Hi Jakub,
> On 4 Nov 2021, at 10:05, Jakub Jelinek <ja...@redhat.com> wrote:
>
> On Tue, Jul 06, 2021 at 11:17:55AM +0100, Iain Sandoe wrote:
>>>> The addition of the CTOR is the fix for the C++ compile fail in the PR,
>>>> the conditional is
>>>> only there because the same header is compiled by C and C++.
>>>
>>> Whoops sorry - I was confused. The patch looks OK to me if you add a
>>> comment
>>> before the CTOR why it was added (maybe quoting the error that happens)
>>
>> Thanks, pushed as below.
>> Iain
>>
>> -------
>>
>> X86: Provide a CTOR for stringop_algs [PR100246].
>>
>> Several older compilers fail to build modern GCC because of missing
>> or incomplete C++11 support.
>>
>> Signed-off-by: Iain Sandoe <i...@sandoe.co.uk>
>>
>> PR bootstrap/100246 - [11/12 Regression] GCC will not bootstrap with clang
>> 3.4/3.5 [xcode 5/6, Darwin 12/13]
>>
>> PR bootstrap/100246
>>
>> gcc/ChangeLog:
>>
>> * config/i386/i386.h (struct stringop_algs): Define a CTOR for
>> this type.
>
> Unfortunately, as mentioned in my
> https://gcc.gnu.org/pipermail/gcc-patches/2021-November/583289.html
> mail, without the new dyninit pass this causes dynamic initialization of
> many variables, 6.5KB _GLOBAL__sub_I_* on x86_64 and 12.5KB on i686.
>
> The following so far only lightly tested patch makes the ctor constexpr
> so that already the FE is able to statically initialize all those.
>
> I don't have access to Darwin nor to the broken versions of clang, do you
> think you could test bootstrap there with this too?
Bootstrap succeeded with Apple clang-503.0.40 (Xcode 5.1.1) on macOS 10.8
which is the earliest version I expect to work (previous xcode impl. have more
C++11 incompatibilities). So OK from a Darwin PoV.
The other reported toolchain with the issue was GCC-4.9.2 as discussed on
IRC - this also seems OK.
Iain
> Especially because 11.x is not going to have the dyninit optimization for
> sure, it would be nice to do this on the 11 branch too.
>
> 2021-11-04 Jakub Jelinek <ja...@redhat.com>
>
> PR bootstrap/100246
> * config/i386/i386.h
> (stringop_algs::stringop_strategy::stringop_strategy): Make the ctor
> constexpr.
>
> --- gcc/config/i386/i386.h.jj 2021-09-28 23:18:35.282563395 +0200
> +++ gcc/config/i386/i386.h 2021-11-04 10:48:47.165086806 +0100
> @@ -78,8 +78,9 @@ struct stringop_algs
> this issue. Since this header is used by code compiled with the C
> compiler we must guard the addition. */
> #ifdef __cplusplus
> - stringop_strategy(int _max = -1, enum stringop_alg _alg = libcall,
> - int _noalign = false)
> + constexpr stringop_strategy(int _max = -1,
> + enum stringop_alg _alg = libcall,
> + int _noalign = false)
> : max (_max), alg (_alg), noalign (_noalign) {}
> #endif
> const int max;
>
> Jakub
>
