ||
+{
+  status=1
+  echo "*** output comparison failed"
+}
+
+exit $status