Implement this change for C++20 that was just approved in Prague.
P1956R1 On the names of low-level bit manipulation functions
* include/bits/hashtable_policy.h: Update comment.
* include/std/bit (__ispow2, __ceil2, __floor2, __log2p1): Rename.
(ispow2, ceil2, floor2, log2p1): Likewise.
(__cpp_lib_int_pow2): Add feature test macro.
* include/std/charconv (__to_chars_len_2): Adjust use of __log2p1.
* include/std/memory (assume_aligned): Adjust use of ispow2.
* include/std/version (__cpp_lib_int_pow2): Add.
* libsupc++/new_opa.cc: Adjust use of __ispow2.
* src/c++17/memory_resource.cc: Likewise, and for __ceil2 and __log2p1.
* testsuite/17_intro/freestanding.cc: Adjust use of ispow2.
* testsuite/26_numerics/bit/bit.pow.two/ceil2.cc: Rename to ...
* testsuite/26_numerics/bit/bit.pow.two/bit_ceil.cc: ... here.
* testsuite/26_numerics/bit/bit.pow.two/ceil2_neg.cc: Rename to ...
* testsuite/26_numerics/bit/bit.pow.two/bit_ceil_neg.cc: ... here.
* testsuite/26_numerics/bit/bit.pow.two/floor2.cc: Rename to ...
* testsuite/26_numerics/bit/bit.pow.two/bit_floor.cc: ... here.
* testsuite/26_numerics/bit/bit.pow.two/log2p1.cc: Rename to ...
* testsuite/26_numerics/bit/bit.pow.two/bit_width.cc: ... here.
* testsuite/26_numerics/bit/bit.pow.two/ispow2.cc: Rename to ...
* testsuite/26_numerics/bit/bit.pow.two/has_single_bit.cc: ... here.
Many uses of std::numeric_limits in C++17 and C++20 features only really
need the min(), max() and digits constants for integral types. By adding
__detail::__int_limits we can avoid including the whole <limits> header.
The <limits> header isn't especially large, but avoiding it still gives
small savings in compilation time and memory usage for the compiler.
There are also C++11 features that could benefit from this change (e.g.
<bits/hashtable_policy.h> and <bits/uniform_int_dist.h>) but I won't
change those until stage 1.
The implementation of __int_limits assumes two's complement integers,
which is true for all targets supported by GCC.
PR libstdc++/92546 (partial)
* include/Makefile.am: Add new header.
* include/Makefile.in: Regenerate.
* include/bits/int_limits.h: New header.
* include/bits/parse_numbers.h (__select_int::_Select_int): Replace
numeric_limits with __detail::__int_limits.
* include/std/bit (__rotl, __rotr, __countl_zero, __countl_one)
(__countr_zero, __countr_one, __popcount, __ceil2, __floor2, __log2p1):
Likewise.
* include/std/charconv (__to_chars_8, __from_chars_binary)
(__from_chars_alpha_to_num, from_chars): Likewise.
* include/std/memory_resource (polymorphic_allocator::allocate)
(polymorphic_allocator::allocate_object): Likewise.
* include/std/string_view (basic_string_view::_S_compare): Likewise.
* include/std/utility (in_range): Likewise.
* testsuite/20_util/integer_comparisons/in_range_neg.cc: Adjust for
extra error about incomplete type __int_limits<bool>.
* testsuite/26_numerics/bit/bit.count/countl_one.cc: Include <limits>.
* testsuite/26_numerics/bit/bit.count/countl_zero.cc: Likewise.
* testsuite/26_numerics/bit/bit.count/countr_one.cc: Likewise.
* testsuite/26_numerics/bit/bit.count/countr_zero.cc: Likewise.
* testsuite/26_numerics/bit/bit.count/popcount.cc: Likewise.
* testsuite/26_numerics/bit/bit.pow.two/ceil2_neg.cc: Likewise.
* testsuite/26_numerics/bit/bit.pow.two/ceil2.cc: Likewise.
* testsuite/26_numerics/bit/bit.pow.two/floor2.cc: Likewise.
* testsuite/26_numerics/bit/bit.pow.two/ispow2.cc: Likewise.
* testsuite/26_numerics/bit/bit.pow.two/log2p1.cc: Likewise.
* testsuite/26_numerics/bit/bit.rotate/rotl.cc: Likewise.
* testsuite/26_numerics/bit/bit.rotate/rotr.cc: Likewise.
This proposal has now been accepted for C++20, with a few changes. This
patch adjusts std::rotl and std::rotr to match the final specification
and declares the additions for C++2a mode even when __STRICT_ANSI__ is
defined.
* include/std/bit (__rotl, __rotr): Change second parameter from
unsigned int to int and handle negative values.
(rotl, rotr): Remove check for __STRICT_ANSI__. Change second
parameter from unsigned int to int. Add nodiscard attribute.
* testsuite/26_numerics/bit/bitops.rot/rotl.cc: Rename to ...
* testsuite/26_numerics/bit/bit.rotate/rotl.cc: Here. Test negative
shifts.
* testsuite/26_numerics/bit/bitops.rot/rotr.cc: Rename to ...
* testsuite/26_numerics/bit/bit.rotate/rotr.cc: Here. Test negative
shifts.
From-SVN: r273706
* include/std/bit (__ceil2): Make unrepresentable results undefined,
as per P1355R2. Add debug assertion. Perform one left shift, not two,
so that out of range values cause undefined behaviour. Ensure that
shift will still be undefined if left operand is promoted.
* testsuite/26_numerics/bit/bit.pow.two/ceil2.cc: Replace checks for
unrepresentable values with checks that they are not core constant
expressions.
* testsuite/26_numerics/bit/bit.pow.two/ceil2_neg.cc: New test.
From-SVN: r273705
Reuse the __is_one_of alias in additional places, and define traits to
check for signed/unsigned integer types so we don't have to duplicate
those checks elsewhere.
The additional overloads for std::byte in <bit> were reviewed by LEWG
and considered undesirable, so this patch removes them.
* include/bits/fs_path.h (path::__is_encoded_char): Use __is_one_of.
* include/std/bit (_If_is_unsigned_integer_type): Remove.
(_If_is_unsigned_integer): Use __is_unsigned_integer.
(rotl(byte, unsigned), rotr(byte, unsigned), countl_zero(byte))
(countl_one(byte), countr_zero(byte), countr_one(byte))
(popcount(byte), ispow2(byte), ceil2(byte), floor2(byte))
(log2p1(byte)): Remove.
* include/std/charconv (__detail::__is_one_of): Move to <type_traits>.
(__detail::__is_int_to_chars_type): Remove.
(__detail::__integer_to_chars_result_type): Use __is_signed_integer
and __is_unsigned_integer.
* include/std/type_traits (__is_one_of): Move here from <charconv>.
(__is_signed_integer, __is_unsigned_integer): New helpers.
* testsuite/26_numerics/bit/bit.pow.two/ceil2.cc: Remove test for
std::byte overload.
* testsuite/26_numerics/bit/bit.pow.two/floor2.cc: Likewise.
* testsuite/26_numerics/bit/bit.pow.two/ispow2.cc: Likewise.
* testsuite/26_numerics/bit/bit.pow.two/log2p1.cc: Likewise.
* testsuite/26_numerics/bit/bitops.count/countl_one.cc: Likewise.
* testsuite/26_numerics/bit/bitops.count/countl_zero.cc: Likewise.
* testsuite/26_numerics/bit/bitops.count/countr_one.cc: Likewise.
* testsuite/26_numerics/bit/bitops.count/countr_zero.cc: Likewise.
* testsuite/26_numerics/bit/bitops.count/popcount.cc: Likewise.
* testsuite/26_numerics/bit/bitops.rot/rotl.cc: Likewise.
* testsuite/26_numerics/bit/bitops.rot/rotr.cc: Likewise.
From-SVN: r272695
For values where the result cannot be represented the shift width would
be equal to the width of the type, which is undefined. Perform two
well-defined shifts instead of one possible undefined shift.
* include/bits/hashtable_policy.h (__clp2): Fix calculation for LLP64
targets where sizeof(size_t) > sizeof(long). Avoid undefined shifts
of the number of bits in the type.
* include/std/bit (__ceil2): Avoid undefined shifts.
* testsuite/26_numerics/bit/bit.pow.two/ceil2.cc: Test values with
the most signifiant bit set.
From-SVN: r263986
These tests accidentally had two dg-do directives. Only the second one
is needed.
* testsuite/26_numerics/bit/bitops.count/countl_one.cc: Remove
redundant dg-do directive.
* testsuite/26_numerics/bit/bitops.count/countl_zero.cc: Likewise.
* testsuite/26_numerics/bit/bitops.count/countr_one.cc: Likewise.
* testsuite/26_numerics/bit/bitops.count/countr_zero.cc: Likewise.
* testsuite/26_numerics/bit/bitops.count/popcount.cc: Likewise.
From-SVN: r263695
P0553R2 is not in the C++2a working draft yet, but is likely to be
approved soon. Neither proposal supports std::byte but this adds
overloads of each function for std::byte, assuming that will also get
added.
* include/Makefile.am: Add new header.
* include/Makefile.in: Regenerate.
* include/precompiled/stdc++.h: Include new header.
* include/std/bit: New header.
(__rotl, __rotr, __countl_zero, __countl_one, __countr_zero)
(__countr_one, __popcount, __ispow2, __ceil2, __floor2, __log2p1):
Define for C++14.
[!__STRICT_ANSI__] (rotl, rotr, countl_zero, countl_one, countr_zero)
(countr_one, popcount): Define for C++2a. Also overload for std::byte.
(ispow2, ceil2, floor2, log2p1): Define for C++2a.
[!__STRICT_ANSI__] (ispow2, ceil2, floor2, log2p1): Overload for
std::byte.
* testsuite/26_numerics/bit/bit.pow.two/ceil2.cc: New.
* testsuite/26_numerics/bit/bit.pow.two/floor2.cc: New.
* testsuite/26_numerics/bit/bit.pow.two/ispow2.cc: New.
* testsuite/26_numerics/bit/bit.pow.two/log2p1.cc: New.
* testsuite/26_numerics/bit/bitops.rot/rotl.cc: New.
* testsuite/26_numerics/bit/bitops.rot/rotr.cc: New.
* testsuite/26_numerics/bit/bitops.count/countl_one.cc: New.
* testsuite/26_numerics/bit/bitops.count/countl_zero.cc: New.
* testsuite/26_numerics/bit/bitops.count/countr_one.cc: New.
* testsuite/26_numerics/bit/bitops.count/countr_zero.cc: New.
From-SVN: r262360
