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

[Rui Ueyama via llvm-commits]

On Wed, Aug 5, 2015 at 10:40 PM, Saleem Abdulrasool <compnerd at compnerd.org>
wrote:

> 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.
>

I tried to use llvm::ARM::WinEH::RuntimeFunction defined in
Support/ARMWinEH.h. Because copy assignment operator is implicitly deleted
(because fields are defined as `const`), I couldn't use that for std::sort.
I don't think we should remove `const` from the fields, so I'd like to
leave this as is.


>
>> 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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