[cfe-dev] aligned 'new'

[Anton Yartsev]

On 05.08.2011 3:28, Anton Yartsev wrote:
> On 21.07.2011 0:58, Anton Yartsev wrote:
>> On 12.07.2011 1:22, Anton Yartsev wrote:
>>> On 24.06.2011 5:43, Anton Yartsev wrote:
>>>> On 30.05.2011 8:35, Chris Lattner wrote:
>>>>> On May 29, 2011, at 8:49 PM, Anton Yartsev wrote:
>>>>>
>>>>>> Hi all,
>>>>>>
>>>>>> I am thinking of the ability of operator new to return memory 
>>>>>> aligned
>>>>>> according to the alignment of the type passed to it (at least of 
>>>>>> AltiVec
>>>>>> vector types whose proper alignment is essential).
>>>>>> The proposed implementation is:
>>>>>> 1) clang: add -fstrict-aligned option. When the option is set it 
>>>>>> cause
>>>>>> clang to define the built-in macro "__STRICT_ALIGNED"
>>>>>> 2) libcxx: add additional placement new declarations to
>>>>>> libcxx\include\new with the additional argument - alignment. Make 
>>>>>> this
>>>>>> declarations conditionalized on the "__STRICT_ALIGNED". Add new
>>>>>> definitions to libcxx\src\new.cpp.
>>>>>> 3) clang: if -fstrict-aligned option is set, when clang sees a 
>>>>>> new of a
>>>>>> type which either has an inherent alignment, or has an explicit
>>>>>> alignment specified by __attribute__((__aligned__(x))), it will
>>>>>> transform the standard new call to a call to the aligned version 
>>>>>> of new.
>>>>>>
>>>>>> Am i on the right way? Any thoughts?
>>>>> I don't think that this is the right way to go.  Instead, you'd 
>>>>> want "new foo" to automatically detect that the alignment of "foo" 
>>>>> is greater than the alignment guaranteed by the system malloc.  In 
>>>>> this case, and if using the default operator new, you'd generate a 
>>>>> call to memalign instead of to operator new (something like that).
>>>>>
>>>>> It isn't clear to me how generally useful this is though, and we 
>>>>> tend to avoid adding tons of language extensions to Clang.
>>>>>
>>>>> -Chris
>>>> Attached is the the patch that substitutes calls to default new 
>>>> operators with calls to functions - aligned analogs of default new 
>>>> operators. This functions may live in the clang's mm_malloc.h 
>>>> header where aligned malloc lives.  The patch is partial, it does 
>>>> not affect deletes and do not contain substituting functions yet. 
>>>> Please review and direct!
>>>>
>>> Ping!
>>>
>> Hi,
>>
>> here is the updated patch that substitute both news and deletes, 
>> please review!
>>
> Final patch with aligned functions added, please review!
>
Ping!

-- 
Anton