[llvm-commits] [patch] AlignAs fixes

[David Blaikie]

Ping.

On Wed, Aug 29, 2012 at 8:56 AM, David Blaikie <dblaikie at gmail.com> wrote:
> Updated based on feedback from IRC. Updated some comments, made Clang
> use the standard feature rather than the __attribute__, removed some
> unused template definitions.
>
> On Tue, Aug 28, 2012 at 3:56 PM, David Blaikie <dblaikie at gmail.com> wrote:
>> Here's an attempt to fix the incorrect/non-portable code in AlignAs.h
>> and its unit test.
>>
>> We were previously trying to align typedefs, which isn't valid in
>> C++11. Even attempting to use alignas correctly won't work on any
>> compiler other than Clang anyway, even those (such as GCC 4.7)
>> reporting C++11 compliance through the __cplusplus macro value.
>>
>> So instead:
>> for __GNUC__, use __attribute__((aligned(x))) of a char
>> for __cplusplus == 201103L || __has_feature(cxx_alignas), use alignas
>> on a char (this code path isn't actually tested at the moment since
>> clang reports __GNUC__ so it hits the first case)
>> for _MSC_VER, use __declspec(align(x)) on a char
>>
>> This doesn't try to align a typedef as we were doing before, so I cut
>> a few test cases & extra types out of the test file - this doesn't
>> change the implementation much because we were stuffing a variable of
>> the typedef'd type in an anonymous struct anyway - so now we just use
>> the template with the aligned member directly.
>>
>> Yes/no/maybe? (I haven't actually looked at the code to see if this is
>> producing correct code - just updated the test cases fairly
>> mechanically & checked that they pass)
>>
>> - David