From: Jonathan Wakely <jwakely@redhat.com>
To: Tulio Magno Quites Machado Filho <tuliom@linux.vnet.ibm.com>
Cc: libstdc++ <libstdc++@gcc.gnu.org>,
gcc-patches <gcc-patches@gcc.gnu.org>,
wschmidt@linux.vnet.ibm.com,
Segher Boessenkool <segher@kernel.crashing.org>,
John David Anglin <danglin@gcc.gnu.org>,
Marc Glisse <marc.glisse@inria.fr>
Subject: Re: [PATCHv2] PR libstdc++/84654 Do not use __float128 if it is disabled by the compiler
Date: Mon, 07 May 2018 20:03:00 -0000 [thread overview]
Message-ID: <20180507200259.GN20930@redhat.com> (raw)
In-Reply-To: <20180501143431.GA6267@redhat.com>
[-- Attachment #1: Type: text/plain, Size: 1244 bytes --]
On 01/05/18 15:34 +0100, Jonathan Wakely wrote:
>On 12/03/18 16:02 -0300, Tulio Magno Quites Machado Filho wrote:
>>Changes since v1:
>>- Completely rewrite of the patch to set ENABLE_FLOAT128 at libstdc++
>> build time and undef _GLIBCXX_USE_FLOAT128 when building user code.
>>
>>--- 8< ---
>>
>>In order to use __float128 in C++ it's necessary to check if the
>>compiler enabled its support too when building user code.
>>This patch changes the behavior at libstdc++ build by setting
>>ENABLE_FLOAT128, which is used to set the value of the exported macro
>>_GLIBCXX_USE_FLOAT128.
>
>Now that we're in stage 1 we can make this change. The patch looks
>right so I'll go ahead and commit it to trunk (it shouldn't interfere
>with testing any last-minute fixes needed for gcc-8).
>
>Thanks for fixing this, Tulio.
Previously _GLIBCXX_USE_FLOAT128 would either be defined to 1 or
undefined, but after this change it can be defined to 0, and the
checks in <type_traits> and <bits/std_abs.h> were not adjusted to
account for that.
This patch restores the previous behaviour, so that when __float128
support is not found by configure the macro will be undefined instead
of defined to 0.
I plan to commit this tomorrow after some more testing.
[-- Attachment #2: patch.txt --]
[-- Type: text/x-patch, Size: 2471 bytes --]
commit aed5af13903fa21632919269c9e7f7c4e02e8887
Author: Jonathan Wakely <jwakely@redhat.com>
Date: Mon May 7 20:46:21 2018 +0100
PR libstdc++/85672 #undef _GLIBCXX_USE_FLOAT128 when not supported
Restore the behaviour in GCC 8 and earlier where _GLIBCXX_USE_FLOAT128
is not defined when configure detects support is missing. This avoids
having three states where the macro is either 1, 0, or undefined.
PR libstdc++/85672
* include/Makefile.am [!ENABLE_FLOAT128]: Change c++config.h entry
to #undef _GLIBCXX_USE_FLOAT128 instead of defining it to zero.
* include/Makefile.in: Regenerate.
* include/bits/c++config (_GLIBCXX_USE_FLOAT128): Move definition
within conditional block.
diff --git a/libstdc++-v3/include/Makefile.am b/libstdc++-v3/include/Makefile.am
index ba5adda95bd..77e6dc2f6be 100644
--- a/libstdc++-v3/include/Makefile.am
+++ b/libstdc++-v3/include/Makefile.am
@@ -1232,10 +1232,10 @@ endif
if ENABLE_FLOAT128
stamp-float128:
- echo 1 > stamp-float128
+ echo 'define _GLIBCXX_USE_FLOAT128 1' > stamp-float128
else
stamp-float128:
- echo 0 > stamp-float128
+ echo 'undef _GLIBCXX_USE_FLOAT128' > stamp-float128
endif
# NB: The non-empty default ldbl_compat works around an AIX sed
@@ -1272,7 +1272,7 @@ ${host_builddir}/c++config.h: ${CONFIG_HEADER} \
-e "s,define _GLIBCXX_USE_DUAL_ABI, define _GLIBCXX_USE_DUAL_ABI $$dualabi," \
-e "s,define _GLIBCXX_USE_CXX11_ABI, define _GLIBCXX_USE_CXX11_ABI $$cxx11abi," \
-e "s,define _GLIBCXX_USE_ALLOCATOR_NEW, define _GLIBCXX_USE_ALLOCATOR_NEW $$allocatornew," \
- -e "s,define _GLIBCXX_USE_FLOAT128, define _GLIBCXX_USE_FLOAT128 $$float128," \
+ -e "s,define _GLIBCXX_USE_FLOAT128,$$float128," \
-e "$$ldbl_compat" \
< ${glibcxx_srcdir}/include/bits/c++config > $@ ;\
sed -e 's/HAVE_/_GLIBCXX_HAVE_/g' \
diff --git a/libstdc++-v3/include/bits/c++config b/libstdc++-v3/include/bits/c++config
index e34524117d6..bfe268da825 100644
--- a/libstdc++-v3/include/bits/c++config
+++ b/libstdc++-v3/include/bits/c++config
@@ -610,9 +610,8 @@ namespace std
#endif
/* Define if __float128 is supported on this host. */
+#if defined(__FLOAT128__) || defined(__SIZEOF_FLOAT128__)
#define _GLIBCXX_USE_FLOAT128
-#if !defined(__FLOAT128__) && !defined(__SIZEOF_FLOAT128__)
-#undef _GLIBCXX_USE_FLOAT128
#endif
// End of prewritten config; the settings discovered at configure time follow.
next prev parent reply other threads:[~2018-05-07 20:03 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-03-01 18:47 [PATCH] " Tulio Magno Quites Machado Filho
2018-03-01 18:54 ` Marc Glisse
2018-03-01 22:04 ` Jonathan Wakely
2018-03-12 19:02 ` [PATCHv2] " Tulio Magno Quites Machado Filho
2018-03-26 15:23 ` Tulio Magno Quites Machado Filho
2018-05-01 14:34 ` Jonathan Wakely
2018-05-07 20:03 ` Jonathan Wakely [this message]
2018-03-01 19:10 ` [PATCH] " Jakub Jelinek
2018-03-01 20:52 ` Jakub Jelinek
2018-03-01 20:56 ` Marc Glisse
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