[llvm] r217325 - [MCJIT] Fix a bug RuntimeDyldImpl's read/writeBytesUnaligned methods.

[Lang Hames]

I'm not sure I'd add a function for that, though you could use an
"increment" variable to merge the loops if you like. I don't think it's
really worth it though.

The commit message could have been clearer, but this is certainly testable:
It's is an attempt to get the RuntimeDyld regression tests working on PPC.

- Lang.

On Sun, Sep 7, 2014 at 9:10 PM, David Blaikie <dblaikie at gmail.com> wrote:

>
>
> On Sat, Sep 6, 2014 at 7:05 PM, Lang Hames <lhames at gmail.com> wrote:
>
>> Author: lhames
>> Date: Sat Sep  6 21:05:26 2014
>> New Revision: 217325
>>
>> URL: http://llvm.org/viewvc/llvm-project?rev=217325&view=rev
>> Log:
>> [MCJIT] Fix a bug RuntimeDyldImpl's read/writeBytesUnaligned methods.
>>
>> The previous implementation was writing to the high-bytes of integers on
>> BE
>> targets (when run on LE hosts).
>>
>
> Not testable? (curious what limitations of your new test infrastructure
> (or curiosities of this issue) make it not applicable to testing this bug)
>
> & any nice way to factor the (admittedly minor) duplication in each of
> these codepaths? (could have a function that takes the increment (1 or -1),
> non-type template parameter if necessary, but it looks simple/inlinable?)
>
>
>>
>> http://llvm.org/PR20640
>>
>>
>> Modified:
>>     llvm/trunk/lib/ExecutionEngine/RuntimeDyld/RuntimeDyld.cpp
>>
>> Modified: llvm/trunk/lib/ExecutionEngine/RuntimeDyld/RuntimeDyld.cpp
>> URL:
>> http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/ExecutionEngine/RuntimeDyld/RuntimeDyld.cpp?rev=217325&r1=217324&r2=217325&view=diff
>>
>> ==============================================================================
>> --- llvm/trunk/lib/ExecutionEngine/RuntimeDyld/RuntimeDyld.cpp (original)
>> +++ llvm/trunk/lib/ExecutionEngine/RuntimeDyld/RuntimeDyld.cpp Sat Sep  6
>> 21:05:26 2014
>> @@ -398,32 +398,30 @@ unsigned RuntimeDyldImpl::computeSection
>>  uint64_t RuntimeDyldImpl::readBytesUnaligned(uint8_t *Src,
>>                                               unsigned Size) const {
>>    uint64_t Result = 0;
>> -  uint8_t *Dst = reinterpret_cast<uint8_t*>(&Result);
>> -
>> -  if (IsTargetLittleEndian == sys::IsLittleEndianHost) {
>> -    if (!sys::IsLittleEndianHost)
>> -      Dst += sizeof(Result) - Size;
>> -    memcpy(Dst, Src, Size);
>> -  } else {
>> -    Dst += Size - 1;
>> -    for (unsigned i = 0; i < Size; ++i)
>> -      *Dst-- = *Src++;
>> -  }
>> +  if (IsTargetLittleEndian) {
>> +    Src += Size - 1;
>> +    while (Size--)
>> +      Result = (Result << 8) | *Src--;
>
> +  } else
>> +    while (Size--)
>> +      Result = (Result << 8) | *Src++;
>
>
>>    return Result;
>>  }
>>
>>  void RuntimeDyldImpl::writeBytesUnaligned(uint64_t Value, uint8_t *Dst,
>>                                            unsigned Size) const {
>> -  uint8_t *Src = reinterpret_cast<uint8_t*>(&Value);
>> -  if (IsTargetLittleEndian == sys::IsLittleEndianHost) {
>> -    if (!sys::IsLittleEndianHost)
>> -      Src += sizeof(Value) - Size;
>> -    memcpy(Dst, Src, Size);
>> +  if (IsTargetLittleEndian) {
>> +    while (Size--) {
>> +      *Dst++ = Value & 0xFF;
>> +      Value >>= 8;
>> +    }
>>    } else {
>> -    Src += Size - 1;
>> -    for (unsigned i = 0; i < Size; ++i)
>> -      *Dst++ = *Src--;
>> +    Dst += Size - 1;
>> +    while (Size--) {
>> +      *Dst-- = Value & 0xFF;
>> +      Value >>= 8;
>> +    }
>>    }
>>  }
>>
>>
>>
>> _______________________________________________
>> llvm-commits mailing list
>> llvm-commits at cs.uiuc.edu
>> http://lists.cs.uiuc.edu/mailman/listinfo/llvm-commits
>>
>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.llvm.org/pipermail/llvm-commits/attachments/20140908/58a68fd1/attachment.html>