__intN patch 3/5: main __int128 -> __intN conversion.

[Jonathan Wakely]

On 25/08/14 23:03 -0400, DJ Delorie wrote:
>
>> I'd like to see the updated version of the whole of patch 3 (tested
>> to be actually independent of the other patches) for review, though
>> I won't be reviewing the C++ parts.
>
>Here it is.  Tested on x86_64.  I include the msp430-modes.def patch
>for demonstration purposes although obviously msp430's __int20 won't
>work without the other patches.

[snip]

>* libstdc++-v3/
>	* src/c++11/limits.cc: Add support for __intN types.
>	* include/std/type_traits: Likewise.
>	* include/std/limits: Likewise.
>	* include/c_std/cstdlib: Likewise.
>	* include/bits/cpp_type_traits.h: Likewise.
>	* include/c_global/cstdlib: Likewise.

These libstdc++ changes are OK for trunk.

Just one question about the include/std/limits changes below.

It seems that __glibcxx_signed_b isn't strictly necessary as it
doesn't use the B argument, so is it just there for consistency?

>Index: libstdc++-v3/include/std/limits
>===================================================================
>--- libstdc++-v3/include/std/limits	(revision 214383)
>+++ libstdc++-v3/include/std/limits	(working copy)
>@@ -122,27 +122,38 @@
> #ifndef __glibcxx_long_double_tinyness_before
> #  define __glibcxx_long_double_tinyness_before false
> #endif
>
> // You should not need to define any macros below this point.
>
>-#define __glibcxx_signed(T)	((T)(-1) < 0)
>+#define __glibcxx_signed_b(T,B)	((T)(-1) < 0)
>
>-#define __glibcxx_min(T) \
>-  (__glibcxx_signed (T) ? -__glibcxx_max (T) - 1 : (T)0)
>+#define __glibcxx_min_b(T,B)					\
>+  (__glibcxx_signed_b (T,B) ? -__glibcxx_max_b (T,B) - 1 : (T)0)
>
>-#define __glibcxx_max(T) \
>-  (__glibcxx_signed (T) ? \
>-   (((((T)1 << (__glibcxx_digits (T) - 1)) - 1) << 1) + 1) : ~(T)0)
>+#define __glibcxx_max_b(T,B)						\
>+  (__glibcxx_signed_b (T,B) ?						\
>+   (((((T)1 << (__glibcxx_digits_b (T,B) - 1)) - 1) << 1) + 1) : ~(T)0)
>
>-#define __glibcxx_digits(T) \
>-  (sizeof(T) * __CHAR_BIT__ - __glibcxx_signed (T))
>+#define __glibcxx_digits_b(T,B)				\
>+  (B - __glibcxx_signed_b (T,B))
>
> // The fraction 643/2136 approximates log10(2) to 7 significant digits.
>+#define __glibcxx_digits10_b(T,B)		\
>+  (__glibcxx_digits_b (T,B) * 643L / 2136)
>+
>+#define __glibcxx_signed(T) \
>+  __glibcxx_signed_b (T, sizeof(T) * __CHAR_BIT__)