Clean up bits/math-finite.h for aliasing types.

This patch cleans up how bits/math-finite.h handles types that are
ABI-aliases of other types.

For such types, no __*_finite functions exist; instead,
bits/math-finite.h must redirect calls to a the functions for a
canonical choice of type for each floating-point format.  (For the
actual public interfaces, symbols need exporting for each type, even
those that are ABI-aliases, because of standard requirements that
programs can declare the functions themselves without including
<math.h>, but that does not apply to __*_finite.)

At present, there is a special-case conditional in bits/math-finite.h
on __MATH_DECLARING_LDOUBLE && defined __NO_LONG_DOUBLE_MATH to handle
redirecting long double function calls to double __*_finite.  This
patch replaces this by a more general mechanism.  math.h, before each
inclusion of bits/math-finite.h, defines _MSUFTO_ as the suffix to use
on the target of redirection, in addition to the existing _MSUF_.
This way, __MATH_DECLARING_LDOUBLE can go away, as can the special
conditional in bits/math-finite.h.  With this patch, math.h is now
prepared for the case of supporting float128 functions as aliases of
long double ones on platforms where long double is binary128, with
_MSUFTO_ appropriately defined for that case, and appropriate _MSUFTO_
definitions can easily be included when supporting _Float32 / _Float64
/ _Float32x / _Float64x (which will always be ABI-aliases of another
type when supported).

Tested for x86_64, and did a compilation test for ARM with
build-many-glibcs.py to cover the long double = double case.

	* math/math.h (_MSUFTO_): Define and undefine for each inclusion
	of <bits/math-finite.h>.
	(__MATH_DECLARING_LDOUBLE): Do not define and undefine for each
	inclusion of <bits/math-finite.h>.
	* math/bits/math-finite.h (__REDIRTO_X): Do not define
	conditionally on [__MATH_DECLARING_LDOUBLE && defined
	__NO_LONG_DOUBLE_MATH].
	(__MATH_REDIRCALL): Use _MSUFTO_ in __REDIRTO call.
	(__MATH_REDIRCALL_2): Likewise.
	(__MATH_REDIRCALL_INTERNAL): Likewise.
	(__REDIRFROM (lgamma, , _MSUF_)): Likewise.
	(__REDIRFROM (gamma, , _MSUF_)): Likewise.
	(__REDIRFROM (tgamma, , _MSUF_)): Likewise.

1 files changed, 16 insertions, 8 deletions

diff --git a/math/math.h b/math/math.h
index 5acbe88906..9162bee50c 100644
--- a/math/math.h
+++ b/math/math.h
@@ -618,15 +618,15 @@ iszero (__T __val)
 /* Include bits/math-finite.h for double.  */
 # define _Mdouble_ double
 # define __MATH_DECLARING_DOUBLE 1
-# define __MATH_DECLARING_LDOUBLE 0
 # define __MATH_DECLARING_FLOATN 0
 # define _MSUF_
+# define _MSUFTO_
 # include <bits/math-finite.h>
 # undef _Mdouble_
 # undef __MATH_DECLARING_DOUBLE
-# undef __MATH_DECLARING_LDOUBLE
 # undef __MATH_DECLARING_FLOATN
 # undef _MSUF_
+# undef _MSUFTO_
 
 /* When __USE_ISOC99 is defined, include math-finite for float and
    long double, as well.  */
@@ -635,29 +635,33 @@ iszero (__T __val)
 /* Include bits/math-finite.h for float.  */
 #  define _Mdouble_ float
 #  define __MATH_DECLARING_DOUBLE 0
-#  define __MATH_DECLARING_LDOUBLE 0
 #  define __MATH_DECLARING_FLOATN 0
 #  define _MSUF_ f
+#  define _MSUFTO_ f
 #  include <bits/math-finite.h>
 #  undef _Mdouble_
 #  undef __MATH_DECLARING_DOUBLE
-#  undef __MATH_DECLARING_LDOUBLE
 #  undef __MATH_DECLARING_FLOATN
 #  undef _MSUF_
+#  undef _MSUFTO_
 
 /* Include bits/math-finite.h for long double.  */
 #  ifdef __MATH_DECLARE_LDOUBLE
 #   define _Mdouble_ long double
 #   define __MATH_DECLARING_DOUBLE 0
-#   define __MATH_DECLARING_LDOUBLE 1
 #   define __MATH_DECLARING_FLOATN 0
 #   define _MSUF_ l
+#   ifdef __NO_LONG_DOUBLE_MATH
+#    define _MSUFTO_
+#   else
+#    define _MSUFTO_ l
+#   endif
 #   include <bits/math-finite.h>
 #   undef _Mdouble_
 #   undef __MATH_DECLARING_DOUBLE
-#   undef __MATH_DECLARING_LDOUBLE
 #   undef __MATH_DECLARING_FLOATN
 #   undef _MSUF_
+#   undef _MSUFTO_
 #  endif
 
 # endif /* __USE_ISOC99.  */
@@ -667,15 +671,19 @@ iszero (__T __val)
       && __GLIBC_USE (IEC_60559_TYPES_EXT)
 #  define _Mdouble_ _Float128
 #  define __MATH_DECLARING_DOUBLE 0
-#  define __MATH_DECLARING_LDOUBLE 0
 #  define __MATH_DECLARING_FLOATN 1
 #  define _MSUF_ f128
+#  if __HAVE_DISTINCT_FLOAT128
+#   define _MSUFTO_ f128
+#  else
+#   define _MSUFTO_ l
+#  endif
 #  include <bits/math-finite.h>
 #  undef _Mdouble_
 #  undef __MATH_DECLARING_DOUBLE
-#  undef __MATH_DECLARING_LDOUBLE
 #  undef __MATH_DECLARING_FLOATN
 #  undef _MSUF_
+#  undef _MSUFTO_
 # endif
 #endif /* __FINITE_MATH_ONLY__ > 0.  */