On 30/04/21 16:24 -0400, David Edelsohn via Libstdc++ wrote:
On Fri, Jan 8, 2021 at 11:10 AM Jonathan Wakely <jwak...@redhat.com> wrote:
On 03/01/21 22:26 -0500, David Edelsohn via Libstdc++ wrote:
>On Sun, Jan 3, 2021 at 9:45 PM Jonathan Wakely <jwakely....@gmail.com> wrote:
>>
>> On Mon, 4 Jan 2021, 00:44 David Edelsohn via Libstdc++,
<libstd...@gcc.gnu.org> wrote:
>>>
>>> Or is there some other reason that _GLIBCXX_USE_INT128 and
>>> __SIZEOF_INT128__ are used in different contexts?
>>
>> Yes.
>>
>> I'll reply when I'm back from taking some time off. Probably Wednesday.
>
>If the uses of _GLIBCXX_USE_INT128 in libstdc++ headers specifically
>are checking if __int128 type is different than "long" and "long
>long", as opposed to the availability of the __int128, can c++config.h
Yes, the test is not just "is __int128 a valid type?" but "should we
use __int128 as a larger integer type?"
We used to use it more widely, but many places that use __int128
conditionally now check __GLIBCXX_INT_N_0 instead, because that is
defined when __int128 is available and we're not compiling in a
"strict ansi" dialect.
Of the two remaining uses of _GLIBCXX_USE_INT128 I think one is wrong
and should test __SIZEOF__INT128__ directly. We specifically do want
to use unsigned __int128 in __to_chars_unsigned_type even if it's the
same as a standard type.
So that leaves one remaining use, and I think that should do as you
suggest here ...
>define _GLIBCXX_USE_INT128 by comparing __SIZEOF_INT128__ to
>__SIZEOF_LONG_LONG__ and __SIZEOF_LONG__ instead of the libstdc++
>configure template typename test?
Yes, that seems fine. But since we only need it in one place, let's
just do that test in that one place. It makes the purpose of the test
more explicit, and so you don't need to look up what
_GLIBCXX_USE_INT128 means and when it's true.
Does the attached patch work for you?
Hi, Jonathan
Thanks for pushing the INT64_T patch.
I tested your revised patch in January and it works perfectly.
Could you push your INT128 patch to trunk when you have a moment?
Thanks, David
I've pushed the attached to trunk after testing on powerpc-aix and
x86_64-linux.
Contrary to what I said in January, I think both sues of
_GLIBCXX_USE_INT128 do want to only use __int128 if it's larger than
long long. For __to_chars_unsigned_type there's no point trying to use
unsigned __int128 if it's the same size as unsigned long long, because
we'd already have chosen unsigned long long.
commit ad0a3be4df5eecc79075d899fd79179d0f61270e
Author: Jonathan Wakely <jwak...@redhat.com>
Date: Tue May 4 12:07:09 2021
libstdc++: Remove _GLIBCXX_USE_INT128 autoconf macro
We don't need to decide whether to use __int128 when running configure,
we can do so at compilation time by seeing if __SIZEOF_INT128__ is
defined and if it's greater than __SIZEOF_LONG_LONG__.
This removes another unnecessary architecture-specific config macro in
<bits/c++config.h>, so the same header can work for 32-bit or 64-bit
compilation on AIX.
libstdc++-v3/ChangeLog:
* acinclude.m4 (GLIBCXX_ENABLE_INT128_FLOAT128): Remove
checks for __int128 and rename to GLIBCXX_ENABLE_FLOAT128.
* config.h.in: Regenerate.
* configure: Regenerate.
* configure.ac: Adjust to use GLIBCXX_ENABLE_FLOAT128.
* include/bits/random.h (_Select_uint_least_t<s, 1>):
Use __SIZEOF_INT128__ to decide whether to use __int128.
* include/std/charconv (__to_chars_unsigned_type): Likewise.
diff --git a/libstdc++-v3/acinclude.m4 b/libstdc++-v3/acinclude.m4
index 7b78e148fbd..94897a654c9 100644
--- a/libstdc++-v3/acinclude.m4
+++ b/libstdc++-v3/acinclude.m4
@@ -3049,15 +3049,14 @@ EOF
])
dnl
-dnl Check for GNU 128-bit integer and floating point types.
+dnl Check for GNU 128-bit floating point type.
dnl
-dnl Note: also checks that the types aren't standard types.
+dnl Note: also checks that the type isn't a standard types.
dnl
dnl Defines:
-dnl _GLIBCXX_USE_INT128
dnl ENABLE_FLOAT128
dnl
-AC_DEFUN([GLIBCXX_ENABLE_INT128_FLOAT128], [
+AC_DEFUN([GLIBCXX_ENABLE_FLOAT128], [
AC_LANG_SAVE
AC_LANG_CPLUSPLUS
@@ -3065,34 +3064,7 @@ AC_DEFUN([GLIBCXX_ENABLE_INT128_FLOAT128], [
# Fake what AC_TRY_COMPILE does, without linking as this is
# unnecessary for this test.
- cat > conftest.$ac_ext << EOF
-[#]line __oline__ "configure"
-template<typename T1, typename T2>
- struct same
- { typedef T2 type; };
-
-template<typename T>
- struct same<T, T>;
-
-int main()
-{
- typename same<long, __int128>::type i1;
- typename same<long long, __int128>::type i2;
-}
-EOF
-
- AC_MSG_CHECKING([for __int128])
- if AC_TRY_EVAL(ac_compile); then
- AC_DEFINE(_GLIBCXX_USE_INT128, 1,
- [Define if __int128 is supported on this host.])
- enable_int128=yes
- else
- enable_int128=no
- fi
- AC_MSG_RESULT($enable_int128)
- rm -f conftest*
-
- cat > conftest.$ac_ext << EOF
+ cat > conftest.$ac_ext << EOF
[#]line __oline__ "configure"
template<typename T1, typename T2>
struct same
diff --git a/libstdc++-v3/configure.ac b/libstdc++-v3/configure.ac
index 95dd9ce5da5..a816ff79d16 100644
--- a/libstdc++-v3/configure.ac
+++ b/libstdc++-v3/configure.ac
@@ -153,7 +153,7 @@ GLIBCXX_ENABLE_THREADS
GLIBCXX_ENABLE_ATOMIC_BUILTINS
GLIBCXX_ENABLE_LOCK_POLICY
GLIBCXX_ENABLE_DECIMAL_FLOAT
-GLIBCXX_ENABLE_INT128_FLOAT128
+GLIBCXX_ENABLE_FLOAT128
if test "$enable_float128" = yes; then
port_specific_symbol_files="$port_specific_symbol_files \$(top_srcdir)/config/abi/pre/float128.ver"
fi
diff --git a/libstdc++-v3/include/bits/random.h b/libstdc++-v3/include/bits/random.h
index 1b9cc5f16a9..0da013c5f45 100644
--- a/libstdc++-v3/include/bits/random.h
+++ b/libstdc++-v3/include/bits/random.h
@@ -99,7 +99,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
struct _Select_uint_least_t<__s, 2>
{ typedef unsigned long long type; };
-#ifdef _GLIBCXX_USE_INT128
+#if __SIZEOF_INT128__ > __SIZEOF_LONG_LONG__
template<int __s>
struct _Select_uint_least_t<__s, 1>
{ typedef unsigned __int128 type; };
diff --git a/libstdc++-v3/include/std/charconv b/libstdc++-v3/include/std/charconv
index 6e407f31e30..193702e677a 100644
--- a/libstdc++-v3/include/std/charconv
+++ b/libstdc++-v3/include/std/charconv
@@ -94,7 +94,7 @@ namespace __detail
struct __to_chars_unsigned_type : __make_unsigned_selector_base
{
using _UInts = _List<unsigned int, unsigned long, unsigned long long
-#if _GLIBCXX_USE_INT128
+#if __SIZEOF_INT128__ > __SIZEOF_LONG_LONG__
, unsigned __int128
#endif
>;
