diff mbox series

Use __builtin_tgmath in tgmath.h with GCC 8 (bug 21660) [committed]

Message ID alpine.DEB.2.20.1711150209170.16320@digraph.polyomino.org.uk
State New
Headers show
Series Use __builtin_tgmath in tgmath.h with GCC 8 (bug 21660) [committed] | expand

Commit Message

Joseph Myers Nov. 15, 2017, 2:09 a.m. UTC 
GCC mainline now supports __builtin_tgmath to allow <tgmath.h> macro
implementations that expand their arguments only once, so avoiding
exponential blowup in the size of macro expansions when calls to those
macros are nested in arguments to those macros.

This patch makes glibc's tgmath.h support using __builtin_tgmath, as a
much simpler and more efficient alternative to the existing
implementation.  (As a side effect, the new feature would make it much
more practical to support decimal floating point in <tgmath.h> with
new compilers; currently, libdfp does not provide a <tgmath.h>
implementation, and making decimal arguments cause integer arguments
to be considered of type _Decimal64 instead of double would have been
very problematic in the old implementation.)

Tested for x86_64 (with GCC mainline).  Committed.

2017-11-15  Joseph Myers  <joseph@codesourcery.com>

	[BZ #21660]
	* math/tgmath.h (__HAVE_BUILTIN_TGMATH): New macro.
	[__HAVE_BUILTIN_TGMATH] (__TG_F16_ARG): Likewise.
	[__HAVE_BUILTIN_TGMATH] (__TG_F32_ARG): Likewise.
	[__HAVE_BUILTIN_TGMATH] (__TG_F64_ARG): Likewise.
	[__HAVE_BUILTIN_TGMATH] (__TG_F128_ARG): Likewise.
	[__HAVE_BUILTIN_TGMATH] (__TG_F32X_ARG): Likewise.
	[__HAVE_BUILTIN_TGMATH] (__TG_F64X_ARG): Likewise.
	[__HAVE_BUILTIN_TGMATH] (__TG_F128X_ARG): Likewise.
	[__HAVE_BUILTIN_TGMATH] (__TGMATH_FUNCS): Likewise.
	[__HAVE_BUILTIN_TGMATH] (__TGMATH_RCFUNCS): Likewise.
	[__HAVE_BUILTIN_TGMATH] (__TGMATH_1): Likewise.
	[__HAVE_BUILTIN_TGMATH] (__TGMATH_2): Likewise.
	[__HAVE_BUILTIN_TGMATH] (__TGMATH_2STD): Likewise.
	[__HAVE_BUILTIN_TGMATH] (__TGMATH_3): Likewise.
	[__HAVE_BUILTIN_TGMATH] (__TGMATH_1C): Likewise.
	[__HAVE_BUILTIN_TGMATH] (__TGMATH_2C): Likewise.
	(__tgml): Make conditional on [!__HAVE_BUILTIN_TGMATH].
	(__floating_type): Likewise.
	(__real_integer_type): Likewise.
	(__complex_integer_type): Likewise.
	(__expr_is_real): Likewise.
	(__tgmath_real_type_sub): Likewise.
	(__tgmath_real_type): Likewise.
	(__tgmath_complex_type_sub): Likewise.
	(__tgmath_complex_type): Likewise.
	(__TGMATH_F128): Likewise.
	(__TGMATH_CF128): Likewise.
	[__HAVE_BUILTIN_TGMATH] (__TGMATH_UNARY_REAL_ONLY): Define using
	new macros.
	[__HAVE_BUILTIN_TGMATH] (__TGMATH_UNARY_REAL_RET_ONLY): Likewise.
	[__HAVE_BUILTIN_TGMATH] (__TGMATH_BINARY_FIRST_REAL_ONLY):
	Likewise.
	[__HAVE_BUILTIN_TGMATH] (__TGMATH_BINARY_FIRST_REAL_STD_ONLY):
	Likewise.
	[__HAVE_BUILTIN_TGMATH] (__TGMATH_BINARY_REAL_ONLY): Likewise.
	[__HAVE_BUILTIN_TGMATH] (__TGMATH_BINARY_REAL_STD_ONLY): Likewise.
	[__HAVE_BUILTIN_TGMATH] (__TGMATH_BINARY_REAL_RET_ONLY): Likewise.
	[__HAVE_BUILTIN_TGMATH] (__TGMATH_TERNARY_FIRST_SECOND_REAL_ONLY):
	Likewise.
	[__HAVE_BUILTIN_TGMATH] (__TGMATH_TERNARY_REAL_ONLY): Likewise.
	[__HAVE_BUILTIN_TGMATH] (__TGMATH_TERNARY_FIRST_REAL_RET_ONLY):
	Likewise.
	[__HAVE_BUILTIN_TGMATH] (__TGMATH_UNARY_REAL_IMAG): Likewise.
	[__HAVE_BUILTIN_TGMATH] (__TGMATH_UNARY_IMAG): Likewise.
	[__HAVE_BUILTIN_TGMATH] (__TGMATH_UNARY_REAL_IMAG_RET_REAL):
	Likewise.
	[__HAVE_BUILTIN_TGMATH] (__TGMATH_BINARY_REAL_IMAG): Likewise.
	(__TGMATH_UNARY_REAL_IMAG_RET_REAL_SAME): New macro.
	(carg): Use __TGMATH_UNARY_REAL_IMAG_RET_REAL_SAME.
	(cimag): Likewise.
	(creal): Likewise.

Comments

Szabolcs Nagy Nov. 17, 2017, 12:11 p.m. UTC | #1 
> +/* There are two variant implementations of type-generic macros in
> +   this file: one for GCC 8 and later, using __builtin_tgmath and
> +   where each macro expands each of its arguments only once, and one
> +   for older GCC, using other compiler extensions but with macros
> +   expanding their arguments many times (so resulting in exponential
> +   blowup of the size of expansions when calls to such macros are
> +   nested inside arguments to such macros).  */
> +
> +#define __HAVE_BUILTIN_TGMATH __GNUC_PREREQ (8, 0)

this breaks the build on trunk toolchains that
lack __builtin_tgmath
Florian Weimer Nov. 17, 2017, 12:50 p.m. UTC | #2 
On 11/17/2017 01:11 PM, Szabolcs Nagy wrote:
>> +/* There are two variant implementations of type-generic macros in
>> +   this file: one for GCC 8 and later, using __builtin_tgmath and
>> +   where each macro expands each of its arguments only once, and one
>> +   for older GCC, using other compiler extensions but with macros
>> +   expanding their arguments many times (so resulting in exponential
>> +   blowup of the size of expansions when calls to such macros are
>> +   nested inside arguments to such macros).  */
>> +
>> +#define __HAVE_BUILTIN_TGMATH __GNUC_PREREQ (8, 0)
> 
> this breaks the build on trunk toolchains that
> lack __builtin_tgmath

Short of getting GCC to adopt something similar to the Clang 
__has_builtin pseudo-macro, I don't see any solution other that 
requiring those who are affected by such issues to update.

Considering that this only affects an unreleased toolchain, I don't 
think the upgrade requirement is unreasonably onerous.

Thanks,
Florian
Szabolcs Nagy Nov. 17, 2017, 1 p.m. UTC | #3 
On 17/11/17 12:50, Florian Weimer wrote:
> On 11/17/2017 01:11 PM, Szabolcs Nagy wrote:
>>> +/* There are two variant implementations of type-generic macros in
>>> +   this file: one for GCC 8 and later, using __builtin_tgmath and
>>> +   where each macro expands each of its arguments only once, and one
>>> +   for older GCC, using other compiler extensions but with macros
>>> +   expanding their arguments many times (so resulting in exponential
>>> +   blowup of the size of expansions when calls to such macros are
>>> +   nested inside arguments to such macros).  */
>>> +
>>> +#define __HAVE_BUILTIN_TGMATH __GNUC_PREREQ (8, 0)
>>
>> this breaks the build on trunk toolchains that
>> lack __builtin_tgmath
> 
> Short of getting GCC to adopt something similar to the Clang __has_builtin pseudo-macro, I don't see any
> solution other that requiring those who are affected by such issues to update.
> 
> Considering that this only affects an unreleased toolchain, I don't think the upgrade requirement is
> unreasonably onerous.
> 

in this case prereq(8,1) would work

(the strncpy diagnostic suppression pragma thing is more complicated
because some gcc-8.0 require it others fail with it, but in general
i prefer to be able to use the same gcc build for a while and also
for bisecting issues.)
Florian Weimer Nov. 17, 2017, 1:02 p.m. UTC | #4 
On 11/17/2017 02:00 PM, Szabolcs Nagy wrote:
> On 17/11/17 12:50, Florian Weimer wrote:
>> On 11/17/2017 01:11 PM, Szabolcs Nagy wrote:
>>>> +/* There are two variant implementations of type-generic macros in
>>>> +   this file: one for GCC 8 and later, using __builtin_tgmath and
>>>> +   where each macro expands each of its arguments only once, and one
>>>> +   for older GCC, using other compiler extensions but with macros
>>>> +   expanding their arguments many times (so resulting in exponential
>>>> +   blowup of the size of expansions when calls to such macros are
>>>> +   nested inside arguments to such macros).  */
>>>> +
>>>> +#define __HAVE_BUILTIN_TGMATH __GNUC_PREREQ (8, 0)
>>>
>>> this breaks the build on trunk toolchains that
>>> lack __builtin_tgmath
>>
>> Short of getting GCC to adopt something similar to the Clang __has_builtin pseudo-macro, I don't see any
>> solution other that requiring those who are affected by such issues to update.
>>
>> Considering that this only affects an unreleased toolchain, I don't think the upgrade requirement is
>> unreasonably onerous.
>>
> 
> in this case prereq(8,1) would work

But this would mean that we do near-zero pre-release testing of this 
glibc feature, which seems very undesirable to me.

Thanks,
Florian
diff mbox series

Patch

diff --git a/math/tgmath.h b/math/tgmath.h
index 108c1a1..1216177 100644
--- a/math/tgmath.h
+++ b/math/tgmath.h
@@ -31,22 +31,76 @@ 
 #include <complex.h>
 
 
-/* Since `complex' is currently not really implemented in most C compilers
-   and if it is implemented, the implementations differ.  This makes it
-   quite difficult to write a generic implementation of this header.  We
-   do not try this for now and instead concentrate only on GNU CC.  Once
-   we have more information support for other compilers might follow.  */
+/* There are two variant implementations of type-generic macros in
+   this file: one for GCC 8 and later, using __builtin_tgmath and
+   where each macro expands each of its arguments only once, and one
+   for older GCC, using other compiler extensions but with macros
+   expanding their arguments many times (so resulting in exponential
+   blowup of the size of expansions when calls to such macros are
+   nested inside arguments to such macros).  */
+
+#define __HAVE_BUILTIN_TGMATH __GNUC_PREREQ (8, 0)
 
 #if __GNUC_PREREQ (2, 7)
 
-# ifdef __NO_LONG_DOUBLE_MATH
-#  define __tgml(fct) fct
-# else
-#  define __tgml(fct) fct ## l
-# endif
+# if __HAVE_BUILTIN_TGMATH
 
-/* This is ugly but unless gcc gets appropriate builtins we have to do
-   something like this.  Don't ask how it works.  */
+#  if __HAVE_FLOAT16 && __GLIBC_USE (IEC_60559_TYPES_EXT)
+#   define __TG_F16_ARG(X) X ## f16,
+#  else
+#   define __TG_F16_ARG(X)
+#  endif
+#  if __HAVE_FLOAT32 && __GLIBC_USE (IEC_60559_TYPES_EXT)
+#   define __TG_F32_ARG(X) X ## f32,
+#  else
+#   define __TG_F32_ARG(X)
+#  endif
+#  if __HAVE_FLOAT64 && __GLIBC_USE (IEC_60559_TYPES_EXT)
+#   define __TG_F64_ARG(X) X ## f64,
+#  else
+#   define __TG_F64_ARG(X)
+#  endif
+#  if __HAVE_FLOAT128 && __GLIBC_USE (IEC_60559_TYPES_EXT)
+#   define __TG_F128_ARG(X) X ## f128,
+#  else
+#   define __TG_F128_ARG(X)
+#  endif
+#  if __HAVE_FLOAT32X && __GLIBC_USE (IEC_60559_TYPES_EXT)
+#   define __TG_F32X_ARG(X) X ## f32x,
+#  else
+#   define __TG_F32X_ARG(X)
+#  endif
+#  if __HAVE_FLOAT64X && __GLIBC_USE (IEC_60559_TYPES_EXT)
+#   define __TG_F64X_ARG(X) X ## f64x,
+#  else
+#   define __TG_F64X_ARG(X)
+#  endif
+#  if __HAVE_FLOAT128X && __GLIBC_USE (IEC_60559_TYPES_EXT)
+#   define __TG_F128X_ARG(X) X ## f128x,
+#  else
+#   define __TG_F128X_ARG(X)
+#  endif
+
+#  define __TGMATH_FUNCS(X) X ## f, X, X ## l,				\
+    __TG_F16_ARG (X) __TG_F32_ARG (X) __TG_F64_ARG (X) __TG_F128_ARG (X) \
+    __TG_F32X_ARG (X) __TG_F64X_ARG (X) __TG_F128X_ARG (X)
+#  define __TGMATH_RCFUNCS(F, C) __TGMATH_FUNCS (F) __TGMATH_FUNCS (C)
+#  define __TGMATH_1(F, X) __builtin_tgmath (__TGMATH_FUNCS (F) (X))
+#  define __TGMATH_2(F, X, Y) __builtin_tgmath (__TGMATH_FUNCS (F) (X), (Y))
+#  define __TGMATH_2STD(F, X, Y) __builtin_tgmath (F ## f, F, F ## l, (X), (Y))
+#  define __TGMATH_3(F, X, Y, Z) __builtin_tgmath (__TGMATH_FUNCS (F)	\
+						   (X), (Y), (Z))
+#  define __TGMATH_1C(F, C, X) __builtin_tgmath (__TGMATH_RCFUNCS (F, C) (X))
+#  define __TGMATH_2C(F, C, X, Y) __builtin_tgmath (__TGMATH_RCFUNCS (F, C) \
+						    (X), (Y))
+
+# else /* !__HAVE_BUILTIN_TGMATH.  */
+
+#  ifdef __NO_LONG_DOUBLE_MATH
+#   define __tgml(fct) fct
+#  else
+#   define __tgml(fct) fct ## l
+#  endif
 
 /* __floating_type expands to 1 if TYPE is a floating type (including
    complex floating types), 0 if TYPE is an integer type (including
@@ -56,48 +110,48 @@ 
    constant expressions.  All these macros can assume their argument
    has an arithmetic type (not vector, decimal floating-point or
    fixed-point), valid to pass to tgmath.h macros.  */
-# if __GNUC_PREREQ (3, 1)
+#  if __GNUC_PREREQ (3, 1)
 /* __builtin_classify_type expands to an integer constant expression
    in GCC 3.1 and later.  Default conversions applied to the argument
    of __builtin_classify_type mean it always returns 1 for real
    integer types rather than ever returning different values for
    character, boolean or enumerated types.  */
-#  define __floating_type(type)				\
+#   define __floating_type(type)				\
   (__builtin_classify_type (__real__ ((type) 0)) == 8)
-#  define __real_integer_type(type)		\
+#   define __real_integer_type(type)		\
   (__builtin_classify_type ((type) 0) == 1)
-#  define __complex_integer_type(type)				\
+#   define __complex_integer_type(type)				\
   (__builtin_classify_type ((type) 0) == 9			\
    && __builtin_classify_type (__real__ ((type) 0)) == 1)
-# else
+#  else
 /* GCC versions predating __builtin_classify_type are also looser on
    what counts as an integer constant expression.  */
-#  define __floating_type(type) (((type) 1.25) != 1)
-#  define __real_integer_type(type) (((type) (1.25 + _Complex_I)) == 1)
-#  define __complex_integer_type(type)			\
+#   define __floating_type(type) (((type) 1.25) != 1)
+#   define __real_integer_type(type) (((type) (1.25 + _Complex_I)) == 1)
+#   define __complex_integer_type(type)			\
   (((type) (1.25 + _Complex_I)) == (1 + _Complex_I))
-# endif
+#  endif
 
 /* Whether an expression (of arithmetic type) has a real type.  */
-# define __expr_is_real(E) (__builtin_classify_type (E) != 9)
+#  define __expr_is_real(E) (__builtin_classify_type (E) != 9)
 
 /* The tgmath real type for T, where E is 0 if T is an integer type
    and 1 for a floating type.  If T has a complex type, it is
    unspecified whether the return type is real or complex (but it has
    the correct corresponding real type).  */
-# define __tgmath_real_type_sub(T, E) \
+#  define __tgmath_real_type_sub(T, E) \
   __typeof__ (*(0 ? (__typeof__ (0 ? (double *) 0 : (void *) (E))) 0	      \
 		  : (__typeof__ (0 ? (T *) 0 : (void *) (!(E)))) 0))
 
 /* The tgmath real type of EXPR.  */
-# define __tgmath_real_type(expr) \
+#  define __tgmath_real_type(expr) \
   __tgmath_real_type_sub (__typeof__ ((__typeof__ (+(expr))) 0),	      \
 			  __floating_type (__typeof__ (+(expr))))
 
 /* The tgmath complex type for T, where E1 is 1 if T has a floating
    type and 0 otherwise, E2 is 1 if T has a real integer type and 0
    otherwise, and E3 is 1 if T has a complex type and 0 otherwise.  */
-# define __tgmath_complex_type_sub(T, E1, E2, E3)			\
+#  define __tgmath_complex_type_sub(T, E1, E2, E3)			\
   __typeof__ (*(0							\
 		? (__typeof__ (0 ? (T *) 0 : (void *) (!(E1)))) 0	\
 		: (__typeof__ (0					\
@@ -109,61 +163,94 @@ 
 					      : (void *) (!(E3)))) 0)) 0))
 
 /* The tgmath complex type of EXPR.  */
-# define __tgmath_complex_type(expr)					\
+#  define __tgmath_complex_type(expr)					\
   __tgmath_complex_type_sub (__typeof__ ((__typeof__ (+(expr))) 0),	\
 			     __floating_type (__typeof__ (+(expr))),	\
 			     __real_integer_type (__typeof__ (+(expr))), \
 			     __complex_integer_type (__typeof__ (+(expr))))
 
-# if (__HAVE_DISTINCT_FLOAT16			\
+#  if (__HAVE_DISTINCT_FLOAT16			\
       || __HAVE_DISTINCT_FLOAT32		\
       || __HAVE_DISTINCT_FLOAT64		\
       || __HAVE_DISTINCT_FLOAT32X		\
       || __HAVE_DISTINCT_FLOAT64X		\
       || __HAVE_DISTINCT_FLOAT128X)
-#  error "Unsupported _FloatN or _FloatNx types for <tgmath.h>."
-# endif
+#   error "Unsupported _FloatN or _FloatNx types for <tgmath.h>."
+#  endif
 
 /* Expand to text that checks if ARG_COMB has type _Float128, and if
    so calls the appropriately suffixed FCT (which may include a cast),
    or FCT and CFCT for complex functions, with arguments ARG_CALL.  */
-# if __HAVE_DISTINCT_FLOAT128 && __GLIBC_USE (IEC_60559_TYPES_EXT)
-#  if (!__HAVE_FLOAT64X				\
+#  if __HAVE_DISTINCT_FLOAT128 && __GLIBC_USE (IEC_60559_TYPES_EXT)
+#   if (!__HAVE_FLOAT64X			\
        || __HAVE_FLOAT64X_LONG_DOUBLE		\
        || !__HAVE_FLOATN_NOT_TYPEDEF)
-#   define __TGMATH_F128(arg_comb, fct, arg_call)			\
+#    define __TGMATH_F128(arg_comb, fct, arg_call)			\
   __builtin_types_compatible_p (__typeof (+(arg_comb)), _Float128)	\
   ? fct ## f128 arg_call :
-#   define __TGMATH_CF128(arg_comb, fct, cfct, arg_call)		\
+#    define __TGMATH_CF128(arg_comb, fct, cfct, arg_call)		\
   __builtin_types_compatible_p (__typeof (+__real__ (arg_comb)), _Float128) \
   ? (__expr_is_real (arg_comb)						\
      ? fct ## f128 arg_call						\
      : cfct ## f128 arg_call) :
-#  else
+#   else
 /* _Float64x is a distinct type at the C language level, which must be
    handled like _Float128.  */
-#   define __TGMATH_F128(arg_comb, fct, arg_call)			\
+#    define __TGMATH_F128(arg_comb, fct, arg_call)			\
   (__builtin_types_compatible_p (__typeof (+(arg_comb)), _Float128)	\
    || __builtin_types_compatible_p (__typeof (+(arg_comb)), _Float64x)) \
   ? fct ## f128 arg_call :
-#   define __TGMATH_CF128(arg_comb, fct, cfct, arg_call)		\
+#    define __TGMATH_CF128(arg_comb, fct, cfct, arg_call)		\
   (__builtin_types_compatible_p (__typeof (+__real__ (arg_comb)), _Float128) \
    || __builtin_types_compatible_p (__typeof (+__real__ (arg_comb)),	\
 				    _Float64x))				\
   ? (__expr_is_real (arg_comb)						\
      ? fct ## f128 arg_call						\
      : cfct ## f128 arg_call) :
+#   endif
+#  else
+#   define __TGMATH_F128(arg_comb, fct, arg_call) /* Nothing.  */
+#   define __TGMATH_CF128(arg_comb, fct, cfct, arg_call) /* Nothing.  */
 #  endif
-# else
-#  define __TGMATH_F128(arg_comb, fct, arg_call) /* Nothing.  */
-#  define __TGMATH_CF128(arg_comb, fct, cfct, arg_call) /* Nothing.  */
-# endif
 
+# endif /* !__HAVE_BUILTIN_TGMATH.  */
 
 /* We have two kinds of generic macros: to support functions which are
    only defined on real valued parameters and those which are defined
    for complex functions as well.  */
-# define __TGMATH_UNARY_REAL_ONLY(Val, Fct) \
+# if __HAVE_BUILTIN_TGMATH
+
+#  define __TGMATH_UNARY_REAL_ONLY(Val, Fct) __TGMATH_1 (Fct, (Val))
+#  define __TGMATH_UNARY_REAL_RET_ONLY(Val, Fct) __TGMATH_1 (Fct, (Val))
+#  define __TGMATH_BINARY_FIRST_REAL_ONLY(Val1, Val2, Fct)	\
+  __TGMATH_2 (Fct, (Val1), (Val2))
+#  define __TGMATH_BINARY_FIRST_REAL_STD_ONLY(Val1, Val2, Fct)	\
+  __TGMATH_2STD (Fct, (Val1), (Val2))
+#  define __TGMATH_BINARY_REAL_ONLY(Val1, Val2, Fct)	\
+  __TGMATH_2 (Fct, (Val1), (Val2))
+#  define __TGMATH_BINARY_REAL_STD_ONLY(Val1, Val2, Fct)	\
+  __TGMATH_2STD (Fct, (Val1), (Val2))
+#  define __TGMATH_BINARY_REAL_RET_ONLY(Val1, Val2, Fct)	\
+  __TGMATH_2 (Fct, (Val1), (Val2))
+#  define __TGMATH_TERNARY_FIRST_SECOND_REAL_ONLY(Val1, Val2, Val3, Fct) \
+  __TGMATH_3 (Fct, (Val1), (Val2), (Val3))
+#  define __TGMATH_TERNARY_REAL_ONLY(Val1, Val2, Val3, Fct)	\
+  __TGMATH_3 (Fct, (Val1), (Val2), (Val3))
+#  define __TGMATH_TERNARY_FIRST_REAL_RET_ONLY(Val1, Val2, Val3, Fct)	\
+  __TGMATH_3 (Fct, (Val1), (Val2), (Val3))
+#  define __TGMATH_UNARY_REAL_IMAG(Val, Fct, Cfct)	\
+  __TGMATH_1C (Fct, Cfct, (Val))
+#  define __TGMATH_UNARY_IMAG(Val, Cfct) __TGMATH_1 (Cfct, (Val))
+#  define __TGMATH_UNARY_REAL_IMAG_RET_REAL(Val, Fct, Cfct)	\
+  __TGMATH_1C (Fct, Cfct, (Val))
+#  define __TGMATH_UNARY_REAL_IMAG_RET_REAL_SAME(Val, Cfct)	\
+  __TGMATH_1 (Cfct, (Val))
+#  define __TGMATH_BINARY_REAL_IMAG(Val1, Val2, Fct, Cfct)	\
+  __TGMATH_2C (Fct, Cfct, (Val1), (Val2))
+
+# else /* !__HAVE_BUILTIN_TGMATH.  */
+
+#  define __TGMATH_UNARY_REAL_ONLY(Val, Fct)				\
   (__extension__ ((sizeof (+(Val)) == sizeof (double)			      \
 		      || __builtin_classify_type (Val) != 8)		      \
 		     ? (__tgmath_real_type (Val)) Fct (Val)		      \
@@ -173,7 +260,7 @@ 
 				      (Val))				      \
 		     (__tgmath_real_type (Val)) __tgml(Fct) (Val)))
 
-# define __TGMATH_UNARY_REAL_RET_ONLY(Val, Fct) \
+#  define __TGMATH_UNARY_REAL_RET_ONLY(Val, Fct) \
      (__extension__ ((sizeof (+(Val)) == sizeof (double)		      \
 		      || __builtin_classify_type (Val) != 8)		      \
 		     ? Fct (Val)					      \
@@ -182,7 +269,7 @@ 
 		     : __TGMATH_F128 ((Val), Fct, (Val))		      \
 		     __tgml(Fct) (Val)))
 
-# define __TGMATH_BINARY_FIRST_REAL_ONLY(Val1, Val2, Fct) \
+#  define __TGMATH_BINARY_FIRST_REAL_ONLY(Val1, Val2, Fct) \
      (__extension__ ((sizeof (+(Val1)) == sizeof (double)		      \
 		      || __builtin_classify_type (Val1) != 8)		      \
 		     ? (__tgmath_real_type (Val1)) Fct (Val1, Val2)	      \
@@ -192,7 +279,7 @@ 
 				    (Val1, Val2))			      \
 		     (__tgmath_real_type (Val1)) __tgml(Fct) (Val1, Val2)))
 
-# define __TGMATH_BINARY_FIRST_REAL_STD_ONLY(Val1, Val2, Fct) \
+#  define __TGMATH_BINARY_FIRST_REAL_STD_ONLY(Val1, Val2, Fct) \
      (__extension__ ((sizeof (+(Val1)) == sizeof (double)		      \
 		      || __builtin_classify_type (Val1) != 8)		      \
 		     ? (__tgmath_real_type (Val1)) Fct (Val1, Val2)	      \
@@ -200,7 +287,7 @@ 
 		     ? (__tgmath_real_type (Val1)) Fct##f (Val1, Val2)	      \
 		     : (__tgmath_real_type (Val1)) __tgml(Fct) (Val1, Val2)))
 
-# define __TGMATH_BINARY_REAL_ONLY(Val1, Val2, Fct) \
+#  define __TGMATH_BINARY_REAL_ONLY(Val1, Val2, Fct) \
      (__extension__ ((sizeof ((Val1) + (Val2)) > sizeof (double)	      \
 		      && __builtin_classify_type ((Val1) + (Val2)) == 8)      \
 		     ? __TGMATH_F128 ((Val1) + (Val2),			      \
@@ -222,7 +309,7 @@ 
 				   + (__tgmath_real_type (Val2)) 0))	      \
 		       Fct##f (Val1, Val2)))
 
-# define __TGMATH_BINARY_REAL_STD_ONLY(Val1, Val2, Fct) \
+#  define __TGMATH_BINARY_REAL_STD_ONLY(Val1, Val2, Fct) \
      (__extension__ ((sizeof ((Val1) + (Val2)) > sizeof (double)	      \
 		      && __builtin_classify_type ((Val1) + (Val2)) == 8)      \
 		     ? (__typeof ((__tgmath_real_type (Val1)) 0		      \
@@ -239,7 +326,7 @@ 
 				   + (__tgmath_real_type (Val2)) 0))	      \
 		       Fct##f (Val1, Val2)))
 
-# define __TGMATH_BINARY_REAL_RET_ONLY(Val1, Val2, Fct) \
+#  define __TGMATH_BINARY_REAL_RET_ONLY(Val1, Val2, Fct) \
      (__extension__ ((sizeof ((Val1) + (Val2)) > sizeof (double)	      \
 		      && __builtin_classify_type ((Val1) + (Val2)) == 8)      \
 		     ? __TGMATH_F128 ((Val1) + (Val2), Fct, (Val1, Val2))     \
@@ -251,7 +338,7 @@ 
 		     ? Fct (Val1, Val2)					      \
 		     : Fct##f (Val1, Val2)))
 
-# define __TGMATH_TERNARY_FIRST_SECOND_REAL_ONLY(Val1, Val2, Val3, Fct) \
+#  define __TGMATH_TERNARY_FIRST_SECOND_REAL_ONLY(Val1, Val2, Val3, Fct) \
      (__extension__ ((sizeof ((Val1) + (Val2)) > sizeof (double)	      \
 		      && __builtin_classify_type ((Val1) + (Val2)) == 8)      \
 		     ? __TGMATH_F128 ((Val1) + (Val2),			      \
@@ -273,7 +360,7 @@ 
 				   + (__tgmath_real_type (Val2)) 0))	      \
 		       Fct##f (Val1, Val2, Val3)))
 
-# define __TGMATH_TERNARY_REAL_ONLY(Val1, Val2, Val3, Fct) \
+#  define __TGMATH_TERNARY_REAL_ONLY(Val1, Val2, Val3, Fct) \
      (__extension__ ((sizeof ((Val1) + (Val2) + (Val3)) > sizeof (double)     \
 		      && __builtin_classify_type ((Val1) + (Val2) + (Val3))   \
 			 == 8)						      \
@@ -302,7 +389,7 @@ 
 				   + (__tgmath_real_type (Val3)) 0))	      \
 		       Fct##f (Val1, Val2, Val3)))
 
-# define __TGMATH_TERNARY_FIRST_REAL_RET_ONLY(Val1, Val2, Val3, Fct) \
+#  define __TGMATH_TERNARY_FIRST_REAL_RET_ONLY(Val1, Val2, Val3, Fct) \
      (__extension__ ((sizeof (+(Val1)) == sizeof (double)		\
 		      || __builtin_classify_type (Val1) != 8)		\
 		     ? Fct (Val1, Val2, Val3)				\
@@ -313,7 +400,7 @@ 
 
 /* XXX This definition has to be changed as soon as the compiler understands
    the imaginary keyword.  */
-# define __TGMATH_UNARY_REAL_IMAG(Val, Fct, Cfct) \
+#  define __TGMATH_UNARY_REAL_IMAG(Val, Fct, Cfct) \
      (__extension__ ((sizeof (+__real__ (Val)) == sizeof (double)	      \
 		      || __builtin_classify_type (__real__ (Val)) != 8)	      \
 		     ? (__expr_is_real (Val)				      \
@@ -331,7 +418,7 @@ 
 		      ? (__tgmath_complex_type (Val)) __tgml(Fct) (Val)	      \
 		      : (__tgmath_complex_type (Val)) __tgml(Cfct) (Val))))
 
-# define __TGMATH_UNARY_IMAG(Val, Cfct) \
+#  define __TGMATH_UNARY_IMAG(Val, Cfct) \
      (__extension__ ((sizeof (+__real__ (Val)) == sizeof (double)	      \
 		      || __builtin_classify_type (__real__ (Val)) != 8)	      \
 		     ? (__typeof__ ((__tgmath_real_type (Val)) 0	      \
@@ -348,7 +435,7 @@ 
 
 /* XXX This definition has to be changed as soon as the compiler understands
    the imaginary keyword.  */
-# define __TGMATH_UNARY_REAL_IMAG_RET_REAL(Val, Fct, Cfct) \
+#  define __TGMATH_UNARY_REAL_IMAG_RET_REAL(Val, Fct, Cfct) \
      (__extension__ ((sizeof (+__real__ (Val)) == sizeof (double)	      \
 		      || __builtin_classify_type (__real__ (Val)) != 8)	      \
 		     ? (__expr_is_real (Val)				      \
@@ -375,10 +462,12 @@ 
 		      __tgml(Fct) (Val)					      \
 		      : (__typeof__ (__real__ (__tgmath_real_type (Val)) 0))  \
 		      __tgml(Cfct) (Val))))
+#  define __TGMATH_UNARY_REAL_IMAG_RET_REAL_SAME(Val, Cfct)	\
+  __TGMATH_UNARY_REAL_IMAG_RET_REAL ((Val), Cfct, Cfct)
 
 /* XXX This definition has to be changed as soon as the compiler understands
    the imaginary keyword.  */
-# define __TGMATH_BINARY_REAL_IMAG(Val1, Val2, Fct, Cfct) \
+#  define __TGMATH_BINARY_REAL_IMAG(Val1, Val2, Fct, Cfct) \
      (__extension__ ((sizeof (__real__ (Val1)				      \
 			      + __real__ (Val2)) > sizeof (double)	      \
 		      && __builtin_classify_type (__real__ (Val1)	      \
@@ -418,6 +507,7 @@ 
 			: (__typeof ((__tgmath_complex_type (Val1)) 0	      \
 				   + (__tgmath_complex_type (Val2)) 0))	      \
 			  Cfct##f (Val1, Val2))))
+# endif /* !__HAVE_BUILTIN_TGMATH.  */
 #else
 # error "Unsupported compiler; you cannot use <tgmath.h>"
 #endif
@@ -654,7 +744,7 @@ 
 /* Absolute value, conjugates, and projection.  */
 
 /* Argument value of Z.  */
-#define carg(Val) __TGMATH_UNARY_REAL_IMAG_RET_REAL (Val, carg, carg)
+#define carg(Val) __TGMATH_UNARY_REAL_IMAG_RET_REAL_SAME (Val, carg)
 
 /* Complex conjugate of Z.  */
 #define conj(Val) __TGMATH_UNARY_IMAG (Val, conj)
@@ -666,9 +756,9 @@ 
 /* Decomposing complex values.  */
 
 /* Imaginary part of Z.  */
-#define cimag(Val) __TGMATH_UNARY_REAL_IMAG_RET_REAL (Val, cimag, cimag)
+#define cimag(Val) __TGMATH_UNARY_REAL_IMAG_RET_REAL_SAME (Val, cimag)
 
 /* Real part of Z.  */
-#define creal(Val) __TGMATH_UNARY_REAL_IMAG_RET_REAL (Val, creal, creal)
+#define creal(Val) __TGMATH_UNARY_REAL_IMAG_RET_REAL_SAME (Val, creal)
 
 #endif /* tgmath.h */