Part of the _BitInt feature in C2x
(http://www.open-std.org/jtc1/sc22/wg14/www/docs/n2763.pdf) is a new
macro in limits.h named BITINT_MAXWIDTH that can be used to determine
the maximum width of a bit-precise integer type. This macro must expand
to a value that is at least as large as ULLONG_WIDTH.
This adds an implementation-defined macro named __BITINT_MAXWIDTH__ to
specify that value, which is used by limits.h for the standard macro.
This also limits the maximum bit width to 128 bits because backends do
not currently support all mathematical operations (such as division) on
wider types yet. This maximum is expected to be increased in the future.
This completes the implementation of
WG14 N2412 (http://www.open-std.org/jtc1/sc22/wg14/www/docs/n2412.pdf),
which standardizes C on a twos complement representation for integer
types. The only work that remained there was to define the correct
macros in the standard headers, which this patch does.
Summary:
These all had somewhat custom file headers with different text from the
ones I searched for previously, and so I missed them. Thanks to Hal and
Kristina and others who prompted me to fix this, and sorry it took so
long.
Reviewers: hfinkel
Subscribers: mcrosier, javed.absar, cfe-commits
Tags: #clang
Differential Revision: https://reviews.llvm.org/D60406
llvm-svn: 357941
include_next when not hosted or unavailable. This follows the pattern in
stdint.h and allows these headers to work even in a freestanding configuration
without a standard library.
llvm-svn: 119343
_GCC_LIMITS_H_ is defined, when __GNUC__ is defined.
Also, we need to stay away from possible conflicts with header guards.
We should use CLANG_ to prefix all header guards.
llvm-svn: 64408
don't typecast CHAR_MIN to char, this makes it not a PP constant
and gives it the wrong unpromoted type. Thanks to Sebastian for
pointing this out!
llvm-svn: 63980
Aaron Ballman