On 03/03/22 22:38 +0000, Jonathan Wakely wrote:
Tested x86_64-linux (-m32/-m64), powerpc64-linux (-m32/-m64),
powerpc64le-linux, powerpc-aix (maix32/-maix64/-mlong-double-128).
Pushed to trunk. I'm inclined to backport this to gcc-11 after some soak
time on trunk (but not gcc-10, because it needs __builtin_bit_cast).
-- >8 --
This removes a FIXME in <compare>, defining the total order for
floating-point types. I originally opened PR96526 to request a new
compiler built-in to implement this, but now that we have std::bit_cast
it can be done entirely in the library.
The implementation is based on the glibc definitions of totalorder,
totalorderf, totalorderl etc.
I think this works for all the types that satisfy std::floating_point
today, and should also work for the types expected to be added by P1467
except for std::bfloat16_t. It also supports some additional types that
don't currently satisfy std::floating_point, such as __float80, but we
probably do want that to satisfy the concept for non-strict modes.
libstdc++-v3/ChangeLog:
PR libstdc++/96526
* libsupc++/compare (strong_order): Add missing support for
floating-point types.
* testsuite/18_support/comparisons/algorithms/strong_order_floats.cc:
New test.
That commit produces a warning due to a typedef that is only needed
for some targets, which caused:
FAIL: g++.dg/warn/Wstringop-overflow-6.C -std=gnu++20 (test for excess errors)
Here's the fix. Tested x86_64-linux, pushed to trunk.
commit 289f65d643e18210433e0f08ccaaf5b08b3d6f39
Author: Jonathan Wakely <jwak...@redhat.com>
Date: Fri Mar 4 10:43:29 2022
libstdc++: Fix -Wunused-local-typedefs warning in <compare>
libstdc++-v3/ChangeLog:
* libsupc++/compare (strong_order::_S_fp_cmp): Move typedef
inside #if condition.
diff --git a/libstdc++-v3/libsupc++/compare b/libstdc++-v3/libsupc++/compare
index a8747207b23..050cf7ed20d 100644
--- a/libstdc++-v3/libsupc++/compare
+++ b/libstdc++-v3/libsupc++/compare
@@ -850,8 +850,6 @@ namespace std
return strong_ordering::equal; // All bits are equal, we're done.
using enum _Fp_fmt;
- using _Int = decltype(__ix);
-
constexpr auto __fmt = _S_fp_fmt<_Tp>();
if constexpr (__fmt == _Dbldbl) // double-double
@@ -899,6 +897,8 @@ namespace std
// bit to be reversed. Flip that to give desired ordering.
if (__builtin_isnan(__x) && __builtin_isnan(__y))
{
+ using _Int = decltype(__ix);
+
constexpr int __nantype = __fmt == _Binary32 ? 22
: __fmt == _Binary64 ? 51
: __fmt == _Binary128 ? 111
