Support for type-generic libm function implementations libm

This defines a new classes of libm objects.  The
<func>_template.c file which is used in conjunction
with the new makefile hooks to derive variants for
each type supported by the target machine.

The headers math-type-macros-TYPE.h are used to supply
macros to a common implementation of a function in
a file named FUNC_template.c and glued togethor via
a generated file matching existing naming in the
build directory.

This has the properties of preserving the existing
override mechanism and not requiring any arcane
build system twiddling.  Likewise, it enables machines
to override these files without any additional work.

I have verified the built objects for ppc64, x86_64,
alpha, arm, and m68k do not change in any meaningful
way with these changes using the Fedora cross toolchains.
I have verified the x86_64 and ppc64 changes still run.

4 files changed, 233 insertions, 0 deletions

diff --git a/sysdeps/generic/math-type-macros-double.h b/sysdeps/generic/math-type-macros-double.h
new file mode 100644
index 0000000000..4149b39a9b
--- /dev/null
+++ b/sysdeps/generic/math-type-macros-double.h
@@ -0,0 +1,45 @@
+/* Helper macros for double variants of type generic functions of libm.
+   Copyright (C) 2016 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/>.  */
+
+#ifndef _MATH_TYPE_MACROS_DOUBLE
+#define _MATH_TYPE_MACROS_DOUBLE
+
+#define M_LIT(c) c
+#define M_MLIT(c) c
+#define M_PFX DBL
+#define M_SUF(c) c
+#define FLOAT double
+#define CFLOAT _Complex double
+
+/* Machines without a distinct long double type
+   alias long double functions to their double
+   equivalent.  */
+#if defined NO_LONG_DOUBLE
+# define declare_mgen_alias(from, to)	    \
+   weak_alias (from, to)		    \
+   strong_alias (from, from ## l)	    \
+   weak_alias (from, to ## l)
+#else
+# define declare_mgen_alias(from, to)	    \
+   weak_alias (M_SUF (from), M_SUF (to))
+#endif
+
+/* Supply the generic macros.  */
+#include <math-type-macros.h>
+
+#endif
diff --git a/sysdeps/generic/math-type-macros-float.h b/sysdeps/generic/math-type-macros-float.h
new file mode 100644
index 0000000000..aab88fdfa5
--- /dev/null
+++ b/sysdeps/generic/math-type-macros-float.h
@@ -0,0 +1,35 @@
+/* Helper macros for float variants of type generic functions of libm.
+   Copyright (C) 2016 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/>.  */
+
+#ifndef _MATH_TYPE_MACROS_FLOAT
+#define _MATH_TYPE_MACROS_FLOAT
+
+#define M_LIT(c) c ## f
+#define M_PFX FLT
+#define M_SUF(c) c ## f
+#define FLOAT float
+#define CFLOAT _Complex float
+
+/* Standard/GNU macro literals do not exist for the float type.  Use
+   the double macro constants.  */
+#define M_MLIT(c) c
+
+/* Supply the generic macros.  */
+#include <math-type-macros.h>
+
+#endif
diff --git a/sysdeps/generic/math-type-macros-ldouble.h b/sysdeps/generic/math-type-macros-ldouble.h
new file mode 100644
index 0000000000..90773fa578
--- /dev/null
+++ b/sysdeps/generic/math-type-macros-ldouble.h
@@ -0,0 +1,32 @@
+/* Helper macros for long double variants of type generic functions of libm.
+   Copyright (C) 2016 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/>.  */
+
+#ifndef _MATH_TYPE_MACROS_LDOUBLE
+#define _MATH_TYPE_MACROS_LDOUBLE
+
+#define M_LIT(c) c ## L
+#define M_MLIT(c) c ## l
+#define M_PFX LDBL
+#define M_SUF(c) c ## l
+#define FLOAT long double
+#define CFLOAT _Complex long double
+
+/* Supply the generic macros.  */
+#include <math-type-macros.h>
+
+#endif
diff --git a/sysdeps/generic/math-type-macros.h b/sysdeps/generic/math-type-macros.h
new file mode 100644
index 0000000000..259cb9421f
--- /dev/null
+++ b/sysdeps/generic/math-type-macros.h
@@ -0,0 +1,121 @@
+/* Helper macros for type generic function implementations within libm.
+   Copyright (C) 2016 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/>.  */
+
+#ifndef _MATH_TYPE_MACROS
+#define _MATH_TYPE_MACROS
+
+/* Each type imports a header which is expected to
+   define:
+
+   M_LIT(x)   - Paste the type specific suffix onto the constant x.
+   M_MLIT(x)  - Paste the type specific suffix used by the macro
+		constants in math.h, i.e M_PI or M_PIl.
+   M_PFX      - The prefixed used by float.h macros like FLT_MANT_DIG.
+   M_SUF(x)   - Paste the the type specific suffix used by functions
+		i.e expf expl exp.
+   FLOAT      - Resolves to the C typename of M_TYPE.
+   CFLOAT     - Resolves to the complex typename of M_TYPE.
+
+  Optionally, these headers may inject a non-standard
+  definition for the following:
+
+  declare_mgen_alias(from,to)
+      This exposes the appropriate symbol(s) for a
+      function f of type FLOAT.
+
+  M_LIBM_NEED_COMPAT(func)
+      This is utilized in macro context to indicate
+      whether func should declare compat symbols.
+
+  declare_mgen_libm_compat(from,to)
+      This is used in conjunction with the above macro
+      outside of macro context to paste whatever is
+      required to generate a compat symbol. */
+
+#ifndef M_PFX
+# error "M_PFX must be defined."
+#endif
+#ifndef M_LIT
+# error "M_LIT must be defined."
+#endif
+#ifndef M_MLIT
+# error "M_MLIT must be defined."
+#endif
+#ifndef M_SUF
+# error "M_SUF must be defined."
+#endif
+#ifndef FLOAT
+# error "FLOAT must be defined."
+#endif
+#ifndef CFLOAT
+# error "CFLOAT must be defined."
+#endif
+
+#define __M_CONCAT(a,b) a ## b
+#define __M_CONCATX(a,b) __M_CONCAT(a,b)
+
+#define M_NAN M_SUF (__nan) ("")
+#define M_MAX_EXP __M_CONCATX (M_PFX, _MAX_EXP)
+#define M_MIN __M_CONCATX (M_PFX, _MIN)
+#define M_MAX __M_CONCATX (M_PFX, _MAX)
+#define M_MANT_DIG __M_CONCATX (M_PFX, _MANT_DIG)
+#define M_HUGE_VAL (M_SUF (__builtin_huge_val) ())
+
+/* Helper macros for commonly used functions.  */
+#define M_COPYSIGN M_SUF (__copysign)
+#define M_FABS M_SUF (fabs)
+#define M_SINCOS M_SUF (__sincos)
+#define M_SCALBN M_SUF (__scalbn)
+#define M_LOG1P M_SUF (__log1p)
+
+#define M_ATAN2 M_SUF (__ieee754_atan2)
+#define M_COSH M_SUF (__ieee754_cosh)
+#define M_EXP M_SUF (__ieee754_exp)
+#define M_HYPOT M_SUF (__ieee754_hypot)
+#define M_LOG M_SUF (__ieee754_log)
+#define M_SINH M_SUF (__ieee754_sinh)
+#define M_SQRT M_SUF (__ieee754_sqrt)
+
+/* Needed to evaluate M_MANT_DIG below.  */
+#include <float.h>
+
+/* Use a special epsilon value for IBM long double
+   to avoid spurious overflows/underflows.  */
+#if M_MANT_DIG != 106
+# define M_EPSILON __M_CONCATX (M_PFX, _EPSILON)
+#else
+# define M_EPSILON M_LIT (0x1p-106)
+#endif
+
+/* Enable overloading of function name to assist reuse.  */
+#ifndef M_DECL_FUNC
+# define M_DECL_FUNC(f) M_SUF (f)
+#endif
+
+/* If the type does not declare special aliasing, use the default.  */
+#ifndef declare_mgen_alias
+# define declare_mgen_alias(from, to) weak_alias (M_SUF (from), M_SUF (to))
+#endif
+
+/* Do not generate anything for compat symbols by default.  */
+#ifndef M_LIBM_NEED_COMPAT
+# define M_LIBM_NEED_COMPAT(func) 0
+# define declare_mgen_libm_compat(from, to)
+#endif
+
+#endif /* _MATH_TYPE_MACROS */