[LLVMdev] Section specialization & COFF.

[r4start]

On 24/10/12 17:03, r4start wrote:
> On 23/10/12 01:30, Michael Spencer wrote:
>> On Mon, Oct 22, 2012 at 7:53 AM, r4start <r4start at gmail.com> wrote:
>>> On 20/10/12 03:15, Michael Spencer wrote:
>>>> On Fri, Oct 19, 2012 at 2:55 AM, r4start <r4start at gmail.com> wrote:
>>>>> Hi all.
>>>>>
>>>>> While compiling next code
>>>>> @A = weak unnamed_addr constant { i32, i32, i32 } { i32 0, i32 0, 
>>>>> i32 0
>>>>> },
>>>>> section ".data"
>>>>> was discovered that llc ignores weak linkage if we emit it in COFF
>>>>> object.
>>>>> Attached patch solves this problem, please review.
>>>>>
>>>>> I found some similar tests in test/Objects/Inputs. Should I do 
>>>>> something
>>>>> like trivial.ll checking or there is a better way
>>>>> to check patch behaviour?
>>>>>
>>>>>    - Dmitry Sokolov.
>>>>>
>>>>> _______________________________________________
>>>>> LLVM Developers mailing list
>>>>> LLVMdev at cs.uiuc.edu         http://llvm.cs.uiuc.edu
>>>>> http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev
>>>>>
>>>> test/Object is not the right place for the test. It should probably go
>>>> in test/MC/COFF as a .ll file, although technically it's codegen...
>>>>
>>>> Also, I'm pretty sure this is wrong for MinGW. What do msvc and
>>>> mingw-gcc produce for c code that generates this?
>>>>
>>>> - Michael Spencer
>>> For this c code(see attachments) cl, mingw and clang produce different
>>> coff's(was used dumpbin with option /ALL):
>>> 1) Cl generate separate COMDAT section with linkage selection "pick 
>>> any"
>>> 2) Mingw place this value to regular section and place special auxilary
>>> record to symbol table
>>> 3) Clang without patch just ignore weakness of this value and place 
>>> it to
>>> regular section.
>>>     But for weak values without explicit section specification it 
>>> use cl-like
>>> way. i.e. generate
>>>     separate COMDAT section with a little difference in naming 
>>> (unique suffix
>>> after $)
>>> 4) With this patch clang will generate correct COMDAT section for 
>>> values
>>> with explicit section specification.
>>>
>>> The problem is in backend. When we have explicit section specification
>>> linkage type is ignored.
>> Looks fine with a test in CodeGen.
>>
>> - Michael Spencer
> Was added test.
> Please review.
> Patch was made by Dmitry Puzirev.
Ping?