Re: RFA (libstdc++): PATCH to implement C++17 over-aligned new

[Christophe Lyon <christophe dot lyon at linaro dot org>]

On 11 September 2016 at 11:38, Jonathan Wakely <jwakely@redhat.com> wrote:
> On 11/09/16 09:08 +0200, Christophe Lyon wrote:
>>
>> On 10 September 2016 at 08:59, Christophe Lyon
>> <christophe.lyon@linaro.org> wrote:
>>>
>>> On 9 September 2016 at 23:20, Jason Merrill <jason@redhat.com> wrote:
>>>>
>>>> On Thu, Sep 8, 2016 at 7:06 AM, Jonathan Wakely <jwakely@redhat.com>
>>>> wrote:
>>>>>
>>>>> On 08/09/16 09:10 +0200, Marc Glisse wrote:
>>>>>>
>>>>>>
>>>>>> Do we want a generic fallback implementation (similar to
>>>>>> gcc/config/i386/gmm_malloc.h)? A windows version with _aligned_malloc
>>>>>> /
>>>>>> _aligned_free would also be possible.
>>>>>
>>>>>
>>>>> Making it work for MinGW would be nice.
>>>>
>>>>
>>>> OK, this is what I'm checking in; could someone test it on MinGW?
>>>>
>>>> Jason
>>>
>>>
>>> Hi Jason,
>>>
>>> I'm seeing problems on arm*linux: the tests aligned-new[1235].C fail to
>>> link:
>>> aligned-new5.C:(.text+0x14): undefined reference to `operator
>>> new(unsigned int, std::align_val_t)'
>>>
>>>
>>> On aarch64*-elf and arm-eabi (using newlib), I'm seeing:
>>> /gccsrc/libstdc++-v3/libsupc++/new_opa.cc:66: undefined reference to
>>> `aligned_alloc'
>>>
>>> Am I missing something in my setup?
>>>
>>
>> I'm seeing an additional problem: to GCC build is broken after this
>> commit for target arm-none-eabi (using default cpu):
>>
>> /home/christophe.lyon/src/GCC/sources/gcc-fsf/reg-240062/libstdc++-v3/libsupc++/new_opant.cc:
>> In function 'void* operator new(std::size_t, std::align_val_t, const
>> std::nothrow_t&)':
>>
>> /home/christophe.lyon/src/GCC/sources/gcc-fsf/reg-240062/libstdc++-v3/libsupc++/new_opant.cc:33:3:
>> error: '__try' was not declared in this scope
>>   __try
>>   ^~~~~
>>
>> /home/christophe.lyon/src/GCC/sources/gcc-fsf/reg-240062/libstdc++-v3/libsupc++/new_opant.cc:37:11:
>> error: expected primary-expression before '...' token
>>   __catch(...)
>>           ^~~
>>
>> /home/christophe.lyon/src/GCC/sources/gcc-fsf/reg-240062/libstdc++-v3/libsupc++/new_opant.cc:37:3:
>> error: '__catch' was not declared in this scope
>>   __catch(...)
>>   ^~~~~~~
>>
>> /home/christophe.lyon/src/GCC/sources/gcc-fsf/reg-240062/libstdc++-v3/libsupc++/new_opant.cc:41:1:
>> warning: no return statement in function returning non-void
>> [-Wreturn-type]
>> }
>> ^
>>
>> /home/christophe.lyon/src/GCC/sources/gcc-fsf/reg-240062/libstdc++-v3/libsupc++/new_opant.cc:30:26:
>> warning: unused parameter 'sz' [-Wunused-parameter]
>> operator new(std::size_t sz, std::align_val_t al, const std::nothrow_t&)
>>                          ^~
>>
>> /home/christophe.lyon/src/GCC/sources/gcc-fsf/reg-240062/libstdc++-v3/libsupc++/new_opant.cc:30:47:
>> warning: unused parameter 'al' [-Wunused-parameter]
>> operator new(std::size_t sz, std::align_val_t al, const std::nothrow_t&)
>>                                               ^~
>> make[4]: *** [new_opant.lo] Error 1
>> make[4]: Leaving directory
>>
>> `/home/christophe.lyon/src/GCC/builds/gcc-fsf-reg-240062/obj-arm-none-eabi/gcc3/arm-none-eabi/libstdc++-v3/libsupc++'
>
>
> Hmm, I'm not sure why it's not failing on all targets, but this should
I don't know either: the same target (arm-none-eabi) but
--with-cpu=cortex-a9 does build.

> fix it. Could you test it?
>
It's not sufficient: I had to apply the same change to new_opvant.cc
for the build to complete.

Thanks,

Christophe