[lld] r244191 - COFF: ARM: Sort .pdata section correctly.

[Saleem Abdulrasool via llvm-commits]

On Wed, Aug 5, 2015 at 10:35 PM, Rui Ueyama <ruiu at google.com> wrote:

> We may want to define these structs in libSupport (although in the linker
> we are only interested in struct size and the first field value.) I'll take
> a look at that tomorrow.
>

The ARM structure is already defined in libSupport.  The linker might not
have need for all the fancy additional support, but if we have a dependency
on Support already, then we get these for free and it avoids divergence.


> On Wed, Aug 5, 2015 at 10:26 PM, Saleem Abdulrasool <compnerd at compnerd.org
> > wrote:
>
>>
>>
>> On Wed, Aug 5, 2015 at 8:45 PM, Rui Ueyama <ruiu at google.com> wrote:
>>
>>> Author: ruiu
>>> Date: Wed Aug  5 22:45:27 2015
>>> New Revision: 244191
>>>
>>> URL: http://llvm.org/viewvc/llvm-project?rev=244191&view=rev
>>> Log:
>>> COFF: ARM: Sort .pdata section correctly.
>>>
>>> On ARM, exception handler entries in .pdata section are 8 byte long.
>>>
>>> Modified:
>>>     lld/trunk/COFF/Writer.cpp
>>>
>>> Modified: lld/trunk/COFF/Writer.cpp
>>> URL:
>>> http://llvm.org/viewvc/llvm-project/lld/trunk/COFF/Writer.cpp?rev=244191&r1=244190&r2=244191&view=diff
>>>
>>> ==============================================================================
>>> --- lld/trunk/COFF/Writer.cpp (original)
>>> +++ lld/trunk/COFF/Writer.cpp Wed Aug  5 22:45:27 2015
>>> @@ -724,14 +724,25 @@ void Writer::writeSections() {
>>>
>>>  // Sort .pdata section contents according to PE/COFF spec 5.5.
>>>  void Writer::sortExceptionTable() {
>>> -  if (auto *Sec = findSection(".pdata")) {
>>> -    // We assume .pdata contains function table entries only.
>>> +  OutputSection *Sec = findSection(".pdata");
>>> +  if (!Sec)
>>> +    return;
>>> +  // We assume .pdata contains function table entries only.
>>> +  uint8_t *Begin = Buffer->getBufferStart() + Sec->getFileOff();
>>> +  uint8_t *End = Begin + Sec->getVirtualSize();
>>> +  if (Config->Machine == AMD64) {
>>>      struct Entry { ulittle32_t Begin, End, Unwind; };
>>> -    uint8_t *Buf = Buffer->getBufferStart() + Sec->getFileOff();
>>> -    std::sort(reinterpret_cast<Entry *>(Buf),
>>> -              reinterpret_cast<Entry *>(Buf + Sec->getVirtualSize()),
>>> +    std::sort((Entry *)Begin, (Entry *)End,
>>>                [](const Entry &A, const Entry &B) { return A.Begin <
>>> B.Begin; });
>>> +    return;
>>>    }
>>> +  if (Config->Machine == ARMNT) {
>>> +    struct Entry { ulittle32_t Begin, Unwind; };
>>>
>>
>> Do we really want to recreate the data structures for the pdata here?  Is
>> a dependency on LLVMSupport something you are trying to avoid?
>>
>>
>>> +    std::sort((Entry *)Begin, (Entry *)End,
>>> +              [](const Entry &A, const Entry &B) { return A.Begin <
>>> B.Begin; });
>>> +    return;
>>> +  }
>>> +  errs() << "warning: don't know how to handle .pdata.\n";
>>>  }
>>>
>>>  OutputSection *Writer::findSection(StringRef Name) {
>>>
>>>
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>>>
>>
>>
>>
>> --
>> Saleem Abdulrasool
>> compnerd (at) compnerd (dot) org
>>
>
>


-- 
Saleem Abdulrasool
compnerd (at) compnerd (dot) org
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