Add narrowing multiply functions.

This patch adds the narrowing multiply functions from TS 18661-1 to
glibc's libm: fmul, fmull, dmull, f32mulf64, f32mulf32x, f32xmulf64
for all configurations; f32mulf64x, f32mulf128, f64mulf64x,
f64mulf128, f32xmulf64x, f32xmulf128, f64xmulf128 for configurations
with _Float64x and _Float128; __nldbl_dmull for ldbl-opt.

The changes are mostly essentially the same as for the narrowing add
functions, so the description of those generally applies to this patch
as well.  f32xmulf64 for i386 cannot use precision control as used for
add and subtract, because that would result in double rounding for
subnormal results, so that uses round-to-odd with long double
intermediate result instead.  The soft-fp support involves adding a
new FP_TRUNC_COOKED since soft-fp multiplication uses cooked inputs
and outputs.

Tested for x86_64, x86, mips64 (all three ABIs, both hard and soft
float) and powerpc, and with build-many-glibcs.py.

	* math/Makefile (libm-narrow-fns): Add mul.
	(libm-test-funcs-narrow): Likewise.
	* math/Versions (GLIBC_2.28): Add narrowing multiply functions.
	* math/bits/mathcalls-narrow.h (mul): Use __MATHCALL_NARROW.
	* math/gen-auto-libm-tests.c (test_functions): Add mul.
	* math/math-narrow.h (CHECK_NARROW_MUL): New macro.
	(NARROW_MUL_ROUND_TO_ODD): Likewise.
	(NARROW_MUL_TRIVIAL): Likewise.
	* soft-fp/op-common.h (FP_TRUNC_COOKED): Likewise.
	* sysdeps/ieee754/float128/float128_private.h (__fmull): New
	macro.
	(__dmull): Likewise.
	* sysdeps/ieee754/ldbl-opt/Makefile (libnldbl-calls): Add fmul and
	dmul.
	(CFLAGS-nldbl-dmul.c): New variable.
	(CFLAGS-nldbl-fmul.c): Likewise.
	* sysdeps/ieee754/ldbl-opt/Versions (GLIBC_2.28): Add
	__nldbl_dmull.
	* sysdeps/ieee754/ldbl-opt/nldbl-compat.h (__nldbl_dmull): New
	prototype.
	* manual/arith.texi (Misc FP Arithmetic): Document fmul, fmull,
	dmull, fMmulfN, fMmulfNx, fMxmulfN and fMxmulfNx.
	* math/auto-libm-test-in: Add tests of mul.
	* math/auto-libm-test-out-narrow-mul: New generated file.
	* math/libm-test-narrow-mul.inc: New file.
	* sysdeps/i386/fpu/s_f32xmulf64.c: Likewise.
	* sysdeps/ieee754/dbl-64/s_f32xmulf64.c: Likewise.
	* sysdeps/ieee754/dbl-64/s_fmul.c: Likewise.
	* sysdeps/ieee754/float128/s_f32mulf128.c: Likewise.
	* sysdeps/ieee754/float128/s_f64mulf128.c: Likewise.
	* sysdeps/ieee754/float128/s_f64xmulf128.c: Likewise.
	* sysdeps/ieee754/ldbl-128/s_dmull.c: Likewise.
	* sysdeps/ieee754/ldbl-128/s_f64xmulf128.c: Likewise.
	* sysdeps/ieee754/ldbl-128/s_fmull.c: Likewise.
	* sysdeps/ieee754/ldbl-128ibm/s_dmull.c: Likewise.
	* sysdeps/ieee754/ldbl-128ibm/s_fmull.c: Likewise.
	* sysdeps/ieee754/ldbl-96/s_dmull.c: Likewise.
	* sysdeps/ieee754/ldbl-96/s_fmull.c: Likewise.
	* sysdeps/ieee754/ldbl-opt/nldbl-dmul.c: Likewise.
	* sysdeps/ieee754/ldbl-opt/nldbl-fmul.c: Likewise.
	* sysdeps/ieee754/soft-fp/s_dmull.c: Likewise.
	* sysdeps/ieee754/soft-fp/s_fmul.c: Likewise.
	* sysdeps/ieee754/soft-fp/s_fmull.c: Likewise.
	* sysdeps/powerpc/fpu/libm-test-ulps: Update.
	* sysdeps/mach/hurd/i386/libm.abilist: Likewise.
	* sysdeps/unix/sysv/linux/aarch64/libm.abilist: Likewise.
	* sysdeps/unix/sysv/linux/alpha/libm.abilist: Likewise.
	* sysdeps/unix/sysv/linux/arm/libm.abilist: Likewise.
	* sysdeps/unix/sysv/linux/hppa/libm.abilist: Likewise.
	* sysdeps/unix/sysv/linux/i386/libm.abilist: Likewise.
	* sysdeps/unix/sysv/linux/ia64/libm.abilist: Likewise.
	* sysdeps/unix/sysv/linux/m68k/coldfire/libm.abilist: Likewise.
	* sysdeps/unix/sysv/linux/m68k/m680x0/libm.abilist: Likewise.
	* sysdeps/unix/sysv/linux/microblaze/libm.abilist: Likewise.
	* sysdeps/unix/sysv/linux/mips/mips32/libm.abilist: Likewise.
	* sysdeps/unix/sysv/linux/mips/mips64/libm.abilist: Likewise.
	* sysdeps/unix/sysv/linux/nios2/libm.abilist: Likewise.
	* sysdeps/unix/sysv/linux/powerpc/powerpc32/fpu/libm.abilist: Likewise.
	* sysdeps/unix/sysv/linux/powerpc/powerpc32/nofpu/libm.abilist: Likewise.
	* sysdeps/unix/sysv/linux/powerpc/powerpc64/libm-le.abilist: Likewise.
	* sysdeps/unix/sysv/linux/powerpc/powerpc64/libm.abilist: Likewise.
	* sysdeps/unix/sysv/linux/riscv/rv64/libm.abilist: Likewise.
	* sysdeps/unix/sysv/linux/s390/s390-32/libm.abilist: Likewise.
	* sysdeps/unix/sysv/linux/s390/s390-64/libm.abilist: Likewise.
	* sysdeps/unix/sysv/linux/sh/libm.abilist: Likewise.
	* sysdeps/unix/sysv/linux/sparc/sparc32/libm.abilist: Likewise.
	* sysdeps/unix/sysv/linux/sparc/sparc64/libm.abilist: Likewise.
	* sysdeps/unix/sysv/linux/x86_64/64/libm.abilist: Likewise.
	* sysdeps/unix/sysv/linux/x86_64/x32/libm.abilist: Likewise.

2 files changed, 64 insertions, 0 deletions

diff --git a/sysdeps/ieee754/ldbl-96/s_dmull.c b/sysdeps/ieee754/ldbl-96/s_dmull.c
new file mode 100644
index 0000000000..a717b0aa07
--- /dev/null
+++ b/sysdeps/ieee754/ldbl-96/s_dmull.c
@@ -0,0 +1,33 @@
+/* Multiply long double (ldbl-96) values, narrowing the result to double.
+   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/>.  */
+
+#define f32xmulf64x __hide_f32xmulf64x
+#define f64mulf64x __hide_f64mulf64x
+#include <math.h>
+#undef f32xmulf64x
+#undef f64mulf64x
+
+#include <math-narrow.h>
+
+double
+__dmull (long double x, long double y)
+{
+  NARROW_MUL_ROUND_TO_ODD (x, y, double, union ieee854_long_double, l,
+			   mantissa1);
+}
+libm_alias_double_ldouble (mul)
diff --git a/sysdeps/ieee754/ldbl-96/s_fmull.c b/sysdeps/ieee754/ldbl-96/s_fmull.c
new file mode 100644
index 0000000000..b7582526a6
--- /dev/null
+++ b/sysdeps/ieee754/ldbl-96/s_fmull.c
@@ -0,0 +1,31 @@
+/* Multiply long double (ldbl-96) values, narrowing the result to float.
+   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/>.  */
+
+#define f32mulf64x __hide_f32mulf64x
+#include <math.h>
+#undef f32mulf64x
+
+#include <math-narrow.h>
+
+float
+__fmull (long double x, long double y)
+{
+  NARROW_MUL_ROUND_TO_ODD (x, y, float, union ieee854_long_double, l,
+			   mantissa1);
+}
+libm_alias_float_ldouble (mul)