float128: Add conversion from float128 to mpn

Reuse the code for __mpn_extract_long_double to implement
__mpn_extract_float128.

	* include/gmp.h: Include bits/floatn.h
	(__mpn_extract_float128): Declare when __HAVE_DISTINCT_FLOAT128 is 1.
	* stdlib/gmp-impl.h: Also check if alloca is not defined before
	including stack-alloc.h.  It could have been defined by other header
	which not necessarily defines HAVE_ALLOCA.
	* sysdeps/ieee754/float128/Makefile: New file.
	* sysdeps/ieee754/float128/float1282mpn.c: New file.
	* sysdeps/ieee754/float128/float128_private.h: Include gmp.h before
	redefining __mpn_extract_long_double to __mpn_extract_float128, then
	redefine __mpn_extract_long_double to __mpn_extract_float128.
	* sysdeps/ieee754/ldbl-128/ldbl2mpn.c: Replace long double with
	_Float128 to allow float128_private.h overrides.

4 files changed, 27 insertions, 1 deletions

diff --git a/sysdeps/ieee754/float128/Makefile b/sysdeps/ieee754/float128/Makefile
new file mode 100644
index 0000000000..6a7b0e0f45
--- /dev/null
+++ b/sysdeps/ieee754/float128/Makefile
@@ -0,0 +1,3 @@
+ifeq ($(subdir),stdlib)
+routines += float1282mpn
+endif
diff --git a/sysdeps/ieee754/float128/float1282mpn.c b/sysdeps/ieee754/float128/float1282mpn.c
new file mode 100644
index 0000000000..f012ccf0a6
--- /dev/null
+++ b/sysdeps/ieee754/float128/float1282mpn.c
@@ -0,0 +1,20 @@
+/* Convert a _Float128 type to multiprecision.
+   Copyright (C) 2017 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/>.  */
+
+#include <float128_private.h>
+#include "../ldbl-128/ldbl2mpn.c"
diff --git a/sysdeps/ieee754/float128/float128_private.h b/sysdeps/ieee754/float128/float128_private.h
index 894e6ac8cb..1e00853c83 100644
--- a/sysdeps/ieee754/float128/float128_private.h
+++ b/sysdeps/ieee754/float128/float128_private.h
@@ -17,6 +17,7 @@
    <http://www.gnu.org/licenses/>.  */
 
 /* This must be included before the function renames below.  */
+#include <gmp.h>
 #include <math.h>
 #undef HUGE_VALL
 #define HUGE_VALL HUGE_VAL_F128
@@ -291,6 +292,7 @@
 #define __kernel_tanl __kernel_tanf128
 #define __lgamma_negl __lgamma_negf128
 #define __lgamma_productl __lgamma_productf128
+#define __mpn_extract_long_double __mpn_extract_float128
 #define __sincosl_table __sincosf128_table
 #define mul_splitl mul_splitf128
 
diff --git a/sysdeps/ieee754/ldbl-128/ldbl2mpn.c b/sysdeps/ieee754/ldbl-128/ldbl2mpn.c
index 71a6f043bd..1c79a5dbe5 100644
--- a/sysdeps/ieee754/ldbl-128/ldbl2mpn.c
+++ b/sysdeps/ieee754/ldbl-128/ldbl2mpn.c
@@ -21,6 +21,7 @@
 #include <ieee754.h>
 #include <float.h>
 #include <math.h>
+#include <math_private.h>
 #include <stdlib.h>
 
 /* Convert a `long double' in IEEE854 quad-precision format to a
@@ -31,7 +32,7 @@
 mp_size_t
 __mpn_extract_long_double (mp_ptr res_ptr, mp_size_t size,
 			   int *expt, int *is_neg,
-			   long double value)
+			   _Float128 value)
 {
   union ieee854_long_double u;
   u.d = value;